Wednesday, February 06, 2008

ej25 dohc heads vs JDM WRX ej20K version3/4 heads

Turbo heads are differnt than NA heads in port shape, chamber shape, and valvetrain sufficiency. turbo's are obviously cammed for turbo, NA heads are cammed for NA power output.

[QUOTE=Sarra;1289638]Well, I've got DOHC 98 Legacy GT heads. I'm not sure if they're the same or not, but I've also heard that the 98 DOHC Legacy heads are very similar to JDM WRX heads as well, so they might be the same.

I'll eventually be upgrading to turbo cams and a better valvetrain setup. I just want to get this ****ing supercharger on finally![/QUOTE]

The heads are similar in original casting, un-similar in the fact that:

cams are differnt. - less aggressive - the ej20K 97/98 head which shares basic structure has ~252 deg cams in some varients.

most dohc ej25 heads found in usa pre 98 are older style rocker arm / hla dohc setups. the ej25dohc in 98 RS has the ver 3/4 ej20K wrx style valvetrain with under cam shims.

ports are completely different. there are no similarities, except for if you had a lot of time and the machine shop to do it, you could port and shape a ej25 dohc 98 rs head into a ej20K 98 sti head. I have had both engines and both heads in my hands (in my car).


No comments: