I've blown my 400hp sti JDM EJ207 engine. The valves went through the cylinder heads, now I have to replace it, the thing is its so hard to get the ej207 sti heads so i might settle for the ej25 sti heads, if it will fit. So anybody has done the swap? or is it just possible to put the EJ25 heads to an EJ207 block? thanks
jojor
yes, it will fit... however, you are going to have to look at the compression. Those heads are not really made for the 2.0... you may have to run a milled head or thicker head gasket depending on what the compression does...
i know that when you put ej207 heads on a 2.5 ltr usdm sti block it raises the compression... so if im on the right track, the ej257 heads should lower the compression... it really depends on your piston setup, head gasket, head work, etc
i say, rebuild your ej207 heads since they are amazing, get a thicker headgasket, and bolt a USDM sti 2.5 onto it. Run a 30R+ turbo and watch it make nice numbers...
i know that when you put ej207 heads on a 2.5 ltr usdm sti block it raises the compression... so if im on the right track, the ej257 heads should lower the compression... it really depends on your piston setup, head gasket, head work, etc
i say, rebuild your ej207 heads since they are amazing, get a thicker headgasket, and bolt a USDM sti 2.5 onto it. Run a 30R+ turbo and watch it make nice numbers...
There are several variables you need to take into account. I assume based on what you are saying above that you intend to use the stock EJ207 block with some newer EJ257 heads.
To determine to compression ratio, you would need to provide a bit more details.
(1) Are you using a completly stock EJ207 block, with the factor forged pistons? Is this a Version 7,8? 9,10,11?
(2) Which EJ25 heads are you talking about? The 04-06 EJ257 STI heads, the 07 STI heads, the 06-07 WRX EJ255 heads?
(3) If you are indeed running and older EJ207 (version 8,9,10,11), it uses a different style cam sensor setup then the EJ257 heads in the US. What ECM are you running, and are you controlling AVCS?
As an example, here is a look at some common configs:
![Image]()
Cheers,
Jeff Sponaugle
Surgeline Tuning
To determine to compression ratio, you would need to provide a bit more details.
(1) Are you using a completly stock EJ207 block, with the factor forged pistons? Is this a Version 7,8? 9,10,11?
(2) Which EJ25 heads are you talking about? The 04-06 EJ257 STI heads, the 07 STI heads, the 06-07 WRX EJ255 heads?
(3) If you are indeed running and older EJ207 (version 8,9,10,11), it uses a different style cam sensor setup then the EJ257 heads in the US. What ECM are you running, and are you controlling AVCS?
As an example, here is a look at some common configs:
Cheers,
Jeff Sponaugle
Surgeline Tuning
wow, a lot of info to digest, but thanks for the info. Ill try my darn best to understand all this. By the way, i decided to get an EJ257 block with 2.71 stroker forged internals and matched it with a 06 ej207 head with avcs, ecu is piggybacked with unichip, and GT40 turbo, just hoping it will work well. Thanks again for the help
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