[Fot] Question 2: (Maybe stupid?) Turning down a piston size

[DSPGTi at aol.com]

Most of today's racing pistons are "cam ground". Turn the piston over, look 
at the different thicknesses of the underside. Massive up top, reinforcement 
around the pin bosses, thin skirt. Modern piston design takes into consideration 
the expansion of every portion of the profile. A true racing piston will 
calculate the expansion rate on every square millimeter and shape the piston 
accordingly. So they are "cam (as in lobe)ground". Kind of oblong or egged or 
whatever term we can use to approximate the shape the piston will take at "race 
temperature".
 
Of coarse we are talking about high reving, close tolerance, precision race 
motors.... not tractor motors.
 
Yes, I have gotten away with turning a piston perfectly round and running it 
at higher RPMs than the TR(3-4)  can achieve. as long as you aren't too 
worry'd about a little piston slap at idle.
 
Dave Y



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