Dual exhausts on a EA8x ?

dfoyl · Post by **dfoyl** » Sat May 10, 2008 6:00 pm

A few months back I fitted a EA82 MPFI exhaust to my EA81 Brumby (thanks Gannon!) as part of the prep work for SPFI (needed the o2 sensor plug), and haven't been entirely happy with the results for a few unrelated reasons.

So, I've been thinking of re-running the exhaust system in a different way and am thinking of running seperate exhausts from each header to the back of the vehicle. I plan to put in a H design to equalise pressure.

I'll run twin inline cat's, and basically use the existing layout for the pass-side, with a mirror-image for the drivers side. I have a few spare exhaust parts from an MY wagon I stripped out and the welding should be pretty easy (I'll just cut & reuse the hangers from the wagon). My only real cost will be a couple of cat's from a wreckers.

Thoughts ?

Dean.

ChPLAT · Post by **ChPLAT** » Sat May 10, 2008 7:14 pm

Not that I'm a mechanic but i think that that would cause a massive loss of power.

Battlewagon · Post by **Battlewagon** » Sat May 10, 2008 7:53 pm

Only one way to find out for sure, thats try it. Probably sound odd though. I wouldn't cut up the exisiting system though, just in case it goes badly.

BaronVonChickenPants · Post by **BaronVonChickenPants** » Sat May 10, 2008 7:58 pm

Without the H joiner it will sound like this:
http://video.google.com.au/videoplay?do ... 6542830137

I wasn't concerned with performance, I just wanted as much noise as possible, and that it did.

I have just cut off some standard MY headers just after the elbow bend, then welded on a standard MY exhaust to each one but I cut the resonator off before it shaped back down to the normal pipe size, so it was about a 3 inch diameter opening.

Not sure what difference the H piece will make.

Jordan.

AndrewT · Post by **AndrewT** » Sun May 11, 2008 10:56 am

If Subaru's design is good enough for an EA82mpfi it should be good enough for an EA81spfi. I can't see why it wouldn't be.

YouTube · Post by **El_Freddo** » Wed May 14, 2008 8:17 pm

AndrewT wrote:If Subaru's design is good enough for an EA82mpfi it should be good enough for an EA81spfi. I can't see why it wouldn't be.

Cos the EA82 MPFI didn't run twin exhausts. There's a brumby I've seen in benders with the twin exhausts out the back. I don't know if they're both blowing exhaust, how its been done or if one's a dummy. I also can't remember how it sounded.

I'd say you'd get a loss of power and no subi note.

Cheers

Bennie

Gannon · Post by **Gannon** » Wed May 14, 2008 8:38 pm

As long as the pipe that goes from the head to the H join is the same diameter and roughly the same length, you shoulnt lose power. Exhaust scavenging only happens before the join into the main exhaust pipe. After the join the individual pulses from each cylinder /bank combine into a steady flow of gas.

Ive been wondering how you are going with your SPFI project. What 'unrelated issues' are you having?

dfoyl · Post by **dfoyl** » Thu May 15, 2008 12:24 pm

Gannon, basically I also changed the rear exhaust at the same time to an aftermarket unit (stainless steel TurboFlo unit from an EA81 sedan), and it needed some persuasion to fit. This has caused the middle piece to flex more which in turn leads to leaks when engine/exhaust is cold.

And I think your comments are spot-on wrt power loss - I do not plan to change the diameter of the existing y-pipe, just seperate them.

Dean.