[SFfiredog]

Guys,
Piston speed is strictly a matter of stroke and rpm.
For example a 4.25" stroke crank at 6000 rpm has a mean piston speed of 4250 fpm. That's moving along pretty good!
For example a '69 NASCAR 427 tunnel port had a piston speed of 4221 fpm at 6800 rpm and a '70 NASCAR Boss 429 had a piston speed of just under 4200 fpm at 7000 rpm.
The 427s use in '66 and '67 at LeMans were limited to 3500 fpm
(5600 rpm)
These numbers are of course constant speed unlike a street engine but were also not designed to run for 10s of thousands of miles like a street engine either.
For me, if I'm building an engine that will see 4250 fpm or higher, more than a few times, I will usually step up to a set of Oliver rods. They are stronger but more important, on average they are about 50 grams each LIGHTER.
Also, the bigger the stroke (the higher the piston speed), the more important combustion chamber efficency is.
With a poor combustion chamber design the piston is moving too fast for the flame front to be completely effective.
This is one of the few places where rod length is important and can affect combustion efficency.
Somebody stop me or I'll go on forever...
--Mike