Tag Archive: project


By Philip Royle

It’s possible to make a racecar faster without adding power. How? Aerodynamics. Over time, SCCA’s General Competition Rules (GCR) changes. In the case of our project ITA Miata, one somewhat recent rule change meant that we could add a front airdam to the car. In a large (although still abridged) nutshell, is what the GCR’s 9.1.3.8.b says on the topic:

A front spoiler/air dam is permitted. It shall not protrude beyond the overall outline of the body when viewed from above perpendicular to the ground, or aft of the forward most part of the front fender opening. This body outline does not include bumpers or bumper mounts. The spoiler/air dam shall be mounted to the body, and may extend no higher than four (4) inches above the horizontal centerline of the front wheel hubs. It shall not cover the normal grille opening(s) at the front of the car. Openings are permitted for the purposes of ducting air to the brakes, cooler, and radiator. Dealer installed or limited production front/rear spoilers/air dams/wings are prohibited. The spoiler shall have no support or reinforcement extending aft of the forward most part of the front fender wheel opening.

NOTE: Integrated bumper assemblies are defined as those designs where an external non-metallic bumper cover completely encloses the primary energy-absorbing bumper and where this cover could be installed in its normal position with the underlying bumper removed. On cars with integrated bumpers, the front spoiler or airdam may be attached to the bumper cover.

Where an air dam/spoiler is used, two total openings may be cut in the front valance to allow the passage of up to a three (3) inch diameter duct leading to each front brake/rotor assembly.

9.1.3.8.c also plays a role in the airdam design:

No part of the car, except for the exhaust system and suspension components, shall be lower than the lowest part of the wheel rims.

Conclusion? We can use almost any airdam that cannot be seen when viewed from above the car, and as long as it doesn’t extend below the bottom of the wheel rim, we’re golden. However, since our ITA Miata has no brake issues, we’d prefer to go with a more aerodynamic airdam than one with brake ducting.

Why do we need an airdam? The less air that goes under the car, the faster the car will go. How much faster? It really doesn’t matter – any amount of “faster” is what we’re looking for, and airdams are a fairly tried and true solution to cutting through the air more efficiently.

Our search for an aggressive airdam led us down two roads. One road required us to fabricate an airdam to mimic the airdams that are currently being run on F and E Production Miatas, and the other road had us shopping for a more turnkey solution. We started researching the Production-class airdams, but one issue we were coming across was front tire clearance. Production allows for a wide body, where Improved Touring doesn’t. The end result is the Production-style airdams on an IT car wouldn’t allow the car’s tires to turn without hitting the airdam. The airdam could be adapted to work, and maybe one day we’ll give it a shot.

The second road involved searching for something that was already on the market. We soon came across the G-Style front lip from Tougerun. This lip is made from durable and flexible polyurethane, and looks like the factory Miata front lip, but on steroids. It also has two openings in the front for brake ducting, should you need it – we don’t. The G-Style lip cost $199 and comes with all the hardware you need. However, the hardware it came with was mostly self-tapping screws, so we purchased 3/4-inch bolts so we could remove the lip should the need arise.

With the unit installed, we broke out some 0.060-inch black plastic, trimmed it to fit the brake ducts, and bolted it into place, using silicone to seal any openings. We also cut a large piece of the plastic to fit under the car and used aluminum to sturdy the tail end of the under tray. It’s important to note that, per the GCR, the airdam can’t extend beyond the front of the fender opening, and the airdam can only connect to the bumper, so when you’re fabricating the under tray, be sure you stay true to the rules.

What’s behind us doesn’t matter

With the airdam attached, we tackled the next issue: making the car narrow. 9.1.3.9.c in the GCR says: Any interior or exterior mirrors may be used. To us, this means no exterior mirrors are needed. Consequently, we ordered up a set of Longacre clamp on spot mirrors from SafeRacer. These mirrors are designed to clamp onto the cage inside the car and offer a convex view of the world, allowing you to remove the side mirrors, smoothing the airflow around the car.

Unfortunately, the clamp on design of the Longacre mirrors didn’t work in our Miata. To solve the problem, we adapted the stock side mirror mounts to hold the Longacre mirrors by drilling holes on the inside of the doors and stripping the Longacre mirrors of their roll cage clamps. We then used the same black plastic to manufacturer covers for the holes that removing the exterior mirrors left.

Did any of these mods make the car faster? We’ll find out in June 2010 when we take the car to Auto Club Speedway and run it in an SCCA Double Regional with SCCA’s Cal Club Region. But for now, we know it made the car look meaner – more like a racecar.

SOURCES:
Longacre, www.longacreracing.com
SafeRacer, www.saferacer.com
Tougerun, www.trougerun.com

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(This article first appeared in the July 2009 issue of SportsCar magazine)

By Jason Isley

No one ever said racing was cheap, but it certainly can be affordable. Typically, the least expensive entry into the realm of Club Racing is learning from someone else’s mistakes. On any given month, the classified ads in SportsCar show pages of used racecars for sale – cars that can often be had for a fraction of what they cost to build. Not only do you stand to save money by buying a used racecar, but you will also cut down on the amount of time spent with a wrench in your hand.

Like any used car, a used racecar can come with its own set of challenges and issues, particularly if the car does not have a clear history. If you are looking at a used racecar and its logbook has vanished, you might want to be cautious; that logbook could be missing because there was something the owner did not want you to see.

But perhaps you can’t find the pre-owned racecar you want, or what you have seen does not meet your expectations. This leaves a number of options. Salvage auctions are popular places to find cars – often what an insurance company writes off as a totaled car is a great start for a racecar. Theft recoveries can be a great starting point, as thieves often go after valuable airbags, seats and stereos – items that are not needed in a racecar.

We chose a different route. Like many of you, we have an older, but still useful car sitting in our driveway. Our 2004 Nissan Sentra SE-R Spec V has served us well as a trusty daily driver, occasional autocrosser and we have even picked up a National RallyCross event win with the car. It was time for it to start its next phase of life as a Showroom Stock C Club Racing car.

There are a number of advantages in using a car you already own – most notably, you know the car’s history and you probably already know how to work on it.

The problem for us was, we had next to no money available – but did we let that stop us? No we did not. Over the course of a few weeks, a plan was made and parts were ordered, and before we knew it, we were racing on a dime.

Getting started

The premise of the Showroom Stock category is it’s a place for members to race street stock, legal automobiles. Essentially, with a few exceptions, you are racing a car as it was delivered from the factory, so it can still be driven on the street. A few wear items will need to be replaced, like tires and brake pads, but for the most part the modifications to the cars are safety related. Passive restraints like the airbags must be disarmed and may be removed. Aside from that, you are mostly installing the required safety gear – this is an ideal class to build for when you already own the car.

To keep the motor running cool, the factory air conditioning system can be removed. For some cars, this is not as easy as it sounds. Many cars that are Showroom Stock legal come standard with a/c, and no provisions were ever made to route the accessory drive belts without an a/c compressor – this generally means custom fabrication.

For our SSC Sentra, the Nissan Motorsports support program offered pieces from another car in the Nissan family that did not have standard a/c, making for a simple and clean removal. Once removed from the car, selling or trading some of the items like the a/c and audio equipment that you are allowed to remove is also a great way to reduce costs on your build.

Another open area is fluids. Using the “ounce of prevention is worth a pound of cure” method, we went to the top of the line. Royal Purple has a complete line of fluids to lubricate every moving part on your car, and its great reputation has been earned on the track. We treated the engine, transaxle and power steering with the appropriate Royal Purple lubes, and after flushing the coolant from our radiator, we poured in some Purple Ice.

To keep the bad stuff out of the engine, we replaced the original paper air filter with a reusable one from K&N engineering. While we were at it, we installed a K&N oil filter to trap any impurities. The handy nut that is integrated into the oil filter also makes changing the filter a snap.

One final step under the hood was to find an acceptable home for our AMB transponder. Most tracks do offer AMB transponders for rent and, in our area, it is about $60 a weekend. Rather than renting, however, we opted to get our own, as this is the kind of item that pays for itself in the long run. Also, owning your own transponder allows you to take advantage of MyLaps.com, where you can pull up race results and personal lap times – something that’s an incredible reference, allowing you to compare your lap times to those of your competitors.

We found a great transponder mounting point off the radiator core support. This position was the optimum height, which Bill Skibby of AMB tells us is around 18 inches. It was also near the front of the car but still behind the main bumper structure, so the transponder remains protected.

The roll cage

If you are building one of the more popular cars, a roll cage can is easy to find – this was not the case with our Sentra. As it turns out, relatively few B15 Sentras have been prepared for Club Racing. Fortunately for us, it seems that no matter how obscure the car, Kirk Racing Products has a roll cage for it. In the case of the Sentra, Kirk offers both a bolt-in and a you-weld kit – the company will even build you a custom cage if you can get your car to Kirk’s shop.

For the ultimate in safety and driver comfort, it is hard to beat a custom cage. Tricks like running the front down tubes through the dash can give the driver a little extra space and help spread the load over the chassis, helping with both safety and stiffening the car. A set of NASCAR-style door bars can help your ingress and egress, as well as offer added protection in a side impact. However, these custom features are optional per the General Competition Rules, and they also come at a price – when you’re building on a budget, you never want to skimp on safety, but sometimes you must give up a little when it comes to convenience.

As a side note, we would never suggest anyone sidestep safety, but luckily the GCR has safety standards in place to prevent you from cutting corners. These standards should always be adhered to or exceeded.

Since our project was very budget sensitive, we elected to forego a custom-built cage in lieu of one of the bolt in variety. We ordered a bolt-in cage from Kirk Racing Products. This cage would get us on track for the least amount of cost while still meeting the GCR’s requirements.

The basic cage kit cost $725, but there was an extra $45 fee for the second pair of SCCA mandated door bars. At the same time, we ordered the optional dash bar for $35. The weld-in kit is actually $50 less, at $675, but the big cost difference comes in labor and installation time – expect to spend twice as much time installing a weld-in, or paying a welder to do it for you.

Since the bolt-in kit shares the same structure and design as the weld-in kit, the fit and level of protection are similar. According to Mark Stewart of Kirk Racing Products, there is not a measurable difference in safety between his two kits. “The weld-in kit has the advantage of helping stiffen up the chassis,” says Stewart.

Certainly, stiffening up the chassis can help in handling and, to some extent, protection in an impact, but the bolt-in kit meets every requirement of the GCR so we knew it was still a safe choice.

With the roll cage kit in hand, we set about removing the seats and pulling up the carpet to prepare for the installation. Or goal was to complete the installation in one day, which Stewart says is about right for the kit we ordered.

The installation starts with placing the main hoop, front down tubes and rear braces in the car. The fit and finish of the Kirk cage was second to none. In particular, the main hoop fit could not have been better – it was snug against the roof and fit perfectly between the sunroof and dome light. Other than a little trimming on some of the interior plastic panels to pass the tubes to the car’s tub, the main cage installation was simple and quick.

One small thing Kirk does that really helps speed up installation and make your life easier is the company pre-drills all of the holes for the telescoping, bolt-together joints. Drilling a few holes may not sound like a big deal, but trying to drill the tube and sleeve with the cage up against the headliner could quickly turn into an act of frustration.

Not having to grind away paint and undercoating to weld the base plates is where you save a lot of time with the bolt-in installation. However, you’re not completely off the hook – the door bars and dash bar still have to be welded in place. The race seat, your door panels and the height at which you run the dash bar, all affect where they are attached, so it can’t be done ahead of time. The great thing is Kirk already has the proper contours cut into the tubes, and they have the GCR-approved slip joints installed, so once you weld them in place they will be removable.

