Design for Fuel Efficient Piston Engines
» Performance Evaluations
Yoke-Arm Technology - Some Performance Evaluations
following performance curves compare
the differences between engines with
the same stroke and displacement.
The blue curves show what happens
when you modify the same engine using
the Fisher yoke-arm technology. These
graphs, produced through computer
modeling, were selected to show some
of the surprising features of the
modeling shows a significant difference
between piston dwells for Fisher vs.
conventional. Yoke-arm design parameters
can vary the amount of dwell to accomodate
different engine applications.
- When calculating at approx.
15% travel of the down stroke
(58.5 degrees crank rotation for
Fisher) during combustion, the
yoke-arm piston dwell for this
particular engine configuration
is about 40% more than that of
conventional. That is enough to
double the fuel economy.
- Also, the added benefits of
higher piston compression velocities
(not shown) promote greater air/fuel
turbulence for extra combustion
efficiencies that further contribute
to fuel savings.
The yoke-arm reduces piston rod angularity
which greatly decreases piston lateral
forces and side loading for much less
piston friction and increased mechanical
efficiencies. Reduced rod angularity promotes less heat build-up which
in turn promotes less piston and cylinder
wear requiring less engine
cooling. These benefits result in
longer engine life and are especially
relevant to air cooled engines such
as motorcycles, aircraft, lawn &
garden, and such.