3 inch > dual?
#1
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3 inch > dual?
I just got my tII... it has an hks exhaust, but people tell me i should go with a 3 inch? Im assuming, 3 inch > dual? Is this true?
#4
The Cause of Death
LOL! Way to be helpful.^^
When these "people" tell you to go with a 3" exhaust, that's usually from the downpipe back. RacingBeat's REV TII exhaust system is 3" from the downpipe to thepresilencer, and I think it splits off to a little larger than 2.5" from the y-pipe back to dual mufflers. Some people also go the 3" downpipe to muffler to 3" catback route.
James
When these "people" tell you to go with a 3" exhaust, that's usually from the downpipe back. RacingBeat's REV TII exhaust system is 3" from the downpipe to thepresilencer, and I think it splits off to a little larger than 2.5" from the y-pipe back to dual mufflers. Some people also go the 3" downpipe to muffler to 3" catback route.
James
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#13
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If you run a 3" from the manifold to a 3" Y inlet that goes to two 2" pipes you should be just fine, two 2.5" if you want to go crazy. Personally, I hate the way tailpipes look on the '7 if it's bigger than 3 actual inches, and in many cases it's like 4 or 5 inches. I'd think you could get good performance out of a free flowing system without having the extra weight of a dual 3" versus dual 2.5".... idk, it's up to you, but ditching the cats will do you tons more good than going to dual 3" instead of dual 2.5", and if you're talking single exhaust, yeah, you'll save more weight, but I won't get into that because I think the '7 looks terrible with single GIANT exhaust, which is what most people do with it...
#14
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I'd think you could get good performance out of a free flowing system without having the extra weight of a dual 3" versus dual 2.5"....
#20
Rotary Freak
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its touche... spelled just like douche
Just messin, but yea, the only reason for going with a single all the way back vs a dual would be weight vs asthetics. I have a 'vert, so its already heavy as hell, so i just went with the RB duals (got them for the car when it was NA, its now turbo, but im still running the NA Y-pipe and mufflers, no cat and no money to replace)
As for the flow, just look at the cross-sectional area of the pipe in each part (not too precise, but close enough). a 3" ID pipe will have an area of (3/2)^2 * pi = 7.07 sq in. Two 2" id pipes will be 2* (2/2)^2 * pi = 6.28 sq in. However, the exhaust doesnt flow through the entire cross section evenly. There is a boundary layer along the pipe wall thatis stopped, and it slows down the gas further inward. The profile looks like:
____________________________
____________________________
................''--,
......................';
......===>.........|
......................;'
................,,--'
----------------------------------------------
---------------------------------------------
so the center section flows a lot better than the rest of the pipe. Thus, even for a 2 pipes (2.25") that have the same cross-section as a 3" pipe, the single 3" will flow better.
Just messin, but yea, the only reason for going with a single all the way back vs a dual would be weight vs asthetics. I have a 'vert, so its already heavy as hell, so i just went with the RB duals (got them for the car when it was NA, its now turbo, but im still running the NA Y-pipe and mufflers, no cat and no money to replace)
As for the flow, just look at the cross-sectional area of the pipe in each part (not too precise, but close enough). a 3" ID pipe will have an area of (3/2)^2 * pi = 7.07 sq in. Two 2" id pipes will be 2* (2/2)^2 * pi = 6.28 sq in. However, the exhaust doesnt flow through the entire cross section evenly. There is a boundary layer along the pipe wall thatis stopped, and it slows down the gas further inward. The profile looks like:
____________________________
____________________________
................''--,
......................';
......===>.........|
......................;'
................,,--'
----------------------------------------------
---------------------------------------------
so the center section flows a lot better than the rest of the pipe. Thus, even for a 2 pipes (2.25") that have the same cross-section as a 3" pipe, the single 3" will flow better.
Last edited by toplessFC3Sman; 06-13-07 at 08:35 AM.
#25
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Mufflers in parallel (duals) are not necessarily quieter. Two mufflers in series would quiet the car down a lot more.
Topless, you have to be an engineer (or really liked physics in school.)
Topless, you have to be an engineer (or really liked physics in school.)