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STi heads on US 2.5 engine

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Old 24 March 2004, 11:43 AM
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Mark A
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Default STi heads on US 2.5 engine

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

Mark
Old 24 March 2004, 12:13 PM
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john banks
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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.
Old 24 March 2004, 04:21 PM
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Mark A
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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
Old 24 March 2004, 06:18 PM
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john banks
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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).
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