what do you gain?

[Tai Mai Shu]

I'm just curious. What do you guys gain in hp/tq when you have on the 2 1/4 inch exhaust piping? Any Charts or graphs? and what range in rpms is it most noticeable?
post your gains. With or without 3 way cat and what muffler you have.

[Semtex]

i beleive that you begin loose hp after 2 1/2 but im not possitive

[Tai Mai Shu]

you lose low end torque but gain more than you lost in the top end. I believe thats how it goes. *shrug*. anyone?

[Protoss]

any exaust over 2 1/8" you will start to see losses in both Hp and torque if you are not a turbo engine. i rock a 2 1/8 exaust and love it. sorry no chart. i'll dyno my car whn i have time... if i have time before december

[JProtege]

Originally posted by Protoss
any exaust over 2 1/8" you will start to see losses in both Hp and torque if you are not a turbo engine. i rock a 2 1/8 exaust and love it. sorry no chart. i'll dyno my car whn i have time... if i have time before december

hey protoss, how'd you get your exhaust set up?
did you swap out your headers too?

[funkdaddysmack]

Nope, bigger is better. A year or so ago, SCC or super street did a test on a stock j-body I think. They put a 2.25", 2.5", and 3" exhaust on the car, the bigger the exhaust, the more power the car made. Unfortunately they didn't post dyno plots, but the larger exhaust DID make more power.

[skr33t_rac3r]

yeah thats right i read that article too the torque ranges were different for all three though

[Protoss]

Originally posted by funkdaddysmack
Nope, bigger is better. A year or so ago, SCC or super street did a test on a stock j-body I think. They put a 2.25", 2.5", and 3" exhaust on the car, the bigger the exhaust, the more power the car made. Unfortunately they didn't post dyno plots, but the larger exhaust DID make more power.

were they testing the 3.1L, a 2.2L or a 1.8L? see a 1.8L cant handle a big exaust. you need the pulse velocity to get **** away from the header. similarily you will LOSE power if you take your exaust right off after the manifold. Dont believe me ask Jessesays

i had a 2.5 exaust and i downgraded to a 2 1/8. it made a difference.

[funkdaddysmack]

Well it was either a j-body or a neon. Can't remember which, so it was probably 2.0l-2.4l.

[D323]

this simple solution is a restrictor. NASCAR uses them. What it is, is a piece of pipe that narrows down to 1 & 7/8" (Stock for our cars, well at least mine I think) and then it widens back out to to desired pipe size. ask the muffler shop that you have this done at if the have a mandrel pipe roller (I think that is what it is called).
The reduction in size will retain back pressure, keeping your mpg from going down the toilet too much, and still give you the added hp and noise. I have plans of making a prototype and have a shop put it on my car. If it works I can probably get them made kinda cheap.
Just ask your local Meineke, or midas, or any muffler shop with a competent worker can have exhaust on your car. Ask for whatever size you want in piping from the cat back, and I would go with a new muffler at the end.
Make sure they use mandrel bends, otherwise it will mess up the pipe.
Make sure they use mandrel bends, otherwise it will mess up the pipe.

[charles]

Originally posted by D323
this simple solution is a restrictor. NASCAR uses them. What it is, is a piece of pipe that narrows down to 1 & 7/8" (Stock for our cars, well at least mine I think) and then it widens back out to to desired pipe size. ask the muffler shop that you have this done at if the have a mandrel pipe roller (I think that is what it is called).
The reduction in size will retain back pressure, keeping your mpg from going down the toilet too much, and still give you the added hp and noise. I have plans of making a prototype and have a shop put it on my car. If it works I can probably get them made kinda cheap.
Just ask your local Meineke, or midas, or any muffler shop with a competent worker can have exhaust on your car. Ask for whatever size you want in piping from the cat back, and I would go with a new muffler at the end.
Make sure they use mandrel bends, otherwise it will mess up the pipe.
Make sure they use mandrel bends, otherwise it will mess up the pipe.

I still don't think you want backpressure, it's the exhaust velocity that you want...

[D323]

True,
by back pressure I only meant a little so that way the o2 sensor reads at least some pressure, and doesnt dump more gas into the engine making your mpg go way down.

I remembered reading an article about this somewhere, most likely off the old board.

[silver03p5]

Originally posted by D323
off the old board.

shh...no talky of the other board

[Protoss]

Originally posted by D323
True,
by back pressure I only meant a little so that way the o2 sensor reads at least some pressure, and doesnt dump more gas into the engine making your mpg go way down.

I remembered reading an article about this somewhere, most likely off the old board.

The O2 doesn't measure pressure. it measures a voltage across the downpipe. That restictr plate is also knwn as a scilencer. its purpose is for sound.

True restriction is bad, but a low flow velocity is worse. and a 2.0L engine will like a 2.5" exaust. a 1.8 and lower wont.

As for mendral.. for 2" SMOOTH crush bend will do just fine... Granted mendral is a better pipe, the gains vs price hike is not all that worth it. You might see a .5 to 1hp increase over the crush bent bretheran. No it wont **** thngs up if do dont go mendral.

if you are going turbo then we are dealing with a whole different issue.

[D323]

good to know.

Would a 2.25in pipe be large enough for a BPT?
(My plans in the future)
I dont want it so loud I cant stand to go for a freeway trip for more than 20 mins.