Linear CPS possible?

[suprant0010]

Long story short, I'm considering a Megasquirt system for a very unique engine application. Not going into detail about it as it tends get way off subject.

My problem is the crank position sensor. It's not possible to mount a rotating pickup wheel on this engine, so I was thinking I may be able to get a linear reading off the piston itself.

Would it be possible to run the engine off of a reciprocating pickup? The main issue I see with it is what happens at bdc and tdc when it changes direction.

[abecedarian]

Since you're hesitant to discuss technicals.
If it uses mechanical valves, perhaps sensors there... say Hall effect sensors in parallel triggered by valve motion?
Pressure sensing, piezo-electrically, intake pulses?
Optical sensing on something external which moves at a fixed ratio with the crankshaft?

[Matt Cramer]

The current code (and possibly hardware) won't handle a linear position sensor.

I suppose you could set up a Hall effect sensor that just triggered at TDC. Theoretically, this would be sufficient to run a single cylinder.

[suprant0010]

the reason the sensor cant rotate is there are no rotating parts, no crankshaft, no cams

So the MS could be set up to simply fire when it passes a single pickup? I assume this would be sacrificing the ability for any kind of timing adjustments.

[Matt Cramer]

the reason the sensor cant rotate is there are no rotating parts, no crankshaft, no cams

So the MS could be set up to simply fire when it passes a single pickup? I assume this would be sacrificing the ability for any kind of timing adjustments.

It can and there is some measure of timing adjustment possible - it's similar to a distributor trigger.

[suprant0010]

the reason the sensor cant rotate is there are no rotating parts, no crankshaft, no cams

So the MS could be set up to simply fire when it passes a single pickup? I assume this would be sacrificing the ability for any kind of timing adjustments.

It can and there is some measure of timing adjustment possible - it's similar to a distributor trigger.

i think this will do the trick...would I be able to put 2 pickups and run 2 cylinders this way, 1 pickup for each cylinder?

[Matt Cramer]

Possibly using the MicroSquirt "twin trigger" mode.