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Tranny interchange

3K views 13 replies 6 participants last post by  west_minist 
#1 ·
Hey all. I recently was offered and H6 motor for my 98 outback. What I was wondering is if the 5MT from the outback is compatible with the H6? I've looked for other posts on this topic and can't seem to find anyone that has tried this. I know I would need to switch over the flywheel and stage 2 clutch I have. Just wanted to know if this is at all possible.

I'm not planning on keeping it for long. Just until I can get my hands on a 6mt. Any help/info would be appreciated. Thanks.
 
#3 ·
which H6 are you stuffing into the little 1998 bay?

such things have happened as mating a 5 speed or a 6 speed to h6 engines, but one would need to get some kind of custom program / work around to the ECU to eliminate a check engine light looking for signals from the TCU of a auto trans that is not present.


EG33 SVX engines are probably the most common for mating to a manual if you are looking for a pre-existing build to follow.
 
#4 ·
The last factory H6+MT from subaru in the USDM was the XT6, which has been gone since 1991.

Yes EZ30 or EG33 will bolt up to your trans and more or less fit the engine bay but that's only like 10% of the problem. Big problem with the EZ30 is (as eagleeye mentioned) making the TCU think it's still involved in that whole "move the car around" process. Engine computer gets all stupid if the TCU isn't happy.

So yeah you could probably make it work, but there are better places to put that motor, and better motors to put in your car.
 
#5 ·
Thanks for the info guys. It's an EZ30 out of an 02 outback. I wanted the H6 only because I don't want to go through all the BS with the headgaskets or turbo blowing on me with the 4 cylinders. Also because it's a stronger motor, with a timing chain and endless possibilities. Also not something you see done very often.

I'll ask my performance guys what they think about the ECU/TCU issue and see if they can figure something out. Thanks again for the info.

What motor/tranny setups do you all recommend? Looking to turbo/supercharge the car in the near future.
 
#6 ·
one of the things you miss out in the pre 2000 bodies is a multilink rear end to take the torque. 2000 and later the rear end stays panted a lot more even with just 165hp / torque.

There might be some h6 builds out on RS25.com with impreza out there,...and I wonder if any one in the US has ever brought in a Aussie H6 ECU that was made for running around with a 5 speed manual. (as they did get them for a few years,...but I can't remember what years of cars got them. = 212hp EZ30D or 250hp EZ30R. )

Easiest build: get a high mileage rust free 2001-2004 LLBean H6 wagon, or maybe a 2001-2004 H6 legacy or outback sedan for lighter weight.

dress the engine you have to how you want it,...and drop swap it in with your trans. (or a better one).

and H6 engines are not immune to head gasket problems. problem owners, too many miles or too much time seems to get to some of them = at least on this board.

2nd easiest build, get a SVX and stick a 5 speed in that. again figuring a way to get around the check engine light.
 
#8 ·
sell me your H6 if you don't need it.

i'd go with an EG33 is I was swapping a Subaru 6 cylinder engine. 10 more HP, more displacement which probably respond better to modifications, and is easier to work on and less headgasket issues than the EZ30.

the EG33 and EZ30 bolt right up to an EJ transmission and drops into the crossmember.
 
#10 ·
#11 ·
whoops that is not a ECU or TCU,

it is a Australian market ignition. with the imobilzer box. (nothing valuable to the issue at hand).
 
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