Welding in the dash and door bars is a point where if you have any doubts about your ability, you should hire a professional. You may have to pay to get these bars welded in, but that is a fraction of what it would cost to have the entire cage welded for you. The GCR requires that all welds meet the Structural Welding Code set by the American Welding Society – if you don’t know what that means, you should definitely not attempt to weld the additional bars yourself.

We evaluated our options for installing the dash and door bars and decided to blow our budget in the hopes of saving money in the long run. Instead of paying someone to weld in the bars, which would have been a few hundred dollars, we decided to invest in a welding machine.

We decided to pick up an HTP America MIG 140. The MIG 140 can handle up to 1/4-inch thick material, and is small enough we can transport it for emergency repairs to our racecars. At $749, the MIG 140 was a great value, but this did nearly double the cost of our cage. However, having this on hand means we won’t have to pay for welding in the future, and the convenience of being able to fire it up at any time we need to, to make repairs or fabricate a small item is a big bonus.

It is vitally important to emphasize once more that if your welding skills are not up to par, you may be endangering yourself on the track in the event of any on-track contact. A roll cage is not an item you should learn to weld on.

The door bar installation is straight-forward, just make sure that you have your race seat mounted in its final location, so you can check for interference. Once the bars are tacked in place you can again remove the seats to make the final welding easier. Our MIG 140 made quick work of our four door bars. However, with the clock ticking, we skipped the GCR-optional dash bar for our Sentra’s maiden outing – we will install this at a later date.

Scavenging parts

With our funds running low, it was time to save some money. One great way to do that is with used equipment. This was easy for us as we were able to tap into our pile of inventory from previous projects. I don’t want to say we are packrats, but some stuff is too cool to get rid of. So, a couple of zero-dollar items helped get us back on track.

Left over from our Project MX-5 car (SportsCar, July 2006) we had a nice Sparco fire extinguisher and a Racetech RT 4009 HR seat, which had also spent time in the Sentra during its brush with RallyCross (SportsCar, July 2008). We also had the Impact Racing harness and quick-release steering wheel from our RallyCross efforts.

If you don’t have your own pile of leftovers, scouring Internet forums can reveal a lot of really good buys on used equipment. For example, a quick search on a Nissan Sentra forum revealed stock Sentra wheels for $50 each – so we bought a pair.

Keep in mind that many items have a limited number of years they can be used, and if you have any doubts about an item’s history, you should pass on it. You would not want to install a used race seat that had been involved in a crash – its structure may be compromised and you could pay a bigger price down the road.

Tip: Save on shipping

Moving on, we had a number of items left on our safety checklist. Our friends at I/O Port Racing Supplies make it easy to spend money – almost too easy. Having a huge selection makes it possible to find everything you need, or just want. We also found you can save on shipping by purchasing a lot of items from one place.

We picked up an I/O Port driver’s side window net and mounting hardware. The net is a combination of mesh and webbing, giving a good mixture of strength and visibility. The spring-loaded top rod makes using the net a breeze, and its low profile design means you won’t impale your head on the mount when climbing in and out.

Even though it’s not required, we also picked up a Safety Solutions C5R right side net. Our project ITA Miata has one of these, and we really love how it firms up the seat and adds protection in a side impact.

The last item needed inside the car was adding roll bar padding to areas where the driver could come in contact with the cage. Once again, I/O Port was our one-stop shop, as the company has a variety of approved padding in varying thicknesses. We used the thicker BSCI SFI 45.1-approved padding in areas where we had plenty of room, and the thinner Longacre padding where the confines were tight.

We also ordered a pair of I/O Port tow straps so we can be towed back to the pits. These soft tow straps are super easy to install, as they can be routed around obstructions and through small openings – but most importantly, you will never whack your legs on them as you work on your car in the pits.

Going fast and slow

The Sentra’s original brake rotors looked a little too weathered, and as our car had the smaller standard brakes, we decided to play it safe and order new parts from the Tire Rack. A set of Brembo blank rotors replaced our old ones, and a set of Goodridge G-Stop lines replaced the factory rubber hoses. The final step was a set of Hawk Blues in the front and HP+ pads in the rear – this setup would allow us confidence while pushing it into the braking zone.

A rather porky car by SSC standards, our Sentra has to weigh 3,100lbs in full race trim, so we knew we needed a durable tire – but it still needed to be fast. Inspired by Lee Niffenegger’s SSB National Championship title at last year’s Runoffs, we decided to outfit our Sentra with the same BFGoodrich G-Force R1 tires he used. The R1s are already a proven winner and have a reputation for being very durable – something we will put to the test.

Once we were outfitted with new rolling stock and brakes, we pulled the Sentra on to our Longacre scales. While our car is not equipped with any ability to adjust corner weights, we were able to affix our ballast within the limits of the rules to help spread things out – more importantly, we knew heading to our first race that we would not be under weight.

The Longacre scales also provide a nice platform for checking our alignment. Using our Smart Strings and Smart Camber gauge, checking the alignment was an easy task, and they are small enough we can bring them to the track for fine-tuning. Over time, these items (which we obtained for past projects) have really paid for themselves by avoiding costly trips to the alignment shop. It is with this same reasoning we obtained the aforementioned welder.

Success!

In March, we took our newly completed Sentra (actually, we were still working on it when we got to the track) to Buttonwillow Raceway Park in Southern California for a Double Regional race weekend.

Our weekend was a success on many levels. First, the car passed tech and now has a logbook – this means all of our hard work paid off. The cage install was completed properly and our seat and belts were all up to par. The only feedback the scrutineers gave us, was regarding the cleanliness under the hood – but come on, it was a RallyCross car.

On the track, the Sentra ran great, aside from some excessive (almost frightening) body roll, the car ran strong and consistent. The biggest concern we had going into the weekend was tire wear. Having to finish the race at 3,100lbs, and essentially having no negative camber up front, we spent the weekend watching the front tires very closely. We were very pleased to find the tires were extremely consistent during the race and, after two days of hard racing, the original set of BFGoodrich tires were still going strong – in fact, they even looked great after running a Tire Rack ProSolo event on them in the same car the very next weekend.

On the racetrack, we were rewarded with a pair of SSC wins, and we managed to finish just outside the top five in a mixed field of faster Touring and Improved Touring racecars (one of which was our project ITA Miata).

Overall, we were very satisfied with our budget Club racer. Tallying up our costs, we discovered that $3,000 was all that was required to get us on track in a competitive car that is eligible for both Regional and National Club Racing. Obviously already owning the car was key for such a small outlay of money, and already owning a seat and harnesses really helped, too. Had we needed to purchase the car, we found comparable model to ours for $7,000 for a car with a clean title – still a reasonable amount of money to get on track.

Equipping the driver

Before you can get on the track at a Club race, you will need to obtain an SCCA competition license. One way to obtain your license is by attending an SCCA accredited Drivers Schools, which is exactly what SportsCar’s Associate Editor Jason Isley did in order to obtain his competition license before taking the Sentra to the track.

Just a short drive from Los Angeles, Calif., located at Willow Springs International Raceway is Danny McKeever and his Fast Lane Racing School. As the official driving school of the Cal Club Region, it is a great choice for anyone looking to make the jump into Club Racing. Previous to opening the Fast Lane school, McKeever spent 12 years as the chief driving instructor for Cal Club, a position currently held by Jim Bishop, who is an active Club racer and a Fast Lane instructor – these guys know what qualities the Club is looking for because they are part of it.

The Fast Lane SCCA course consists of three days, with most of that time being spent on track. While the on-track fundamentals (as well as a test) are given in the classroom, this represents only about an hour of each day – the rest is spent on the track.

One very nice feature about the Fast Lane school is that they will let you bring your own car – this can be a great way to get some extra seat time in your new racecar. However, using the Toyota Celica GT-S school cars really allows you to focus on the task at hand, and the Improved Touring-like prep of the Celicas makes them a very lively ride.

At Fast Lane, the class size is kept small to maximize the instructor-to-student ratio; this also means more track time for everyone. Rather than working from preset criteria in the car, the instructors work on what the individual students need – if you need work on the basics, that’s what they do. The instructor’s goal is to take each person to their next level.

The Fast Lane school, or any of SCCA’s other approved Drivers Schools, is a great choice for anyone looking to complete their SCCA school requirements, or just looking for some great driver coaching.

To find an accredited Drivers School in your area like Fast Lane, go to http://www.scca.com, click the “Club Racing” tab at the top and select “Accredited Schools” in the left hand bar.

Personal safety on a budget

Preparing the car is only part of the equation – a driver’s personal safety is a completely separate, but equally important matter. Just like anything in motorsports, often the only limitation is your budget. However, not having a lot of money to spend does not mean you won’t be protected. The basic rules apply: shop smart and you can save big.

When shopping for helmets, we looked at number of options. With cost being a concern we decided to stick with a fiberglass helmet, versus the more costly composite units. The HJC AR-10 was only slightly heavier than the Si-12 composite version, and meets the same SA2005 requirement – but gets it done for $400 less.

When selecting a driving suit, the SFI and FIA rating systems are very useful, as the GCR spells out a minimum requirement for your safety. Looking to Vesta Motorsports, we found a good range of suits, all at great prices. From Vesta’s Safe-Quip line we selected the 120 Series multi-layer suit. Constructed of Pyrovatex FRC and Nomex, it offers great protection and comfort at a very reasonable $279.99. A pair of Safe-Quip 351 gloves, and RaceQuip Euro shoes finished off the package for less than $150. Don’t forget the Nomex socks – we found a pair from Sparco for around $20 on the Internet.

For this race weekend, we also chose to test a head and neck restraint. A head and neck restraint is currently not required equipment for Club Racing, so using one is strictly a personal choice.

The unit we tested was the Hybrid Pro by Safety Solutions. The Hybrid Pro simply disappears once it is strapped to your body – it almost becomes part of your drivers suit, and we found it did not hamper entry or exit from the Sentra in the least. It is also one of the few devices that will work at any layback angle, so no matter what type of car you have (be it production based or open wheel) you will be able to use this device.

The unit we tested was the full carbon fiber unit, and it was a little pricy at $995, but Safety Solutions recently released a composite version of the Hybrid Pro at a very reasonable $649, and we expect that unit to be just as easy to use.

Data Acquisition

Once you leave your Drivers School it is up to you to find the fastest way around a racetrack. You can spend lots of time testing, hire a driving coach and run infinite laps to learn the quick way around the track, or you can use a virtual driver coach.

At our Double Regional race weekend, we were fortunate enough to meet up with the team from RLC Racing, and they were nice enough to install the Track Commander in our Sentra for the weekend.

In the past, we have had experience with various data systems and lap timers, but this one had a feature we’d never used before – predictive lap timing. Rather than coming in at the end of a session and downloading data in the attempt to lower your lap times, the predictive lap timing feature breaks the track up into segments on the fly – as you race around the track, you are instantly updated as to your segment time, and the display tells you if you are going faster or slower than your previous fastest lap. If you try a new line through one corner, you’ll get instant feedback telling you whether or not it worked.

RLC’s 3.5-inch display is easy to read, even in direct sunlight, and the full color display alleviates confusion – there it is just taunting you, if you see green you know you went slower. Seemingly, with every mistake, the display lights up and lets you know you just slowed down. It is a relentless, full-time driving coach that tells it like it is – but used properly, the pay off is quicker lap times during the same track session.

Aside from this very useful feature, the Track Commander also has GPS mapping, lap timing, PC playback analysis and can be synchronized with video. The data is collected via a 3-axis g-force sensor and GPS at speeds of up to 20Hz. The information is stored internally, and can be transferred to your PC using a USB cable or Flash Stick.

