Forged Pistons

[mo1988]

im going to start my build in a few months and im going to fit forge pistons, iv read on other forums that sometimes these pistons can tap due the the side wall clearences being out. any one fitting forge pistons on their GT had any problems

[philg]

in general alloy forged pistons can slap pretty much in any engine. this is because ally forged pistons expand faster and more then cast pistons. so piston to bore clearance is generally larger to allow for the expantion when the piston heats up. "slap" should only occur when cold. many new types of pistons materials are better so you can run much tighter clearances then few years back. wossner pistons in the gt run about 0.07mm skirt clearance.

[mo1988]

tapping when cold is allright, but i also read some of them can tap when the engines warmed up

[philg]

they can do yes.

[mo1988]

they can do yes.

what pistons did you use in your big build

[philg]

wossner.

[mo1988]

been looking at the exact same ones. going to find a good machinist first so i can get the block bored out

[philg]

cant bore the block without pistons first.

[Debo]

With Wossner's you can just bore to the size you are buying - in this case it would be 81mm. You bore to exactly that, because the piston comes in at just under it.. thus giving you the right clearance. They are manufactured this way (so I have been told by Wossner themselves).

[GezGT3]

With Wossner's you can just bore to the size you are buying - in this case it would be 81mm. You bore to exactly that, because the piston comes in at just under it.. thus giving you the right clearance. They are manufactured this way (so I have been told by Wossner themselves).

id rather wait and get the block bored to the pistons that get delivered. no piston is going to be "exactly" the same