hey guys i have a 01 sh and right now i have aem cai, dc header (soon to get smsp heaer), random tech high flow cat, and greddy evo 2 cat back, and aem pulleys. Just wondering since im going to get th smsp header should i get a 2 and a half inch exhaust for my flow and power to be better or is there not much of a difference and im fine where im at? thanks guys

 

All the research I've done says the 2.5 is the proper size for the H22. I'm running a Greddy Evo 2 off an RSX with 2.5 inch custom pipe.

 

have you noticed that some exhaust companies like rsr, invidia and apexi from japan use 60mm tubing which is like 2.33 inches I believe

 

add greddy and hks to that list

 

I just got a 5zigen fireball, and the piping is 2.5 inches all the way no bottle necks or anything, just 2.5 all the way, and supposedly this is what you want with the H22

 

i quess it would depend on if you were going for a diffrent sound, or going for speed and haveing a alot of good bolt ons. if ur just going for sound why spend all that cash, 2.25 systems are cheaper in most cases. if your gonna try and get more power out of it, i would go for the 2.5" systems, they cost a little bit more but there worth it with the right set up.
i have a 2.25" system no bottle necks and it sounds good, i really cant tell a diffrence in the car, except mabey it feels like its not working as hard.. i dont feel much of a power gain.(but i only have the exhaust with a stock airbox and no upgrade on a header)

 

just to note the 60mm converts to about 2.38 or so, and .12 of an inch will not make much difference.....

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by mgags7 &raquo;</TD></TR><TR><TD CLASS="quote">just to note the 60mm converts to about 2.38 or so, and .12 of an inch will not make much difference.....</TD></TR></TABLE>

[Using Pi x (Radius)^2]

60mm Exhaust is Approx 2.38"
Cross Sectional Area is 4.45 sq inches

2.5" Exhaust
Cross Sectional Area is 4.91 sq inches

I dunno about everyone else, but I think that's a difference.

 

It depends on what you want, 2.25" will give better low/midrange torque and 2.5" will give a more free flowing top end but lose some low/midrange torque. I personally would stick with 2.25" unless you have loads of engine mods like cams etc.

My centre pipe is only 2" diameter but has no bends in it and my car has a nice steady power gain all the way to the rev limier at 8K where it makes 185whp peak, the power curve doesn't drop of at all.

I could change my centre pipe fo 2.25/2.5" diameter and the engine would probably make peak power before 8K and then tail off but I would lose my midrange torque which I prefer for daily driving, as opposed to all top end power.

 

well i had on my 99 base a complete 2 1/4 exhaust now the half pipping is 2.5(where the pipes are straight its 2 1/4,when it comes to the part when the pipes curve its 2.5)

 

I have a invidia 60mm n1 style cat back system and (click the dyno) my car hit 167 wtrq with it and I believe that the exhaust helped it do it --- a 240sx in ITuner hit the same torque number with an invidia setup so it kinda made me wonder if there exhaust systems are that good????

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 97Preludeguy &raquo;</TD></TR><TR><TD CLASS="quote">I just got a 5zigen fireball, and the piping is 2.5 inches all the way no bottle necks or anything, just 2.5 all the way, and supposedly this is what you want with the H22</TD></TR></TABLE>

it's 60mm not 2.5". also, there's a bottleneck where the exhaust bolts to the cat. iirc, it tapers down to 2"

 

Exhaust systems are designed to augment a certain RPM range of your motor. 2.5 will be ideal for top-end power, but the smaller 2.25 will give better midrange torque.

One thing to keep in mind is the size of the collector on your header; you want the exhaust system to be fairly consistent throughout: if you have a big jump in size between the collector and exhaust, it can hurt you a bit.

 

So do you think having a bigger exhaust system with a nitrous setup,
would be beneficial just like a turbo application?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by SKDRCR &raquo;</TD></TR><TR><TD CLASS="quote">So do you think having a bigger exhaust system with a nitrous setup,
would be beneficial just like a turbo application?</TD></TR></TABLE>

Yes and No !!!!

A bigger bore exhaust will help and let the gasses out quicker when using the Nitrous but you will lose low/midrange torque for normal running especially if the piping is too big.

it's always a trade off, I personally would go for 60 mm piping, this would be a good compromise.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by firthy &raquo;</TD></TR><TR><TD CLASS="quote">

Yes and No !!!!

A bigger bore exhaust will help and let the gasses out quicker when using the Nitrous but you will lose low/midrange torque for normal running especially if the piping is too big.

it's always a trade off, I personally would go for 60 mm piping, this would be a good compromise.</TD></TR></TABLE>

True; nitrous motors can be tricky for the street, since a lot of the tuning goes towards when the nitrous is spraying.

The difference in exhaust choice on a turbo car as opposed to the nitrous car is the fact that the nitrous car will only need big enough piping to pass the exhaust it puts out, while the turbo car will take as big of a pipe as you can stick on it. The turbo spools up by means of a pressure differential across the turbine of the turbo, so you can't really go too big on the exhaust size. Nitrous, on the other hand, flows like an n/a motor, so you can go too big.

IMO, I would go w/ the 2.5" piping if you'll be spraying nitrous. That will give you enough diameter to pass the nitrous' exhaust easily, and it will still be fine when not spraying.