legacycentral bbs

Ive got a 92 legacy ss with 151k on it. Im going to swap the heads to some dohc but my question is which heads should I go with? I've been tolt that ej20g heads are plug and play and bolt right up, Ive heard that ej20H or twin turbo heads work well also, you just have to plug off the driverside head oil supply, so which is better or is there another combo superior to these?

-Grant

The ej20g and ej20h heads have a 49cc combustion chamber. You can use a thinner HG to compensate for loss of CR.
The ej25d heads have the 46.6cc chambers like the stock ej22t heads, co CR is not changed. These require a little work on tapping oil and coolant turbo feed lines.

i was told the 20H heads flowed better than the 20G heads.

yeah Ive heard the same thing on the 20H heads also. I wanted to avoid making an oil tap if I could get away with it. Although the 25d heads are easier to come by at junk yards

25D heads have big ports, but the cam profiles are counter productive.

25d heads will lower your comp ratio. stock heads are 40cc 25d heads are 46, resulting in a 7.6:1 comp ratio. the 20g/h heads are even worse, 6.9:1 comp ratio which is useless. you cant use a thin HG on any of those heads due to the 22t pistons protruding from the bores at tdc.

I suggest reading over this thread if you haven't

http://bbs.legacycentral.org/viewtopic.php?t=38247