Head Swap

[morgie]

I want to swap my head.. mine is crap. to much hair.

okok just joking.

Seriously. A friend here is swapping is old 2.5RS 98 engine for a WRX one, and offered me the 2 heads of it's 2.5 engine (engine is diing slowly) for a low cost.

The heads are DOHC, and were planned 2 times, up to 0.015" or.. 0.15" .. ( 15 thousandth )

Question : Are these Heads swappable on our engine ? heard they are flowing better than the 2.2l ones.. and were a perfect fit, but I think that was for the SOHC heads.. not sure. Also, is that planned thing not too much ? will it rise the compression-ratio to high ?

thanx !

[kelley]

they will fit they do flow considerably better than the stock 2.2t heads.
from charts I have theyshow a compression ratio with this set up of 7:1.
now I'm not 100% sure on this but this is what I have found so far.

[mile hi]

They will fit and they do flow better than the stock heads. We did cc these and I should be able to give you the comp. ratio tommorow. These heads are on the 400+ monster that we have running and it has had no major problems so far. You will have to provide an oil supply to the turbo and a drain.
AL(CO)
al@iwtu.net

[RaZor]

Not so fast you guys!!!

Not that much of a bolt on operation

Take the time to read that...
http://www.xmission.com/~dac/library/headswap.htm

[Legacy777]

Yes.....read larry's write-up......you may change your mind.

[mile hi]

Right it is far from a bolt on item I will try and get a list on the mods needed to do it right also. I think that the comp ratio should be higher than 7:1 as that is what we got with the EJ2Ot heads and it was pretty sad because of the low comp ratio.
One interesting thing is that the 400+hp car is running a stock EJ22t short block with no problems at 30lbs boost. The only failure in 2-3 months was a exploding lifter\camshaft incident. The block problems that it has had were with a fairly high milage EJ22t short block that did spin a bearing.
AL(CO)
al@iwtu.net

[mile hi]

Ok the '98 heads have oil and water but you will have to make custom lines and make a drain into the oil pan (or We can furnish one) the intake manifold to use would be a '98 RS Impreza as your IAC will fit it. The compression ratio will be very close to 8:1 but a little higher becuse of the milling that has been done. Use the EJ22t head gaskets and the 2.5 belt.
This should work well like I said the high hp engine we have here is working very well except for the lifter trouble but that happened at very high RPM. Look at larry's post because I probably have missed something.
AL(CO)
al@iwtu.net

[mile hi]

OK there is oil and water in the '98 heads and you can install fittings but custom lines will have to be made for the turbo and a drain will have to be made in the pan for the oil (or we can supply one). Your CR will be a little over 8:1 with the milling that has been done. Use the EJ22t head gaskets and the 2.5 belt and plastic. The best intake manifold for you to use would probably be a '98 Impreza RS as your IAC will fit. Should make a nice motor our 400hp+ engine is using this setup and the only failures were a exploding lifter and cam at very high RPM and another block spun a bearing but this was a older used short block assy. If you need any parts or advice we can help.
AL(CO)
al@iwtu.net

[IggDawg]

THe '98 heads have NA cams tho. I thought those were poo for a turbo system. I would go with the SOHC heads since getting proper cams would be much cheaper. in fact, in a SOHC setup you could just swap cams right?

[Legacy777]

The cam issue was something that I'm not sure if Larry took into account or not.

But typically, turbo cams will have less overlap duration between the intake & exhaust valves since the intake charge is being forced in, and does not require more time to scavenge the combusted a/f mix out of the cylinder.

There are some other issues like lift and other timing issues that probably should be addressed.

There is a thread in the Norm Asp. forum on nasioc where I listed the cam specs for the turbo and n/a cams.

Actually.....I might have posted it in here as well.....don't remember. But you can search if you're interested.

[magicmike]

in fact, in a SOHC setup you could just swap cams right?

I was contemplating getting different cams when I had my motor rebuilt. I was told by someone at cobb tuning that the SOHC heads are whats limiting the air flow, not the cams, so better cams wont help, not to mention I could not find any aftermarket cams period.


Mike