My motor has always had a bit of piston slap when cold. Once warm it is pretty much gone. If I recall, I *think* my engine builder had said he uses 7 thou. I know this is quite large, but then again it depends on the piston. I believe my engine builder has a relationship with Ross pistons.

My buddy with a Buschur 2 litre has very little piston slap, if any. So I assume Buschur uses a much smaller number.

My other buddy has a JAM motor. Again pretty quiet. He recently snapped a timing belt and we had to replace 16 valves, 4 pistons, etc... we measured the pistons JAM sent and his bores. The piston to wall was about .1mm or 4 thou.

What are various piston manufacturers piston to wall recommendations for big boost motors, and how might this effect the motor in terms of oil consumption? I've always had to add about a quart of oil every month for the past 2.5 years of running my motor (2.4l) which is why I ask if a loose piston to wall could contribute to oil consumption.

 

I use 3.5thou on Cp pistons.

Mark

 

i think generally its adviseable to go to no more than 4 thou.

but it all depends on material properties of the piston some do expand more than others.

i *believe* its the amount of Si in the piston. (correct me if i am wrong please)

 

i think generally its adviseable to go to no more than 4 thou.

but it all depends on material properties of the piston some do expand more than others.

i *believe* its the amount of Si in the piston. (correct me if i am wrong please)