12 g
    I woke up with an idea. No mass air flow sensor. No maximite
    required. Use a potentiometer that is geared to the throttle with a
    small cog belts. Put 5 volts on top of the pot.

    Or you can use a leaner pot with a slide throttle.

    5 volts wide open zero volts closed.

http://www.sdp-si.com/products/miniature-products/miniature-belts-and-pulleys-inch.php <http://www.sdp-si.com/products/miniature-products/miniature-belts-and-pulleys-inch.php>

     Then use my one chip $1 555  EFI.

    Super low cost super simple TLC 555 based electronic fuel injection.


    <http://www.rotaryeng.net/simple-cheap-555.html <http://www.rotaryeng.net/simple-cheap-555.html>

    You can use a low cost Harbor Freight Voltmeter to monitor the pot
    voltage..

    There is no system EFI or carb that is lower cost.

    Paul Lamar


    Paul,

    That is a throttle position sensor TPS

    Why not put a pot in the cockpit at the rotation pivot of the
    throttle lever?

    Kinder environment



    Joe Berki

    Paul,

    Jst  a thought about eliminating the MAF.

    Do we lose altitude compensation?

    Joe Berki

    Yes. But when you take off at a high altitude airport with a carb
    equipped engine you must adjust the mixture anyway.

    The mixture pot can increase or decrease the voltage applied to the
    pot connected to the throttle and then the  555 at any throttle
    setting.

    This is a quick, dirty and low cost  EFI way of getting your engine
    running. You fine tune it with the mixture control just like you do
    any carb equipped aircraft engine.

    Paul Lamar


   My Continental IO-360s have mechanical FIs that simply meter fuel into a common injection spyder based on throttle position. This fuel is then equally  divided (based on pressure) to individual fuel injector/vaporizers located in each intake manifold.  (GAMI injectors are tuned per cylinder).  Fuel flow is further moderated by the manual mixture control, which is used to lean for cruise, high altitude, and to shut down the engine.  Simple and reliable.

   It would seem that Paul’s 555 system triggering off of CAS (using RPM as a proxy for power and fuel requirements), moderated by a manual mixture control, might well be the simplest solution for our EFI?

   BTW, considering the space restraints, potential damage by a broken belt, and mounting considerations of front sensors, might it be more practical to mount Hall effect sensors on the redrive adapter plate and have a magnet strategically located on the flex plate instead?

   If we will be using Maximites to control the ignition, the current $56 color Maximites have an empty breadboard area that could also house the 555 EFI circuitry.

   Scott Gettings


    On the question of eliminating maf and  using map, you asked if you loose altitude compensation and the answer is you don't have too. I am not familiar with the maximite but I am sure it can be done just like a megasquirt we use a air temp sensor  and two map sensors one for barometric pressure and one for engine manifold pressure. So with having barometric pressure and air temp the computer calculates the density altitude and gives you altitude compensation. I am confident Paul could do the same with maximite, also the tps is really not needed for aircraft but I like to have it.


On most after market ecu's the tps is just used like a accelerator pump on a carb and flood clear mode so if you give it full throttle while cranking it shuts off the injectors. Its nice to have tps but not necessary you can do map based acceleration so if it senses a rapid change in manifold pressure it gives it a extra squirt of fuel, but with aircraft we don't need rapid throttle response.  As much as i like the idea of using a mass air flow sensor there sensitive to moisture so you need a good air box to eliminate water ingestion in the rain and with everyone wanting to have control over the mixture with a pot or switching maps I think a maf is a waste of time and complexity unless you were going to do single lever control with different target egts or afr per power setting. That's just my thought, I am still considering using one myself.
Thanks, Jacob Sturges



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