Hi all,

Currently have a forged 2.5 in my type r that only has v2 wrx heads fitted, and as such when it went for mapping the heads wouldn't flow past 1.2 bar(ish). I have a set of v3 sti heads from my old engine, what work needs to be done to get them to fit? Is it a case of just putting on a thicker head gasket to keep a low compression ratio or am I talking out of my rear?

Thanks in advance

 

I am pretty sure it is just getting the correct thickness of gasket to keep the right compression. Given that I guess heads and or block have been skimmed.

I had some V4 STI ones on a forged 2.5 and dont remember much if anything being done to them.

(If you have the standard semi closed block with all the forged bits in. You really want to take to about 1.5bar for safety. So the block will become the limiting factor once the V3 heads are on and flowing enough)

 

Thanks for your input mate correct, unfortunately the block hasn't been pinned or re-sleeved etc so yeah 1.5 bar is the limit. I didn't build the engine I bought it second hand with running in mileage on, else I'd have had the block strengthened, bit of a shame really! I just need to get these heads on, car made 334/380 with an "avo 500" turbo and the wrx heads, but it's slow spooling, being an older turbo. So it's all in one big hit and over far too quickly. Hence the heads and probably an sc42 or 46, leaning towards the 42 for the spool up. Cheers!

 

version 3 heads will need to be machined on the clove parts to suit the block rather than jacking it up on gaskets to get the required compression ratio with a thinner gasket.