exhaust?

[B16aJWHO]

I am putting a t3 turbo on my b16a with stock internals and i am planning on running 7-10 psi. what size piping should i use on my custom exhaust?

 

[swanny]

3 inch or if ya wanna be stealth keep the stock exhaust and put a cut out on it

 

[LSTurboCivic4DR]

I would run a 2.5", that should be good enough for the T3. I dont see a need for a 3" and there hard to fit also. If you want the 3", Thermal sells a good 3" system prefabbed for you car, and if you upgrade later, it would save some money insted of buying 2 exhausts. Look at what your overall goal for the car are. If you plan on running more boost later or a bigger turbo, spen more on the 3" now, if you are going to run light boost with that turbo for good, go 2.5", its plenty of flow.

 

[posol]

2.5-3"

 

[InsaneCivicSedan]

3" mandrel = quickest spool

 

[preluderjs]

Is that right? Cuz the idiot i bought my car from has piping that i believe is 3" and the throttle response sux and takes longer to spool than I think it should.... but then I do have a tiny turbo too. Is a T3 that much larger than a K03?... anyone have any idea at all?

 

[posol]

the exhuast can only be as effective as the downpipe coming off the turbo. most kits use a 2.5 DP. turbos hate backpressure, and thats why the larger exhaust gives more power.

there's a lot more to spooling a turbo than exahust size...

proper manifold design that keeps backward flow out of the head
gas flow to spool it in the first place
post detonation
eld's
overall size
motors displacement/cfm of air flow pushing out
VE
and so much more

 

[preluderjs]

Would the slightly smaller exhaust help at all though? My turbo is incredibly small... and my "effective" downpipe has a hole in it for now and when I noticed the throttle response. + everything else is stock on the car.

 

[posol]

smaller does NOT help at all in any way. some peeps are stepping to 3.5" downpipes and 4" exhausts on their high power-ed cars lately

 

[SolReaver]

Originally posted by preluderjs@Nov 19 2003, 07:03 PM
Would the slightly smaller exhaust help at all though? My turbo is incredibly small... and my "effective" downpipe has a hole in it for now and when I noticed the throttle response. + everything else is stock on the car.

um, no. Think about it. If there is backpressure (restriction) in the exhaust, thats restricting the turbo from spooling up. Remove that restriction and see the turbo spool faster, thus making more power faster

note how when peeps run open downpipe they gain 95 whp as compared to with an exhaust

 

[preluderjs]

Ok, that all makes a lot more sense and it should actually help my spool time... but I'm still not sure about throttle response: I mean specifically how long it takes the engine to respond to input. If I'm just a dumbass and it has nothing to do with exhaust size just say so.

 

[TommyTheCat]

A lot of people are saying 2.5" is fine up to something like 300-350hp*. Then you start switching and moving up towards 4"(Which is ungodly large, 1000+ supra need apply only).

Going with a a 2.5" versus a 4" for a t3, I hardly think you'll see an increase in low rpm boost.

*This is reflective of turbo choices for the power range. I.E. not a T78 or GT40.