What is a flatplane crankshaft? What is a crossplane crankshaft?
These engines get their names from the design of the crankshaft, and have key distinct differences.
Flatplane engines have the primary forces balanced out, so the crankshaft can be light and fast revving.
Crossplane V8 engines have the secondary forces balanced out, making them very smooth with the addition of counterweights to balance out the primary forces.