A Learning expeirance.

To start off with I have built many VW so called Hybrid engines but have yet to do much with a Subaru other than bolt on a turbo so this is all new to me and if I state something wrong or if someone has more input please feel free to jump in and help me out.

So I started out by ordering what was REFERED to as a Big port JDM head and I was very excited to think her a 207 head cheap awesome. Well this did not end up being the case only because of my lack of Subaru knowledge.
So the parts arrived.
The block is a refurb EJ25 semi closed deck block with Mahle forged 8.1:1 pistons, OEM forged crank and rods, Cosworth race bearings and ARP hardware. I know nothing to talk about but hey..

Here is where it gets interesting.
The person I’m dealing with is Jeremy at Outfront motorsports in Cali. They mainly build Sandrale motors for ralliyand fun, whatnot.
So he tells me he can hook me up that he has these awesome JDM big port heads and it would make a great addition to the block. So as stated before I think he is referring to 207 heads.
The heads arrive and they turn out to be a JDM 2.5RS NA heads and boy are the ports big I am not disappointed at all.
So far the most I can come up with based on markings on the heads are they are B type but I’m having a hard timing finding other heads with the same port shape to compare to. Jeremy stated he will have all the head info for me by Wednesday so I guess I will wait on that. Model year ect.

The casting is already gasket matched which I found odd until Kyle corrected me.
The head does have AVCS and the cams needed to be modded to make the cam sensor work.
The cams are from a 2007 Sti and other small variation needed to be made for this to work correctly like larger sensor O-rings. I will also require a breather adapter that they are kinding making a billet one for me.

Jeremy stated that they have completed 4 of these swaps into Sandrales and a dun buggy but never a street car this should be interesting.

Now I’m still taking in all this information myself and its a lot of tid bits of info I have gathered so I could be way off but I’m excited about trying something new.

nothing like the smell of fresh block in the morning.

What kinda CR are you going to see with those JDM heads? I doubt they gave that CR with the mahle pistons and tnat head combo. Looks pretty cool.

I hope to assemble my ej257 next week.

Evan

Pistons are 8.1:1 with the head its 9.1:1.

Damn!

Should be fantastic off boost. Ill be watching with interest.

My tune I have now is for stock 9.5:1 and I made 302whp on 18psi.
I also forgot to state this is going to be for E85.

Nice dude E85 ftw!

You interested in a crower stage 2 cam/valvetrain setup? PM me if so.

Man if these cams didn’t need to be machined to work in this head I would totally get em lol.

What machine work is needed? Now I am just plain curious.

The keyway used by the cam sensor needs to be extended. Nothing big.

Ok finally.

The heads were made for JDM Legacy only, the first year with AVCS.
Ports are larger than USDM STi but were designed for a higher air speed than the 207 heads with the large ports.