It would seem that the new electronic system being developed by Champion will need aircraft power to start but will be self sustaining once running.
You must absolutely need aircraft power to start the engine, anyway 
Or a very strong wind
It’s great to know something is happening. I really believe that a product which does only half the job is never going to succeed – in GA or in most other business areas.
Peter wrote:
You must absolutely need aircraft power to start the engine, anyway
Or the Armstrong starter, which I’ve used a couple of times :-) However, the Armstrong starter doesn’t really work all that well with a lot of nosewheel planes (and I suspect would be completely impractical with a TB20). I once tried to hand start a Grumman Cheetah, but the position of the prop is all wrong for it (by contrast most small tailwheel planes have the prop in an ideal position for hand starting).
I had to google on armstrong starter
Yes, of course, that is another option. Needs considerable care and competence; I know a really great guy who wrote off his plane, very nearly avoided severe damage to a nearby parked multi-million € commuter turboprop, and terminated his long flying career, by making a mistake with this, and that was on a small homebuilt plane.
People have hand propped IO540/550-size engines, successfully.
Reading further back this long thread, some have expressed doubts that MPG gains claimed are real. And I also get the impression that a lot of comparisons are not using meaningful criteria. For example it looks likely that Bendix mags are much better than Slick mags; the latter are often said to be so crappy that they are recommended to be binned rather than overhauled. Any MPG gains are likely to come from a change of ignition timing, to variable timing, which is something that GA would benefit from.
Peter wrote:
Any MPG gains are likely to come from a change of ignition timing, to variable timing, which is something that GA would benefit from.
If there is a MPG gain, would you say it is because variable ignition timing would allow more aggressive leaning or because the engine is more efficient already with rich mixture?
leaner mixture and more complete combustion -
would you say it is because variable ignition timing would allow more aggressive leaning or because the engine is more efficient already with rich mixture?
I don’t know but would think both.
The fixed ignition timing of our engines is a compromise; AIUI it is worked out for correct combustion in cruise. But the BTDC angle setting goes back many decades, long before people started managing their engines more optimally.
What I don’t “get” is how an electronic magneto replacement which senses only the MP – like the Surefly – is going to do it correctly. It can’t know the mixture, for example.
Peter is right – the fixed timing is a compromise, between 2 extremes – starting the engine and cruise conditions -
PIilot + Engine monitoring system + brain + surefly = adjusts the compromise by leaning further than the fixed timing would allow you in cruise and getting better combustion .
The challenge of course is with retarted timing and more complete combusion your chts will go up (relative to fixed timing) so you need to lean agressively
Fixed ignition timing is set for maximum manifold pressure and cruise RPM (oversquare limit), lower MP than that may benefit from a little additional advance, or at high altitude (low MP) and higher RPM from a lot of extra advance. At low altitudes, meaning at say 24 inches or higher MP it probably won’t make a lot of difference to efficiency, at high altitudes it will be more useful.
I haven’t experimented with it, but EGT should cool when adding advance rich of peak, allowing more manual leaning. I’d be interested to see data on this, on an aircraft engine.
Motorcycle engines on small throttle openings may go to 50 degrees advance, particularly those with larger bore cylinders like an aircraft engine. Exhaust oxygen is in this application used for mixture control, not EGT.
