straight pipe?

[macder]

you can do whatever you want to your car as long as all emmisions realted components are still there. What i have done is gut my cat, so it looks like its there, but noting inside

[91_TSI_TALON]

dude u know u will lose HP cause u have no back pressure!!!

[macder]

LOL, i have a cold air (ram air) installed meaning i get more air into the engine, meaning i have to get it out quicker to get more air in. It's all about free flow. Somebody tell him please

[macder]

BTW my car is a 4g63NT so it makes even more sence

[macder]

Sorry for posting 3 in a row, but most people will install just and intake, or just an exhaust thinking they are gaining significant HP. You will not gain significant HP unless u do your intake, headers, and exhaust, due to free flow of air, the quicker it gets out, the quicker it can get more, meaning more compression = more HP.

[91_TSI_TALON]

well macder man was i even talkin to u about losin back pressure no i was talkin to riff he has no mods like u so y dont u just stfu!!!!

[EclipseRST]

ok first of all... macder use the edit button if your goin to post 3 times in a row! and second of all... your wrong! your not goin to get a significant about of hp out of intake and full exhaust! and yes you need back pressure on a n/t. thats why its hard to find 3" exhaust for a n/t eclipse! and it does not make more compression by making the motor breathe easier. the only way your goin to get a significant amount of hp is if you have a forced induction (turbo/supercharger). oh and its header not headers!

91 tsi talon... take it easy, no need to start fights!

[kjewer1]

91 talon, please adjust your attitude, and speak proper english (see rules).

On a turbo car you need no additional backpressure from the ehxuast. On any car, backpressure is bad. Let me see if I can use the search button to find an old post of mine...

False. Backpressure is never good. ashah000 got it right. You want velocity, to exploit the scavenging effect and pull more aif/fuel in during valve overlap. Smaller pipes increase velocity, thats physics. Increased backpressure is a sideeffect of smaller pipes. So unfortunately poeple confuse the two. Its also possible to increase velocity efficiently, meaning less increase in backpressure pre increase in velocity. Thats the whole trick... Ehxuast backpressure has no effect on comrpession ratio.

http://www.automotiveforums.com/vbul...t=backpressure

[EclipseRST]

well in that case you need back pressure... cause there is no way to get velocity without it! am i right?

[kjewer1]

(damn, you guys both posted in the time it took me to write that reply)

Nope. Its easy to confuse the two, but they are seperate. Block off the tailpipe. TONS of backpressure, no velocity The size of the pipe (given some gas flow level) has a large effect on velocity and a small effect on backpressure. Cats and other restrictions have a large affect on backpressure and velocity, making both worse. Just going from a 3" straight pipe down to a 2" straight pipe (no mufflers/cats/etc) will have a very small impact on backpressure, but the velocity will go up significantly. Thats the best way I can think of to describe it.

[91_TSI_TALON]

yes you are!!

[kjewer1]

Originally Posted by 91_TSI_TALON

sry man i just got mad cause i know what im talkin about i went to school for this stuff.

Being "educated" and "knowing what you are talking about" have nothing to do with being right Automotive schools are another big perpetuator of common automotive myths...

[91_TSI_TALON]

true i think they basically made me think to much of myself. LOL

[kjewer1]

Not your fault they gave you bunk information Just dont be afraid to listen to other explainations of a particular subject and possibly reform your opinions about it.

[EclipseRST]

i know you dont want back pressure but you have to have atleast some... thats why when you have 3" exhaust = no back pressure and a low velocity, and when you go to a 2.5 the back pressure gets greater! there is no way to get rid of it without hurting the hp of the motor!