Toyota Supra MKIV - Project Supra: Relaunch, Part 2

It's been a long time. Some of you probably even forgot about the car already. Our MKIV Supra project started life back in 2004 in its original white form. After extensive performance upgrades it morphed into what you see here.

During this process we installed Tein coilovers, Brembo brakes, iForged wheels with Bridgestone tires, and went a step further with a full engine rebuild and an SP71-GTS turbo upgrade-all controlled with an AEM engine management system. But in May 2005, our 1,000-mile old motor nearly seized and our main bearings were toast due to the dreaded crankwalk. The car sat for over two years but we at least got a few things done, including its change of color (PPG Estoril Blue), Sparco Siena seats and '98 model headlights from Champion Toyota.

Fast-forward to May of 2007 and the car was ready to be fired up with a brand-new engine rebuild, using the same Pauter rods and Pro-Gram billet main caps, but with new and improved JE Pistons. Sadly again, the day came to fire it up and the engine locked up. In a panic to get the project moving, we ordered a brand-new factory short-block, which you can order for a very reasonable couple grand from Champion Toyota. Shortly after, we found out our block was actually OK and had locked up at the oil pump from improper pre-lubrication. We'll keep the engine as a spare for now.

The headaches continued, however, when attempting to get the car back together. During its two-year absence-between having it stored at various automotive shops and being stripped-down for a color-changing paint job-several parts were missing. First, the cam caps for the cylinder head couldn't be found, so there went our head. A new head was purchased from Champion Toyota and was sent to Amazon Racing to get massaged and fitted with our Ferrea valvetrain, which included titanium retainers, dual valvesprings and 1mm oversized valves. Amazon also completed a five- and four-angle radius valve jobs to the intake and exhaust sides, respectively. Amazon lapped each valve for optimal seal against the seats when each valve is closed, and back-cut the top outside edges of the intake valves for improved velocity when opened at low lift.

Amazon then sent the head to get flow bench tested in order to baseline the flow before its minor porting and mirror polishing. After the work was done it was resent and at 0.4-inch valve lift and 28 inches of water, the figures improved by an additional 19 percent on the intake side and 22 percent on the exhaust

Once the long-block was completed at Amazon it went to House of Power, where owner Josh Rickards was in charge of putting the long-block together and back in the car. He also had to put up with the numerous "little things" that kept the car there for weeks before he gave it his seal of approval for transport.

Another part that turned out missing during a previous tow was the freshly painted T-top, which would've set us back another $2,000 for a new one. In order to transfer the car from California to its home near Kansas City, Miss., we needed another one fast. After an exhaustive search we came across Turbo Toys on the East Coast, which specializes in used Supra and various Nissan parts. The company sold us one from a crashed silver MKIV. It was a perfect fit, of course. Now we just needed to paint it.

Several other little missing parts added to this money pit, but a couple really raised our blood pressure. First, the little wheel to the throttle linkage was nowhere to be found. At first we thought, "No big deal." Then, Toyota told us it only sells the entire throttle body assembly together for $1,200. Thanks to its extensive experience with Supras, UPFD in Westminster, Calif., came through for us with a factory throttle linkage that fit our polished throttle body. Then there was UPS' loss of our '98 headlights that we got from Champion Toyota a while back. We had sent them to Umnitza to get a set of its new "Angel Eyes" installed. But on their way to Kansas City, Miss., they got lost in Nebraska. Thankfully, we insured them and were covered. Another set was sent to Umnitza and was returned with the rings installed. All we had to do was connect the gray wire to the turn signal's lead wire.

With Umnitza's product in there we were even more excited to combine them with a set of 6000K xenons from HID Outlet, which match them perfectly. HID Outlet carries a plethora of applications for a variety of import cars. The HID kit for Supras uses the industry-leading Phillips Ultinon ballasts and come wired in a way that makes it virtually impossible to get wrong. The install takes about two hours if you're careful, and the lighting performance makes this upgrade definitely worth it.

Fast-forward to late 2007 and the car has been looking and running strong. We did find a couple of nuisances, however. The first was how tall our Sparco Siena seats turned out with the supplied brackets, which we couldn't even tilt fully forward because they'd come in contact with the roof. There was also barely enough room for our legs under the steering wheel.

This time we contacted Corbeau and got a pair of its CR1 high-density injection-molded, fully adjustable seats. They weigh 26 pounds on their own and 35 pounds with brackets, saving nearly 5 pounds per side over our previous setup. They're perfect, both in fit and in color, and only took about two hours to install. They're also fairly comfortable and at $349 per seat (plus brackets), extremely affordable. The CR1s come in your choice of blue, black, red, yellow, and gray and can be ordered with optional Microsuede or leather. Corbeau also offers a wider version of the seat.

