Re: Headers & exhaust
About exhaust systems in general. When I was racing the quarter mile, we did many test on exhaust systems. We discovered that the biggest exhaust system is not always the best system as far as making power. 3 inch dual exhaust system is for cars making tons of power.. lets say 600 hp or more. big inch pipes will move more exhaust out but if you dont have the power, it will kill your torque numbers too. LT5's are not known for there torque so cars that are not stroked to a bigger size or heavily modified will suffer in the low end big time. I had a 468 cube Corvette that I decided to put full competition side mount headers on it and even after a fresh rebuild I lost torque compared to my stock exhaust manifolds. I should have bought the regular competition header which were smaller and created some back pressure to maintain good torque numbers. I finally decided, since those exhaust cost me so much money, to change the rear gear to a 3.55 from a 3.08 diff to try to make up for the torque that I was losing.
On the other hand, on my 1200 hp mustang I had 4 inch exhaust dumping to 5 inch supertrapp mufflers. That car had to have that kind of exhaust but I dont think our zr1's will benefit much with 3 inch exhaust and will lose a certain amount of torque. I would imagine that on big inch 415 cube lt5's it would work good but on the rest I would bet it would not work as good as 2.5 inch exhaust. Of course if you put cats on anything you are destroying top end and torque numbers. If all you require is a visual the hollow out the cats. One 3 inch pipe flows more than 2 2 inch pipes for example. 2 2.5 inch pipes is just what the doctor ordered on most of our torqueless cars. Our cars are rpm horsepower makers and everybody knows that torque always wins on the street. I would not sacrifice any of my torque just to put a bigger pipe and maybe some more peak horsepower. By the time you get to your peak power at 7200 rpm... the race is over.
fyi.
ed ramos #3028
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