Straight Piped

[gloryaccordy]

if you are trying to make power you NEVER want back pressure.

if you have back pressure you are losing power.

what you need is good flow, which is based on velocity.

having high velocity exhaust flow is very important to making power, but the amount of exhaust flow has to be matched to the piping you are using.

too small a pipe creates back pressure and you lose a lot of power.
too large a pipe leads to very low velocity exhaust flow leading to loss of power.
a well matched pipe size to the engine leads to the optimal exhaust flow allowing for proper scavenging, and high velocity flow, creating better power and economy.


try blowing through three things....
a garden hose, a coffee stirrer type straw and a regualr straw. you tell me which one flows the best. its the same deal with your exhaust.

Great post.

Like Zipcreature, due to circumstances beyond my control I too ran for a few weeks without an exhaust beyond my B-pipe, and I too loved it. Throttle response was better, the off-throttle burble was awesome, and when I finally got my exhaust fixed, there was a notable decrease in torque from about 1-3k RPM. Judging from that I don't think you can really have "too big" of piping...I was basically running an open exhaust and my low-end torque increased...but having optimal sized piping definitely helps.

Think about it...from a regular sized straw to a coffee can there's no difference in difficulty in flow. The regular straw just has the maximum velocity.

[Jarrett]

Bingo! two, your not going to pass emissions, cause youre releasing unburned gas in the air.

Is there an added combustion process going on in the catalytic converter I'm not aware of? It's just gas that hasn't been converted to CO2. If it's unburnt, then that's not an issue involving the exhaust.

Guys, you all know better than the arguments you're making. If you have a street car, where you're not constantly worried about maximum exhaust flow, then back pressure is good. At the RPMs your engine likely sees, you'll need pressure or you can burn up exhaust valves. Don't argue that because I've seen it happen many times and I don't give a rat's ass what your personal experience is.

If you're racing all the time and not driving on the street, or you're a little ricer and you race around everywhere you go on the street, back pressure is less of a necessity. You're constantly on the gas and are flowing much more air at a rate the factory exhaust or any restrictive exhaust for that matter is designed for. Even high performance stuff is designed to be somewhat streetable.

[According2Aaron]

So if I ran a straight pipe, what piping would everybody agree I'd need, 2.5 or 3? Which would everybody agree has better performance and better fuel mileage? I'm interested in running a straight pipe for extra performance/noise but I won't if the loss of fuel mileage isn't worth it.

[Jarrett]

You WANT extra noise? I'm doing everything in my power possible to build an exhaust that will have power with minimal noise, mainly so people might not think CB7s are so rice after all. Then you go off and do the exact opposite. Ricer.

[v4lu3s]

i love the myths that circulate.

[lowcord]

I would say if you have a stock setup dont go over 2.5" and you will get what your looking for the noticble increase of power and throttle responce. But in my case im turboed and have 3" from the turbo all the way back to the muffler wich is 3" through w/o cat and my car loves it

[Mike]

ehhhhh please no strait pipesss.... pleeassee?.....lets try to earn respect for our cars. if u want power work, save some money and get 272 or some shit. dont just embarris your self by makin an exhuast that sounds like shit

[1greencb7]

lotsa noise!!!

i have stock pipe from the headers all the way to the cat.conv. i then had 2.5 pipe from there to my huge canon which is like 23 or 24 inches long and the tip is huge! (i can almost fit both fist inside it!!) and i have an AT, and if i drop my car into 2D low, i can set off car alarms!! and even in D4, at about 22 or 2300 rpm, it rattles my back window, so i dont know what that tells ya...

[91accordwagon]

i have stock pipe from the headers all the way to the cat.conv. i then had 2.5 pipe from there to my huge canon which is like 23 or 24 inches long and the tip is huge! (i can almost fit both fist inside it!!) and i have an AT, and if i drop my car into 2D low, i can set off car alarms!! and even in D4, at about 22 or 2300 rpm, it rattles my back window, so i dont know what that tells ya...

I'd tell ya to get a real exhaust system.

[According2Aaron]

You WANT extra noise? I'm doing everything in my power possible to build an exhaust that will have power with minimal noise, mainly so people might not think CB7s are so rice after all. Then you go off and do the exact opposite. Ricer.

Excuse me for being a V8 guy who owns a Honda. It's the skeet ride. Read my member's ride thread for more. We V8 folks like loud exhaust. I'm looking for an ANSWER to my question, not an asshole like you to start shit. Honestly.... Didn't your mother teach you any respect? Didn't she teach you that if you don't have anything nice to say, don't say anything at all? Bastard.