peterhum

Got one of the last 2007 2.5 hawkeye STis, running standard engine internals, intercooler & Turbo but 3" Miltek with sports cat, panel filter, inlet hose & Ecutek map to ~340 BHP- was all done by Rich at 'Powerstation' back in the day- a really nice flexible drive & has been 10 year reliable.

Now started blowing a little exhaust into the coolant on power @ 60K miles, so the lump is coming out -I ain't got time to do it, so I'm going to be paying labour. Min cost at local independent is £1500+ VAT (I thought this was decent inc. quality Cam belt & tensioner, all gaskets etc.) BUT...

Question is, if I wanted to go beyond 340HP, still on road or occasional track day- not for competition, say to low 400's- what mechanical parts do folks recommend upgrading whilst the lump is out- if I go this way? I stopped at 340 last time precisely because I didn't want to do mechanical upgrades on a (then) nearly-new car.

I guess forged pistons & upgraded rods, 11mm head studs, main bearings- but anything else? What will std STI clutch take- seems like at 60K I might as well replace it. Oil pump? At what point does the STI gearbox start to complain? despite driving it hard, I am reasonably sympathetic and don't tend to dump the clutch from standstill

Given that you can go on for ever, I'd better say that I'm not looking to spend the value of the car again here- it is a semi-daily drive (and I have to look slightly responsible at work), so I probably want to keep the TMIC to look standard at a glance. I also want to keep the driveability as far as I can- It is the fact that the STi works as an 'ordinary' car when it has to that led me to choose it.

Sorry for the mile-long post, but the sticky said to be thorough!

Peter

trevsjwood

iTrader: (2)

referring from my own engine build sheet I have :- Mahle 4032 forged pistons, Manley forged rods, acl bearings, cosworth 11mm headstuds, cosworth headgasket. Oil pump and possibly water pump. The six speed is a good unit, clutch, you need something like an excedy pinkbox or similar.
I'm no expert but Paul Finch built my engine and he is.
hope this helps, starts the ball rolling anyway.
Trev

peterhum

Many thanks- the internals seem pretty consistent with just personal preference on component brands vs price.

Reassured that the 'box should be OK, I think I'm going to go for it.

Peter

joz8968

iTrader: (13)

I think it's 'accepted' that a properly forged 2.5's 'safe' limit is c.450-70bhp - @ 1.7/8 barg.

Something to 'aim for', perhaps...


I've been in a passenger in a UK Hatch STi, with a SC46 running around 450bhp. It makes for a devastating A-B roadcar!

trevsjwood

iTrader: (2)

the problem is you're forging a weak block and as I understand using a non specialist garage to do the work which all may be ok but for me I'd certainly want cosworth head gasket/ headstuds over say a cometic /arp items. The Mahle 4032's are probably as quiet a forged piston and that has got to be personal preference as with rod's but which must be forged for 400's hp.
Trev