Sources:
AMB i.t., http://www.amb-it.com
BFGoodrich Tires, http://www.bfgoodrichtires.com
Fast Lane Racing School, http://www.raceschool.com
Hawk Performance, http://www.hawkperformance.com
Kirk Racing Products, http://www.kirkracing.com
HJC Helmets, http://www.hjchelmets.com
HTP America Inc., http://www.htpweld.com
I/O Port Racing Supplies, http://www.ioportracing.com
Impact Racing, http://www.impactraceproducts.com
K&N, http://www.knfilters.com
Longacre, http://www.longacreracing.com
Nissan Motorsports, http://www.nissanusa.com
Race Ramps, http://www.raceramps.com
Racetech, http://www.racetechseatsna.com
RLC, http://www.rlcracing.com
Royal Purple, http://www.royalpurple.com
Safety Solutions, http://www.safetysolutionsracing.com
Smart Products, http://www.smartracingproducts.com
Sparco, http://www.sparcousa.com
Tire Rack, http://www.tirerack.com
Vesta Motorsports, http://www.vestamotorsports.com

(This article was originally published in the May 2009 issue of SportsCar magazine)

By Philip Royle

It wasn’t long ago that Club Racing’s Improved Touring class severely limited ECU modifications. “The engine management computer or ECU may be altered provided that all modifications are done within the original housing,” read 9.1.3.D.1.s. With the 2008 GCR, however, that section was swapped in favor of a far more modern, tuner-friendly rule: 9.1.3.D.1.a.6, “The engine management computer may be altered or replaced. A throttle position sensor and its wiring may be added or replaced. A MAP sensor and its wiring may be added. Other existing sensors, excluding the stock air metering device, may be substituted for equivalent units.” And, with that, new power possibilities surfaced in Improved Touring.

Up until the rule change, if Improved Touring racers wanted more power from their factory ECU, they were forced to either cram entirely new electronics into their factory box or find a solution that involved re-tuning the stock system. Both were possible, but the first was tricky and the latter didn’t always offer the tuning level desired by most racers.

The allowance of aftermarket engine management systems opened a world of potential power for many in the Improved Touring community, and we figured it was time to take a closer look to see if it was a modification Improved Touring racers should consider.

It’s important to note that ECU tuning and replacement isn’t Improved Touring specific – in fact, a variety of Club Racing, Solo and RallyCross classes allow ECU modifications and replacements. Each class has its own specific requirements, so you should check the rules for your class to find the engine management system that’s right for you.

A compromised past

People have been tuning racecars without the use of standalone engine management systems or reprogrammed ECUs for years. However, doing so has often been a case of drastic compromise.

“Playing with the air/fuel meter you’re just trying to trick the stock meter,” says Jerry Hoffmann, owner of DIYAutoTune.com. You’re never going to get that perfectly flat air/fuel curve all across the wide-open throttle range – and you’re never going to keep it at the optimal level at part throttle. The cars I’ve seen come to our shop [without a standalone system or correctly tuned ECU] have come in with their air/fuel ratio so messed with that the cars run well at speed but they idle horrendously.”

When the Improved Touring rules allowed only in-the-box ECU modifications, racers were able to get power from some cars by reprogramming the stock computer, but similar to the mechanical tricks, the results were often compromised.

“In a lot of cases, you don’t really have access to the factory ECU,” explains Shawn Church, owner of Church Automotive Testing in Wilmington, Calif., a company that has tuned many championship-winning SCCA racecars in both Solo and Club Racing. “For example, most Mazda ECUs haven’t been opened up. For those kinds of cars, your best choice is to go to a standalone system. In general, this is true for OBD II Hondas and most Toyotas, whereas for a Subaru or Evo, we have almost complete access to the factory ECUs. It really depends on what manufacturer and what ECU you have.”

Virtually eliminating the compromises are aftermarket engine management systems. “[Standalone systems] are the final 3- to 5-percent you’re looking for,” says Church, noting that before you make this modification, everything else needs to be optimized on the car. “You need to have the right intake, exhaust, the right cams if that’s allowed, before those gains really start to make a difference for you.”

What to look for

“The first thing drivers need to ask themselves is do they have someone to tune [the standalone ECU] or can they tune it themselves,” says Church. “Usually, the standalone ECU manufacturers will have a list of approved tuners. The second thing you want to find out is whether it’s a plug and play type of system. For most people they won’t want to have to do anything more than plug the new box into the factory harness – if you have to do extra wiring or add sensors, that makes the [installation] process a lot more difficult. And the third thing is you want to ask is if the system offers the sorts of features that you think you need for your setup.”

Church tells us that for most racing applications, people only need control over fuel, timing, cam timing, idle, rev limiters and knock sensors. “Some people may want data logging, traction control and boost control, but most standalone systems will feature what the majority of people are looking for,” he explains.

Electromotive and MoTeC are two high-end, feature-jammed engine management systems you’re undoubtedly familiar with. When it comes to choosing an aftermarket ECU, however, you’ll want to double-check the rules for your class. Improved Touring allows the replacement, but not the addition, of sensors. Electromotive, for one, relies upon an ultra-accurate crank trigger sensor for its timing needs. However, if your Improved Touring racecar comes equipped with a slew of factory sensors or you’re running a Club Racing or Solo class with liberal engine management rules, these high-end engine management systems and their additional features may be the ticket to your success.

While DIYAutoTune.com is a MegaSquirt retailer, Hoffmann is quick to point out that not all cars require an aftermarket ECU solution. “With a true ECU hack, like a Hondata hack, you have almost as much flexibility with the factory ECU as you do with a standalone,” says Hoffmann. “With some of the better ECU hacks, you’ve got almost the same level of flexibility with the fuel and spark tables as you do with an aftermarket standalone.

“Basically, with a mapable solution, whether it be a remap of your stock computer or a complete standalone system, if you can re-tune at all different load and rpm positions you’re going to be able to get the proper air/fuel ratio and, more important for power, the proper ignition timing at all partial and full throttle events,” says Hoffmann.

“Theoretically, the factory ECU can control everything an aftermarket ECU can,” Church says, “but in most cases you don’t have access to those features. For example, on the AEM [Programmable Engine Management System], injector phasing is something you can control, where that is pretty much fixed on any of the factory re-tunes you can do – and that can sometimes pick up four to seven more horsepower on a high-power car.”

There are a variety of engine management systems on the market – and depending on the car you’re racing, a re-tuned factory ECU may be all you need. An Internet search will turn up an array of options for your particular application – compile a list of the options you think you’ll need, and once you have your choices nailed down, call the manufacturer or distributor and ask questions. You may find the most basic of solutions is all you need, or it could be your racecar could benefit from a more complex system boasting more options than you can imagine. Once you’ve taken the plunge, though, all that’s left is to head to the track and enjoy your newfound power.

Dyno tuning 101

While most of us will never tune an engine management system on the dyno ourselves, the process is fascinating to learn about.

“The first thing we do is start with a very safe baseline,” says Shawn Church of Church Automotive Testing. “We always want to be adding more fuel and less timing than we think we’re going to need. For systems like the MegaSquit PNP and AEM [Programmable Engine Management System], those systems already come with pretty good baseline maps, and they get you going in a safe manner.”

Church then tunes the part throttle maps, making sure the engine is operating with a reasonable air/fuel ratio.

“Once we get the part throttle fuel right, we then do our full throttle fuel, and that’s when we start accelerating the car through the full rpm range,” Church continues. “Once we get the fuel dialed in, we look at the ignition timing. Typically, we want to run the least amount of ignition timing necessary to get the maximum amount of power, because this gives more breathing room with an inferior quality fuel or on a really hot day. If the engine picks up significant power with the addition of timing, then we’ll add more timing to see what the engine does.

“Where we add timing is also determined by the torque curve – where the torque curve is at its peak, you usually want the least amount of ignition timing. If we have a dip in the torque curve, then we’re going to want to put in some more timing. Typically, as the torque curve drops off, we add more timing.”

The result is a smooth torque and horsepower curve – as was the case with our project Miata.

Putting the claims to the test

Having a 1996 Mazda Miata Improved Touring A project car at the magazine, the idea of tuning the ECU for the modifications seemed ideal. Like many weekend warriors, the ECU on our project car was completely stock – the power output was respectable, but no matter how hard we tried, we always found ourselves losing ground both on race starts and corner exits.

We opted to install a MegaSquirt PNP from DIYAutoTune.com, with Shawn Church from Church Automotive Testing tuning the car. The MegaSquirt PNP installed in minutes, and (with minor bracket modifications) even bolted to the factory ECU location.

Once the Miata was on the Dynapack dyno, we ran baseline numbers using the stock ECU. The horsepower peaked at 131 at 6,800rpm with 118.5lb-ft of unconfident torque at 5,200rpm. From there, the stock unit was swapped for the MegaSquirt PNP and Church began the tuning.

Within 30 minutes, the Miata motor’s power had grown significantly. The peak power had increased by some 9hp and the torque had an additional peak 7lb-ft. However, from 2,500 to 4,000rpm the torque curve had increased by more than 10lb-ft, and the power was far more linear and predictable.

It’s important to note that our Miata went from a completely stock ECU with no air/fuel trickery or mechanical timing advance to a tuned standalone engine management system. So, while our experience saw roughly a 7-percent peak horsepower improvement, your gains will vary.

Numbers are only numbers, so a week later we put the newfound power to the test by running a Double Regional weekend with Cal Club Region at Buttonwillow Raceway Park. Since we’d never run this particular track configuration we had no existing data on which to base our improvements, but we did have the rest of the field as a marker. Suddenly, the car stood a chance on race starts, and the car no longer experienced quirky power characteristics exiting turns.

The MegaSquirt PNP for our particular Miata retails for $725, and DIYAutoTune.com says it’s working on plug and play applications for other types of vehicles. We did consider several other systems before deciding on the MegaSquirt PNP, but the things that attracted us to the product were the ease of tuning, the simple installation and the relatively minimal cost – considering the power we obtained, we couldn’t be happier with the results.

What Project Miata has been up to

The last installment of Project Miata came in the August 2008 issue. In that issue, we added a Racing Beat header and exhaust, removed the catalytic converter and installed a Torsen differential with 4.30 gears.

We knew we were eventually going to capitalize on the ECU rule change for Improved Touring, so we have recently been bolting on as many power adders as possible before attaching the MegaSquirt PNP.

First on the table was a Fuji Racing under-drive pulley. The lightweight, small diameter pulley bolts in place of the factory crank pulley. For our car, we ordered the appropriate non-a/c, non-power steering $109 pulley. Installation was a matter of loosening the alternator, unbolting the stock pulley and installing the FujiRacing unit using the factory bolts. We also replaced the pulley belt with one that was one size smaller than stock.

Next, we ordered an Improved Touring intake from ISC Racing Services. We are currently running 1.5-inch front ISC shock mounting plates and 1-inch rear plates and have had good luck with everything ordered from this company. The intake costs about $250, comes with a high-flow Green Filter cone and leaves the MAF in the factory location, making this a legal IT modification.

Since heat is the enemy of all racecars, we called Design Engineering (DEI) and ordered a 12×24-inch sheet of DEI’s Reflect-A-GOLD for $34. This sheet is a polymer laminated glass cloth that is capable of operating in temperatures of up to 850 degrees F and should help keep our intake temperatures relatively low.

While we were ordering heat barriers, we also ordered DEI’s Floor and Tunnel Shield. One of the problems we’ve found with our Miata is, the driver’s right foot gets toasty while resting against the transmission tunnel. DEI’s shielding is just 0.19-inch thick and is capable of handling temperatures up to 1,750 degrees F. It also acts as a sound barrier. With this shielding, the driver’s right foot felt normal all race long – mission accomplished.

