467-Ratman

My JC whitney side pipes are on finally and tomorrow its going to the muffler shop to hook them up. My question is will I need to adjust my carb because of the increased back pressure? My old mufflers had very little back pressure and I was running 2.5inch pipes. Thanks for the help and tomorrow I will take some pictures!

Smokehouse69

Don't bet on less back pressure with the side pipes, I believe the JC Whitney/Dynomax side pipes have glasspacks that are sort of restrictive. One of the guys a couple of years ago put them on his SBC and pulled them off and went with Hooker's with spiral baffles when he went to a Big Block in the car.

stingraymaniac

nope there are not glasspacks in them.

NHvette

I was under the impression that the tubes had inner/outer tubes with
fiberglass absorber material - glass packed.

In any event, I think you'll end up about the same restriction.

The resistance of the pipe alone increases with length - and decreases with
cross-sectional area.

2.5" pipe --> area=4.91 sq. in.
2.0" pipe --> area=3.14 sq. in.

Assuming no bends, a 6 ft piece of 2" pipe has same restriction as a 10 ft piece of 2.5" pipe.

It gets more complicated than that, when mufflers and bends are added - but
you get the point. I think they will be close to the same.

:seeya

stingraymaniac

there are a innner outer tube but its only penetrated with some holes that are the
silencer i think
couldn´t see anything in the holes on my pipes but i can be wrong
i shall mount mine this weekend