Exhaust Y pipe- welded the Y part

[ausubaru92]

I finally got the Mig ready and thought about the perfect length of the Y pipe, If the volume of the first piece of pipe before the 2-1 collector equaled the volume of the cylinder that fed it????

 

so by this theory, 1.8l ea82, 2 cylinders per exhaust, 0.9ltr volume per exhaust pipe , at 40mm (1 & 3/4") pipe = 72cm of 40mm pipe gives 904cc of volume

 

Would this be right??????

 

Ive seen somewhere before that 29" is the good length, this = 74cm

[TomRhere]

This article may help you some in your calculations.

 

http://www.jodel.com/index.asp?p=exhaust&engines

[ausubaru92]

Ok, i have welded it and put it on my car to test

 

all i can say so far is its bloody noisy, and has a cool tone (except for a bit of backfire on deacceleration)

 

Low end is improved (around 2k) but not sure about top end

 

would there be much difference between 2" and 2 & 1/4" in noise and power

I want good tone but not loud. i spose that will depend on the muffler

[idosubaru]

no experience with your car but i would guess 2.25" is too large unless it's a turbo and depending what you're looking for. i've run some larger exhausts on an XT6 and after a point...like 2.5" with no cat i think it looses way too much low end for me.

[torxxx]

I would do 2 inch y pipe to 1 3/4 after the Y to 2 inch for rear diff, back

 

put a muffler in there somewhere

[TomRhere]

I like it..

 

Did you block-off the air tubes, the 1" diameter pipes going into the head at the exhaust ports? If not, would be source of back-fire.

[ausubaru92]

yep, cut the tube at the flange on the exhaust and welded a bolt head in there but my exhaust gaskets leak and my fuel mixture isn great either

 

Ive decided to go 2" back from there and i spose i should prob put a cat on, maybe i can get one from the wreckers