Afternoon,

Just looking for some advice on what a safe power level is for my car before I start to look increase it.

I've got a 2010 Wrx Sti which has already had the following done to the engine:

New hardened crankshaft
Late semi-tapered STI con-rods
Mahle pistons and rings
ACL race bearings
Oil pump replacement
Oil cooler modene.
Semi closed deck engine
Any ideas with this spec engine what the power limits of the engine is? (So that I can stay well away from it).

Car is currently fully stock.

Any help would be greatly appreciated.

Thanks

Luke

 

What head gaskets and studs ?

 

Factory new age rod are known to survive 400, factory head bolts might handle it but not for long periods. The best advice will come from the guy who built the engine.

 

On a stock 2.5 semi block I was advised that 1.6 bar/450bhp is as far as you want to go due to the lack of liner support. Its this reason i've gone 2.1 as originally I fancied the 2.5 torque in my blob but there were just too many factors involved in building a strong, reliable 2.5 for me to justify it.

 

without arp head bolts and cosworth or like gaskets i would be hanging on the side of caution , my first fsti build with out arp bolts lasted only a few years at around 1.3 bar till hg went , put back together with arp and a number of years down the road all is well , i thought i heard 1.4 bar was a good place to be but every one has there own thoughts the more boost the more likely it will go wrong , i’m on about 330 bhp and little lag and i’m happy with that , plus mpg is good

 

Paul Finch has indicated 380HP on standard rods but that might not be the limiting factor if the head gasket and bolts are standard.
Trev

 

Seems awaste once you have the engine split to NOT fit decent rods and head studs/bolts, its a small cost compared to the labour costs of stripping it again.
it basically limits the car to low level standard tuning . The blocks seem hit or miss.some last at + 500 for a while but with an insert and decent head studs can easily .take 550 all day long.

 

The yanks run the standard blocks very hard.but nearly always run meth or E85. The main enemy of a standard block and split liners seem to be det and high cylinder pressures.

 

This guy does a 10.02 on a standard EJ257 with 500+bhp.

"engine is literally untouched from the valve cover down to the oil pan"

 

i recently saw a cs400 which i assume was standard with a split liner , the 2.5 is a great lump for torque and drives very well , and drives very differently to a 2 litre , the 2 litre same mods has less torque , the mrs beats me off the lights in her 2.5 litre 310 or so bhp fsti v a jdm sti 2 litre with probably around 340 bhp , the good side the 2 litre is a stronger engine , i want grunt plus economy and reliability so all scoobies i have had i have cat back and a remap and been happy with that as it’s a quick car to start , so how much power ? it is a balance of bhp reliability fuel economy etc , the more bhp the worse fuel economy , my friend moded his fsti , turbo injectors etc , fuel economy was poor and the engine gave up , he said himself he regretted doing what he had done mod wise , as above arp head bolts and a good hg make are important

 

Any idea safe bhp on this 2.5 spec?

Block conversion to closed deck with 14mm threads
Mahle 4032 pistons
ACL race bearings
Williams H beam rods ARP bolts
11mm oil pump
14/12mm RCM headstuds
RCM head gaskets

 

When Litchfield made the mark 1 T25 the figures they run were about 360bhp/ 390 torque. Think they only had uprated pistons.

 

450 - 500.

4032 pistons a bit unusual for the that spec, It looks like a build for over 500?

 

Piston choice was to reduce slap from cold, not looking to exceed 4-420 to be honest, spec is for reliability and longevity (hopefully ) after the second hg failure it was the only way forward. Do you agree?