snipe99

hey i was planning on getting either 3" piping or 2.5" catback. But in the same moment i realized i didn not know how some things worked. I know for a turbo no back pressure is good thats what the 3" piping would be for. But if i were to get th supercharger would 3" or 2.5 " piping be better.

Joe_Dezod

I finally got the jump on matty with a tech question... WOOT...

A 3" is unneccessary unless you already have a turbo kit on your car making over 400whp.

A 2.5" is great even for turbo, we're using that. Some back pressure is still good to have with a turbo, just not a lot. Do not go to a 3" for many reasons. Biggest reason is it will sound HORRIBLE. Also, as exhaust fumes travel down the pipe towards the muffler, it decreases in temperature. The decrease in temperature causes an increase in density. Dense air will actually create even more back pressure, which would keep any power gains minimal. A 2.5" will preserve most of the temps, and still flow enough exhaust fumes for any supercharged tC or a street driven turbocharged tC.

Joe_Dezod

I cut that post short in case the rapid man post-***** himself beat me to it haha. I hope that helps give you a general understanding. If you have more q's to ask, feel free to. Between myself, matty, sciondad, and a couple other members, we'll be able to take care of ya.

XD40tC

Figure I can ask a related question or two in here. If I get a custom shop to make me a full 2.25'' system, will I get better gains over the 2.5'' if Im still N/A? Id like to get the supercharger later on but that will be a pretty long time from now and who knows, I may decide to just stay N/A. If I did get the charger would there by any negative effects with the 2.25'' or will I just have massive low end torque? lol. What I want is more low end torque. Right now I dont have a whole lot. Will getting the 2.25'' full setup give me any or will I just not lose any? How does it work? I hear the stock pipe is a little bigger than 2.25'' but if I have a nice high flow muffler and a good header and s-pipe it should flow much better than stock right and perhaps I will have more low end? Please help this damn n00b!!!

loginskinner

wait i read that wrong. i hear that the 3 inch isnt a good choice unless you plan on big numbers on the dyno.

snipe99

ok so it looks like im goin for the 2.5 inch piping becasue im planning on the supercharger right now if it ever comes out but if anything turbo is always an option. thanx for your help guys. just out of curiousity is anyone planning on amking an intercooler for the s/c

Joe_Dezod

We at Dezod plan on doing a custom intercooler upgrade system for the S/C.

2.25" is decent for a moderately tuned NA setup. It will keep your low end power and still sound nice. It's definately optimized for your setup. With a ported head and better cams I'd go with a 2.5" setup. For bolt-ons, a 2.25 is ok, but some 2.5" setups will still yeild a littler bit more top end power.

matty-tC

thanks for taking my light work Joe LOL

turbo2liter

Backpressure is never good. Honda K series motors (similiar in size to yours) are showing HUGE gains going to 3in instead of 2.5in on N/A applications. Bigger is always better with exhaust.

jmiller20874

By that logic, I should get a 6" exhaust with a trash can size muffler and be making a **** load of power right. Not all engines are created equal, bigger isn't ALWAYS better. Save the Honda logic for Honda motors, they don't have the same technology, they run higher RPM's, they aren't the same.

Lonely_Raven

OK, now explain why t2l.

It's easy to just spout what other people are saying on the
internet, but back it up with science and/or proof.

Scott17

That's what I'm talking about!!!!

uncompiled

This totally depends on your exhaust setup. While you say that backpressure is never good, odds are that you're not talking about doing a header-less dyno run. For the street, you have to worry about whether it's legal and whether you want the increased attention. In terms of performance, you also have to account for the type and number of bends and the length of the tubing. Even if you have a straight pipe exhaust with no cat, you still have to factor in the piping length. With a poorly designed 3" exhaust system on an otherwise stock car, it's possible to increase backpressure and lose throttle response. Like Joe@Dezod said, having an exhaust that's too big for the application can actually slow down the exhaust pulses. That's why your car needs to be tuned as a system, not as random bits and pieces that have been thrown together. Figure out what you want to do and then tune it for that application. Overall, I really don't think the gains are worth the sound... unless what you're looking to gain is a buzzy sound.

If all you care about is maximum power, it's going to sound horrible. If you've seen a Spec/ITA Civic race, those cars are really REALLY loud, but that's why they're race cars and not street cars. I don't know about you, but I'd rather install a well-designed exhaust and sacrifice some top-end power for the ability to have a car that I can tolerate driving around town.

On another note, it's really fun to beat kids with really loud cars in your really stock-looking car... or is it?

matty-tC

they rev quite a bit higher though.. i think those gains are more between 6krpm and redline

kungpaosamuraiii

turbo2liter is right though, in the end.. the top end. By his logic, it's best to run with no exhaust pipe which is true - aka running an open down pipe.

I'll bet that a tC with a 3" exhaust will show some very good gains over a 2.5" tC but at the cost of quite some flow down low where the engine isn't making enough pressure to combat the backpressure. This set up should actually work better in a big track race or on the highway since you'll constantly be in the upper powerband but it'll be loud still.

matty-tC

i'll stick to my 2.5" stainless custom exhaust. it'll be good for 250whp

turbo2liter

Backpressure is never good, not for any engine. It kills power and torque. The air needs to move through the engine, not run into a higher pressure in the exhaust which impeded flow.

You are talking about the scavenging effect. I'd like to see some tests of 3in on your bigger displacement, lower revving engines. I think the 3in would show gains across the band.