Subject: Oil Metering Pumps
From: rotaryeng
Date: 9/17/2012, 6:04 AM
To: AAAA Put this in the To box 


 Speaking of Oil Metering Pumps Richard Sohn came up with a good way of
 using the RX8
 version in an aircraft. They are not really pumps but that is another
 whole subject.
 Normally these RX8 "pumps" are controlled by the computer to  control HC
 emission to
 a ridiculous low levels driven by water melons :) (I still put a half
 ounce of 2
 cycle oil per gallon in the tank of my RX8. Ironically it still passes
 draconian
 California  smog tests with the lowest number the official testers have
 seen.)

 Putting oil in the fuel works great because the amount of oil depends on
 the power
 alone because that is what the apex seals want. The oil actully cools the
 seals as
 they normally run too hot. Over 500 F.See the attached jpg.

 It is a long standing tradition with 2 cyle engines. It also distributes
 the oil
 better in the combustion chamber. Anywhere from one ounce to four ounces
 per gallon
 works great. See the Walmart funnel.

 However some people think mixing oil with the fuel is too much trouble so
 there is a
 demand for a way to do it automatically. Richard makes and sells an
 adapter that
 feeds 2 cycle oil from an aux tank rather than using crankcase oil.
 Crankcase oil is
 not the best oil to put in the combustion chamber as it does not burn
 without residue
 unlike 2 cycle oil.

 http://www.fairpoint.net/~res12/html/omp_adapter.html

 To quote Richard:
 "The RX8 OMP is equipped with a position sensor,  which monitors the
 position of the
 control shaft on the pump. This position sensor may be replaced with an
 adjuster  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."

 Paul Lamar



 Paul,

I made a similar OMP adapter for the 20b pump.  The difference with my
adapter is that it uses a 1/4-20 screw to control the oil flow.  As with
both systems, it takes a bit of trial and error to get it adjusted
properly.

Mark



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