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compression ratios?
Posted: Mon Oct 02, 2006 7:18 am
by asc_up
So anyways i'm trying to get my 2.2L n/a up to 150 chp so i was thinking about doing a head swap and putting the 2.5 heads on.
I asked a subaru shop around here and the guy said i would lose compression and it wouldn't work as well.
is this true?
Posted: Mon Oct 02, 2006 4:02 pm
by entirelyturbo
Sure is. Head volume of the EJ25 heads is larger.
You could get the worst-flowing heads of the entire EJ line, the EJ18 heads off an early 1.8 Impreza. That would up your CR, but I don't know how much. No one has measured the head volume of EJ18 heads, but I plan to do it sometime in the near future.
If you desperately want to have a higher CR, you could have custom pistons made and have your heads milled a tiny bit.
But if you want N/A power, the best thing to do would be to have headwork done, cams reground, a little extra fuel, and some halfway-decent engine management. PM Matt Monson, he just recently did this with an EJ22.
Posted: Mon Oct 02, 2006 10:48 pm
by asc_up
so if i put the 2.5L heads on it will actually decrease my hp?
Posted: Mon Oct 02, 2006 11:07 pm
by Matt Monson
If you put the Ej25 heads on your engine, it will probably be about a wash. You will be trading lower compression ratio for increased flow.
A more appropriate approach for NA HP would be to put an Ej25 shortblock against your stock heads. That will bump your CR a fair bit, in addition to upping your displacement at the same time.
Then, get a set of cams from Delta, which run about $175. It won't get you anywhere near your desired 150chp, but it will make a big difference over stock. It depends on what dyno you run it on, but I would guess you will be around 190-200 Chp...
Posted: Tue Oct 03, 2006 6:13 am
by asc_up
ok cool.
any idea what the whp would be?
and where might i find the 2.5 short block? like a website or just a junkyard?
Posted: Wed Oct 04, 2006 6:13 am
by Project_Legacy
junkyard would be a good one. i think they made them from 97 and on? your in washington? east or west of the mountains?
Posted: Thu Oct 05, 2006 12:06 am
by asc_up
west
Posted: Thu Oct 05, 2006 3:54 am
by Project_Legacy
the roy y junkyard may be a good one to check out, if you are near there, thats around the tacoma/spanaway area.
Posted: Thu Oct 05, 2006 5:16 am
by asc_up
hmmm ok then...
i'm in university place.
how much do you think they would charge me for it?
Posted: Thu Oct 05, 2006 6:45 am
by Project_Legacy
not too sure, but i did pick up a 94 ej22t for $550 bout 1 and a half years ago. most likely you will have to buy the whole 2.5 longblock, i would say around $700 maybe depending on mileage?
Posted: Thu Oct 05, 2006 7:28 am
by asc_up
hmmm ok.
but i just need the short block right?
Posted: Thu Oct 05, 2006 7:36 am
by Project_Legacy
that sounds like what they were saying.
you can even resell those heads you get if u wanted to.