As expected, the only drawback from installing the larger intercooler is the slightly longer time it takes to fill the core, which contributes to turbo lag. However, it was only less than 100 rpm slower to react until the second turbo came online.
One thing we realized with these last dyno runs was that Project Supra is maxed out at about 370 whp on California's crappy 91-octane pump gas. In order to see what our end results would be with the stock turbos we added a few gallons of Sunoco 112 octane racegas to the mix. With what is now approximately a 94-95-octane gas mix, the EMS-controlled wastegate was set to stay closed a little longer. To our surprise, the turbos wouldn't boost manifold pressure past 17 psi. Karamikian adjusted the timing a bit and was able to coax out a maximum of 395 whp and 376 lb-ft of torque.
Our numbers may sound a bit on the low side when considering other Supra owners have seen over 400 whp at similar boost levels with the stock twins. However, a quick check of our compression told us something was wrong in the #4 cylinder, which was down nearly 40 psi. Couple that with a nearly 100k mile engine/turbos and you can see why the power drop is possible.
(Horsepower): new Baseline,...
(Horsepower): new Baseline, 16 psi (Blue); Turbonetics intercooler, 15 psi (Red); Turbonetics intercooler, 16 psi (Green). All third gear runs on 91-octane fuel. We couldn't get a good tach signal so we had to resort to plotting against MPH in order to get the baseline to show its peak hp figure.
(Torque): new Baseline, 16...
(Torque): new Baseline, 16 psi (Blue); Turbonetics intercooler, 15 psi (Red); Turbonetics intercooler, 16 psi (Green).
(395 whp graph): In the end...
(395 whp graph): In the end our arthritic engine came up with 395whp on a fourth gear pull. At 17 psi this isn't too bad considering we have an ill #4 cylinder and our relatively old engine and turbochargers. But the turbos are out of lungs. This is as good as it will get...for now.
So where does this power drop lead us? Whether it's a bad valve or a bad piston ring in the #4 cylinder, it won't matter for long. The entire engine will be undergoing surgery and receiving much stronger internal organs at Speed Force Racing. By the time you read this we'll hopefully have the tuning done and the car dyno tested with its new lungs-an SP71-GTQ turbo kit from Sound Performance. Yes, it's going to get a lot more fun now. Stay tuned.
Author's note: At this year's Hotchkis Media Challenge our Supra DNF'd during its second run on the dragstrip when trying to slip the clutch during a 6000-rpm launch. The disc seized to the flywheel and the car wouldn't run once put into gear. We replaced the unit with another Centerforce unit, which we will be testing the torque limits of with our new setup, as well as a Fidanza lightweight flywheel. Special thanks to RJ and Matt Hunt of UPFD for taking the car in on a Friday evening and having it ready the following business day.
According to Calicchio, many...
According to Calicchio, many companies make intercooler kits with piping going from the intercooler to the throttle body that doesn't perfectly fit around the A/C lines. The Turbonteics kit fits perfectly.
Eosport's Gary Karamikian...
Eosport's Gary Karamikian was once again in charge of tuning the AEM EMS. As you can see, tuning on the road under the Southern California sun can sometimes necessitate conjuring up new ways to view a laptop screen.
Shortly after the intercooler...
Shortly after the intercooler tests, UPFD installed a Fidanza flywheel. At over 20-pounds lighter than our stock 36-pound flywheel, the car revs faster in the top end. Enthusiasts concerned with off-the-line performance may want to keep the heavier flywheel to more effectively launch off the line. An engine with a lighter flywheel such as this helps revs climb with much more ease once the car is already in motion. A lighter flywheel also aids in heel-and-toe rev matching during downshifts-something road racers prefer. Made from 6061 T6 billet aluminum with accompanying Grade-10 aerospace fasteners and a replaceable 1050 steel friction surface, this flywheel is a great bang for the buck. Just make sure to raise the idle a couple hundred rpm to avoid engine stalls at a traffic signal.