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Compression Ratio of a EJ20H block + SS Heads
Posted: Thu Jan 01, 2009 4:54 pm
by BXSS
The motor in the wife's OBS is getting pretty up there in mileage, so I was thinking of possible replacements.
I have a set of SOHC SS heads with just over 100k on them + a EJ20H block with about 60K on it that I was thinking of putting together for a freebie motor.
I know with stock DOHC heads the EJ20H is supposed to have 9:1 C/R, but what would the C/R of the EJ20H block be with SS heads?
Posted: Fri Jan 02, 2009 2:01 am
by Matt Monson
Here's a couple of threads to get you going...
http://bbs.legacycentral.org/viewtopic. ... ght=hybrid
http://bbs.legacycentral.org/viewtopic. ... ght=hybrid
Given that the EJ20H uses heads with a smaller combustion chamber than the Ej20G Legacy engine, I suspect yours would be in the high 9's, maybe even over 10:1. I don't know that it would be a good turbo option, but if you just used her NA heads with it, it would probably be a decent NA engine.
Posted: Mon Jan 05, 2009 2:01 pm
by BXSS
Thanks!
Posted: Wed Mar 04, 2009 9:06 pm
by BXSS
I read that the combustion chambers of EJ20Gs & EJ20Ks are the same & I always hear that EJ20K's & EJ20H's are the same basic head so I'm confused as heck right now...
I was thinking a CR of about 9.5:1 but have never compared the EJ20H & EJ20G heads to each-other side by side....
I'm not trying to boost a TD04 past 5psi on her motor but do not want something too stressed either
Am I way off on the CR info / numbers?
Posted: Sun Mar 08, 2009 1:06 am
by BXSS
Had a fun day today & cracked open a EJ20H Freebie block I got from a friend + a blown EJ20G block for another friend & the pistons look to be the SAME on both blocks!
The exhaust ports on the EJ20H are SMALLER than WRX EJ20G e-ports - did not really compare intake ports but I should have...