In my quest for more useful knowledge i am wondering what kind of piston speeds are the limit? i know some of you guys out there deal in F1 and such. i had jotted a number on a small piece of paper an F1 guy told me a few months ago but i have misplaced it and it is important now. i think it was 28m/s or was it f/s?/ball valve thanks for the help i am really looking for a max this engine will only run for 200 miles then be rebuilt. i am trying to maximize breathing with the best trade off of stroke and rpm.

Normally people talk in terms of mean piston speed - ie, the stroke X 2 X revs per sec.  About 25 m/s is around the maximum for mean piston speed, if you know what I mean. This is true for a lot of high revving production motorcycle and car engines, to even things like F1 engines are about this mark.

The actual true maximum, as opposed to mean speed, also depends on the rod length as well as revs and stroke length, but people just normally talk in mean values.

In the mid and late 90's I worked for one of the 2 Japanese engine suppliers in CART. During the off season we were able to solve our valve train reliability issues to where we could run the engines @ 15,000rpm for 200 miles.
The maximum piston velocity was around 38m/s.
This was 200 miles of WOT track testing on a super speedway. As we approached the 250 mile distance (we had a 300 mile race coming up at Motegi in Japan in less than 6wks) when we discovered that the pistons were now the weak link. The center of the piston was cracking (due to inertial forces of the mass of the material in between the 4 valve reliefs in the center of the piston) and causing catastrophic failures. We spent ~$250k as a band aid fix to this problem since we didn’t have enough time to have new forging dies designed, built and new pistons tested.
I still have one of the band-aid pistons as a paperweight. It showed signs of cracking @ 250 miles, but it lived 350 miles before a pencil sized hole burnt through the crown.

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