Will STi 7&8 heads fit directly onto the US STi 2.5 engine? or is machining required and if so how much?

Mark

 

I believe they fit directly. NASIOC guys have done a lot of this. Do a search there to work out your compression ratio. If going for big power try to get big ported heads... spec C, US STi or STi 5/6 heads.

 

Cheers John

A chap in the groupbuy has a spec C and wants to use the 2.5 STi short engine with uprated rods and pistons with the Spec C heads etc, what do you recommend, e-mail if you prefer.

Mark A

 

He should speak to the person building the engine. Ron at Axis Power Racing sells some nice looking rods and pistons.

There are a few that believe that the rods and pistons are at least as good as the block - the thin bore walls may cop it before the pistons or rods do. For this reason I am holding off on changing the rods and pistons, will see what the standard short motor does with 450-500 BHP (conservative figures).