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I was considering putting a set of the 2.0 Dual Cam Turbo heads on my 91 Legacy Sport Sedan. It's got a freshly rebuilt 2.2 Turbo. What could I expect to gain from this conversion? Also, what mods are involved? Do I have to do anything to the computer? Will they bolt right up?
Thanks
-Andrew

Search you must, my young Jedi...
Plug in DOHC to the search engine, lots of folks have done this...

Here's one;

http://bbs.legacycentral.org/viewtopic.php?t=34671

As long as you use older JDM heads (not new '02+ WRX heads) you are fine, your sensors will work.

Gains... well, that's subjective, most guys make turbo & IC upgrades at the same time, so no solid numbers really exist for just the head swap.

No computer issues, again, if you stick with older heads.

I appreciate it! I have been looking, and I can't find a list of heads and the differences between them. Do you have to modify the block at all? One big other thing....Are the combustion chambers of the dual cam heads the same size as the stock 2.2 Turbo heads or are you dealing with a compression ratio difference. Am I seriously mistaken or didn't they make some 32 valve heads for Subarus? What did the Japanese version of our cars have? As opposed to the American muscle car engines I work on, I can't seem to find casting numbers and combustion chamber sizes readily available. I just didn't want to install a set of these heads on my 2.2 Turbo block and have my compression drop you know?

8 VALVES PER CYLINDER?? Not likely... you're thinking of V8's again. All EJ-series heads are 4-valve/cyl, whether single or dual cam.

There's no mods needed to the shortblock to fit any series of head, just make sure the headgaskets you buy match the BLOCK you're using (2.0 = 93mm 2.2 = 98mm 2.5 = 100mm)
Stick with metal, multi-layer HGs, (Cometic) stay away from the fiber ones.

You also need the correct intake manifold for the heads you're using, SOHC and DOHC intakes ports are different.

I'm not real sure about combustion chamber sizes, I believe they're more or less all the same, what you need to watch is deck clearance; how far the piston comes out of the bore. EJ22T protrudes about 0.020, so use HG thicker than that...

Snoop around the pre-2002 engine threads in NASIOC, too, lots of info there.

Yeah! You're right, I was thinking V8 again, and not only V8 but also a 32 valve ENGINE with 4 valves per cylinder.....Damn I can't get used to talking about 4 cylinder engines!! That would make sense that the intakes are different, and I'm glad you told me which head gasket to buy! Aren't there some dual cam heads made in the US? Maybe any of the other year Legacies from 95-2000? Maybe something dual cam that I could pick up at the local junkyard? Thanks for the info!

Aerotech wrote:
As long as you use older JDM heads (not new '02+ WRX heads) you are fine, your sensors will work.


No computer issues, again, if you stick with older heads.

What about phase 1 ej25 heads from a 98rs? iirc they were basically the same as the jdm wrx heads.

just asking since I have a set with supertech springs and retainers and some delta cams.

Spilner wrote:What about phase 1 ej25 heads from a 98rs? iirc they were basically the same as the jdm wrx heads.

just asking since I have a set with supertech springs and retainers and some delta cams.

They will work just as well as JDM heads with the exeption that they do not have the oil feed/drain and water return for the turbo.

PhyrraM wrote:

Spilner wrote:What about phase 1 ej25 heads from a 98rs? iirc they were basically the same as the jdm wrx heads.

just asking since I have a set with supertech springs and retainers and some delta cams.

They will work just as well as JDM heads with the exeption that they do not have the oil feed/drain and water return for the turbo.

true, so it would just be a matter of tapping those holes then?

Spilner wrote:true, so it would just be a matter of tapping those holes then?

Here is an old thread that shows the differences between the two.
http://bbs.legacycentral.org/viewtopic.php?p=247763