preludesh07

i need an opinion. im ordering the revhard turbo kit from afterhourz for my SH.
I currently have a greddy evo exhaust (2.25in piping) just put it on like a month ago. my question is, the kit comes with a 2.5" DP then i have a stock cat and then the evo cat back, will this be too constrictive for my FI set up (7psi)? and if so, what problems will i run in to? too much back pressure causing slower spooling?

I did use the search forums before i asked this so dont yell at me just yet.

thanks

 

phayze one

I'm thinking that will be too small. You will probably want to customize some 2.5" piping and get an apexi n1 muffler or something similar.

NtPReLuDe

you won't make as much power thats for sure. If thats not a problem then you're set

ziggity

get a brullen exhaust or get the custom piping form this place

http://www.accordinglydone.com/store...hp?cPath=21_27

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20th anniversary Prelude SH Turbo'd

sharkcohen

In my experience with my JRSC, a 2.5" downpipe mated to the stock cat and exhaust increased apparent manifold pressure (causing detonation, had to retard timing) and dropped midrange performance. When the exhaust is smaller in diameter than the downpipe, the exhaust becomes a bottleneck. I highly suggest a custom 2.5" exhaust. The stock exhaust is only 2" in diameter!

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preludesh07

I already have an evo exhaust (2.25") as stated above so im not running any 2" exhaust. Also when i bought my new exhaust i noticed it was the same diameter as the other cat-back (the one i took off) which seemed strange to me, however my car was totaled before i bought it (this is the reason i have a 12gal fuel tank also) so i wasnt too surprised.
On a side note, my Evo exhaust bolted straight up to the flange on my catalytic converter which means it is also 2.25", does anyone know the outlet size of the stock cat?

Enhanced

So Shark, what you are saying is that a 2.5 downpipe isn't a good idea because it may cause detonation even with a 2.5 custom exhaust? I am looking into getting a 25inch piping job done with stock cat and AC Revolution exhaust, how is that for a FI set up?

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Joe

2007 Brilliant Red Audi A4 2.0T Quattro S Line - Leased

sharkcohen

Huh? No, I said that a 2.5" downpipe performs poorly with a smaller diameter exhaust, at least in my experience. I was able to stave off the detonation by adjusting the timing. I think it is best to run an exhaust equal to or larger than the downpipe.

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sharkcohen

Woops, my bad, I did read that, but wasn't thinking when I posted. Still, you would be better off with a 2.5" exhaust, or perhaps larger (including downpipe) depending on how much boost you plan on running. The EVO was not designed with FI in mind (and it is 60 mm, not 2.25", by the way).

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preludesh07

so i suppose the conclusion would be that a 2.5" exhaust (with 2.5" cat) would be better with my 2.5" DP at 7psi. however, i am planning on upping my boost someday and seeing as i just got my evo (now gonna have to resell) i think im gonna go straight to 3" exhaust to save me the hassle of redoing my exhaust a 3rd time like i would if i got a 2.5" now.
will 3" cause too little back pressure at 7psi?

buh_buh

No need for backpressure if your FI

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preludesh07

yeah i realize that but doesnt too large of exhaust piping cause blow by or is that something different?

MugenPoweredLude

so then why do some people run 3" exhaust and some run 2.5"???

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-Anthony- PSN/Xbox Live GT: Evoking1230
2005 EVO VIII-SOLD/R.I.P.
2000 Honda Prelude SH - Gone But Not Forgotten

ziggity

hell buscher racing as a 3.5 inch exhaust for DSM and the turbo outlet is 2.5 IIRC but most people decide on the exhaust size from how much boost they will be running and the DSMs can withstand some crazy pressures hence the 3.5 inch exhaust

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20th anniversary Prelude SH Turbo'd

MugenPoweredLude

so the higher the boost the bigger the piping....say i were to push i dunno ~15-20psi(just for example sakes) it would be good to have 3"???

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-Anthony- PSN/Xbox Live GT: Evoking1230
2005 EVO VIII-SOLD/R.I.P.
2000 Honda Prelude SH - Gone But Not Forgotten

sharkcohen

Yes.

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preludesh07

so there will be no ill effects by having a2.5 or 3" exhaust at 7psi correct? and if thats true then i should just get 3 so when/if i up my boost i will have neccessary piping right?