Sport Pilot wrote:

The Diesel is not an Otto cycle it is a completly differant cycle. The
Diesel is a constant pressure cycle where the presure is constant
through the expansion phase.


I wouldn't say the ENTIRE expansion phase. That would not be that great
for efficiency- sort of like a steam engine running with no cutoff. And
if one injects fuel into the cylinder at the instant just before BDC,
that fuel would be pretty much wasted. I was under the impression that
the cycle would look something like the steam (Rankine) cycle in that
the way Diesel envisoned it it would be either constant enthalpy or
constant pressure of part of the expansion phase, adiabatic during the
rest. The point where it changed would correspond to what would be the
throttle opening on a steam or SI engine. At full "throttle" the
changeover would be late in stroke, light load early in stroke.