We also ordered DEI’s Radiator Relief, which claims to reduce engine temperatures up to 30 degrees F. Installation of this product was as simple as adding it to our radiator after we flushed the system in preparation for the race.

SOURCES:
AEM, http://www.aempower.com
Church Automotive Testing, http://www.home.earthlink.net/~spchurch/churchautomotivetesting
Design Engineering Inc., http://www.designengineering.com
DIYAutoTune.com, http://www.diyautotune.com
Electromotive, http://www.electromotive-inc.com
FujiRacing, http://www.fuji-racing.com
ISC Racing Services, http://www.iscracing.net

(This article first appeared in the August 2008 issue of SportsCar magazine)

By Philip Royle

There are flaws with every racecar, and ours is certainly no exception. Thus far, our project Improved Touring A 1996 Mazda Miata has run like a champ, yielding a growing collection of second and third place trophies. The problem? The car isn’t fast. While we were legitimately beating other ITA competitors, our little project car was hardly hanging with the frontrunner. We were, in fact, getting our butt handed to us. Luckily, the car is far from finished.

To this point, we had yet to expand the motor’s power output, even in the most basic sense. There were also a handful of very non-desirable parts living underneath the car – namely an open differential and a tall rear end gear ratio. Beyond that, we’d also simply bolted items like the Koni race coilovers and Eibach springs on the car, neglecting to take advantage of the adjustability by corner weighting the vehicle.

Tying up loose ends

Our 1.8L Miata was the epitome of the “Whispering Death” (as some had lovingly dubbed Showroom Stock back in the day) – namely, our Miata was sporting a stock exhaust system. Beside the stock components bottling up potential power, they were also keeping the car way too quiet. Racing door-to-door with an RX-7 often left us wondering if RX-7 pilot was even aware of our presence.

Like with much of this buildup, our solution was probably not the obvious one. Racing Beat has long been known for producing quality Mazda products – and its header and exhaust system are no exception. Our order included the Racing Beat header ($425), Sport Connecting Pipe, which doesn’t include a silencer ($130), and Power Pulse Muffler ($276). While not an inexpensive option, this setup would guarantee we would always pass sound requirements at any SCCA venue, including some of the more restrictive Solo events we also compete in. A Mazdaspeed cat-delete pipe ($40) rounded out the exhaust system.

When we ordered the exhaust from Racing Beat, we also ordered the exhaust manifold gasket (the only gasket not included) and we supplemented some of the included bolts with our own.

This setup isn’t necessarily the lightest available. The Racing Beat components with the Mazdaspeed pipe weighed in at a hair over 44 pounds, roughly 6.5 pounds lighter than the stock setup. If you’re in the market for lighter equipment, there are a number of Spec Miata exhaust systems that could potentially knock another eight pounds off – but in our case, weight was not a concern. An Improved Touring A Miata has a minimum weight of 2380 pounds. Based on the track scales at our first race, we’d bolted 100 pounds of ballast onto the passenger floor. Consequently, a lightweight exhaust could take a backseat to ease of install and not killing our eardrums.

We also opted not to dyno the car. We did so for multiple reasons, the most obvious being that while this system is all but guaranteed to pick up power, it’s equally as guaranteed not to generate as much power as a deafening Spec Miata setup. We also have plans to capitalize on a 2008 General Competition Rules and Specifications Improved Touring rules changes regarding the ECU in a later project installment, at which point we’ll spend time tuning the car on a dyno.

The next glaring problem with our Miata was the open differential and tall gearing. While it’s debatable as to how much the open differential was actually slowing us down, a factory Torsen limited slip differential couldn’t hurt – and there’s little doubt the 4.10 rear end was not the best to be using. While installing a Torsen was a given, the question was what gearing should we choose.

Flatout Motorpsorts is a company with notable success racing Mazdas, including Miatas in both Spec Miata and ITA. A call to Flatout revealed that our realistic choices for final drive ratios involved the traditional 4.30 rear end or shorter 4.80 gears. However, after testing both setups, the Flatout crew settled on the 4.30 as ideal – not to mention the easiest to install since it’s a direct bolt-in for 1.8L Miatas. Consequently, we ordered and installed a complete differential from a 1999 Miata, which housed the 4.30 gearing and Torsen.

As a side note, we’ve been running different tire sizes to find out if the 205/50-15 tires on most Miata racecars is truly the best size. In addition to the 205mm size, we’ve also been competing on 225/50-15 Kumho Ecsta V710s. With the tall 4.10 gearing, our data showed that coming off several turns the Miata simply did not have the power to rotate the larger diameter tires. Hopefully the gearing change will allow more flexibility when it comes to running varying tire sizes.

We also discovered the wide 225mm tires, while offering more lateral grip than the 205mm tires, rubbed on the fender lip. To solve this problem, we ordered a fender lip rolling tool from The Tire Rack. This tool isn’t inexpensive ($259), but if you’re going to roll fenders on multiple cars, this tool will quickly pay for itself. The process was quick and, best of all, successful.

Professional help

With the car in – what we considered – good shape, we thought it time to get a professional opinion before fine-tuning the setup. Consequently, we headed to Tri-Point Engineering and ProParts USA.

Tri-Point Engineering is no stranger to the SCCA. The company not only campaigns the reigning SPEED World Challenge Touring Car Mazda6 racecars, but it has also setup a variety of Club Racing cars. Along with selling performance parts, the company also offers racecar setup as a service at its Canoga Park, Calif., headquarters.

The Tri-Point team checked the car’s alignment and cross weights and inspected the suspension setup. With a half tank of gas and the cold tires filled to 32psi, the Miata had a cross weight of 47.5 percent. While the cross weight wasn’t horrible the camber and toe were way off. We had set the camber to -2.5 degrees front and rear and set zero toe over a year ago. Now, the car now sported -2.3 degrees of camber in the front, -2.2 degrees in the left rear and -1.7 degrees in the right rear. There was also slight toe-out in the front and toe-in in the rear.

Tri-Point made a number of recommendations about the setup, including adding forward rake to increase aerodynamics, balancing the car on the scales closer to 50 percent, setting the camber to larger negative numbers and correcting the wonky toe. Tri-Point also noted that, in order to take the car’s handling to the next level, we should remove any binding in the suspension. A key component for this would be to allow the dampers to freely pivot at the upper mounting points.

Setting up the car

Beyond Tri-Point’s notes, there was also the issue of the rear suspension travel – or lack thereof. The Koni race shocks we are using are shorter than stock. With the ride height set to just over 5 inches to the lowest point on the rocker panel, the rear shocks were sitting on the bump stops. While raising the ride height and drastically cutting the bump stops would solve the problem, that particular solution would not offer the amount of shock travel we’d like.

A common solution for first generation Miatas is to install damper hats from a 1999-’05 Miata. These factory hats can be purchased through Mazda Motorsports and reportedly offer between 0.5 and 0.75 inches of additional travel for about $25 a corner.

With the back of the our Miata resting on the bump stops, we decided to go a little more extreme, so we ordered four upper shock mounts from ISC Racing Services. ISC is very experienced in the world of ITA Miatas, having built several winning ones – the company has also built Miata damper hats to solve the exact problem we were having.

The ISC shock mounts are direct replacements for the factory units and add roughly 2 inches of shock travel, although the company will build custom height hats to fit your needs. The cost is about $39 per corner, or $45 for custom hats. While the ISC units do utilize a bushing at the top of the hat permitting shock pivoting, this movement probably matches the amount built into the factory hats. While we would have liked to go with a pivoting damper setup like Tri-Point described, we were more interested in greater suspension travel at this point in time.

With the shocks disassembled, we also took the time to trim about a third off the Koni bump stops. Also, if your shock shaft is larger than the hole in the ISC mount then drill out the hole to slightly larger than the shaft. This was the case with our Koni shocks.

With the suspension installed, we adjusted the ride height to 5.5 inches in the front and a touch higher in the rear (the car was sporting the larger diameter 225mm tires, so we wanted to leave room for when we swapped to shorter 205mm tires). This was when we discovered increased shock compression with extremely short shock bodies results in almost no rear droop. Should the lack of droop have too negative of an affect, we could either have ISC custom make rear hats or order a set of rear 1999-’05 Miata hats, depending on how much droop we think we’ll need.

Not to second guess the setup without going to the track, we broke out the corner weighting and alignment equipment.

The scales we used are the Longacre Computerscales DX with PC download corner weighting scales. These scales are one of Longacre’s top-of-the-line scales, costing $2,049, but the company’s $1,098 scales would do just as good of a job. The more expensive scales boast 10 memory settings, auto leveling and shows you the wheel weights and partial percentages at the same time – the less expensive unit does not. However, for the average Club racer, the less expensive Longacre scales would be perfectly acceptable, although the extra features did speed up the corner weighting process.

To make loading the car onto the scales easy, we used a set of Race Ramps scale ramps. Race Ramps is known for its lightweight ramps, and is continuing the tradition with these ramps, which weigh in at less than 4 pounds each. These ramps match the height of the average corner weighting scale and offer a flat area allowing you to push the car off and on the scales with ease.

After looking at the initial weight distribution numbers, it’s obvious why the Miata is such a popular vehicle. By simply setting a ride height with a slight forward rake and a half tank of fuel, our Miata already had a 51 percent weight distribution – and following two shock collar adjustments we had the car sitting where we wanted.

LF: 625lbs.            RF: 628lbs.
LR: 567lbs.            RR: 560lbs.
Total weight: 2380lbs.
Cross weight: 50.2%

The trick to corner weighting any car is to remember to disconnect the swaybars beforehand, have the driver sitting in the car and to remember that any change you make to one corner will affect the diagonal wheel in the same fashion. Raise the shock collar on the right rear and you’ll increase the weight on that wheel and the left front.

Next, we broke out the SmartRacing alignment tools. SmartRacing produces a number of handy and affordable components for setting toe and camber. We started by stringing the Miata with the SmartRacing SmartStrings to measure the toe settings and then calibrated the SmartCamber tool with hands free adapter. The SmartStrings cost about $408, and the SmartCamber tool runs about $260.

While the process of doing your own alignment isn’t quick, it is very precise and allows you the ability to try a variety of settings with the freedom of changing it at the track. Consequently, we got a little adventurous.

As before, we set the car to zero toe, allowing for the least rolling resistance. At the same time, we set the rear camber to -2.4 degrees. Up front, however, we set the camber to -3.8. Many spec Miatas seem to run -2.5 in the rear and about -3 in the front. Owning the SmartCamber and SmartStrings means that should we find the car too much of a handful, we can adjust the alignment settings at the track to correct any problems.

Up next for the Miata is to work out any handling issues and then hunt for more power and speed, capitalizing on a couple recent Improved Touring rules changes – hopefully winning a couple races along the way.

The right rear end

When it came to swapping the differential, we had several choices. Having never built an ITA Miata before, we contacted Flatout Motorsports for some advise. Flatout was founded in 1994 by three autocrossers, Nick Leverone, Andy Bettencourt and Steve Ulfelder. The company had limited success at the time, but the crew breathed new life into it in 2003. By then, the Flatout founders were road racing.

“The company really took off in 2005,” explains Leverone. “In 2004-’05 we started renting out some Spec Miatas, and that started the company on a path to do more with road racers. In 2006, we took on our first arrive and drive client.”

The Bellingham, Mass., company’s arrive and drive program involves Flatout maintaining and transporting owners’ cars. Presently, this constitutes the majority of Flatout’s business. In addition to their own racing, this allows Flatout to see what works and what doesn’t, as the customers all share their setup.

“Everyone shares data with each other [on the arrive and drive program],” says Leverone, “and it helps everyone on the team do better.”

