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

Hi Mark,

I feel your pain on that. A couple of years ago working in the oil patch and
fuel went to $1.40/ liter ($5.30/ US gal). Some of the guys drove until almost
empty and went to fill up. The fleet cards had a $150 fuel limit. Worked OK
for $1.00/Liter or less. The trucks have 140L tanks. Caused all sorts of
grief. Had to fill up every night.

Dale Davies