(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.

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