When it came to our gearing question, Leverone had some firsthand experience. “We found the 4.88 gears, even at a track like Lime Rock [where shorter gears can come in useful] the gears were putting Andy into a bad position [in his ITA Miata] when it came to shifting and running out of gear.”

Following that, Flatout installed the 4.30 gears with a Torsen and the result has been Bettencourt running right at the track record at several tracks in the northeast.

“Some tracks may lend themselves to the 4.88,” says Leverone. “You may talk to someone that says a 4.60 or 4.44 is a more suitable gear ratio for all the tracks, but…I think the 4.30 has proven to be the best gear ratio for the [ITA Miata].”

SOURCES:
Flatout Motorsports, http://www.flatout-motorsports.com
ISC Racing Services, Inc., http://www.iscracing.net
Kumho Tires, http://www.kumhousa.com
Longacre, http://www.longacreracing.com
Mazdaspeed Motorpsorts Development, http://www.mazdamotorsports.com
Race Ramps, http://www.raceramps.com
Racing Beat, http://www.racingbeat.com
SmartRacing Products, http://www.smartracingproducts.com
Tri-Point Motorsports and PowerParts USA, http://www.tri-pointengineering.com, http://www.propartsusa.net
The Tire Rack, http://www.tirerack.com

(This article first appeared in the July 2008 issue of SportsCar magazine)

By Jason Isley

It has been nearly a year since our Project Sentra graced the pages of SportsCar. When we last visited our 2004 Nissan Sentra SE-R Spec V, the car was in the Rally Stock Front Wheel Drive (SF) class and we had aspirations of moving into Rally Prepared Front Wheel Drive (PF). Unfortunately, the conversion from Stock to Prepared trim took much longer than we had planned – but isn’t that the story of any project?

Phase one of our transformation from a dusty Stock car to a Prepared monster was driver safety and comfort. The first item on our list of modifications was to install a proper race seat and harness system. This would also aid in keeping the driver safe in the event of an incident.

For the race seat we decided to raid our storage bin, so we dug out a lightly used Racetech RT4009HR. This seat was rescued from a previous project car that has since gone away, but we liked the seat so much we hung onto it just for an instance like this. The RT4009HR is FIA approved, lightweight and is just about as comfortable as race seats get. We turned to Beta Motorsports for help installing the seat. Beta owner John Coffey combined the existing stainless steel mounts, which were on the seat from our previous installation, with some aluminum plate to create a solid mount for our seat.

While we had the car at Beta Motorsports, we also had Coffey design and install a harness bar so we could correctly utilize a five-point harness. To make the bar as strong a possible, Coffey welded a 1.5-inch steel tube directly to the Sentra’s B-pilar.

As is the case when building any project car, you sometimes jump too far ahead of yourself – and we’re no exception to this rule. After Coffey attached the bar, it occurred to us that we hadn’t double-checked the RallyCross rulebook to see if this modification was legal for the Prepared class. The rules did not clearly address this type of installation, so we contacted Jayson Woodruff, who is a member of the RallyCross Board

“The harness bar is well within the spirit of Prepared,” says Woodruff. “There’s also the Stock allowance of ‘additions of protective equipment,’ and more specifically ‘driver restraints,’ which can certainly be argued.” Whew.

With the legalities of our harness bar taken care of, we attached a five-point restraint system from Impact Racing. These lap belts tighten from the center, allowing for easy belt adjustment while in the race seat – a big bonus for us since this car would see multiple drivers.

The downside to our driver safety upgrades was that ingress and egress was now more difficult – even uncomfortable – due to the lack of range in the factory tilt steering wheel and high side bolsters on the race seat. To solve this issue, we once again turned to the past project car take-offs pile. This trip to the pile revealed a red leather Isotta quick release steering wheel.

While we can’t say for sure why this particular item was ever saved, it solved the current problem and gave us a touch of bling. An added bonus was this wheel has a built-in chronograph and shift light – functional bling. To fit the steering wheel to the Sentra we had to modify a Momo hub adaptor from a Nissan 350Z, as there is presently not a direct fit part for this application.

Freeing the power

Well on our way to a Prepared class car, we knew it was time for more power. We placed a call to AEM for a number of parts. AEM sent both a Short Ram Intake and a complete Cold Air System designed for our Sentra, so we could figure out which would be best for our RallyCross application. Comparing both systems, we were concerned that installing the Cold Air System, which locates the filter element behind the front bumper, would expose the system to a lot of dirt, so our plan was to opt for the Short Ram Intake despite the fact that this system would pick up hotter air.

Once we removed the stock intake system, which includes a large intake chamber behind the front bumper, we discovered it was actually cleaner behind the bumper than in the engine compartment. Consequently, we shifted gears and installed the complete Cold Air System – no more sucking hot air from the engine compartment.

With an increased volume of cooler air coming into the engine, we needed to be able to evacuate it as well. The restrictive stock header was replaced with a DC Sports header. The 4-2-1 header design is ceramic coated and also removes the stock catalytic converter.

The Prepared class rules require a working catalytic converter in the exhaust system, so we took advantage of the allowance to upgrade to a high flow unit. We selected a spun metallic catalytic converter from Magnaflow Performance Exhaust. The metallic core offers a free-flow design that is still EPA compliant, allowing for maximum power. Inside the massive Magnaflow catalog we also found a direct fit cat-back exhaust system for the Sentra. Having used Magnaflow on a number of projects in the past we knew we couldn’t go wrong with these parts.

Good looks and grip

When we started to research the conversion from Stock to Prepared, we spoke with a number of drivers and rally car builders about which parts to upgrade. In almost every case, the answer was: “It’s a waste of time.” We looked at suspension changes, shedding weight, more power; we were told that it all makes very little difference on a RallyCross course. However, the one item that everyone agreed as the most important modification was rally tires.

A call to Falken landed us a set of Azenis RS-01D 215/60-15 tires in the soft compound. According to our sources, this set of tires should transform the car and create an entirely new experience. The downside, however, is that Falken no longer sells these tires, but if you shop around the Internet, you can probably find a set or two floating around.

What self-respecting RallyCross car can show up on a rally tire without wheels to match? Team Dynamics is one of the leaders in rally wheels, as well as being a supporter of the SCCA National RallyCross program (even offering contingency), so it was a no brainier to pick up a set of Team Dynamics wheels.

The Pro Rally 1 is a very rugged design that combines a cooling venturi to direct airflow along with great protection for the brake rotors and calipers. To get the full rally look, we went with a set in white that measured 15×7-inchs. We did have to do a small amount of machining to get the Pro Rally 1 to fit the Sentra – the hubs on the Sentra are a little larger than many cars with a similar bolt pattern, but as solid as these wheels are we don’t think that the small amount of material we removed will be an issue.

The National Challenge

With all of our planned modifications completed, all we needed now was an event with a high caliber of competition, and lucky for us, the RallyCross National Challenge series was making a stop in nearby Lucerne Valley, Calif. This is when thing started to go wrong. Shortly before the event SportsCar Editor Philip Royle, the only person on staff who had any RallyCross experience, suffered a hand injury, relegating him to the role of spectator. This left us heading to the National Challenge with an untested car setup and a rookie driver behind the wheel.

Upon arriving at the event site, the news just got better. We found that we would be the only entry in the RPF class. That would take the pressure off and give us an easy win, but not wanting to take the easy road we opted to move to Rally Modified 2 (M2) – the top level class for any two-wheel-drive car. Now we had 10 drivers to compete with.

Figuring a mid-pack M2 finish would be respectable, Associate Editor Jason Isley took his position behind the wheel and prepared for his RallyCross debut.

After the initial runs, our guess looked to be accurate as we were sitting dead center in the results. Then things started to turn around. With each run, Jason started to make the adjustment from autocrossing on pavement to autocrossing on the dirt. At the end of the day, after 10 runs spread over three different courses, our Project Sentra was in first place in M2 and held the second quickest total time for the event.

Needless to say, we were thrilled with the results. It is pretty clear to us that with some more seat time, some testing and a little elbow grease setting up the car for the surface, our Sentra could be a contender for a RallyCross National Championship. Now it’s just a matter of getting the car to Tennessee.

Sources:
http://www.aempower.com
http://www.betamotorsports.com
http://www.falkentire.com
http://www.impactraceproducts.com
http://www.magnaflow.com
http://www.momousa.com
http://www.nissanusa.com
http://www.racetechseatsna.com
http://www.scca.org
http://www.teamdynamicsracing.com
http://www.tirerack.com

(This article first appeared in the March 2008 issue of SportsCar magazine)

By Philip Royle

It had been decided from day one: Project Miata would eventually turn into an Improved Touring A Club Racing car. It wasn’t until the roll cage prep work began, however, that reality hit us. This was going to be a race car. There would be no going back. And with that, we unceremoniously ripped out the carpet, tossed the stock seats aside, chucked the factory seatbelts and wrenched out the dashboard.

Up to this point, the Miata had gone through a variety of iterations. First the 1996 Miata autocrossed in Stock class trim, then in STS2, it had a brief stint in SM2, it went back to STS2 and finally the car wound up in CSP, where it will remain forever unless the Solo Events Board deems to the class ITA Miatas elsewhere.

There was a wrench in the works, however. At the time, it was early October and we wanted to make a Regional race on the Nov. 17-18 weekend – the last race of the season in our region. Work had to be done, and it had to be done fast.

Pay a shop to do this part

The point of this project has been to build a competent autocross car – not a nationally competitive one – that would be easily converted into an SCCA Club Racing car and could still autocross. Consequently, almost everything we’d installed along the way would transfer directly to Club Racing and would make the final conversion relatively simple and as inexpensive as possible.

The first step was to install a roll cage. There are a couple ways to go with this. The first is to have a custom roll cage installed. There are many advantages to custom cages, as the cage will be built around the driver, meaning there will be no question as to head clearance and harness angle. The downside is this usually takes longer than installing a pre-manufactured roll cage and the cost is often more.

The alternative is to have a welder install a pre-manufactured roll cage. Going this route can help cut costs because in theory the labor time is reduced. This method, if done correctly, can also guarantee the roll cage is completely SCCA legal as the pre-manufactured roll cages generally have already been used by Club Racers and have passed tech many times.

For Project Miata, we ordered a MiataCage.com roll cage. The roll cage is an eight-point cage that has been used in Spec Miatas nationwide, including many championship-winning Miatas – there is no doubt this cage is legal. The kit consists of 24 pieces of 1.5-inch by 0.095-inch DOM tubing and, according to MiataCage.com it weighs roughly 100 pounds installed. The kit comes with landing plates, gussets and an installation guide. The cage is also designed with NASCAR bars on both the driver and passenger side and allows for the passenger seat to be reinstalled if so desired. The kit retails for $950 and we received our kit shortly after the order was placed.

To install the MiataCage.com roll cage, we called Beta Motorsports in La Habra, Calif. Beta Motorsports owner John Coffey has been an active SCCA member for years and has competed in everything from fendered cars to Spec Racer Fords. He has also helped build many competitive Club Racing and Solo cars. We also tossed a couple other chores at Coffey, like installing the kill switch, the Cobra Imola 2 race seat we’d ordered from Sube Sports and installing the Momo Rally Model 78 steering wheel with the I/O port quick release in such a fashion that we could go back to the factory steering wheel should we so choose.

With the roll cage half installed, we returned to Beta Motorsports to test various seating positions. After measuring, marking and climbing in and out of the car a multitude of times, we decided on a seating position that would offer the best visibility while keeping the seat low. Coffey also installed the Ultra Shield six-point harness we’d ordered from OK Miata, positioned the Safe-Quip window net and attached the MiataCage.com hard top mounts.

