Yea === I agree with doc. The bottom end would stay together at 8500 (if built right-not stock block) But ya will need a set of head's and intake system that will flow 325CFM+ to make power above 6500RPM's.
Don't want to here from people saying the "are" making HP up there 'cause I haven't heard of but maybe 3 on this board with a N/A 396+ making 1.6-1.7HP per CI. The ones I have heard are running SB2.2 or 12-15* stuff so there is your intake capabality right there with the heads flowing in excess of 360CFM.

 

Ok...I just spent some time using derivatives to calculate the speed of a piston at a given position (degrees). I then made an equation for it, and put it in a graphing program, so that I can substitute in the stroke, rod length, degrees, and rpm (I haven't gotten to completely check it though). How does this help to build a better engine?

 

I'm not sure if it helps much. If you pick a reasonable Average Piston Speed (RPM * STROKE/6) which has worked for engines of the type and cost you plan to build, you'll come up with a max rpm.

5000 ft/min can be used if you have light pistons and strong rods/crank. That would give you 10,000 rpm for a 3 inch stroke and 7500 for a 4 inch stroke.

4500 ft/min would be my choice unless I was very wealthy. That still allows 7200 for a 383 SBC. As was mentioned, heads are probably going to be more of a limiting factor in your engine build than piston speed, unless you build Cup, PS, F1 or similar engines.

 

Well if you want add in how the induction system will work with the bottom end relative to piston speed.... My "good buudy" Erik and I had a discussion on the Ford Forums about this.

CSA x Ft/sec = (Bore x Bore x Stroke x .7854) x (RPM/360)

CSA x Ft/sec = (Bore x Bore) x (Piston Speed/60)

Either one of those forumlas will help you solve for the max speed you want to turn the motor with a given setup. Well as long as you have a ft/sec barrier for the average intake port velocity. I use 330 ft/sec for a really good 23° head.

Bret