Oil Metering Pump Adapters for Wankel
Engine
Wankel engines, such as the one used in the MAZDA RX8 sports car,
need oil in the combustion area for lubricating the metal seals.
Most stock rotary engines use a metering pump which injects a small amount
of engine oil from the oil pan into the intake manifold and/or directly into the
combustion chamber. Engine oil is designed to lubricate sleeve bearings and
carry heat from the engine interior to some cooling areas.
In the RX8 the heat is removed from the oil via an oil cooler. When engine
oil is injected into the combustion chamber, it only is partially burned,
leaving some unburned deposits behind. These deposits can build up and reduce
engine performance; cause the apex seals to stick; reduce compression and
eventually lead to an engine overhaul.
One obvious method of preventing this is to disconnect the metering pump
altogether and mix two-stroke oil to the gasoline like some older two-stroke
engines require. With this method it has been demonstrated that two-stroke oil
is an effective lubricant and there is no build up of combustion residues.
The Metering Pump Adapter, as offered by Real
World Solutions, takes
the solution one step further in allowing the builder to still use the stock
metering pump, but supply it with two-stroke oil. With the Adapter installed,
all that is needed is a small oil tank with two-stroke oil, connected to the
Metering Pump Adapter. The oil level in the tank should never be less than 6”
above the metering pump.
Oil consumption is approximately 1/100 of fuel used.
Renesis
OMP Adjuster
(not for Series 2 engines)
The
RENESIS engine is becoming increasingly popular for conversion for use in
experimental
airplanes. Using the Oil Metering Pump for top lubrication is an open
question,
because most after market EMSs do not provide an output for OMP control.
In
the RX-8 automobile the OMP oil flow is controlled by engine RPM and pump-rate.
The
pump-rate
control is activated by the engine computer. This pump-rate control is used to
increase
oil flow when there is an increased power demand at low engine RPM. This
condition
does generally not occur in an airplane.
When
the engine is used with an EMS with no output for the OMP, the only option is to
mix
some oil in the fuel for top lubrication. The preferred oil used for this method
is
two-stroke
oil for its ability to readily mix with gasoline and lower combustion residues
than
regular motor oil.
To
overcome this draw back in aircraft use, the OMP pump-rate control can be fixed
to a
certain
position, and the oil flow will only change with engine RPM.
Solution
Picture
1
The
RX-8 OMP is equipped with a position sensor, (Picture 1), which monitors
the position of
the
control shaft on the pump. This position sensor may be replaced with an adjuster
(Picture 2 below ) to set the control shaft to a fixed position. In this way, the OMP is fully
functional,
giving
an oil amount comparable to oil mixed in the fuel.
Picture
2
Real World Solutions, Inc
