my 1998 sti has a rebuilt block with cosworth pistons ,its only done 7000 miles and it suffers from piston slap when cold . when warm it sounds sweet and dosent use any oil.
i've been told its normal for cosworth pistons, does anyone know if this is true

 

i'm thinking as i have je pistons now, that is quite nrmal for lighter pistons to give a bit of noise of it. i find this is the caes, but as no problems have arose and no det appearing, that all is ok anyways.


hope that answers your question

 

Piston slap when using Cosworth pistons in a Scoob is a known characteristic. As long as it goes away on warming it's not a problem. Warm the engine gently before using boost.
JohnD

 

try a search, im sure a few of the biggish names on this board have discussed this (one of the johns im sure of it)