David,
No problem - just noticed that the thread had drifted with some data falling off from factual into conjecture. I generally lurk on this forum - knowing that some very talented builders (such as Keith and George) have made a significant financial investment here - and I am not yet in a position to do so. Both of them are good folks, have well deserved excellent reputations, and appear to treat their customers well. My fledgling operation is more parts sales oriented - - but I certainly enjoy a limited degree of competition
Keith's flow data must be compared to other parts on his bench - as should my current range of ET ported stuff be compared to other parts on our bench. Please note that I always reference multiple corrobarating(sp?) sources when possible. That is because flow numbers - like dyno numbers - will vary from location to location and operator to operator. Dynos and flow benches are excellent directional tools - - but they are not the sole predictors of an engine's performance in the car. There is so much more involved - but the numbers are lots of fun to talk about...
Since I am "in" on this thread I may as well toss a couple opinions out as well. These are opinions - - not hard facts...
As to bore - - bigger is better as long as there are airflow limitations. Once you are flowing air at or beyond the engine's needs ther are no further advantages to larger bore - - except for ring friction.
As to stroke - - more is better until the rules guys throw you out. Except for that friction thing. Ring friction increases with RPM (simple factor of distance traveled). More displacement outweighs friction - - see rules comment.
Bore/stroke relationship - - I consider this as an output and not a number to work towards or design for. I'd rather go for as much bore as the engine/airflow needs/wallet allows - - stroke to whaever the rules/wallet permits.
Weight - - I need to lose ten pounds. Piston weight is really only significant in that lighter parts will allow more RPM before failure. RPM is power, but if you don't need more RPM spend your money elsewhere. Unless you are running NHRA Comp Eliminator or F1 unloaded RPM gain rate (i.e. blipping the throttle) means very little once your in gear. Inertial gains are real, but very, very small in proportion to other things.
As to rod length my thoughts mirror those of the guys at Reher-Morrison. I select the stroke, design the piston as far as desired ring pack, pin size and skirt without punching through the
oil groove - - and choose the rod that fits. When working with common available rods, the pin height will change to get something "off the shelf" - I don't attach any religion to ratios at all (within rational ranges - no 5.090 rods and 3" compression distances..). My preferred compression distance is somewhere between 1.25 and 1.35 - - a range which delivers plenty of real estate for rings and a nice stable skirt package for bore stability. I would trade a shorter rod to gain a better and more stable ring pack in a minute.