Piping differences and issues for h22's and f22

[h22sparkle]

I need some opinions from you guys about different diameters in exhaust piping for my allmotor set-up. Okay now first-off a h22 with stock internals is nice but with the exhaust pipin on our cb7's literally tend to choke the hp out of it


. Now I wanna know if my setup in piping diameter will be helpful or hurtful to me cause my car feels like it has no kind of midrange power. Its 2.50 now but i was wonderin if i change it back to 2.25 will i be okay cause i tend to race from a dead stop. BUt my car has the power I only have a obx CAI,stock jdm header and a custom 2.50 exhaust piping with a obx muffler. Should i change that header as well? Voice your opinions people im taking note postive opinions please thanks

[PRIMOCB7]

i was always told for a N/A setup, 2.25 is the best way to go. you go w/ larger piping(2.50, 2.75..etc) when turbo, nos, is involved; and i don't think there is nothing wrong with the jdm header when compared to aftermarket headers, unless you want a polished or chrome look w/the headers.

[BustedLX]

Well with 2.5" you do lose some low end torque but make up for it in topend HP because the engine can really breathe. Going to 2.25" will give you some more back pressure and help out your bottom end if that's what's hurting.

[h22sparkle]

How can i get back my back pressure though yet keep the power?

[h22sparkle]

What about a catylic converter ?

[MRX]

Even with the "high-flow" cats your still trading off one side of the powerband for another. The only option i've seen where you can have top end and bottom end performance is an exhaust cut out device. People say they get rusted easily or can even get stuck wide open so i'd rather just focus on one aspect of the power band. You really have to decide whats more important to you. Its either gonna be your top end, mid-range, or low-end...you can have 2 of the 3 but never all of them

[h22sparkle]

Yeah thanks for the info guys

[DrLove'sKuDang]

has your car been tuned at all to take advantage of the high rpm flow? i say keep it the way it is. the only time you need lowend is off the line... but within a couple seconds your in the topend. and whenever you shift, you stay in the top. nobody races at 3000rpm. if i hadnt spent good money on my exhaust, id go 2.5"... hell, i might still and just have the muffler welded back on.

[h22sparkle]

its strange i beat a maxima 99 gxe by a nose but yet i lost to a toyota celica 2002. I think that celica was juicin. On top of that my third gear is startin to act up due to me racing i think the synchros are startin to go . Good thing i brought some synchromesh I hope itll help imma change out the fluids tommorrow

[Andrew]

When is the backpressure myth going to fucking die?

[h22sparkle]

ahahahah exaclty thats what i thought it was but i realized that one is for long range the other is for from a start

[DrLove'sKuDang]

man that sucks, losin to a celica. but youre probably right, he must have been squeezin to beat you. but still, that guy must have been pretty pissed... even with a shot(or some kind of assistance) he still barely beat an accord.

[BustedLX]

So, squeeze back.

[h22sparkle]

Ive decided to put on a kteller hi-flow cat im tired of the smell that is one major migraine giver.

[deevergote]

Ok, to clear up a few things here:

1) Honda catalytic converters don't rob much hp at all... if it's as much as .5hp, I'd be amazed. Honda has designed their converters to be very free flowing. Because of this, any stock replacement converter (quality, anyway) will be the same. Taking off your cat will do nothing but pollute the air and make you look like an idiot. h22sparkle, kudos for putting yours back on (though hi-flow when referring to Honda cats is pretty redundant. You can't get much more out of it.) Of course, running a stock Accord cat with an H22 and a 2.5" exhaust system would rob some power, simply because of the smaller diameter piping that it was designed for.

That leads me to point 2:
2) The optimal piping for a N/A H22 is 2.5". That gives you the best response throughout the powerband, without putting you in limp-mode anywhere in it. 3.0" would be great for FI applications, but you would need to rev upwards of 6k RPM to get any use from it in a N/A setup. Like fizzbob7 said, smaller diameter will increase backpressure and give more low end, but smaller than 2.5" for an H22 wouldn't be good for anyone who cares to race (sparkle...). You'd pull for 50 feet, and then have your ass handed to you by less powerful cars... provided they have a decent exhaust system themselves!

Finally:
3) What's this "backpressure myth" Andrew? Backpressure plays a significant part in engine performance. Too much backpressure, and you'll have exhaust gasses mixed in with your intake charge, creating less power. Too little, and the scavenging effects created by high-velocity exhaust gasses will be reduced, again causing a contamination of the intake charge.


As an example, try running a few blocks while trying to breathe irregularly. You'll get tired really fast. The engine acts the same way. If it can't breathe smoothly and properly for it's designed use, then it's not going to perform as it should.