Big bore short stroke or small bore big stroke

[xstfudonniex]

smaller bores generally resist detonation better, therefore respond to nitrous and boost better, Bigger bores generally allow better cylinder heads because you can run bigger valves and they will not be as shrouded, the smaller strokers also allow for more RPM and less piston speed.

This is all absolutely true. With the short stroke comes a reduction in piston speed and friction. This also increases piston dwell time because the piston is not moving at as high of a fpm rate. Lots of people run really long rods to try and gain this "advantage" I dont really think there is a lot of power there. So a larger bore flows better, but would you agree that there is friction picked up with the larger bore? Or is it a negligable difference?

In my application (408w 4.03in 4in stroke) i had the choice of a 6.000 6.125 6.200 or 6.250 rod, the 6.2 rod was a little more money than 6.0 and 6.125 and any longer put the pin into the ring stack. I went with the the 6.200 rods because of the rod ratio, whether or not it will make any difference il never really know.

[3V Performance]

Is there a gear rule? or max rpm controlled by a chip?

If not then:

Biggest bore first for block used then match biggest crank to max cubic inch.

No gear rule or chip.

Then the key here is to build it to turn some RPM's. Our 4412 steel valve stuff see' over 8000 all year.

[hitchcock]

smaller bores generally resist detonation better, therefore respond to nitrous and boost better, Bigger bores generally allow better cylinder heads because you can run bigger valves and they will not be as shrouded, the smaller strokers also allow for more RPM and less piston speed.

This is all absolutely true. With the short stroke comes a reduction in piston speed and friction. This also increases piston dwell time because the piston is not moving at as high of a fpm rate. Lots of people run really long rods to try and gain this "advantage" I dont really think there is a lot of power there. So a larger bore flows better, but would you agree that there is friction picked up with the larger bore? Or is it a negligable difference?

In my application (408w 4.03in 4in stroke) i had the choice of a 6.000 6.125 6.200 or 6.250 rod, the 6.2 rod was a little more money than 6.0 and 6.125 and any longer put the pin into the ring stack. I went with the the 6.200 rods because of the rod ratio, whether or not it will make any difference il never really know.

I dont really think in motors like these it will make a measurable power difference. Yeah the rad ratio gets better but it's also heavier. It will help reduce cylinder wall side loading and make rings live longer.