[Luce]

I'll bite. I haven't seen a good explanation and I think I have a good grip on the subject.

A flat crank looks like the crank you would find in a 4 cylinder where the throws are 180 degrees apart. Using it in a V8 makes the engine fire LRLRLRLR instead of the familiar RLRRLRLL pattern all american V8s share. Some start at different parts of the sequence, and some may do it backwards, but they all share the same pattern.

The big advantage is the exhaust pulses are evenly spaced on each bank making standard headers scavenge better. That's why the GT40 had the bundle of snakes, so each collector and muffler gets an equally spaced pulse every 180 degrees of crank revolution

The disadvantage is the block internal stresses. The kinetic energy in the pistons is being transferred from left to right bank and back every 180 degrees, making the 2 banks of cylinders want to flap like butterfly wings.