Angular speed variation within a single turn at very low rpm is typically the issue, when there is an issue.
Airborne_Again wrote:
During the start sequence of the engine, the EIS sets the ignition timing to 0 TDC and does not begin to fire until approximately 50 RPM. This allows the engine to overcome compression strokes
My guess would be that an electronic magneto (i.e. the self powered type of electronic ignition) will have a capacitor and some smoothing circuitry and may need a few spins to charge up enough to make a spark?
The RPMs are just an angular speed. You don’t need a full turn to start the engine with a normal magneto, either.
But can it be hand propped if 50 rpm is needed? Clearly it doesn’t fire just because some pickup passes a point. I mentioned E-mag. They have an internal alternator that supplies power, and will run without any additional power, just like a mag. But the RPM needs to be high enough for it produce power. These can be hand propped AFAIK, but only when a battery is connected.
LeSving wrote:
See Silvaire’s post. Also the E-Mag needs what? 3-400 rpms ?
Quoted from Electroair’s web site:
During the start sequence of the engine, the EIS sets the ignition timing to 0 TDC and does not begin to fire until approximately 50 RPM. This allows the engine to overcome compression strokes and develop a smooth acceleration to a normal operating RPM. Once the engine RPM reaches ~250RPM, the ignition timing steps to seven degrees BTDC and then advances to engine ignition timing (20deg, 25deg, etc.) once the engine RPM reaches ~400RPM. The dynamic changing of the ignition timing during the start sequence happens in a blink of an eye, so to speak, and helps to insure an easy start everytime.
So it is perfectly possible to start an engine using the Electroair electronic ignition. Indeed, it is clear from their web site that you can replace either the impulse or non-impulse magneto with the electronic ignition.
If you think differently, please provide some substantial argument.
See Silvaire’s post. Also the E-Mag needs what? 3-400 rpms ?
Peter, you simply turn off the side that you don’t want.
The Leburg ignitions are designed to work at low rpm.
My Turbulent currently has both magnetos set identically but initially had one that was relatively retarded. Perhaps to give you more chance of starting without it kicking back – there is no impulse mag.
Airborne_Again wrote:
A battery-driven electronic ignition should be able to provide a full power spark at zero rpm.
I believe the issue is the way the spark (and injection timing) is calculated on automotive-style systems. There is a phase sensor (often on the cam) that provides input on the engine position, and the spark timing is calculated from that data. However, that calculation is not valid unless the engine is running at constant speed. Therefore no spark is provided below cranking rpm. That’s not to say it can’t be done with a different kind of system, as per the kick start motorcycle example.
Delay the spark beyond where the old magneto has fired.
Peter wrote:
It can’t do that if the second magneto is still installed
What can’t do what…?