Soon thereafter, we returned to the shop, picked up the Miata and started the mad dash of throwing parts at the car to make it pass tech.

The mad dash

We had a few weeks left to make the car SCCA Club Racing legal. We didn’t need a fast car, we simply needed something that would enable us to complete a Regional race.

The first step was to paint the roll cage. For that, we purchased Rust-Oleum black enamel, emery cloth, a can of paint thinner and a roll of masking paper. We found the quickest method of getting through the painting process was to mask the car in large sections, scuff the roll cage with the emery cloth, clean the cage with paint thinner, wait for everything to dry and then squirt as much paint as possible in every which direction. When you’re done you will have undoubtedly missed a few spots, but if your luck is like ours, the bare spots are nothing some roll cage padding can’t cover.

Speaking of which, we used a liberal amount of BSCI roll cage padding to protect ourselves from the roll cage. It’s important not to skimp on roll cage padding. While the GCR doesn’t necessitate its use, it’s highly recommended to utilize padding that meets or exceeds SFI 45.1 or FIA 8857-2001 for curved padding. If you use a different type of material, the padding may drip during a fire, possibly leading to injury. Also, in the event of an accident, softer padding may not completely stop your helmet before it impacts the cage; BSCI’s padding has great energy absorbing properties. The padding we installed is SFI 45.1 approved and cost about $20 for a 36-inch stick. It’s easy to cut through the padding with a small saw, and the adhesive backing holds the padding in place around the cage. For security, we also used cable ties around the padding.

The last items we installed were items we’d neglected to order beforehand. Luckily, before Project MX-5 went back to Mazda in mid-2007, we’d stripped out some goodies we knew would come in helpful on other projects. In the days before our Club race, we popped the hood and plumbed in the 7s Only Racing fuel test port, attached the Sparco fire extinguisher and dressed up the interior with an SV Technologies video camera mount and helmet hook.

We also realized we’d forgotten a safety item we weren’t willing to race without: a center window net. For that we placed a panicked call to MiataCage.com, at which point the company immediately shipped us a Safety Solutions net. The center window net is another item not required by the GCR, but it is highly recommended. Installed correctly, the center net not only helps direct the head in the event of a side impact, but it also helps reinforce the headrest and shoulder portion of the race seat. We installed it per the instructions so the bottom two straps cradle the race seat and the top strap connects to the main hoop. We attached the front strap through one of the car’s dash vents and onto the MiataCage.com roll cage dash bar.

As everyone knows, stickers make a car fast. When the car was an STS2 Solo car we’d ordered a set of Solo Performance Specialties magnetic numbers, and we plan to continue to use those when we autocross. For the track, however, vinyl was the way to go. For that, we contacted iZoom Graphics for the company’s LeMans Style Race Car Number Set. The set includes two white door meatballs with numbers, a hood meatball with number and two class stickers, all for $52. We also ordered a variety of other stickers, including car numbers for the rear bumper – something that is not required but the GCR recommends.

Installation of the stickers was very straightforward, although at first the task seemed daunting. All the stickers came on graphed backing paper, making trimming and lining up items very easy. The set also came with complete instructions as well as an application tool. With a steady hand, we attached the 19-inch door meatballs and the accompanying black outline with no issues. The key with sticker application is to take your time. It took us roughly two hours to apply all the stickers, including the necessary SCCA Club Racing stickers, and the result is rather attractive.

Finishing the car, we installed a set of Kumho V710 205/50-15 tires on the Motegi Traklite 1.0 wheels. We chose Kumho V710s for a variety of reasons. Club Racers and autocrossers alike have had massive success on this tire, and in fact, our Associate Editor Jason Isley has won three Solo National Championships driving on the V710. The tire has proven that it is a good choice if the plan is to autocross and Club Race on the same setup – which we plan to do. ITA rules allow for any size tire that can fit on the 15×7 wheel, so eventually we’ll test the 205/50-15 against a 225/45-15 to find the advantages and disadvantages of each configuration.

The final item we’d forgot to order was brake pads. As a base setup (and to save time and money), we purchased a set of Hawk Blue 9012 front brake pads and retained the stock rear pads. In the Nov. 2007 issue of SportsCar, we’d interviewed a number of drivers regarding tuning with brake pads and we noted that lighter cars can make-do with stock rear pads. Good front pads, however, are a necessity. This brake setup is one we’re going to tweak in a later project installment to find the best balance for our applications.

We had also forgotten to defeat the car’s steering wheel locking mechanism. A trip to the Internet revealed the problem could be solved by drilling a hole with a 5/32-inch drill bit in the small rectangular area of the forward facing portion of the lock mechanism. Centered from side to side, measure 9/32-inch from the top and with the key in the accessories position, drill until you’re through the metal casing. Install a 3/4-inch sheet metal screw in the hole and the steering lock mechanism is defeated. If you ever need the steering to lock, simply remove the screw.

To the track

With one day to go, the car was ready to make its first Club race, but then we realized the car had a stock intake, exhaust and ECU. While we couldn’t do anything about the exhaust or ECU, we did manage to cobble together an intake using spare parts from our Project Sentra. Did this increase the car’s power any? If it did we couldn’t feel it, but it didn’t hurt and it dressed up the motor.

The race we attended was the last Club race of 2007 for Cal Club Region in the Southern Pacific Division. The race was at Buttonwillow Raceway Park in Buttonwillow, Calif. While not a famous track, it is one of our local favorites. The first mistake we made, however, was not adjusting the suspension from its STS2 Solo settings. On street tires on the Solo course, we’d discovered our Miata would dramatically oversteer; consequently, we had disconnected the rear Racing Beat sway bar. At Buttonwillow, this setup meant we had to drive deep into every corner using heavy trail braking, ultimately heating the front tires and resulting in lost grip on turn-in. We plan to reconnect the rear bar for the next race. In fact, we did reconnect the rear bar and autocross the car with the Kumho V710s and the car was mostly neutral, but it was far more drivable with the rear roll bar connected on the V710s then with the rear bar connected on the Hankook Ventus R-S2 street tires we were using in STS2.

We’d also never weighed the car before going to Buttonwillow. After the race, we pulled the car on the scales and discovered the Miata was 97 pounds underweight. That will obviously be fixed before the next race, too.

There’s a lot we plan to do before the next Club race and autocross. While adding power is on the agenda, first up is to get a good baseline suspension setup performed by people who know what they’re doing. Up to this point we’d simply installed the Koni 8041 RACE shocks and Eibach springs, set the ride height to 5.25 inches, set camber at -2.0 degrees and the toe to zero. The car has performed admirably, but we know there’s a lot of untapped speed. From there we’ll fish for more power, and who knows, we may even work on our driving.

SOURCES:
Beta Motorsports, http://www.betamotorsports.com

BSCI, http://www.rollbarpadding.com

Hawk Performance, http://www.hawkperformance.com
I/O Port Racing Supplies, http://www.ioportracing.com
iZoom Graphics, http://www.izoomgraphics.co
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Kumho Tires, http://www.kumhousa.com
MiataCage.com, http://www.miatacage.com
Momo Italy, http://www.momousa.com

OK Miata, http://www.okmiata.com

Safe-Quip, http://www.racequip.com

Sparco USA, http://www.sparcousa.com
Sube Sports, http://www.subesports.com
SV Technologies, http://www.svtek.com

(This article first appeared in the September 2007 issue of SportsCar magazine)

By Philip Royle

It turns out, building an STS2 autocross car that can also Club race is tricky – so tricky, in fact, that Project Miata is now a C Street Prepared car. Why the class change? With roughly 80,000 miles on the stock clutch, launching the car was beginning to involve hefty, undesirable clutch slip. Following a couple interesting launches, it was obvious a clutch with a little more grab was needed – and since this car will ultimately be a Club racer, we were forced to install a heftier clutch than STS2 rules allow.

Choosing the right performance clutch isn’t difficult. Many clutch manufacturers have easy to follow guidelines on their Web sites, noting vehicle usage and modifications as deciding factors as to which product is ideal. Our search led us to a company called Fidanza. Fidanza’s roots are in SCCA Club Racing, and consequently, the company understands the needs of the racer.

Fidanza offers four clutch configurations, all made with varying clutch material. Fidanza clutches range from carbon Kevlar to Kevlar to ceramic to sintered iron, with each material offering unique holding qualities. Other clutch manufacturers offer clutches constructed of similar materials, while some offer clutches with a completely different construction. Regardless of manufacturer, though, the important thing is you use the right clutch for your application.

Getting enough clutch

Our project Miata would never see gobs of power, but the car itself would encounter plenty of abuse. As a result, we needed more than a stock replacement clutch, and it seemed Fidanza’s Kevlar or ceramic clutch would do the trick – ultimately, we opted for ceramic.

To be sure we were ordering the right unit, we called Bob Sheid, vice president of Fidanza, and he explained our options.

“The Kevlar clutch will hold about 60-percent more torque than the stock clutch, but it has a break-in period,” explains Scheid, noting that break-in periods may not be ideal for Club racers. “The material has to be heated and cooled a couple times, so we recommend a couple hundred miles of break-in. Once it’s broken in, you can abuse it because it won’t glaze.

“The ceramic is an aggressive material and will hold about 80-percent more torque than the factory clutch. It can be driven on the street, but you have to be forgiving.” Scheid noted that, unlike Kevlar, ceramic clutches have no break-in period. The downside is ceramic can glaze, although it is tough to do.

Sheid noted that installing a ceramic clutch will result in some clutch chatter. “It’s the nature of the beast,” says Scheid. “[Ceramic is] very good at holding power, [but] when you let off of the clutch pedal, this clutch is going to engage. It’s not going to slip for you.”

Since ceramic – as well as Kevlar and sintered iron, for that matter – can aggressively hold power, clutch surface area can be minimized. Consequently, material can be trimmed from the edge of the clutch to reduce weight and increase cooling. This trimming forms the pucks that many are familiar seeing on performance clutches. The ceramic clutch we chose is a six-puck clutch; it weighed 3lbs. 7.1oz. Interestingly, the stock clutch we removed weighed 2lbs. 8.8oz.

Scheid also pointed out the importance of a good pressure plate. The pressure plate is responsible for clamping the clutch against the flywheel, transferring the engine’s rotating power to the transmission.

“The things that are most critical on a pressure plate are the fingers in the middle, called the diaphragm,” explains Scheid. “The stronger those springs are, the more holding power the clutch is going to have. The downside is it usually takes more leg to press it.” To reduce the chance of a hard clutch pedal, Fidanza makes the pressure plate’s springs longer and uses leverage to keep the clutch pedal in check.

When we weighed the Fidanza pressure plate, it measured 9lbs. 2.8oz. The stock used pressure plate’s weight was about equal at 9lbs. 0.6oz.

You’re there anyway

Installing a clutch isn’t easy. For the Miata, it required removing a bulk of the underside of the car. Needless to say. doing this on jack stands is a pain and not something we wanted to tackle. Consequently, we headed to Advanced Performance Industries (API) in Cypress, Calif. API prides itself on working on a variety of vehicles, rather than specializing on a specific marquee. API is also an authorized Fidanza distributor.

API also suggested replacing the rear main seal. While the seal wasn’t leaking, the fact that it was a $25 part meant we should replace it anyway. API also noted that if you’re going to swap the exhaust, this is a great time to do so since it will be removed anyway.

Also, if the rules for your specific class allow, both Fidanza and API suggest installing a lighter flywheel while replacing the clutch – sadly, Improved Touring rules require the use of a stock, unmodified flywheel. But since the flywheel would be removed to replace the rear main seal, we chose to install a new stock flywheel.

