Efficiency
As regards an engine: refers to the relative value of the heat put into it, and the work got out of it. The higher the compression the greater the efficiency. The value of the work of the very best motor-car engine, when revolving at its best speed, is never above 20 per cent. of the value of heat put into it.
The efficiency of the transmission system is not too good. The average gear-box and final bevel drive absorbs between 15 and 20 per cent. of the engine's power.
Explosion in the Carburettor." Popping" in the carburettor is due to either a weak mixture, or sometimes derangement of the inlet valve mechanism.