350/350 on a Hawk STI

May have a Hawk STI Type UK lined up, its had serious money spent on handling/suspension. However its also running a 350/350 Powerstation remap. As I understand it, the 2.5 lumps are prone to piston failure on big numbers.

Think its a risky buy running such numbers? Dont think Id dare boot it in case it goes pop!?

Think that's the same setup mario is running on his hawk

oHUTCHYo wrote:

May have a Hawk STI Type UK lined up, its had serious money spent on handling/suspension. However its also running a 350/350 Powerstation remap. As I understand it, the 2.5 lumps are prone to piston failure on big numbers.

Think its a risky buy running such numbers? Dont think Id dare boot it in case it goes pop!?

That power/torque is spot on mate. The Hawks are fine up to 360/380 BHP -it's after that figure that it is recommended that you go down the forged route. It is absolutely fine the way it is.

Great stuff, cheers lads

I thought the hawks were on the limits at 360-370?

Bigclarky wrote:

I thought the hawks were on the limits at 360-370?

That's about right Clarky

Am not to clued up on the 2.5's but do the wrx & sti have the same pistons/rods?

come on lads leave us hawks alone they mighty fine up to 400bhp then you need to forge bits, andy forrest just mapped mine to 350 / 360 and fantastic, jonny gav is running his at 375 / 380 all fine and dandy to. but suppose if ya hammer them daily things could be diff.... fooking hope not.

I would consider fitting forged pistons if I wanted to go over 380hp, up to that power they are fine so yours is spot on at 350hp.

Anyone shed a bit of light on my question?

The WRX and STI 2.5 block/crank/rods are the same, the pistons are the same design but the WRX has slightly higher compression.

So are the crankshafts and blocks different aswell Jonny, am expecting the sti is semi and the wrx is open deck

No, blocks are exactly the same, so are the crank and rods.

2.0 ltrs rule lol

wrx 2.5's are EJ255 Sti's are EJ257 difference is open deck Z25 n semi Z25C, i believe only sti's also have the extra breather on the crank case's which is used to balance the crank case and head pressures but i could be wrong on that, Ive a wrx hawk set and sti set of hatch casings in-front of me and they defiantly different

I was under the same impression as you drew the wrx was a ej255 and the sti was a ej257

Need to correct myself here, the hawkeye WRX EJ255 and STI EJ257 short motors are identical in the uk market, they are both semi closed with the same crank rods and pistons, the higher compression in the WRX comes from the head design.

Do not confuse these with USDM 255 and 257 motors as there are differences.