The Miller cycle was developed by Ralph Miller in the 1940s.
With the introduction of turbocharging to the 4 stroke diesel
engines, the Mean Effective Pressure and thus the power output
of 4 stroke engines rose by 50 - 60%. However this was about the
limit; If the inlet air pressure was increased further, then the
charge air reached excessive pressures and temperatures on
compression causing burning of the LO film and thermal
stressing. Miller challenged the thinking of the day by closing
the inlet valve before the piston reached bottom dead centre.
This had the effect of lowering the cylinder pressure as the
piston continued downwards, as well as dropping the temperature
of the air (Boyles and Charles' Law). Although the engine is
still doing work as the piston is descending on the inlet
stroke, there is a saving in work during the compression stroke,
and the maximum air temperature and pressure is reduced on
compression. The timing of the inlet valve of Miller's engine
was governed by a mechanical link arra