>
> >Marc Pedings's injector flow tester is working
> >great. Thanks again Marc. I notice the MSD and 2nd
> >gen Nippon Denso injectors work down to about
> >.8 ms. While the red and yellow RX8 injectors
> >quit around 1 ms. All of them draw about
> >.6 to .7 amps at 95% duty cycle.
> >Next step is plumb them up and measure the flow
> >as a function of pulse width and RPM. I still need
> >a few parts like a 50 psi fuel pressure gage which
> >I will order tomorrow from McMaster Carr.
> >
> >Paul Lamar
>
>
> Might I suggest an oil pressure gage. I've had no problems using
them,
> namely the same one for ~10 years.
>
> Cheap & easy to get from your favorite auto part store.
>
> Marc Pedings
>
> Thanks for the tip Mark.
>
> Paul Lamar
>
> The next day. ---------------------------------
>
> Got the system working. See the attached jpg. Found out a very
interesting
> fact. The RX8 red injectors quit working at 1 ms and below if you up
the
> fuel pressure much above 40 psi. I set it up with 1.1 ms and 1800
RPM
> for an half hour at 40 psi and I got 75 ml. That is 150 ml per hour
or
> about
> 4.8 ounces of fuel for both. Lets see that is .01875 per injector
> or .0375 gallons for both, Since there are 6 pounds in each gallon
> that is .225 pounds. At .55 pounds per HP per hour that is less than
> about .4 HP. I doubt the engine will idle at .4 HP. What I saw on
> the dyno was about 10 HP at idle so these injectors are rather
> amazing. They are probably near useless for our purposes. I'll check
> the mid range shortly just to make sure. They have a nice foggy
> spray pattern however. Check my arithmetic.
>
> The return line had very few air bubbles in it and they were moving
fast
> in
> a 3/8 ID return line so if you are not returning fuel to the tank
you
are
> drawing
> from, this system will empty that tank lickity split, mostly while
you
are
> taxiing out to take off. ALWAYS return the fuel to the tank you are
> sucking from. I don't know what the flow rate was yet but I will
test
it
> shortly. The MSD high pressure pump was drawing 8.75 amps at 12
volts.
>
> I connected my auto parts store vacuum pump to the pressure
regulator
> and discovered a slow leak. What this means is the regulator will
> not lower the pressure at part throttle (15 inches of Hg MAP) and
> your engine is likely to run too rich. Hopefully putting Teflon tape
on
> the 1/8th pipe thread where the intake pressure goes into the
regulator
> will fix the leak. If you are having problems with Tracy's EFI
system
> this vacuum pump is a good investment to check for leaks in the
> vacuum system feeding Tracy's pressure sensors.
>
> Also I consider a good aircraft manifold pressure gage a must.
>
> BTW McMaster Carr has some cheap 2.2 inch diameter gages with 1%
accuracy
> and silicone fluid filled for damping at about $15 dollars each. I
am
> using
> the 60 psi version for monitoring the fuel pressure. Works great.
>
> Paul Lamar
Paul,
Love the work you are doing on this. Very interesting, well thought
out
and is laying solid groundwork to build on.
After looking at the test set-up, might suggest you consider
re-arrange
some of the electrical and test gear.
Considering nothing on that bench is explosion proof and you are
testing
injectors, there a bound to be a few stray fumes floating around.
Have some firsthand experience in such things that makes me more
"aware"
these days.
Excellent work!
Steve Webre
Broussard, LA
I am pretty careful. What sort of re-arrange do you have in mind?
Paul Lamar
The Rotary Engine NewsLetter. Powered by Linux.
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Copyright 1998-2005 All world wide rights reserved.
Nothing fancy. Just lengthening wires and hoses for more physical
separation between tanks and test bench. Then electrical gear on one
end of the bench and the injector test jar on the other w/ a fan
somewhere keeping fresh air moving and fumes well below LEL.
Some time back, was in a shop watching someone else test injectors in a
jar on a small bench. 2 gallon tank was under the bench, pump and crude
homemade control box on top.
Life was good until in the midst of testing, there was a small "WHOOSE"
across the top of the bench. This resulted in an arm being jerked,
pulling the hose to the injector, which knocked over the glass jar,
which spilled a small amount of fuel resulting in a very small bench
fire.
Unfortunately, that small amount of fuel dripped under the bench and
onto the tank. Naturally, the fire followed and the excitement level
went up several notches.
Quick use of fire extinguisher saved everything. Nothing damaged but
egos.
What hit all involved was how things quickly things went from "This is
working great!" to "Oh S___!!" within 5-7 seconds.
Seems a few stray fumes "flowed" along the bench top and found an
ignition source. A slightly different layout of the test rig would have
either kept this from happening completely or made it a non-event.
Steve Webre
Broussard, LA
Good suggestions Steve. Thanks. I have a large fan. I'll install it and turn
it on. The hangar door was open so there were a few zephyrs in there.
Paul Lamar
The Rotary Engine NewsLetter. Powered by Linux.
ACRE NL web site.
http://www.rotaryeng.net
Copyright 1998-2005 All world wide rights reserved.