STI block SOHC heads completed.
 

Well all of my annoying questions paid off.. I finished swapping out my block on my 2.5RS.. First I will explain why I did this... My car had been running "funny" for a while.... idling rough, hesitation, and leaking oil out of the valve cover vents.. so I thought great I blew some piston rigs, but to be on the safe side I took it to a dealer... YES A DEALER, and they did a leak down saying that I was leaking 70% from my number 4 cyl. So I thought ####.. I must have a freakin hole in my piston... The dealer said that it would be a minimum of 1400 to take everything apart to see what the problem really is.. I thought to myself.. Funk that!!!!! So I did some research on the new STI block assy.. and asked a million dumb questions and found out that MAYBE all of my stock parts including all of my pumps, etc will swap to the USDM sti block.... So I went that route.. Well I tore my motor aprt a few days ago and discovered that there was absolutely NOTHING wrong with my motor.. Nothing at all.. I did a leak down.. after I turened my right side cam to TDC (will explain ) and did a leak down my self... it only leaked 5 % and this is with a motor that is missing a piston ring (took one off to look at it) and bone cold... pretty good huh? apparently my right side cam sprocket slipped about 30 deg. clockwise and m,y car had been runing like that fro quite some time.. I don't know how, or how long but it was off.... way off.. I paid 1400 dollars for a timing belt... oh well at least I have a new block... but ZI am for sure going to go down to the dealer where I had the work done and ***** thme out.. I won't tell anyone who they are ( Ehrlich Subaru in Greeley CO) because I don't want them to get a bad rap ( $%^$heads) BUt everything does sawp perfectly.. the vent on the top of the sti block is in the way of the water pipe, but some grinding and hammering made room for the vent.. and man it is soo awesome.. my car runs great.. everything works flawlessley.. If anyong has any questions or anything please write me.. I am excited!!! woo hoo!

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congratulations on the swap, nice work!

Awesome work, I am planning on doing this myself so I can run a VF30 at high boost on my RS. [size=1]But please don't cross post. Thanks. [/size]

are you still NA?

how much do you want for the 2.5 shortblock?

no I am not still N/A I have a GT25 DBB turbo.. I am not too sure what I want for the shortblock.. pm me,

That is awesome!
So are you saying that everything from the RS engine can swap onto a new STI shortblock? What did you do about the ECU?

yes EVERYTHING swaps.. I have the stock ECU right now with a rising rate fuel pressure regulator.. but I will soon have (Monday) an FTC1 that is made by split second.. it has 3D mapping of both fuel and ignition... it is pretty sweet.. but to get back to your question.. everything swaps.. the sti block looks identical to an RS block even down to the "EJ25" printed on the block... The stock ECU will work just fine though, it will just lower the compression to 8.2:1

Sounds great, I'm happy for you. Kinda weird that you can use the RS ECU. The best combination of old school style with new school technology.

what exactly do you ahve done to your car? did you have the sti block on while you were still na? if so, did you notice anything? would that be a good block to mate with twe heads/ cams/ springs/retainers? worth doing this swap for a na build? what did this cost you all together?

thanks a lot in advance for the multiple questions!

no i didn't run my car NA with the sti block, I have a turbo. This is an awesome block to mate with twe heads, cams, springs, etc as long as they are 2.2 or 2.5 liter parts.I would not recomend doing this swap if you are going to run NA. on a 2.5 RS they have 10:1 compression, and the sti is 8.2:1 compression.. lower compression withoput added induction equals LESS horsepower. When you run NA you want to have higher compression to make more power.. hope this helps.

Could you perform one more little experiment for us? Would you mind finding the exact volume of the SOHC head combustion chamber? And more importantly, find the volume that the RS piston displaces above the deck? That way, we can determine exactly what the new static compression ratio is of the hybrid motor.

By the way, thanks for verifying this. I am putting ported/cammed SOHC heads onto an EJ257 block next month for my own turbo kit.

will do!

Congrats on the Conversion!

Few questions though:

How high you think you would be able to rev the motor? What would limit revvin it? Valves, valves springs or the whole heads?

Thanks in advance.

I wouldn't want to rev past the 6200 rev limit due to the fact that I still have the stock SOHC 2.5RS heads.. If I were to have headwork done than I could rev to about 8000 safe.

our valves are really strong.
All you'd need to do it upgrade the springs.
COBB has a set, but of course, they are expensive.
I want them too for my RSX-T