Subaru WRX Forum banner

2.5L Swap Info

4K views 8 replies 5 participants last post by  cegpcola 
#1 ·
I plan on swapping to a 2.5L short block and was looking at these helix injectors from gruppe-s for a wrx and was wondering if they would also fit on the new block. Or should i just buy the ones for the sti? http://www.gruppe-s.com/Subaru/subeng.htm They are the 820cc and 860cc helix injectors at the bottom of the link.
 
#7 ·
thanks trauma, aren't you in the middle of a 2.5L swap too? Will every thing bolt right up like water pump, oil pump and whatever else? I will probably get new head studs and gaskets. I am still debating CP forged pistons since i only plan to keep the block for a year or so.
 
#8 ·
Yea it will all bolt up I'm replace everything just because the motors apart and i might as well put all new stuff while its out. I know people have said do new head studs but after talking to alot of people over it the Stock sti one are fine unless your trying to build a beast of a motor then go ahead and replace them just remember you have to tighten them after i think its 1000 miles or so. As for the head gasket use either the Sti one which i think is .021 mm or the 2.5rs gasket which is .051 again i think those are right either way the STi one will give you a higher compression around 8.8:1
The 2.5rs gasket will give you a lower compression of 8.4:1
I can get you the actual part number if needed. I'm going with the 2.5rs gasket due to hopefully going a 20g here soon after the swap is complete.
 
#9 ·
About the injectors, The STI uses Side feed and the WRX uses the top feed. If you are just replacing the short-block, you will use the top feed injectors. The fuel rails are what determines the injectors, as well as the pig tail on the wiring harness.

I am running a Crawford S2 (2.5L STI block, STI forged Crank, STI Forged Rods, with CP Forged Pistons) and WRX Heads. The compression can be pulled down with the right set of pistons. I am running the WRX heads setup from CP which with the STI head gaskets, gives me an 8.1:1 compression ratio. On top of this I am running the FPGreen, which makes for one torque monster. I am considering going to a GT35R within a few months, once I finish building the Transmission that I blew a few months back.

If I can help anyone out with anything, feel free to let me know.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top