Question for experts on VR sensors
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Question for experts on VR sensors
A friend of mine has a Subaru engine conversion for his light aircraft. Can a VR sensor be triggered by a permanent magnet instead of a ferous toothed wheel? The magnet would be mounted in a aluminum flywheel (a hole drilled into the face of the flywheel and the cylindrical magnet pushed in), the pole of the magnet flush with the backside of the flywheel facing the sensor with the sensor behind the flywheel (parallel with the axis of rotation). We are trying to trigger a GM HEI 45 module.
EDIS Signal
With Ford EDIS the answer to your question is basically no. The VR sensor measures the magntic properties around it, the toothed wheel when spinning in front of the sensor basically produces a wafe form in the sensor, the missing tooth causes an anomoly in that wave form. The EDIS module looks for this anomoly as it's reference point.
I'm not familier with the GM system, but the GM engines I have looked at in the past still use the 'variable relutance' type sensors and a toothed wheel. The control elecontics are not looking for a pulse (which your idea produces), but a specific change in the overall wave form.
To sum up, I dont think you idea will work as it produces a signal that the electronics are not designed to process. If yoiu make custom electronics that would not be an issue.
I'm not familier with the GM system, but the GM engines I have looked at in the past still use the 'variable relutance' type sensors and a toothed wheel. The control elecontics are not looking for a pulse (which your idea produces), but a specific change in the overall wave form.
To sum up, I dont think you idea will work as it produces a signal that the electronics are not designed to process. If yoiu make custom electronics that would not be an issue.
Bearing in mind that I'm
Bearing in mind that I'm soooo unqualified to give advice on aircraft engines (and are you/friend qualified in, and really serious about, modifying the ignition system of an aircraft engine?) and I don't know squat about the GM HEI 45.....
A VR sensor will almost certainly respond to a passing magnet. Probably better than a piece of passing ferrous.
Providing the HEI 45 can process the electrical output of a VR sensor (it's a pretty low voltage, and also one which changes according to rpm) and you get the right number of pulses/missing teeth detection per crank revolution then maybe it would work.
Remember that in the stock EDIS system, the 36-1 wheel is there to provide 35 half sine waves and a discontinuity at the missing tooth position, the latter being detected by the EDIS module and used to operate the whole system - see http://www.bgsoflex.com/mjl/mjl_edis_summary.html.
Whether a single half sine wave at a (pretty low voltage) from a VR sensor once per crank revolution is sufficient (electrically and functionally) to drive the GM module, I don't know....
A VR sensor will almost certainly respond to a passing magnet. Probably better than a piece of passing ferrous.
Providing the HEI 45 can process the electrical output of a VR sensor (it's a pretty low voltage, and also one which changes according to rpm) and you get the right number of pulses/missing teeth detection per crank revolution then maybe it would work.
Remember that in the stock EDIS system, the 36-1 wheel is there to provide 35 half sine waves and a discontinuity at the missing tooth position, the latter being detected by the EDIS module and used to operate the whole system - see http://www.bgsoflex.com/mjl/mjl_edis_summary.html.
Whether a single half sine wave at a (pretty low voltage) from a VR sensor once per crank revolution is sufficient (electrically and functionally) to drive the GM module, I don't know....
Where are the Subaru guts?
I don't know much about aircraft conversions, but why aren't you trying to use the Suby computer for spark and fuel?
Vintage 550 Spyder replica VW type1 2165cc 9.8:1 Dual Weber 44 IDF RABY motor MJLJ V3/TPS