I am really impressed by your web-page on 555-based EFI systems for
 aircraft
 engines.
 Mazda rotary engines have always been of interest, especially in 200+ hp
 airplanes.
 However, my main interest for now is obtaining simple EFI systems for my
 two
 experimental motorglider projects, which have 16 & 42 hp piston engines.

 The 16 hp project is a highly modified a Moni motorglider with new landing
 gear, composite wing span extensions & Y-tail, and a 4-stroke engine.
 The engine I have selected is the Teledyne-Continental 4A032, a flat-4
 military engine made for ground-based power units, 8 cu.in. displacement
 per
 cylinder, for a total of 32 cid.
 The stock engine has electronic ignition and an undersized float-type
 carburetor, but the carburetor is inadequate for aircraft use, so that sent
 me searching for a simple EFI solution.


 Such small cylinders could necessitate using a single throttle body
 injector, but some very small motorcycle engine injectors are now being
 made
 that may allow multi-point injection.
 The clever way you have integrated the mass flow sensor and lean control
 into the timer IC is a really ingenious way to control the engine.
 I was thinking that the 555-based system you decribed could be modified to
 eliminate the separate shaft trigger by using the ignition spark from one
 of
 the cylinders, since that is already a pulse trigger coming from the
 internal shaft position sensor.
 In any case, I was hoping that you might have components available that
 could be used to speed the development of a simple EFI system for this
 engine.

 My other motorglider project is my own two-seat design for which I have
 selected a very similar military surplus engine, the 4A084, which is a
 flat-4 with 84 cid.
 It would be ideal to use same basic EFI system developed for the 32 cid
 engine on this larger 84 cid engine.
 By the way, several 4A084 engines with conventional EFI systems are flying
 today, though these are much more expensive and complicated computer-based
 EFI systems.
 Les Smoot has a couple of them flying on his J-3 Kitten LSAs... see the
 Yahoo "Surplus Engines" group for more info.
 The potential market for an EFI system for the 84cid engine is much larger
 than for the 32cid.

 If you have any 555-based EFI kits, components, plans, etc. that I could
 purchase, please send me any information you may have available.
 I don't want to bother you with a lot of calls & questions, and don't
 expect
 anything for free.
 Thank you for your time, and please keep up the good work!
 Happy Thanksgiving.


 Sincerely,
 -
 Daniel J. Moser, President/CTO
 Compositex, Inc.

 I moved away from the mass air flow sensor as one, it is non linear and
 two, it is more expensive than a FreeScale zero to 5 volt pressure sensor.
 Everything else works pretty much the same. I just have not updated the web
 site yet.

 I have not had the new pc boards made but you are welcomes to copy this
 design.

 Paul Lamar


Am I correct in assuming that the squirt of fuel from the injector should be
initiated just as the intake valve starts to open?
If this is the case, it seems to me that you can actuate the trigger pulse
into the 555 timer IC with a mechanical contact switch on the intake valve
lifter.

When the intake valve starts opening, the grounds the trigger, sending the
proper width pulse to the injector.
If it works, that switch could replace the pointed steel shaft rotor,
sensors, rectifying diodes, and eliminate the need for the very critical gap
adjustments.

The only thing I can think of to watch for with the switch option is to
design it properly as to not allow engine vibration to bounce open the
switch to avoid sending false trigger pulses.
Did I miss something?