D-train

i have a set of sealed power/speed pro forged pistons but i cant find a reccomended piston to bore clearance does any body have an idea or recomendation

LTD351T

I know 45 thou is a lot, if its n/a probaly 25-30thou would be my GUESS, i'm sure I'll be corrected tho.

xdclevo

I think it is around 3 thou, but i will try and find my spec sheet. The clearance is smal er than some think, and not the 6 or 7 thou which used to make the big "rattlers" when cold. I assume TRW forged is the same piston as well, just named different. There is a website somewhere if you search. I found one a few years ago.

LTD351T

a lot depends on the application as well, theres no way in hell you would run 3 thou in a turbo drag engine, more like 40 plus.

D-train

i found out they run 7 thou i didnt know this but a 4.030 piston is actually to suit a 4.030 or 30 thou over bore. so the piston is whatever clearance is needed smaller then the bore

russxr67

Do you know how much 40 thou even is mate.?? its 1 mm . Show me anyone who runs 1mm piston to bore clearance. 3-4 thou sounds about right for a forged piston.

xdclevo

You would break a piston skirt before you got to 2000rpm with 40 thou, or even 20 thou for that matter. Making the ring gap larger for that application i would beleive.

LTD351T

yeah 1mm sounds like heaps I have read it wrong, 0.00X not 0.0XX, der. Mine is .005 clearance, thats for turbo, so less for n/a, .003 as already stated.

northiam

Its normally stamped on top of the piston! 0.001 to 0.003 sounds more like it thou.

ALKY

THE CLEARANCE YOU ARE SUGGESTING IS MAYBE PISTON TO HEAD CLEARANCE PISTON TO BORE IS ANY WHERE FROM .002" TO .009" DEPENDING ON SKIRT STYLE .MOST PISTONS HAVE THE CLEARANCE BUILT INTO THE PISTON IE= 030 OVER PISTON WOULD MEASURE SAY .023 THEREFORE IT WOULD HAVE .007 " CLEARANCE