That's how the trip computer works on my BMW motorcycle.  I think they
run a counter when the injector is getting a pulse.  At some
predetermined count, they reset the counter and increment the fuel
usage by 0.1.  That little unit could probably be adapted to our
engines also, but the user interface really sucks.  All the functions
are accessed with two push buttons.  http://www.fuelplus.com/  $229

I did learn that the speedometer on the bike is electronic.  It counts
a pulse from somewhere on the drive train for the odometer and
speedometer functions.

Bob W.


On Sun, 11 Feb 2007 14:19:16 -0500
"Ed Anderson" <eanderson@carolina.rr.com> wrote:

MessageI'm not out of retirement yet!  These things may just be a money hole {:>).

The simple one uses the pulse duty cycle technique - it doesn't know (or care about staging).  So the fuel flow at idle (before staging) will be double (assuming your are using 2 injectors before staging and 4 after staging) that when all injectors are staged.   However, at idle, there is not a whole lot of interest in fuel flow  and while it will be double the actual, it will change to reflect changes in A/F.  You could divided it by 2 - provided you remembered to bring your calculator. {:>)

The simply one does not have a fuel totalizer - just not possible with this approach.  Well, I guess you could put in a circuit to integrate the instantaneous  flow rate over some time period - but then the simple one starts not to be so simple anymore {:>)


On  the more advanced Monitor , I was working on a circuit to detect when there were no pulses on the secondary injectors indicating that staging had not yet occurred and to divide the fuel flow rate in half.

However, the EC2 puts out a staging flag for the EM2 that I can more easily use to do the same thing.

Either one would work on a Subaru set up as long as it uses electronic fuel injection.

Ed



----- Original Message -----   From: Russell Duffy
  To: Rotary motors in aircraft
  Sent: Sunday, February 11, 2007 11:53 AM
  Subject: [FlyRotary] Re: Fuel Totalizer


  Simple/Inexpensive

  One is a simply Fuel Flow and Air/Fuel ratio (LED) indicator in a package small enough to fit in the 2 1/4" instrument hole.  But, that is all the information it will provide - Fuel Flow and Air/Fuel Ratio.  This will be the cheaper version.  This will have a 10 segment LED bargraph for the Air/Fuel Ratio and a 3.5 digit LCD readout for the Fuel Flow.

  Hi Ed,

  Good to see you're giving up retirement.  This will give you something more productive to do that cleaning up goose crap at the airport :-)

  I would imagine you will be able to sell quite a few of these simple versions to the Subaru folks that are using fuel injection.  With that in mind, I'd suggest allowing for single injector (rather than staged injector) operation.  At least I don't think the Subaru guys run staged injectors.

  Speaking of Subaru's, I have to admit that they sure run well in the gyro world.  The Subaru is running on nearly all the two place gyros, and they just don't seem to be having any problems, even though they run high power virtually all the time.  The gyro I'm training in has 1400 hours on it's engine!  I'm not about to convert, but I can't help but be impressed.

  Cheers,
  Rusty

-- N93BD - Rotary Powered BD-4 - http://www.bob-white.com
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