Hi,

I have a WRX STi Spec D 07/07 with 24k on clock.

I am curious as to how different a WRX engine is compared to an STi?

I hear of stronger internals etc in the STi, but then also about chocolate pistons (in both)

How much stronger is an STi engine over a WRX? Different materials used?

 

Im no tech but from what I hear there are 3 types of block. Open , Semi and closed deck blocks.
The open and semi closed allow a very small degree of movement of the walls where as a closed deck block doesnt. I believe the spaces are filled with aluminium and machined.
The Strongest block is the CDB STI JDM which I hear is good for around the 400 mark.

 

Sure, I'm aware of the STi being a semi closed deck, but i'm wondering about the moving parts?

 

The 2.5 isnt a good engine as far as Subaru are concerned, the 2ltr is a much stronger block with better internals.
It really depends on what you want to do with your car though? you can still quite happily tune the 2.5 to 360bhp, much more than that and it gets tricky with the reliabiltiy.

Tony

 

Thank you Tone. I'm only considering 315bhp PPP. Would like to up the power, but with something that my engine will happily cope with / tolerate.

 

Hi bud, I have a wrx Hawk
It is now Modified with a Forged engine.
Alan Jeffery Did all the engine work, and they know there Subaru engines
They told me that the wrx and sti engines are both semi closed deck, and all internal parts are the same,
they are said to be good for 350bhp
I was running 300bhp but with 370lbs torque
my engine let go, but I do drive it hard.
the 5 speed gearbox will start to let go before the engine.

Bez

 

He told you that the WRX and STI engines are identical ???

 

the 2.5 short block is afaik.