As promised yesterday, here are the modifications we made to our customer's GT, so far. First, this is a street car, not a race car. Nothing we have done in anyway infringes on it's streetability or driving comfort.
The first order of business was to put the GT on the chassis dyno (at Westech Performance, almost next door to our facility) and find out where we were starting from. The HP was 550 at 6400 RPM, pretty much as advertised.
We mounted an all-billet supercharger overdrive unit on the front of the blower. This increased the boost from the OEM 12# up to 18#. Obviously we could have gone higher but the customer lives here in California and our gasoline is a little iffy with higher cylinder pressure. Next, we bolted on our new (not yet in full production) dual-inlet 75MM throttle body in place of the OEM 70MM unit. Even with the stock blower ratio and OEM TB, we noticed that the hose in front of the TB (the black corrogated unit going from the air inlet to the TB) would collapse at 6000 RPM from too much vacume. This is not easy to see since we had to have the car running at full throttle on the rollers with the hood tilted up, leaning over the engine (almost life threatening in itself, LOL). We spent $14,000 having a mold made so that we can duplicate the plastic sleeve we used that fits tightly on the inside of the hose. This problem vanished. Next, we added the Borla exhaust and finally, we played around on the computer with the SCT flash system to come up with a reasonable "street" tune-up. The HP went up to 710 at 6500 RPM with these mods.
Motor Trend magazine used this GT to do some standing 1-mile tests, with about 7 or 8 other "super cars". In OEM trim, the stock GT did the standing mile at 171 MPH (no ET's). Our customers GT, and after the mods, 194 MPH. At the end of the day, after all of thetestes, only two cars were still standing. Our customer's GT and a Hennessy Viper. The Viper was an all-out twin turbo RACE car with race tires, lightweight body components, full roll cage, etc. It did run over 200 in the mile. The GT was totally street legal, with OEM tires, stock clutch, etc. Hell, during these M-T tests, when we took a break, we drove it over to the resturant and had lunch about 20-miles from the test facility. The furthest that the Viper went was back in the trailer.
Anyway, we will be offering these modifications in some kind of a kit some time soon, or folks can just get what they want seperately.
Our customer is an adventurous guy. We just picked up another GT block and crank for him and we are going to go "twin turbo" on this engine. It seems that he wants to hunt up a certain Hennesse Viper. We are looking for a straigh 1000 HP on the chassis dyno for this street GT.
BTW, talking about horsepower, in our Cougar Pro 5.0 car, the twin turbo 4.6L 4-valve Cobra motor (281 cubic inches) is putting out over 1800 HP at 9200 RPM on the engine dyno, on gasoline, and at "only" 45 pounds of boost, LOL. That's about 6.4 horse per cubic inch.
