The present work deals with the possibility of an alternative internal combustion spark ignition engine, operating in Otto's cycle, with any fuel and with compression ratio limited by rm, for example, which the levels of power, torque, specific fuel consumption, emissions and knocking are considered optimyzed and satisfactory, be operated in a compression ratio, rM, higher than rm, so that with an adequated set of spark ignition, combustion chamber shape and correct air fuel mixture, that levels prior obtained with rm may be reached or even exceeded. Therefore, it may obtain, at least, the same cycle's thermal efficiency with different compression ratios (rM > rm) without any detriment on the engine's performance and durability.
With rM this is possible due to the mentioned set, function of the used fuel, generated thermo dynamic cycle different from that with rm, where the peaks of pressure and temperature are not higher.
Calculations and experiments on vehicles and engines confirmed that possibility.