The Wankel rotary spark-ignition engine, while lighter and more compact than a reciprocating: park-ignition engine of equal maximum power, typically has worse eficisncy due to significantly higher gas...

The Wankel rotary spark-ignition engine, while lighter and more compact than a reciprocating: park-ignition engine of equal maximum power, typically has worse eficisncy due to significantly higher gas leakage from the combustion chamber and higher total heat loss from the hot combustion gases to the chamber walls. Based on the design details in Figs. 141-13 and 1-14 suggest reasons for these higher losses.