exhaust question
#31
Well you can't really tune a store bought set of headers, you have to custom build them to a very specific length and each tube has to be exactly the same length.... this can only be done with long tube headers.
No, it won't produce the same power, and you can seriously harm an engine if you run open heads with no headers or manifold on it. Besides, what makes you assume there is no backpressure when you run open heads?
What most people don't get is that chaos creates backpressure, and the whole idea behind headers is to control the exhaust flow so there is no chaos. Even shorty headers control the flow way better than an exhaust manifold, where all the exhaust is dumped into an open chamber. Another common misconception is that bigger exhaust pipes reduce backpressure. An exhaust system can be too big a diameter for the amount of exhaust that is flowing through it... thus creating chaos in the flow pattern.
No, it won't produce the same power, and you can seriously harm an engine if you run open heads with no headers or manifold on it. Besides, what makes you assume there is no backpressure when you run open heads?
What most people don't get is that chaos creates backpressure, and the whole idea behind headers is to control the exhaust flow so there is no chaos. Even shorty headers control the flow way better than an exhaust manifold, where all the exhaust is dumped into an open chamber. Another common misconception is that bigger exhaust pipes reduce backpressure. An exhaust system can be too big a diameter for the amount of exhaust that is flowing through it... thus creating chaos in the flow pattern.
Last edited by 95_318SLT; 09-01-2009 at 01:21 AM.
#33
ok i know from my personal expierince when i ran a exhaust that i built with *******ly no backpressure it actually made the engine run rougher in a quarter mile then i bought a professionally tuned exhaust with a good amount of backpressure not a lot but like the perfect amount and in the quarter i ran better so i would always recomend a little backpressure
#34
What I want to know is how do you know there was backpressure? Did you measure it? My next door neighbor back in his drag racing days had a camaro with a built 540 big block stroker that he built a set of headers for with the purpose of producing a vacuum at the collector... i.e. no backpressure. This engine pushed out 860 hp naturally aspirated.
When the exhaust ports are closed on any given cylinder during intake, compression, and power strokes, the exhaust having backpressure or not has no bearing on whats going on in the motor. It won't effect how the gas is sucked into the cylinder, and it won't effect how the gas is compressed or ignited, the only thing that matters is during the exhaust stroke how the gas gets out. Tell me why you think a piston having to work harder to push out that cylinders exhaust because the pipes have backpressure is a good thing?
When the exhaust ports are closed on any given cylinder during intake, compression, and power strokes, the exhaust having backpressure or not has no bearing on whats going on in the motor. It won't effect how the gas is sucked into the cylinder, and it won't effect how the gas is compressed or ignited, the only thing that matters is during the exhaust stroke how the gas gets out. Tell me why you think a piston having to work harder to push out that cylinders exhaust because the pipes have backpressure is a good thing?
#36
I also agree with your second point. Like I said earlier in this thread, you won't notice the difference in daily driving.
#37
Removing a cat is a Federal offense in the US regardless if you have emissions or not and the fines aren't cheap. You will gain hardly anything by removing it, especially on a 3.9 and you can make your exhaust plenty obnoxious while keeping the cat. Straight pipes sound awful on most engines, inlcuding V8s, do everyone a favor and get a good muffler. Any tool can make an exhaust loud, making it sound GOOD is another story.
#38
#40
You can get "summit brand" (actually pacesetter) headers from summitracing.com for $154.95. You may be able to find something cheaper on ebay though.
http://www.summitracing.com/search/D...?Ns=Rank%7cAsc
http://www.summitracing.com/search/D...?Ns=Rank%7cAsc