Question and thoughts about Oil injection.

 Because the series 1 RX-8 engine is a bit short of oil injection as
  Paul
 has mentioned could or would an option be to add some sort of oil
 injection into the intake system to spray a fine mist into the intake
 system? I think this would be rather like a 2-stroke oil injection
 system/s used on Rotax engines and the like.

 My thoughts were use the oil injection system that exists on the Rotary
 but add another injector into the intake system to spray 2-stroke oil
 using a Richard Sohns adaptor.

 Does anyone have any thoughts about this?

 I'm just thinking out loud with ways to add lubrication oil for the
  Apex
 seals, without requiring to premix it. My thoughts about this is you
 don't need much oil at low RPM eg when idling on the ground, warm up,
 low rpm for descent and the like but you do need more oil for high
  power
 settings to ensure that there is enough lubrication for the seals when
 they are under high power.  What do other think of this and if so what
 size spay nozzle/s would be needed?

 Regards David (Australia)

 --

 The oil injection takes place when there is a vacuum in the intake
  chamber. The injector has a one way valve so atmospheric pressure does
 the actual injection. The metering pump does just that. It meters the
 oil to the injectors. The metering pump controls a stepper motor by
 sending out pulses on four wires. The cheapest and easiest way to
  modify
 the amount of oil metered is to insert a low cost microcomputer in the
 wiring harness that reads the pulses and modifies them in such a way
 that increases the amount of oil metered.

 http://www.imagesco.com/articles/picstepper/02.html

 I recommend something like a BASIC stamp as a 3rd grade student can
 learn to program it in BASIC. Here is the company I would go with as I
 have extensive experience with their product and their $100 prototype
 board is extremely easy to use.

 The final product could cost under $20 for parts.
  http://www.zbasic.net/

 Paul Lamar

 ---

 I have every intention of still using the original oil injection holes.
 I did find this info on the racing beat website.



http://www.racingbeat.com/mazda/performance/rotary-tech-tips/oil-filters-mop
  .html


 It is near the bottom of the page.

 RX-8 - Race Tips:- While undertaking development work on the RX-8
 Renesis engine for SCCA T2/T3 use, we decided to introduce extra oil
 into the fuel to monitor the effect. To our surprise, this additional
 oil increased power! Further dyno testing found that by adding 10
  oz. of
 Royal Purple 2-Stroke Oil to 6 gallons of fuel, we gained an average of
 1.7 HP from 2000-9000 RPM, along with an increase in peak power of
  4 HP.
 We validated this increase by changing back to a "non-oiled" fuel - and
 the power returned to the previous level. Later, we tried the same test
 with another brand of synthetic oil with nearly the same results. For
 racing applications, the addition of a high quality synthetic oil
 increases power and most certainly decreases wear. The only negatives
 are the cost of the oil and an increase in the tendency to foul the
 spark plugs. (Note: We have not performed these tests on non-RX-8
 engines yet, these results are unknown.)

 I guess that injecting or premixing some additional 2-stroke oil into
 the fuel is apparently a better option and as such worth doing although
 not at the rate that racing beat suggest for high end racing
 applications, however any improvement in power is a bonus, improvement
 in lubrication obviously is the aim without causing plug fouling.

 Also from the Racingbeat site:- The metering rates for stock engines
 vary, so consult an appropriate shop manual for your carâ??s
 specifications. In normally aspirated racing vehicles we use either a
 setting of 5cc/5minutes (total flow - 2,000 RPM, warm engine, arm
  in the
 "full throttle" position) on the metering oil pump or premix 3.5 oz of
 good quality synthetic oil (preferably 2-stroke motorcycle "oil
 injection" oil) to 5 gallons of fuel. The requirement for turbo engines
 in racing is high enough that use of a metering oil pump is
  impractical.
 Therefore, we premix up to 22 oz of oil to 5 gallons of fuel in a
  600 HP
 2-rotor. If you are not pressing your engine this hard, you can use
 proportionally less oil.

  From this and other past posts in the newsletter. It would appear that
 somewhere between 100 ml and 200 ml per 20 liters (200:1 - 100:1) would
 be about the optimum amount to inject for use in flying.
 If the oil is injected both into the original oil nozzles and then
  using
 another oil nozzle to push oil into the fuel system right before the
 injection pumps that should be fairly elegant and would not require
  premixing oil into fuel.

 I'm in the process of doing my engine now within the next few months it
 should be finished on a test stand and ready for running using Tracy's
 Computer system and engine monitoring system,

 At the moment the making the adaptor for the gearbox is in progress,
 that will be finished shortly.
 Then it's on to putting it all together and building the wiring system
 etc for it.

 Regards David.


 Paul, Re oil injection if the oil in injected on the suction side
  of the
 fuel pump, after a little while the fuel in the tank/s will have
  lots of
 oil in it/them, because the fuel pumps flow at least twice the
  amount of
 fuel required by the engine, so each time it goes around the fuel gets
 another dose of oil, unless of course you are referring to a
  carburetted
 version.

 John Burey

 Good point. Back to the dwg board :)

 Paul Lamar

 --

 I did think about that it appears that the default way for the RX-8
 engine is a return-less fuel injection system. Maybe based on that it
 could work. However if using a return based system then the issue
 becomes interesting. Maybe injecting into the fuel before it enters the
 fuel rails might be an option, provided the return line was based
  on the
 pressure regulator being before the fuel rail/s and use a check
  valve to
 ensure no back wash of the fuel. However I suspect that the OMP
  does not
 have the pressure for this to work.
 Otherwise maybe a couple of nozzles one in each primary intake port
 for each rotor and spray it in directly, the ventri effect should help
  this. which is what I was musing about to start off with.

 Regards David

  Paul,
  if you sent the return back to the header tank, then it still works.
  Larry

  So you are saying inject the oil into the line from
  the main tank to the header tank?

  Paul Lamar


  On a simpler, more basic level, when adding the oil to the fuel
  tank(s). How
  rapidly does oil disperse in the fuel? If filling a partial tank, do you
  guess the amount of fuel you will load, and add the oil first, or
  will it be
  OK to fill your tank(s), then do the math and add the precise amount
  required?
  Herb Karkheck

  We have no numbers on this. As far as I can tell in 12 years it
  does not seem to matter. Taxiing way from the fuel pump probably
  disperses the oil in the fuel. Sloshing in the air probably helps.
  The vast majority of people flying use premix.

  Paul Lamar

With my EFIS and capacitive fuel probes, the fuel level readings
are pretty accurate, so I have a pretty good idea of how much fuel it
will take before I pump the fuel.  I usually don't fill up until I'm
down to about 10-15 gallons per tank.  Since each tank will hold 47
gallons, I can usually put one quart in each side and stop at 32
gallons/tank.  I pour the oil in while I am pumping the gas.  (This
takes a little practice.)  If I go over the 32 gallons, I can add a few
extra ounces after the fact to bring the oil/fuel ratio to 1 oz/gallon.

My fuel system returns the unused fuel to the currently selected tank,
so running the pump for a minute or so will guarantee a good mix.

I recently had my credit limit raised so that I can fill up with
only one credit card.  ;-(

Mark