silverwrxnor

Well, background is that my head gasket on my MY05 EDM 2,0 STI (arp,cp,forged rods,jun cams, rotated gt35R, Motec M800, 411hp/511nm) currenty blew. And when the engine was opened up, some marks on the crank appeared. Not so strange as it has been under stress for a long time and larger outputs whith another turbine housing (480/600nm++) and alot of track driving.

So, a new STi V9 cross drilled crank, cosworth bearings etc wouldn cost so much but then the neverending question appears:

why not a new 2,5L shortblock?

checking around some new JDM 2,5 sti (forester?) engines appear for sale.

What is the difference between this JDM shortblock and the EDM 2,5 sti as we know. Rods? Pistons? Crank? How much is their limit on std internals?

scoobysmiff

iTrader: (2)

Std limit is between 350-400bhp, depends on who you are talking to, the problem appears to be with the pistons which are installed at the factory with extremely tight tolerances.
This is due to them being coated with a Hypereutectic coating to stop expansion with heat.
These tolerances are tight so as to make the engine sound quieter when cold, however, for an engine to produce more power it will run hotter and as such the tolerances on the pistons are too tight once the heat gets higher than normal when more power is being asked for.
Run the 2.5 but get the pistons changed, most who can supply you a 2.5 block can facilitate this, i am getting ScoobyMainia to sort mine, speak to Mike Tuckwood he is a Top Geezer

Hypereutectic piston - Wikipedia, the free encyclopedia This might shed some light