12 h
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
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
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
I thought that the accuracy for MAP was tricky with a P Port and
connecting both rotor housings together to try to average the
measurement was a solution. Getting away from MAP would eliminate
this. Just want to learn how to build a system for the P Port
Joe Berki
Just use the MAP in each rotor with each Maximite. The oil injection hole
is a good source.
Identical software.
Paul Lamar
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