Sport Pilot wrote:

mastic wrote:

Bryan Martin wrote:


Not so. In the Otto cycle, the fuel and air are introduced to the cylinder
during the intake stroke. In the Diesel cycle only the air is introduce to
the cylinder during the intake stroke, the fuel in injected at the end of
the compression stroke.

Wrong. Mr Otto invented the four stroke cycle and it is named after
him. The fuel or when it's introduced has nothing to do with it, Otto
refers to the cycle.


SO? He didn't mention fuel in the part you snipped. Diesel is a
differant cycle named after Mr. Diesel.


Actually, today's Diesels can operate over several cycle types. Modern
high speed Diesels as used in cars are closer to the Otto cycle than
they are to Rudolph's cycle. In his original engine the fuel was
supposed to be injected at a rate to create a constant combustion
temperature or a constant pressure. This really would take a feedback
of temperature or pressure during the combustion stroke, and was- and
is- extremely hard to do. The slower the speed of the engine, the
better current Diesels approach the intended Diesel cycle, as seen on an
indicator diagram. The indicator diagram on high rpm Diesel auto
engines look a lot like the diagram of an Otto cycle.

There are people developing Diesel systems using closed loop pressure
sensing to adjust fuel injection rate, but to my knowledge no Diesel car
or truck engine using this feature has ever made it to production.
Current production Diesels use open loop injection, so it is a hybrid
cycle, somewhere between true Otto and true theoretical Diesel.