Don Stauffer wrote:
Sport Pilot wrote:

Don Stauffer wrote:

Sport Pilot wrote:

Completely wrong, the Otto cycle has nothing to do with four stroke
engines. Don is right its not four cycle, I used it incorrectly. The
Otto and Diesel cycles are actually refering to the thermodynamics
chart of temperature pressure and volume, they invented their cycles on
paper and books, the engines we use are only close approximations. The
two stroke ignition engine uses the Otto cycle as it is has the four
phases of intake, compression, power, and exhaust, and the pressure is
not constant. The Diesel two stroke is a Diesel cycle because it also
includes the same phases and the fuel burns at a fairly constant
pressure.


I guess I'd quibble with the statement that the Otto cycle has nothing
to do with four-stroke engines- it was the first successful cycle to
incorporate four strokes. yes, there are other four stroke cycles, but
the Otto cycle is still by far the most common. There have been several
other four-strokes, several two-strokes, at least on six stroke- I
suspect several also.

New IC engine designs are among the most numerous US patents. Just
because something is patentable, of course, does not make it good or
successful, and most of these patents were for approaches that offered
insufficient advantages.

BTW, as I understand the new Miller cycle, I don't consider it a truly
new cycle- just a clever mod on the Otto. I don't consider the Otto
cycle to require valve openings at closings at the top or bottom dead
center, exactly.


The confusion is that Otto invented the first four stroke engine and
called it the Otto cycle, not because of thermodynamics but because he
put it in a motorcycle. However the thermodynamic cycle can be
reproduced with a two stroke engine. Its just that the intake and
exhaust cycle's are much shorter.


I am not sure what you mean by exhaust and intake "cycles". There is
one cycle- the actions that the engine goes through before everything
repeats. Do you mean the portions of the cycle during which the exhaust
and intake take place- they definitely take less crankcase revolution angle.

In the Otto cycle it is easy to break it down into four operations, each
lasting one stroke. A two-stroke is more complicated, because it still
has (existing, contemporary ones, do anyway) four seperate functions of
intake, compression, combustion and exhaust, but have to do it in two
strokes.

Sorry for the confusion, the two stroke doesn't take a stroke for those
functions so I used cycle, can't think of anything else to call it.