Where are all the H6 gurus at??

[Dori Ninja]

Let's get a thread worthy of sticking for 6 cylinder info... What are all the Subaru factory options, what's easiest in what aspects... Where's the aftermarket support found... Etc.!!!

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[Yamazaki]

Do you mean for the engines only or parts in general? Also, do you mean the 3rd Gen, 4th Gen, 5th Gen...? There are a lot of members on here with H6's of 3rd and 4th Gen vintages. I don't think we have a 5th Gen H6 on the forums yet though. At least not active anyway.

[Dori Ninja]

I'm saying everything lol I think it would be helpful to have a go to thread for anything and everything H6...im contemplating swapping to one version or another and I am dreading all the bs posts I have to filter through just to get information... :/

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[Wiscon_Mark]

I found on our Tribeca that a cat-back exhaust seems like a worthy upgrade if we want some more power by taking some measurements of the exhaust piping:

Exhaust runners (headers) are 2 1/8s" each.

Midpipe (where the system is joined) is 2"

Axleback pipes are 1 1/2" each.

The midpipe especially seems like a big restriction. The cat joins the header runners together and is a bit larger (hard to measure with all the heatshielding, but it then reduces at the midpipe flange.


I'm sure the exhaust system on a Legacy is different, but probably similar.

The EZ H6 engines are NOT good candidates for boost as they're much more compact than the EG33 was and have much thinner cylinder walls, cooling ducts, etc. The Gurus on Nasioc seemed to think boosting one would cause pretty quick headgasket failure given the build.

That being said, exhaust and a tune could net some good gains. There's also a (super expensive) JDM aftermarket plenum for the intake that is supposed to result in a lot of throttle response gains, but probably doesn't do a ton for power.

I guess if you're looking for more info on specific EZ series motors, you're going to have to give us what you're looking for in your swap and what vehicle you're using with what transmission, etc.

My advice would be to do the EZ36. Same footprint as the EZ30 with a lot nicer torque curve and fewer issues experienced with headgaskets, etc.