I adjusted the equation above in a downloadable graphing
calculator and took a somewhat large screenshot. Its only
43.3k to download though if you're interested (3169x1085 PNG):
http://www.bigblocksix.com/whittey/long_vs_short.png

Blue is stock (short) rod and red is the long rod. The
horizontal orange line is the 0.200" dwell time. In this
map, X=0 is TDC and X=180 is BDC.

Here are some thoughs:

A long rod will have a higher MEP during those beginning crank
degrees due to decreased cylinder volume.

The more 'suck' of a short stroke engine increases pumping
losses. The higher the vacuum, the higher the energy per unit
pressure drop is needed (wordy).

I somewhat disagree with the statement above involving
rotating mass and rpm. The higher the conrod mass the:
1) less power due to inertia
2) increaseed streeses on the crank due to increased inertia
3) increased tension stresses on the rod itself before and
after TDC on the exhaust stroke

Naturally that increases the rod bearing/cap/bolt loads as
well. 

Long rod motors will have higher main bearing stresses than
short rod motors.

A short rod has more dwell at BDC allowing you to keep the
intak open a couple degrees longer (allowing intake inertia to
do some more work instead of just compressing itself against a
closed valve).

How it all averages out? Your guess is as good as mine.


-=Whititey=-