The other issue was what could be a waning Third gear synchro, which wasn't an issue back in 2005 with the last motor. At first it was bad but as we put more miles on it, it's been getting a little better. Normal driving is ok, but speedier upshifts need a rev match for the time being.

Next came the fun part: tuning. Since the car's original AEM engine management system software was lost due to a laptop crash it was time for a fresh start. Having tuned my T66-turbocharged BMW M3 with the help of evosport tuning guru Gary Karamikian we had a good idea of how we'd start with this one. Still, in order to save time we looked at an experienced owner's base map to get an idea of what these cars like for ignition and what kind of engine noise the knock sensors pick up.

When it came to mechanical engine noise, our knock sensors told us we've got a loud car. Whereas anything over 0.5 volts would raise red flags on my previous BMW, at idle the Supra sees over that and creeps up to a whopping 4 volts at anything past 7,200 rpm-no matter how much timing we threw at it. Some other Supra maps we looked at were similar with engine noise while others were a little quieter with knock sensor activity.

Moving on, to tune knock control we filtered out engine noise by filling the fuel tank with 92-octane fuel and a couple gallons of 112-unleaded racing fuel. Then we brought all boost cells in the ignition map to 5 degrees advanced. Without turning up the boost from the minimum 13 psi from our HKS GT wastegate, we were confident we wouldn't see detonation. When we logged the runs and tried this again at 10 degrees across the board, we were relieved to see the sensors registering pretty much the same voltage for both runs.

After driving 1,500 miles on the new engine we wanted to get an idea for how the motor was faring with the SP71-GTS turbo kit, since it felt strong. For dyno testing we sent the Supra to Imagine Auto in Lenexa, Kans., a highly respected shop that specializes in turbo Porsches. The Supra was strapped to its Mustang Dyno for some shakedown passes in Third gear, and we were pleased to see just how well it responded to little advances in ignition timing.

On its first pass, at just 5 degrees of ignition, the car surpassed 400 whp at a registered 12 psi (without turning up boost we lost a psi on the dyno due to the lesser load the car sees on the road). By doubling the ignition to 10 degrees that figure jumped to 467 whp.

Prior to dyno testing we came up with an ignition map of our own during road testing, which at 12 psi starts at 15 degrees in the midrange and slowly ramps to 17 degrees on up to 8,000 rpm. It's also tuned to drop 2 degrees for each 2.5psi increase in boost. Some people have told us we can run more ignition but we chose to stay a little on the more conservative end and not press our luck, yet. Still, the dyno confirmed a satisfying 527 whp at 7,700 rpm at just 12 psi, with a fuel-rich 11.1:1 air/fuel ratio across the board. The number was still climbing to what would've been well into the 540s at 8,000 rpm, but the dyno software was told to quit registering past 7,700 rpm for that run.

It was clear that Amazon's headwork and Ferrea valvetrain, coupled with the SP71-GTS turbo, was significantly helping airflow. After all, we still have a 3-inch exhaust system, which we hope to change soon. These runs were done using inexpensive NGK R5671A-9 plugs gapped to 0.026 inch, which work beautifully.

Since we're testing in Third gear the torque wasn't high-the last run whipped up 380 lb-ft of torque at 6,500 rpm. In Fourth gear, however, previous experience on this dyno tells us that figure should be in the mid-400s at around 5,500 rpm. Not the torquiest car, but we're taking things a little slower in the beginning. We wanted to find out what that figure in Fourth gear would be but, as Murphy's Law would have it, that 526whp run also ended with a severed clutch. At redline a loud bang, followed by the car not going back into gear told us we were done for the day. The Centerforce single-disc clutch had been holding torque fine but it didn't like the higher rpm. We hope that this was the source of our transmission woes. We'll see.

If everything comes through we'll be replacing it with Fidanza's new twin-disc setup and continue testing a variety of power adders to the Supra. Next, with our new HKS 272-degree cams in there, we'll see what cam timing our engine likes by tweaking the AEM cam gears once again, followed by seeing how boost response is affected using both a manual boost controller and our AEM electronic boost control solenoid.

Author's Note: Special thanks to Thomas Sowell and Champion Toyota's continued help and support of this project, which would be nowhere without these guys.

Also, thanks to Bill Perkins from supraforums.com, who's tuned the Supra extensively over the years and was kind enough to send us one of his AEM maps to look at and get the ball rolling faster. He had no idea he was helping our project car, but was rather just nice enough to help.