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I'm going to complain now, so if you don't want to hear it, skip over this post. This is a complaint in general, it is NOT directed towards anyone.
I don't understand why people keep talking about "backpressure" and exhaust systems.
I don't know which moron with a V8 back in 1962 started it, or why people keep poisoning fresh young minds with this crazy explanation of how an internal combustion engine's exhaust system works, but it has to stop!
I've actually written about this, it's on my friend's web site. I think it's a good explanation, here's the link
http://ruesparadise.com/HTML/Exhaust.htm
BTW (shameless plug here) he does some good vinyl graphics work, so check out his site
But, here's is what I am basically saying in the article. Backpressure means NOTHING!
The only thing that matters is VELOCITY! Exhaust gas velocity! The faster the exhaust gasses are moving, the more power your car will make, PERIOD! Actually, it's the same thing with the intake too. The faster you can get the air into the engine, the more power you will make.
It doesn't make a difference if you can get an engine to run on buckshot and chicken shit, the faster you can get the buckshot and chicken shit through the engine, the more power you will have.
Having too big of an exhaust pipe, too big of an intake manifold plenum, too big exhaust ports will cause your car to run like shit and have no power. It can also cause hesitation, bad gas mileage, and poor drivability.
A small exhaust pipe lets a small amount of gas flow quickly, and slows down a large amount of gas (that's easy for most people to understand, think a 5.7L V8 running at 6000 rpms with a 1 inch exhaust pipe, it wouldn't run too good)
Now, with a large exhaust pipe, if you are only putting a tiny amount of gas flow into it, that gas will slow down! This means less power.
Now, this means a car with a tiny engine and a huge exhaust will not run right at low rpms (or maybe not at all). It isn't due to "backpressure" at all, it's due to slow exhaust gas velocity at low rpms.
Just check out this exchange we had on the message board
http://www.2gnt.com/dcforum/DCForumID13/3333.html
Saberkahn and I are saying the exact same thing. It is in regards to head porting, not exhaust, but the principle of air velocity applies to both intake and exhaust. Eclipse804 saw major drivability and power problems becasue the head on his car was ported too much.
Right now in some nascar cars (I think it was nascar) the V8s being used have the same size, or SMALLER ports than the factory stock heads! This is to keep the exhaust gas velocity up and get them more power.
"Tutto fa brodo."
Todd Scungio
98 RS
15.173 @ 90.70 MPH
And also a 2011 Ralliart
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