Once API removed the stock clutch assembly and flywheel, we found the stock clutch had almost no signs of glazing, and the flywheel and pressure plate looked mostly fine. Considering the car has seen uncountable autocrosses and a number of weekend track days, not to mention daily commuting duty for the first seven years of its life, it’s fair to say the stock clutch is one sturdy unit.

On the road again

With the Fidanza 4.3 ceramic clutch installed, the car does experience some clutch chatter. We have found, however, revving the engine to 3000rpm or above nearly eliminates the chatter on slow starts. The engagement is quick, but since this clutch uses a marcel and a sprung hub, both of which smoothing clutch engagement, it is tolerable. And amazingly, the clutch pedal pressure is almost identical to the stock setup. On the Solo course, launches are a breeze with a very fast engagement, resulting in ample tire spin to put the car in motion.

Per Solo rules, however, changing the clutch material moves the car from STS2 to CSP. Since the car still sports the Hankook RS-2 street tires, we’re left – for the moment – with a very under prepared car.

Because the car is not daily driven, we could afford to install a heftier clutch than we need at the present time. Would we recommend someone install a ceramic clutch on a daily driven car? Probably not. Dealing with stop and go traffic with the ceramic clutch’s engagement characteristics would quickly drive you up the wall – although it could be done. Sadly, since Kevlar clutches require a break in period, the ceramic clutch is the obvious choice for a Club racer that isn’t ready for the sintered iron setup.

Now that the Miata is a CSP car, we can begin to strip out certain components and prep the car for the roll cage, seat and other components needed to obtain a Club Racing logbook. We are about to hit the point of no return with this project. On the plus side, though, disassembling a car is really fun.

SOURCES:
API, (714) 229-0880, http://www.advancedperformanceind.com

Fidanza, (440) 259-5656, http://www.fidanza.com

(This article first appeared in the August 2007 issue of SportsCar magazine)

By Philip Royle

Good old-fashioned seat time – there’s no substitute. In any form of motorsport, the number one way to go fast is usually logging time behind the wheel. You need to be comfortable with the car and the stresses of competition, not to mention familiarizing yourself with the details that make up that specific kind of competition. If you’re not up to speed with the ins and outs of that form of motorsport, you can easily find yourself nervous and a little on edge. Shot nerves don’t make for smooth hands.

Beyond familiarizing ourselves with RallyCross (and consequently entering a number of events), we needed to get to know our project 2004 Nissan Sentra SE-R Spec V a little better. We originally chose the car for the purposes of RallyCross based on the car’s light weight (2710 pounds), helical limited slip differential and excellent 175hp 2.5L I-4 motor – all of which should make the car a solid front-drive RallyCross competitor. Had we researched deeper, we would have also discovered a couple of the Sentra’s quirks – quirks we would have to eliminate if we had any hopes of competing.

First, the car utilizes a drive-by-wire throttle assembly rather than a traditional throttle cable. This isn’t really a surprise considering the vast majority of new cars use a drive-by-wire setup. The downside to this system is that manufacturers often set the car’s computer to cut the throttle should the brake and gas pedals be pressed at the same time for more than a couple seconds. Nissan is one such manufacturer.

Workarounds for these systems are usually fairly simple – it’s just a matter of finding the solution. With the Sentra, the workaround involves pulling the brake light fuse. In the Sentra, that fuse is located in the driver’s compartment, on the left side of the steering wheel. The brake fuse is a 10-amp fuse positioned second from the left on the top row of the fuse box (a special thanks goes to SPDiv’s Mark Anton, who also RallyCrosses a Sentra and aided in our fuse removal when we discovered our Sentra’s shop manual had abandoned this project without us knowing). With the fuse removed, the car can be driven with one foot on the gas and the other on the brake without the car thinking it knows better.

Because removing this fuse does stop the brake lights from illuminating, if you drive your RallyCross car on public roads to competitions, we highly recommend pulling the fuse once you get to the course and reinstalling it before the drive home.

The second “quirk” is ABS. The consensus from everyone we spoke to was that ABS is bad, and thinking through how to RallyCross a front-wheel-drive car, it’s obvious why. A common technique for competing in a front-drive car is to floor the gas pedal and press the brake to slow the car, never letting off the gas (this is why we pulled the brake light fuse). Using this method of driving makes it very difficult to lock the car’s front tires, thus allowing the driver to maintain steering control – equally important is the fact that the brake pedal is pressed so hard the rear tires lock. With the front tires pulling the car and the rears tires locked, the car rotates nicely through the turns. This isn’t exactly easy on the brakes, but it is effective and far more consistent then pulling the handbrake.

Disabling ABS is usually a simple process in any car – pull the ABS fuse. In our Sentra, the ABS fuse is located under the hood next to the battery. It’s a 40-amp fuse marked “ABS SOL.”

With the two fuses sitting in our pocket and our left foot ready to practics a completely different style of driving, we took to the RallyCross course. No ABS and a throttle that doesn’t cut while left foot braking made our Sentra feel downright sprightly when compared to driving with all the fuses in place. Also, keeping the throttle planted resulted in smooth weight transfers, allowing us to drive the line we were aiming for.

Running on dirt without ABS is tricky, however, as it makes locking all four tires easy. Should you lock the front tires on a front-drive car, you stand the chance of stalling the motor. In the case of our Sentra, the motor would re-fire immediately upon releasing the brake pedal – left foot braking, however, completely eliminated this problem as it made it all but impossible to lock the front tires. It’s tempting to slightly release the gas pedal upon corner entry to allow the car to decelerate faster, but doing so while not locking the front tires proved incredibly difficult and all but impossible to repeat with any level of consistency – and with RallyCross, consistency trumps one fast run.

Our final prep for the Sentra involved setting the alignment – this is the Sentra’s final quirk. The only alignment settings that can be adjusted on the Sentra without replacing bolts, drilling out holes, or adding camber plates is the front toe. Since several RallyCross competitors told us an accurate alignment isn’t completely necessary, we chose to adjust the car’s toe while the car was on the trailer. We measured 1/8-inch of toe in, so we dialed in 1/4-inch of toe out. The difference was unnoticeable on the dirt, but since in theory toe out is better than toe in, we figured it couldn’t hurt.

With the basics out of the way, the next step is to move the car from RallyCross’s Stock to Prepared class by installing a set of rally tires and good 15-inch wheels. We’re also going to strip the car of as much weight as possible as allowed in the Prepared rules. And who knows, we may even get good at this left foot braking thing, too.

(This article first appeared in SportsCar magazine’s July 2007 issue)

By Philip Royle

The best projects start with a bang. Unfortunately, this was more like a pop, followed by low-speed thunks. The thunks were accompanied by rattles, and those rattles eventually manifested themselves into a more tangible puddle of oil.

After six years and nearly 30,000 miles of abuse, the left rear shock on the 1996 Mazda Miata kicked the bucket. It did so on the way back from an autocross – at least it went out in the line of duty.

The car had originally been purchased for daily transportation, but not being able to leave well enough alone, the car soon found a number of goodies bolted to it. In the moment before the shock opted show the world its smelly, oily goodness, the car was sitting atop a set of 16-inch aftermarket wheels with horridly old tires, had a Hard Dog roll cage, some Racing Beat sway bars and adjustable end links, Mazdaspeed braided steel brake lines and, of course, four good Tokico Illumina shocks with Vogtland springs. Then came the bang.

The Tokicos can’t be blamed for giving out. The suspension had seen many lapping days at various Southern California tracks, and had also competed in an uncountable number of autocrosses. The shocks were designed for the street, not the track, and a blown shock is sometimes the price you pay for not following directions.

The bang also happened at an interesting point in the car’s life. While once serving as daily transport to and from the office, the Miata now only sees the street when it’s on its way to some kind of competition, usually autocross. Now that the shocks needed replacing, it was time to rethink the entire setup.

A plan is formed

As it was, the Miata was an STS2 Solo car, but not a very competitive one. The limiting factors in the car’s regional competitiveness were shocks, springs and, of course, the decrepit tires.

After perusing the options, it was decided that constructing a nationally competitive STS2 car wasn’t in the cards. Rather, the goal would be to build a car that could both autocross and Club race on a regular bases, with the knowledge that the Miata would probably wind up not dominating either. That’s right, this car is going to be a compromise – but a fun compromise.

To determine the best method to go about this, we headed to the rulebooks. Since the Miata was a first generation 1.8L car lacking the differential, it only made sense to build it to Solo’s STS2 class. Once the car was up to speed in Street Touring, a cage would be welded in, a race seat would be mounted and the car could compete in Club Racing’s Improved Touring A. At that point, the car’s Solo classification would shift from STS2 to C Street Prepared, and further modifications could be made – like adding the needed diff.

The goal for now, however, is to build a car with parts that cross from Solo to road racing, making the leap to Club Racing far more affordable.

Sounds like a plan.

Parts are ordered

The first step was deciding which shocks and springs to use. Since the car rarely sees daily commuting, this was simple: we needed race coilovers.

About two years ago, Koni released its 8041 RACE series of adjustable dampers. Koni’s goal was to design a race shock that would hold up to both Solo or Club Racing duties. An added bonus was that a set of four shocks could be purchased for under $1,000 – not too shabby. Last year, the company expanded its lineup, and with it, an application for the Miata. Pay dirt.

With the shocks ordered, we started our search for quality race springs. Koni’s 8041 RACE dampers were valved for a variety of spring rates, so we decided a safe starting place for spring rates would be to follow the Spec Miata lead and order 700lbs. front springs and 325lbs. rears. The Koni’s can fit both 2.25-inch inner diameter (ID) springs and (with an adapter) 2.5-inch springs. After some searching, we finally ordered a set of Eibach’s 2.25-inch ID 6-inch tall front and 7-inch tall rear ERS race springs. We also ordered a couple helper springs and spacers.

This setup should also complement the Racing Beat front and rear sway bars and adjustable end links that are already on the car.

If the Miata were to eventually wear ITA stickers, the current 16-inch aftermarket wheels would have to go. STS2 rules allow for any wheels 7.5-inches wide or narrower and CSP’s wheel rules are also relatively open. However, Club Racing’s General Competition Rules state ITA cars that came stock with 14-inch diameter wheels (as the Miata did) can step up to a maximum of 15-inch diameter wheels with a maximum width of 7 inches. Consequently, the search was on for a set of affordable and lightweight 15x7s that would look nice on the car.

Motegi Racing offers a variety of performance wheels, and it’s also one of only a handful of companies that offer a lightweight 15×7 wheel in flat black – since the car’s hardtop is flat black, this was viewed as a sign, and Motegi Traklite 1.0 wheels were ordered. When the wheels arrived, they were tossed on the scale to see if these lightweight wheels stood up to the claim. The scale measured the wheels at 10lbs. 15oz. each. They weren’t kidding – these are light. Plus they look darned good on the car and were relatively affordable at $232 a piece.

Tires was an interesting subject. Anyone looking to compete with Improved Touring cars would need DOT-legal R compound tires; however, STS2 rules mandate a UTSG rating of 140 or greater and a tread width of 225mm or smaller. A popular tire in the class is the Falken Azenis, but by all measures, the Hankook Ventus R-S2 should be competitive in the class. Consequently, we ordered a set of the 205/50-15 Hankooks. Our experience in the past on Hankooks has proven positive, and we wanted to see how these would fare against the competition.

The final part ordered was a lightweight battery. STS2 and CSP rules are very forgiving when it comes to battery replacement, allowing for virtually any battery with a similar OE voltage to be bolted into the car in a variety of locations. ITA rules, however, are more specific, stating that batteries must be of “similar” weight and are fitted in the standard location.

