It just struck me that using thing head gaskets on an ej would cause the intake manifold to improperly line up with the heads. Is this true?

Nope, the difference is so small that it doesn't really matter. I've got thin head gaskets in my RS to raise the compression.

Not a problem, but since you have an EJ22 with pistons that clear the deck, you could potentially have valve clearance issues...

The thin head gaskets are 0.027 inch vs 0.042 inch for stock
The decrease of 0.015 mils is so small that if clearance were a problem, it would already show up in stock cars

Not a problem, but since you have an EJ22 with pistons that clear the deck, you could potentially have valve clearance issues...


Actually I don't have a Subaru at all. =)

I'm just researching my next car. I hadn't really considered a 2.2l Impreza until about a week ago. Seems like a good base so far. It's on the short list with a handful of other four cylinder cars.

BTW...Thanks everyone for all the help so far.

Oh wait.... then could the ej25 heads be used on an ej22 with thin head gaskets to get the lost compression back?

Are the ej25 heads taller? Would the lessen the possible interferance issues with thin gaskets on the ej22?

Sorry,
You were asking about 2.2l cam gears in your other thread. Anyays, look for a thread title "high compression Frankenstein" You are going the wrong way. Ej25 bottom end with Ej22 heads for higher compression. Ej25 heads have more combustion chamber volume than Ej22.

G. Subramian,
Be careful what you assume. Your engine is phase II, my remarks were meant towards a phase I engine. Maybe it isn't an issue on your engine. Unless you have measured it and done a clay test, I wouldn't go around telling people they can safely do this on their engine!!!

I'm pretty sure the phase I ej22's are non-interefence engines. Shouldn't that make a thinner head gasket more feasable?

Hello:
I have a phase I EJ2.2 with the Cometic thin gaskets, Delta cams and heads that have been milled 10 thousands with no problems.
Regards John

That's what I was reffering to by "lost compresion". Can a thinner headgasket make up for the sompression lost with the ej22/ej25 setup? And will it interfere?

Hello:
I have a phase I EJ2.2 with the Cometic thin gaskets, Delta cams and heads that have been milled 10 thousands with no problems.
Regards John

Right on. How's that setup working for you? How does it pull?

It is in a 93l wagon with light wt. bumper beams, carbon fiber hood, light wt battery, no AC, and most of the sound deadening stuff removed.
The engine has an intake, Borla headers and Stromung Exhaust from the headers back as well as a light weight flywheel, cams as noted above. The heads also have been PnP'd in the bowl and seat area and matched to the intake. The seats have been ground and narrowed to move the contact area with the valves to the very edge of the valve to increase low lift flow. I advanced the cams back to stock specs by using a off set key at the crank for the first head and repositioning the idler pully at the bottom for the second head. I would retard them back a bit if I had some engine management and could raise my red line.
This car has 4.11 gears.
It feels much faster than mysisters stock RS's in a straight line. No track times or dyno numbers though.
No comparison in the handling or braking.
I plan to get some engine management next, then some equal length headers.
When I'm tired of it I'll get a phase II 2.5 block, every thing should swap over except the flywheel.
I think most of the improvement in the car and best money spent was on handling and braking. I consider myself more of a chassis person anyway so I am biased in that regard.

Thank you for the good info, john. I Might be hitting you up for details in the future. You think with a higher redline you can pull more out? There alot of hearsay about the intake manifold choking out high end, what is your experience? Does it get wheasy towards the top?

I think the manifold on my 2.2 is adiquite. I havn't run over the stock redline yet. The torque begins to drop off up high but is the manifold the primary cause? If there is a bottle neck in the intake system it is probably at the valve or valve/camshaft timing. I also doubt my intake system is tuned to the exhaust and if the cam is only tuned to one of them I am lucky. I also have no idea what the 1.8 ECU is doing but Matt (above) says the 1.8 ECU has pretty good timing. There are a lot of variables.
But I am not relly building a race car anyway. If I really want to go faster I need some driving lessons.