Wailing at full throttle,...
Wailing at full throttle, the new manifold and carb setup finally broke us over the 300hp mark, and did it handily by posting 311 hp. It looked good, too.
Our 1.75" Hedman headers merge...
Our 1.75" Hedman headers merge into a single 3" exhaust system with a 3" catalytic converter, and it showed a load of back-pressure, registering nearly 6 psi when we gauged it. Pushing against that kind of resistance will cost plenty of power. To find out how much, we uncorked it and suddenly had 326 hp at the tire (+15 hp). So much for the muffler-man's wive's tale that an engine needs back pressure to make torque. We were up everywhere.
Adding a 1" spacer really...
Adding a 1" spacer really helped when we tuned the old induction combo, but it added hardly anything with the bigger carb and Air Strike intake. One extra horsepower was hardly enough to register, but it did hang in there longer up top.
PHR Chassis Dyno Test * SuperFlow Chassis Dyno * Tested At Westech
The Weiand Air Strike/Holley 750 HP induction system was worth plenty of power from the low end of our test range all the way to the top. With open exhaust, the induction really turned on, but even through a single exhaust with a cat-con, we had a substantial gain. Note that we are peaking fairly low in the rpm scale-below 5,000 rpm. Considering that the bottom end of this engine is built to be rock-solid dependable to over 7,000 rpm, there is still a huge amount of power remaining to be tapped. We probably won't build it up to that kind of rpm range, but even another 1,000 rpm can add serious numbers to the power curve. After a new exhaust, there may just be a cam change in our future.