Why only 3" exhausts
12-31-08, 04:10 AM
#2
why must you ask these questions? na jk.
Well first you gotta understand how to achieve horsepower with a turbocharged system. If you did then your question would be pointless.
Basically in a turbocharged system, maximum boost levels are reached faster when their is the least amount of backpressure. It also creates less stress on the turbines themselves which makes them more efficient and last longer.
And no, 3' isn't excessive anyways because the FD flows alot so that exhaust needs to get outta there asap. As a smaller diameter exhaust increases backpressure it decreases max hp capability, it also generates more heat, which is the rotary's worst enemy.
Well first you gotta understand how to achieve horsepower with a turbocharged system. If you did then your question would be pointless.
Basically in a turbocharged system, maximum boost levels are reached faster when their is the least amount of backpressure. It also creates less stress on the turbines themselves which makes them more efficient and last longer.
And no, 3' isn't excessive anyways because the FD flows alot so that exhaust needs to get outta there asap. As a smaller diameter exhaust increases backpressure it decreases max hp capability, it also generates more heat, which is the rotary's worst enemy.
12-31-08, 04:32 AM
#3
3" is the SMALLEST for the FD, its stock size is 3" unlike the FC which is primarily 2.5" up until the y-pipe.
The fact that your using the term EXCESSIVE mean your probably not big on noise in which case you need to buy the Racing Beat dual tip cat-back system, its amazing.
The fact that your using the term EXCESSIVE mean your probably not big on noise in which case you need to buy the Racing Beat dual tip cat-back system, its amazing.
12-31-08, 10:42 AM
#5
Original Gangster/Rotary!
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I'm running a 4 inch turboback on my 500R 67mm single turbo 
For the size of the compressor wheel I get very good response and great spool up, if I floor it cruising at 3k rpm I see 15 psi by 3400-3700 rpm depending on what gear I'm in......it's a more responsive setup than my old non-seq BNRs (keep in mind also a much more expensive setup).
For the size of the compressor wheel I get very good response and great spool up, if I floor it cruising at 3k rpm I see 15 psi by 3400-3700 rpm depending on what gear I'm in......it's a more responsive setup than my old non-seq BNRs (keep in mind also a much more expensive setup).
12-31-08, 01:05 PM
#7
I'm running a 4 inch turboback on my 500R 67mm single turbo
For the size of the compressor wheel I get very good response and great spool up, if I floor it cruising at 3k rpm I see 15 psi by 3400-3700 rpm depending on what gear I'm in......it's a more responsive setup than my old non-seq BNRs (keep in mind also a much more expensive setup).
For the size of the compressor wheel I get very good response and great spool up, if I floor it cruising at 3k rpm I see 15 psi by 3400-3700 rpm depending on what gear I'm in......it's a more responsive setup than my old non-seq BNRs (keep in mind also a much more expensive setup).
what about in 4th gear? at what rpm do you get full boost cruising in 4th?
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12-31-08, 08:07 PM
#8
My brother got a 3" for his evo and its to loud, plus cops around here hate Japanese cars, and would love to pull me over. Is the stock system really 3", does a rotary motor need more exhaust flow than combustion motor?
I read maximum boost by Corky Bell and it says 3" is way too big for under 400hp.
I read maximum boost by Corky Bell and it says 3" is way too big for under 400hp.
12-31-08, 08:11 PM
#9
3" is the SMALLEST for the FD, its stock size is 3" unlike the FC which is primarily 2.5" up until the y-pipe.
The fact that your using the term EXCESSIVE mean your probably not big on noise in which case you need to buy the Racing Beat dual tip cat-back system, its amazing.
The fact that your using the term EXCESSIVE mean your probably not big on noise in which case you need to buy the Racing Beat dual tip cat-back system, its amazing.
01-01-09, 12:57 AM
#20
01-01-09, 01:13 AM
#21
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That is the same book that gave most of us the idea that water injection into a turbo system was anathema to good design. Informative book for sure, but don't take everything in it as gospel.
01-01-09, 05:41 AM
#23
hmm, that doesnt really make sense, I would think horsepower would be horsepower regardless of the type of engine. It doesn't mention anything about engine type, or the amount of cylinders having any effect on flow. Anyone want to elaborate how a 300hp rx7 flows more exhaust than a 300hp v6? I guess it is different though
Also if that were true, wouldnt that mean the rotary has to flow like twice as much fuel and air as a regular combsution engine to make the same power?
Also if that were true, wouldnt that mean the rotary has to flow like twice as much fuel and air as a regular combsution engine to make the same power?
01-01-09, 07:26 AM
#24
Back to your question.....a 3" exhaust isn't excessive. As others have said, it's standard. A downpipe, high flow cat and quality cat-back and you shouldn't have problems with noise levels. Header-wrap will also tends to quiet things...a little. We also have factory forced induction, with a chassis design that pretty much prohibited the dual exhaust found in the FCs. Maybe that's why they were designed with a relatively large bore. And then I've seen arguments that this is really a 2.6 liter displacement motor too.
And it's not the Cop's dislike of Japenese cars. More like a rationalization for how they're driven that causes issues. But that's a subject for the lounge, not here.
And it's not the Cop's dislike of Japenese cars. More like a rationalization for how they're driven that causes issues. But that's a subject for the lounge, not here.
01-01-09, 08:31 AM
#25
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My brother got a 3" for his evo and its to loud, plus cops around here hate Japanese cars, and would love to pull me over. Is the stock system really 3", does a rotary motor need more exhaust flow than combustion motor?
I read maximum boost by Corky Bell and it says 3" is way too big for under 400hp.
I read maximum boost by Corky Bell and it says 3" is way too big for under 400hp.
Cops in so cal don't hate japanese cars, and don't pull everyone over.