[cjsgarage]

David,
I'm struggling to remember everything I've learned (especially just recently) and am no expert by far. But I have taken a few classes from experts and read more than one book on the subject. THANK YOU for starting this thread. It's cool to have insight from giants like Ron Sutton and all the other well-learned ones on this forum.

anywho. One of the points I actually can remember from my last class: High Performance Engine Design and Theory from Allen Osborne was that, the bigger bore always seem to make the better power. And I understand your desire to move the powerband down the RPM range.. but there's a reason NHRA and others are up to 4.7 bores. Something about shrouding the valves.

The other point I remember him saying was, to use the longest rod possible. Not necessarily as a stroker.. he meant pushing the rod up into the piston as far as you can--getting a wrist pin as close to the piston head as possible.

I looked for my notes on the class, but they escape me for the moment.



anyway. What about building the more common over-square engine with camshaft designed to pull the power band a little lower? Just a devil's advocate kind of thing.

It seems like you're pretty set on what you want to do, build the 3.78x4 engine. Maybe you'll have enough parts to build a second one if you use all OEM parts, and you can try oversquare similar displacement as you mentioned on page 1.
I do think Dynomation5 would serve you well at this point. It's made by Motion Software.



More food for thought: This is something I found on another forum:
Where B = bore, S = stroke, N = number of cylinders, and C = a constant for fuel quality, materials, stress levels, etc.:

HP ~ B^1.65 × S^.5 × N × C
(after F. W. Lanchester)

Removing N, most power by far, is big bore + short stroke