In 1995, Automotive Mechanical Engineer, Brad Howell-Smith was researching the internal combustion engine and its efficiency and losses. He found that if a typical engine’s Mean Effective Pressure map from the combustion cycle was simulated against a conventional crankshaft device, that the efficiency of that device was only 65% efficient.

For an example, at 20-40 degrees After Top Dead Centre (ATDC) when the pressure in the cylinder is at its highest, a crankshaft connecting rod

arrangement provides low mechanical transfer to rotational force.

Most of the force is applied downwards on the main journals and is wasted as a mechanical loss. At between 70-80 degrees ATDC, the crankshaft mechanical device has high efficiency because the connecting rod is around 90 degrees to the crank.

At the crankshaft’s point of highest efficiency, the piston has travelled approximately 40% down the stroke, and the pressure in the cylinder is around half of peak.

This interesting finding meant that the formula for working out engine losses must include the mechanical losses caused by the poorly efficient crankshaft device. It is believed that all losses have been accounted for in the formula. The problem is there is not enough percentage left in the standard calculation to add this loss.