cycle time equation

how can i use this equation for rotary engines?

With a 4 stroke piston engine we have one complete cycle for every two revolutions of the crankshaft. With a rotary engine we have one full cycle for every rotation of the eccentric shaft. While there are three combustion events per rotation of the rotor, the rotor rotates at 1/3 of eccentric shaft speed. So in a nutshell, your cycle time is simply half of what you'd calculate for a piston engine.