MKIV Supra Turbo Road Racer AEM EMS Convert

Postby Innovative Tuning Fri Aug 20, 2010 12:58 pm
One of our customers has been a long time road racing instructor for Trackmasters and his weapon of choice is a MKIV Toyota Supra Turbo.

I've been tuning this car for around 5 or 6 years now. The owner had a MAP ECU for a bit which was severely limited in what it could do so we get him an AEM EMS standalone to better handle the engine controls. At the time ViPec wasn't available. After installing a 61mm single turbo conversion and supporting mods the car misfired on the AEM EMS at about 17 psi. This is a common issue on Supras with AEM EMS and all the AEM guys go out and buy HKS DLI boxes to allow them to run higher boost levels without hard misfiring.

Last fall the Supra's clutch began to act up and we discovered it was doing this because the stock engine had MASSIVE crankwalk. Year after year this engine took a great deal of abuse at a dozen or so track weekends a year. It compression tested fine, but it was spent. It turned out one of the main bearings had almost totally disappeared and the crank was grinding against a main cap.

We went ahead with an engine build and performed a number of upgrades at the same time including a better intercooler, custom intercooler piping, custom breather box, Exedy multiplate clutch/flywheel, a Precision 6765 turbo, and we made a custom baffled meth tank setup to add a meth kit that would work well on course.

After the engine build and with the new turbo, intercooler, etc. the car was prepped to make more power than ever before. Unfortunately the AEM EMS and HKS DLI didn't make that possible. The first DLI box died after a few months and the second wasn't providing enough spark energy for the engine to run smoothly while in boost. We spent a great number of hours checking the car over before deciding to put all new coils on the car. Even that didn't help. We used dwell settings from AEM and AEM customers with no change.

At that point I told the owner I was going to put a ViPec Supra plug and play unit that we had here for another car in his Supra for testing purposes and see what happened. In a couple hours I was doing full boost pulls and the car ran better than ever. There wasn't a hint of a misfire so we took the HKS DLI box off the car. It still pulled totally clean so the problem was solved. We had already stopped selling AEM EMS units due to some other issues with them, but this was about as definitive a back to back test as you'll get.

This dyno graph shows the car running the same timing advance, boost level, and AFRs with no mechanical changes aside from swaping the ECUs.

After that the switch from AEM EMS to ViPec was a no brainer. I continued with the tuning including using the ViPec to totally control a methanol injection system. I set the ViPec so it turns the meth pump on full blast at 5 psi and then I set up a 3D map to control the methanol injector which ramps flow up progressively. That way there's never a delay before methanol spray which avoids a temporary lean condition and the addition of methanol is seamless. We set the car up with a single switch that engages the meth system and enables the offset fuel/timing maps so he can turn the meth on/off any time he likes. Then a second button enables his high boost level (22 psi) which he uses to smoke the other instructors in their GT3s and Z06's etc.

The safety mechanisms built into the V88 already came into play, providing a warning and protection for the engine during an overheat condition on track which the owner also loves.

I look forward to getting a ride in it at Watkins Glen one of these days when he's instructing.

This car has two in tank walbros Y'd together into a -8 feed to an aftermarket rail, into an Aeromotive FPR, then into the factory return line. The walbros have their own wiring and relays.

I'd post deadtimes, but we don't know what injectors he has. He got them from a buddy used and we think they're 850cc. I set a low fixed pulse width via the fuel map and worked the dead times down with the engine idling until the injectors seemed to start operating erratically and then added a couple tenths of a ms back. This is far from an ideal method, but it got the job done and the car runs flawlessly. Normally we get injectors from suppliers that provide this info so I don't have to do this...

We bypassed his clutch switch. The bottom end that crankwalked was bone stock and original to the car. It had a lot of miles on it and he did around 12-15 track days a year for around 5 years on it so I'd say he got his money's worth out of it.