Rotary history 

Rotary vs. piston

Lighter weight
Because there is no need for pistons, connecting rods or a crankshaft, the main engine block of the rotary engine is correspondingly smaller and therefore lighter in weight with better handling and performance.

Smaller size
Proportional to its output, the rotary engine is substantially smaller in size than a conventional engine. The new RENESIS is about the same size as a small four-cylinder in-line engine. The rotary engine’s small size is not only beneficial with regard to weight, but also allows improved handling, optimal positioning of the drivetrain and increased space to be given over to driver and passenger comfort.

Lower vibration
All the parts in a rotary engine spin continuously in one direction, rather than violently changing directions like the pistons in a conventional engine. Rotary engines are also internally balanced minimising vibration levels.

Higher power
A rotary engine’s power delivery is smoother. Because each combustion event lasts through 90 degrees of the rotor's rotation, and the output shaft spins three revolutions for each revolution of the rotor, therefore each combustion event lasts through 270 degrees of the output shaft's rotation. This means that a single-rotor engine delivers power for three-quarters of each revolution of the output shaft. Compared to a single cylinder piston engine, in which power is delievered to only a quarter of each revolution of the output shaft.

Higher reliability
The rotary engine has far fewer moving parts than a comparable four-stroke piston engine. A two-rotor rotary engine has three main moving parts: the two rotors and the output shaft. Even the simplest four-cylinder piston engine has at least 40 moving parts, including pistons, connecting rods, camshaft, valves, valve springs, rockers, timing belt, timing gears and crankshaft.