Because we prefer non lead-acid batteries, and we’re suckers for carbon fiber, we ordered the B106 race battery from Braille Auto Development. The Braille battery measures 5.75 inches across, 4.25 inches tall and 3.25 inches deep (the stock battery is 7.5 inches across, 7.25 inches tall, 5 inches deep). We also ordered Braille’s billet battery tie down. The Braille battery tipped our scales at 7lbs. 7oz., and the bracket weighed about a pound. We also ordered Braille’s battery charger wince we’ve been known to drain a battery or two.

We’re pretty sure this battery won’t fly in ITA (despite installing it close to the factory location). Should it prove really, really illegal in Club Racing, we’ll move the battery to one of our other project cars because, well, carbon fiber batteries are too cool to pass up.

We also thought it time to order a complete set of magnetic numbers, so we did so by calling Solo Performance Specialties (SPS). The company has long supported autocross, and its owners are active SCCA members. Also, we were tired of taping numbers to the side of the car every time we competed. SPS also sent out a set of STS2 letters – if we’re not going to win, at least we’re going to look like we know what we’re doing.

Installations are completed

Step one was to ditch the blown shock. For that, we headed to Shoreline Motoring in Huntington Beach, Calif. We’ve used Shoreline in the past, and we’ve grown to love the shop. While the shop’s clientele aren’t necessarily having the shop wrench on their race cars, Shoreline’s one of a few shops that offers good, honest advice, doesn’t charge extortionate fees and uses torque wrenches on parts that require them.

During the installation, the decision was made to run the helper springs in the front only, and to move the threaded collar mounts down one notch on the shock bodies. Shoreline also modified the factory bump stop, retaining the rubber spring seat and replacing the stock bump stop with the supplied Koni unit (this required drilling out the factory spring seat to fit over the Koni shaft).

While at Shoreline, we also had the car aligned. For an alignment starting point, we decided to look at what two forces in the Miata world were doing. With a little online searching, we found Jim Daniels’ Spec Miata setup as well as Andy Hollis’ STS2 Miata setup. We opted to start with the Jim Daniels Spec Miata alignment, with the knowledge that we’d have to dial the toe by hand as needed for autocross. As it stands, our alignment is:

FRONT
Camber: -2 degrees
Caster: +3.5 degrees
Toe: 0

REAR
Camber: -2 degrees
Toe: 0 degrees

The car’s ride height is set at 5.25-inches from the ground to the bottom of the pinch weld.

The car’s previous settings were -1.2 degrees negative front camber, -1 degree rear camber, and a hint of toe out in the front. The finished result is a car that definitely turns in slower than before – it’s obvious we’re going to have to tweak the toe settings for Solo.

Also, the car has yet to be corner balanced. This is something we’ll tackle in a later installment.

The battery installation was simple. Parts of the factory battery hold down were removed and the billet aluminum Braille brace was bolted in. To mount the Braille unit, we marked the holes we’d need, pre-drilled four holes, and then attached the base using the supplied screws – which, incidentally, hold the battery far more securely than the factory setup.

The car is far from done, and in fact, we have yet to take the car to an autocross with its current setup. Street driving, however, has shown that the linear Eibach springs are far firmer on small bumps than the previous progressive springs. While that leads to a more abusive ride, it also results in a more predictable feel, especially from the back of the car, over transitions – and with the Koni’s adjustment set halfway between soft and hard, the ride, while stiff, isn’t completely out of the realm of being drivable on a daily basis. The full hard shock setting, however, should only be used for competition.

As for the Hankook tires, our experience in other cars with the Ventus R-S2 tires, have shown the tires to display a predictable breakaway while offering ample grip for a street tire. And while we didn’t, we would recommend shaving the tires if competition is your primary goal. Shaving would reduce the tread squirm that most full tread depth tires suffer from. To better evaluate these tires, we have a couple tests in the works.

The clock is ticking on this project. Our goal is to have the Miata’s logbook by early next year, but to do so, we’ve got to raid a couple parts bins, take care of a couple maintenance issues, fix a slipping clutch and finally weld in a roll cage – all without going broke, and – even more importantly – not compromising the car’s performance to the extent that we wind up with a car that isn’t good at anything.

SOURCES:
Braille Auto Development, (941) 312-5047, http://www.brailleauto.com
Eibach Springs, (800) 507-2338, http://www.eibach.com
Hankook, http://www.hankooktireusa.com
Koni http://www.koni.com
Motegi Racing, (866) 4MOTEGI, http://www.motegiracing.com
SPS Performance, (877) 614-SOLO, http://www.soloperformance.com

(This article first appeared in the May 2007 issue of SportsCar magazine)

By Philip Royle

Just over a year ago we thought it was about time we built a RallyCross car. After all, RallyCross looked like a blast. With fast yet safe speeds on a dirt (or snow) playing ground with somewhat familiar autocross rules, what’s not to like? Once our minds were made up that this was a project we could sink our teeth into, we started shopping for a solid base car that would be up to the riggers of racing on the dirt. Our requirements were simple: the car needed to be powerful, somewhat lightweight and have a limited slip differential from the factory. We also decided early on that we wanted a front-drive car (this was very much an arbitrary decision on our part, so you’ll just have to go with it).

As it turns out, finding the car was easy. We chose a 2004 Nissan Sentra SE-R Spec V that, with the exception of a few squeaks and rattles, was in exceptional condition (and at the time was only two and a half years old).

The Spec V is powered by a 175 hp, 16v, 2.5L, four-cylinder motor, but thanks to the engine’s relatively large displacement, the motor produces a smooth 180 lb.-ft. of torque – 10 more ponies than the normal SE-R, and 49 more horses than the 1.8L Sentra.

For those looking to save money with the non-Spec V SE-R, it’s important to note that – at least with this model year – only the Spec V comes with the helical limited slip differential, and it’s the diff that plays a key roll in the Sentra being an ideal RallyCross car. With a peg leg powering the car on a loose surface, finding traction would be all but impossible.

Both the SE-R and Spec V come with a quicker steering ratio (15.8:1 vs. 17.48:1) than the standard Sentra, but oddly have a larger turning diameter.

The potential downside to the SE-R and Spec V models are the transmissions the cars came with. The V was only available with a 6-speed manual, meaning the gearing is a little close. While this is good for around-the-town grunt, it can limit you when racing on courses where the speeds hover around 60 mph – as is the case in autocross and many RallyCross events. However, not having to worry about tuning around an open differential makes dealing with a 6-speed tolerable. Also, this model SE-R is a must-avoid car as it was only available with a four-speed slush box. What was Nissan thinking?

The Amazing part of the Spec V is the price. Brand new, the V had a base price of $17,500, which was only $200 more than the SE-R. That $200 got you 17-inch wheels as opposed to 16s, the better tranny, and the V came with spring rates that were 15-percent stiffer up front and 16-percent stiffer in the rear than the SE-R.

An option our V wasn’t equipped with, which we would have liked, was the Brembo brake package. This package includes bling gold Brembo four-piston front calipers clamping 12-inch rotors, with rear rotor measuring 10.9 inches. The stock rotors on our model are 11-inch up front and 9.13-inch in the back. The calipers are also single piston all around. Our model also came equipped with ABS.

New, our little Spec V dinged the register at under $20,000. If you were shopping for a similar model right now, you could probably find a good example for between $11,000 and $13,000. Not exactly cheap, but racing isn’t cheap.

So it was just over a year ago that we obtained our V with the goal of hitting the dirt – this was about the time Southern California RallyCross events dried up. There were some events taking place six or seven hours north, but that was too much of a drive for us – we opted to wait for the events to come to us.

And here we are.

Today, Southern California is getting back into the swing of things with many RallyCross events slated for 2007, and that’s not to mention the Western States Championship that will take place in Jean, Nev., in September. It was time to dust of the V and go racing.

The plan is to build a competitive, highly modified RallyCross car. As the project progresses, we’re going to see what needs tweaking on the V and improve those areas. The first goal, however, was to see how the car would react in its bone stock configuration.

We loaded the car onto the trailer and towed the V north to Jean, which (as mentioned) is the future site of the Western States Championship. Since the goal is to compete at this event, this looked as good a place as any to baseline the car.

The dry lakebed in Jean is rough, but the surface breaks up quickly. What this means is that by the third run you quickly stop running a race line and start looking for available traction. This also means there’s a lot of dust flying around, and if you’re not careful (and the door seals aren’t sealing quite up to snuff) you can wind up with a lot of dirt entering the cockpit.

A good tip is to ignore the dirt as it flies around the cabin.

Since our Sentra was still sporting the stock Continental 215/45-17 ContiSportContact summer tires, traction wasn’t exactly plentiful; however, this didn’t mean the car was out of control. With ample mid-turn left foot breaking and some not-so-subtle yanking of the handbrake, the car would rotate nicely, and the differential would allow you to floor the gas and power out of the slide. With just enough angle through the turns a good rhythm could be had.

By the end of the event, it was obvious our vehicle choice was a good one. The car pulled hard in second and third gear, and the power was just enough that throttle modulation was necessary – once aggressive tires are added, however, this will probably not be the case. As for the stock tires, they did a fine job, but the surface was a little tough on them, leaving the front left tire with a nice bubble on the sidewall. While RallyCross isn’t an overly damaging sport, it’s not nearly as easy on street tires as autocross, so we recommend bringing a separate set of tires to race on.

The event results were promising. Out of 16 entrants, we finished third – and since we were beat by a rear-drive Toyota MR2 (sporting somewhat aggressive, yet still Stock legal, tires), that meant we were the fastest front-drive car. Our overall total was 9.11, with first place overall scoring an 8.85. Second place overall scored a 9.07 in the same MR2. Finishing fourth overall was a Dodge Neon ACR, with a 9.27.

Our plan now is to add a couple components to the Sentra while sticking to the Stock rules. That basically means we can bolt on snow tires. We’re also going to play with disabling the ABS, since that’s allowed by the rules, to see how different the driving experience is, and which suits our driving style best.

Ultimately, we’re going to prep the car for the front-wheel drive Prepared or Modified class, depending on how much power we think we’re going to need, and hopefully compete at the Western States Championship. Now that we have one event under our belts, we’re experienced, confident and boisterous. We’ve also left the event completely addicted to a new type of racing. Oh man, this is going to be a fun and dirty project.

RallyCross car prep

With no knowledge of how to set up a Stock-class car for RallyCross, we took our autocross knowledge, mixed it with a liberal amount of trackside advice and then hoped and prayed all went well.

As far as we were concerned, the most important thing was that the tires stay on the rims. Finding a consensus on what tire pressure to accomplish this, however, was difficult. The advice ran the gamut from the somewhat vague, “Run those pressures high,” to one competitor pumping his street tires to 50 psi. In autocross, 40 psi is a good starting point, so we decided to try that. We ended up filling the tires to 39 psi front and rear (39 psi was chosen because it was nearly 40, but not – don’t ask why). The tires never pulled off the rim, so from the looks of it, relatively small sidewall tires (215/45-17) can safely run at around 40 psi on a not-so-grippy dry lakebed without unseating. Had there been hard ruts, we may have bumped up the pressure another couple pounds, but at that point we could risk blowing the tire.

As it was, we did end up damaging a tire. With two of six runs remaining, the front driver’s side tire formed a bubble on the side, just below the tread. The bubble didn’t stop us from finishing the day, though, and the bubble got no worse (this being the advantage of towing to an event).

The final setup trick was taping down the handbrake button. Having watched many a rally, we knew the handbrake played a key role in making sure the car rotated nicely. Having no clue how the car would react on the dirt, we took some duct tape and liberally taped the button. This allowed for the handbrake to be used during the event without worrying about the handbrake not releasing.

As it turns out, this was an incredible idea, and it aided dramatically through a couple tight turns. Without the handbrake, our score would not have nearly been as low as it was.