Hey every one,
Well my names Mike, I am 17 and pretty soon im getting an 86 Iroc z28.. And tonight I was talking to a guy that use to have one and he told me that instead of duel exhaust that I should have a dule set up then go into a 3 inch since tip, he said it adds back pressure and better flow, and adds better hp gains,

so i was wondering if this is a ligit set up and it anyone has tried it thanks

 

"duel exhaust that I should have a dule set up then go into a 3 inch since tip"


was that english??

for a stock or bolt on TPI motor, you don't need a true dual exhaust. there just isn't enough flow requirements to warrent it.

running a Ypipe, into a 3" single pipe back to the muffler will produce enough flow to support your engine. many guys in the 4th gens are running 400hp through that setup with minimal losses.

i've heard that TPI motors like backpressure to produce torque...but i'm not sure how founded this is.

 

Yes, a y-pipe will do fine. As for the back pressure theory, its totally false. Adding back pressure always hurts performance. This theory probably got started when people realized that sometimes smaller diameter header primaries would produce better power. This is due to increased exhaust gas velocity and in return a decreased pressure due to Bernoulli's principle. The increased gas velocity only helps with power up until you try to force more gas through the pipe than it can easily handle, in which case the back pressure builds.

 

I agree with what's been said. True duals is pointless, and a 3" pipe after the y-pipe is a good idea. It will handle more power than you will probably have. If I remember right it can handle somewhere around 450 hp before it adds back pressure.

"he said it adds back pressure and better flow, and adds better hp gains"

That is a load of junk. Like 91-Z28-L98 said, back pressure will always hurt your performance. What is needed is scavenging. That means the gas that is coming out is pulling out the next set of exhaust gasses, and frees up power on the piston so it doesn't need to work as hard to push the gas out. A lot of people put x-pipes on their true dual set ups for this reason.

 

you would see a power loss in a 305 if you went a 1 3/4 tube header,

but single 3" is more than enough for most systems,

and all the bends required to do a true dual setup is fairly restrictive,

its all about matching your system,

its not always the bigger the better