Frank H. Cicerale
October 1, 2007

According to Jim D'Amore of JDM Engineer-ing, the fuel system is a needed quantity with the intercooler installation. In addition to upgrading the fuel system, D'Amore also swapped out the 32-pound injectors that came with the FRPP Super Pack for a set of short-style 48-pounders that are also found on the GT500. "We definitely needed to change the injectors," he says. "The ones that come with the 400hp kit are 32-pound injectors. Before we put in the fuel system that came with the kit, I had the fuel pressure set at 60 psi, almost double the stock setting, which is 39 psi. I had to raise the fuel pressure up that high because the injectors were too small. The 32s are good for around 360-370 rwhp, and we were making 380 rwhp before the intercooler."

We removed the 400hp kit's 3.875-inch blower pulley and the fuel rails from both sides of the engine. Make sure you have rags down to sop up any fuel that may come out of the fuel rails.

Knowing that the intercooler would allow him to maximize the timing and fuel curves of the engine due to a lessened chance of the powerplant running into detonation, D'Amore changed the injectors and the tune before the car hit the dyno. "We changed the injectors to the 48s that are found on the GT500 because they are good for around 500-550 rwhp," he says. "The new injectors, coupled with the FRPP fuel system, allowed me to keep control over the fuel system. The FRPP fuel system is a good one, for up to 700 rwhp if used correctly."

In addition to upgrading the fuel system, D'Amore also reworked the tune to take advantage of the added benefits offered by the intercooler. "The tune for the car is completely different than what it was before, especially in regards to the transmission," he says. "I changed the timing, fuel curves, and the cold-start function because of the intercooler. The car now has 18 degrees of timing and shows an air/fuel ratio of 11.8:1 at 6,000 rpm. Also, boost is now up to a peak of 12.5 pounds." The intercooler lowered the air charge, allowing D'Amore to run more timing without fear of running into detonation. Also, the boost level, which registered at 7 pounds without the intercooler, was safely raised to 12.5 pounds, thanks to the smaller 3.375-inch pulley (originally a 3.875-inch pulley).

Here, the size difference between the 400hp kit's 3.875-inch blower pulley (left) and the Big-Boost kit's 3.375-inch pulley (right) can be seen. The smaller pulley allows the blower belt to drive the supercharger faster, resulting in more boost and, ultimately, more horsepower.

With the kit easing the ability to make more power, getting the tune right is the key to making that power while keeping the powerplant from burning up. Also offered with the hardware for the upgrade kit is a voucher to get a calibrator with an FRPP-created tune. "When compared to the 400hp tune, the 500hp tuner is a totally new calibration," Kershaw says. "The biggest difference is the strategy for the electronic throttle control. We're able to open it up more and fully utilize the blower's potential without having to worry about charge temp or fuel delivery."

Of note, though, is that this kit is recom-mended for S197 cars that have a manual gearbox slung in the trans tunnel. "The intercooler itself isn't the problem with the automatic cars; it's actually that we do not feel confident that the automatic will hold up at the 500hp level," Kershaw says. "At 400 hp, we feel confident that the trans will hold up. We worked with the transmission calibrators at Livonia transmission, which did long-term testing at the 400, 450, and 500hp levels with the 5R55S transmission. Our findings were that at 400 hp, which does not require an intercooler, the trans held up with our revised calibration. At 450 and 500 hp, it wasn't instantaneous failure by any means, but we didn't feel confident offering the kit knowing it will fail beyond the warranty period. We only sell the kit currently with a calibration for the manual trans. We may offer it for the automatic in the near future, but we will require the customer to agree to terms that they are aware that the life of their transmission will be severely limited."