Don Stauffer wrote:

A 4-stroke diesel is still an Otto engine. An Otto cycle engine is one
with four strokes, intake, compression, power, and exhaust. Doesn't
care whether SI or CI.

Whoops

Before everyone jumps on me, I left off an important qualification. I
was specifically talking about cars, airplanes and highway trucks.
Large Diesels, (stationary, large ship, etc) do run a different cycle-
the true Diesel cycle.

However, even the true Diesel cycle of larger engines is not the true
cycle Diesel really wanted. He couldn't develop the true cycle he
wanted (constant enthalpy), and a large Diesel comes somewhat close. A
high speed (vehicle) engine doesn't even come close with even today's
technology. It is pretty close to an Otto cycle, though still not
exactly. Otto cycle has infinitesmal fraction of cycle for ignition and
burn, while even a high speed Diesel (and even the SI engine) still
ignites and burns over a finite angle of crank rotation. Still, the
result, as I say is MUCH closer to Otto than the cycle Rudy had
intended. Still makes a good engine, however :-)