Detonation

DETONATION means, “to explode”
In diesel engines the spontaneous combustion of the fuel spray (see diesel engine combustion section) causes a true explosion and results in the noise levels of such engines being called “Diesel knock”. It is due to the extremely high speed burning causing noise levels, which are discharged by the engine, from its surfaces as low frequency vibrations and are difficult to muffle.

In spark-ignition engines quiet combustion can be altered by too high a compression ratio, over advanced ignition, lean or rich mixtures or engine overheating. Such bad conditions develop spontaneous ignition to cause explosions hence DETONATION and metallic sound is called PINKING.

All devices which perform such a tasks, together with those which measure the transmitted torque, by a shaft whilst it is driving some mechanism (pumps, ships propeller, power station alternators, etc) are called DYNAMOMETERS or WATER ELECTRIC or EDDY CORREN BRAKES. They are widely used in engineering industries with engine test beds and Vehicle Rolling Roads being direct applications.