Lightspeed Electronic Ignition Direct Crank

[jarhead]

Originally Posted by osxuser

A little off topic perhaps, but what is the advantage of using this setup over a sensor in the mag drive?

If you're going all-electric, it frees the other mag pad for mounting an SD-8 standby alternator, if you so desire.

[osxuser]

I thought those bolted to the vac pump pads... anyway, thanks for the clarification. I never really like the setup on the flywheel, it scares me to have the sensors that exposed and spinning. I was gonna do a hall effect sensor in the mag hole when my time comes.

[chuck]

Originally Posted by avpro56

The direct fired crank sensor is much more precise than using the mag drive. Gear lash will make timing bounce around as much as 5 degrees,

5 Degrees! Are you sure about that? That seems like a pretty big number. That's about 2 teeth on a 149 tooth gear. Has someone hooked encoders to the prop and the mag gear and measured this bounce? Is there and easier way to measure this? Seems like randomly having something between 20 and 30 degrees of advance would not run very smoothly at all.

Chuck

[avpro56]

Originally Posted by chuck

5 Degrees! Are you sure about that? That seems like a pretty big number. That's about 2 teeth on a 149 tooth gear. Has someone hooked encoders to the prop and the mag gear and measured this bounce? Is there and easier way to measure this? Seems like randomly having something between 20 and 30 degrees of advance would not run very smoothly at all.

Chuck

Chuck:

I have not measured this. But keep in mind that 5 degrees at the magneto drive is not what I said, I said 5 dgrees of ignition timimg. Since the mag drive gear turns much slower than the crankshaft, errors are magnified. It was a leap of faith for me to accept that there is gear lash while the engine is running under load, but it is a factor with all of the power pulses.

The 5 degress quote comes from Kalus Savier. I'd like to see the data on it, but I have read the same figure elswhere. If I can find that source I'll post it here.

[gmcjetpilot]

I think the claims of timing inaccuracies and HP usage with the mag timing trigger (verses crank trigger) are exaggerated.

Claims the mag timing housing set-up cost HP and is inaccurate may only be crank trigger guys trying to feel better about all the work they expended setting up those magnets?

Sure there must be some mag drag HP loss but I think we are talking factions of HP. As was suggested once its set up with gear back lash accounted for, the timing should be accurate. Frankly timing only needs to be so accurate in an engine that runs constantly at one RPM most of the time. I seriously it will float back and forth but may be off say one degree or two all the time. Not a big deal. Both HP loss and timing accuracy can be measured.

Setting up the crank trigger magnets is a pain. The mag timing housing hall effect trigger is simple and easy. That is the big diff.

Scenario / day dreaming - The circuit board set-up, to me, for the light speed ignition seems kind of weak. Not saying any have failed but over years and years of heat and vibration whats going to happen.

What if some piece of stuff(?) gets in there, in between the mag/sensor gap and causes damage to the sensor or board?

I am going with dual LSE and two mag driving triggers just for simplicity. Also running the wires from the front of the engine to the brain box is a bit of a pain. That long wire run reduces the weight perceived weight advantage a little. Just opinion.

[AlexPeterson]

Originally Posted by gmcjetpilot

SNIP

I am going with dual LSE and two mag driving triggers just for simplicity. Also running the wires from the front of the engine to the brain box is a bit of a pain. That long wire run reduces the weight perceived weight advantage a little. Just opinion.

Does LS still recommend 50 hour internal inspections of the mag hole mounted units? This should be considered in any decision.

[gmcjetpilot]

Originally Posted by AlexPeterson

Does LS still recommend 50 hour internal inspections of the mag hole mounted units? This should be considered in any decision.

Good point I don't know. That is a way short time interval. I'll ask Klaus next week.

[AlexPeterson]

Originally Posted by gmcjetpilot

Good point I don't know. That is a way short time interval. I'll ask Klaus next week.

Their on-line manual says this:

"The Hall Effect sensor module should be removed every 50 hours and inspected for gear, bearing, and seal wear. After first inspection, inspect as necessary or at least every 100 hours by removing cover plate and checking for bearing and seal wear."

I believe elsewhere in this forum there is discussion about why.

[gmcjetpilot]

Originally Posted by AlexPeterson

Their on-line manual says this:

"The Hall Effect sensor module should be removed every 50 hours and inspected for gear, bearing, and seal wear. After first inspection, inspect as necessary or at least every 100 hours by removing cover plate and checking for bearing and seal wear."

I believe elsewhere in this forum there is discussion about why.

Alex thanks I see that. One time gear inspection and removing the cover plate every 100 hours is not too bad. It's still easier than drilling the engine case and flywheel for magnets. That may be another issue with the circuit board set up? Can you inspect it. To get the crank trigger you have to take the flywheel off, which means taking the prop off. Any way both triggers work, choice is ours.

PS: I also recall you need a LARGE DIA pulley flywheel to mount the trigger magnet. Check with lightspeed but per this link it appears "Large diameter alternator pulley required (8.5" ID)". Our FW pulleys come in 7.5" and 9.75" O.D. So it appears if you have the smaller pulley the crank trigger is out. I have a 7.5" pulley which keeps the alternator RPM down.

[Captain Avgas]

Originally Posted by gmcjetpilot

Scenario / day dreaming - The circuit board set-up, to me, for the light speed ignition seems kind of weak. Not saying any have failed but over years and years of heat and vibration whats going to happen.

What if some piece of stuff(?) gets in there, in between the mag/sensor gap and causes damage to the sensor or board?

The bottom line is that although both the LSE Crank sensor and the Hall Effect sensor are good products the Crank sensor has proven to be empirically more reliable than the Hall Effect sensor in a relative sense. How do I know that.....Klaus Savier of LightSpeed told me. Additionally Bart Lalonde at AeroSport who installs a LOT of both types says the same thing.

It's hard to beat a system for reliability when it has no moving parts.