C
cnewingham
Guest
I seem to have piston piston slap when my motor is cold but as it warms up it goes away. I have read this is normal with forged pistons and not to worry but want to make sure and see who else experiences it.
My car does this, but I don't think it has forged pistons :icon_conf...My 7M was rebuilt by the previous owner, and I don't know what kind of internals were used...but it definitely sounds like piston slap when it's cold, kinda sounds like a diesel engine until it warms up, then it goes away completely. It has done this the entire time I have owned the car.
mine do this aswell, running with ross pistons. they will do it even at operating temp slightly but if i take it for a run it tightens up and is all good. its the silicon content of the pistons. i forget weather its a high content or a low content but one of them expands more then the other at operating temprature. because they expand so much extra clearance is required so when cold they make a little noise. nothing to worry about really as long as it goes away.
I heard this was common with the JE pistons... Do you have JE? I dont know if its good or bad really, but its the main reeason I went with Wiseco pistons... I havent heard anyone with Wiseco having slap issues...
je are the only ones that will slap causethe lack of a skirt they are lighter then ross and wise co ect but they just last as logn as the full skirt ones
yeah JE's have a lot shorter skirt and usually slap, i have heard good things about ross, but weisco FTMFW... i am running weisco's and lately i have been getting a little noise the first 5 mins after start up but only below 1000 rpm, but it has never done it before about a week ago....... then again it was 2 degrees Farenheight this morning
If they never slapped at all, and you have Ross or JE pistons, then the machine shop probably set up the clearances too tight! Run a little nitrous or a lot of boost and that could be a major problem! It may sound like a diesel without a loud slapping, but you can still hear the difference from stock pistons.
We have found the JE pistons are a little quieter then Ross when you use the recommended bore size.
We have found the JE pistons are a little quieter then Ross when you use the recommended bore size.
^^^
what he said
it all depends on your piston to wall clearance.
Bigger for big boost, and nitrous.
A little slap doesn't hurt, as the pistons do expand.
I got my ross pistons coated, and i plan on running .004 piston to wall clearance, so i might experience a little slap, but i plan on running big boost as well.
I know slap was more common in ross pistons, but it really just depends on your clearance.
Bigger for more boost and nitrous, smaller for n/a's
what he said
it all depends on your piston to wall clearance.
Bigger for big boost, and nitrous.
A little slap doesn't hurt, as the pistons do expand.
I got my ross pistons coated, and i plan on running .004 piston to wall clearance, so i might experience a little slap, but i plan on running big boost as well.
I know slap was more common in ross pistons, but it really just depends on your clearance.
Bigger for more boost and nitrous, smaller for n/a's
i knew everything was fine, my machine shop just knew i was planning on running 35psi boost and a 300 shot :naughty:
My bro went with diamond racing pistons (forged) not a damn problem, hes makin 650 all motor and still no problem (small block chevy), so i prolly will be buying some of those.
I have J.E. pistons,.. I don't have that problem yet,... forge pistons have more piston to wall clearence due expansion. I guess your problem could be normal