Exhaust mod for ea82 carbed *please help*

[ausubaru92]

I was thinking of making a kind of 'header' (if thats what it is called) for my n.a. Subie to gain a little power.

the Y pipe that comes from the engine joins like more of a T than a Y and the 2 pipes are of different length, this setup i assume is less than ideal.

 

SSSSSOOOOO......... i was thinking of buying some exhaust pipe and constructin my own header.

 

This is how i imagine it

 

2 pipes running from the engine (prob stock size, to aid scavanging, please advise on this if i am wrong) these 2 pipes will join behind the tranny into a 2 & 1/2 pipe (proper Y join) and then go to CAT, turbo muffle ect

 

How do you think this will work, will i gain much benefit from it (im looking for low to mid range power, like for general driving, not for a race car)

 

Thanks guys

[Hodaka Rider]

How do you think this will work, will i gain much benefit from it (im looking for low to mid range power, like for general driving, not for a race car)

 

 

 

Stock size from heads is good, maybe slightly bigger.

2.5" is WAY too big for the rest on a non-turbo. 2" would probably be the best for your purpose. If you wanted to move the power up to high RPM's, 2.25". 2.5" will lose you power everywhere on your application.

[archemitis]

i agree wholeheartedly. should work good, as long as you usemandrel bends.

[NorthWet]

... Stock size from heads is good, maybe slightly bigger.

2.5" is WAY too big for the rest on a non-turbo. 2" would probably be the best for your purpose. If you wanted to move the power up to high RPM's, 2.25". 2.5" will lose you power everywhere on your application.

Based just on buk-lernin' and not much practical try-it-and-see, I do not understand why any vehicle would "lose power" with large pipes for cat/muffler on back.

 

The critical area would be from port to first major obstruction... cat or muffler. After that you could just dump to atmo for all the engine should care. Running large pipes should just be a compromise between stock size and open-air. Anybody have a good explanation why I am wrong? :-\

 

I also think that perhaps a smaller-than-port-size pipe might give ideal low-mid range torque. The port is significantly larger than either runner on its own and, although pulses aren't 180deg apart, should just need to handle flow from one cyl at a time.

 

But then, I would try to keep the runner flows separate and do a tri-y pipe. Heck of complicated, though.

[archemitis]

all i know for sure is 1 7/8 from the head back, straight piped sucks alot. no low end at all, and not much of a reward up top to justify it.

[MilesFox]

if your pipes are too fat the motor will not have any scavenging effect, and it would only be benificial at way high rpms. too fat of pipes will have no torque. ever drive a car with NO y-pipe at all. slow to move but responsive on the highway.

 

a skinnier pipe will get the exhaust gases moving on thru, the exhaust pulse.

 

if you are making a pipe why not make duals?

 

from the heads to the collector you should use 1.75 inch pipe. same for duals. after the collector you can go 2 inch.

 

after the muffler you can go as fat as you want

 

basically on a stock setup, the y pipe does all the scavengoing effect, put a muffler after the flange for the backpressure, and then the rest is pure flow/sound after the muffler

[subiemech85]

so when the glasspack is in the stock location, is it acceptable to run 4" after ??

[MilesFox]

really the y pipe is all the exhaust needs. immediately after that is the muffler for sound, then the rest is just pipage to the back. the 'bomb has one end opening bigger than the other. the small end is the exit, so if you want rpm or torque, put the bomb on one wat or the other. simple theory for the home brew exhaust system

[ausubaru92]

The y pipe was my main focus point.

 

Does the length of them matter,.... is the longer they are before they join the better or is there a 'happy-medium' length they should be?

[ausubaru92]

I hate to be a pain but i realy need to know if the length of the pipes from the heads matters

 

in your opinion, should i join the pipes on the stock place, before the tranny or make them longer and join after the tranny

 

i assume i should try to make em the same length (the stock ones are of different length, by about 2ft)

 

thanks to anyone who can help

[TomRhere]

Can not for the life of me find the web site I read it on, it had to do with Soob motors in airplanes. Anyways, thinking I read on there that 26-1/2" on the lead pipe length before they hit the Y. Maybe it was 29-1/2". Was one or the other though.

 

 

 

Sorry couldn't be of more help.