Ford edis with megajolt

[CATPart]

thanks Dan, thanks Larry.

toolbuilder's post is interesting (saw his cool setup at Inyokern last weekend). The response to mixture setting is not able to be included in a timing map is it?

It also makes me think I could never pinpoint timing so precisely in my fixed pitch, wood propped, efis-less, autopilot-less RV-4. Maybe I could use my 2 reluctor setup for a WOT full rich climb setting and a lean cruise setting. And I am not against using a megajolt, which could be added to my proposed system at any point, and then throw a switch to advance the entire map!

I also read this amazingly long thread last night http://www.vansairforce.com/communit...d.php?t=108079

[Toobuilder]

If my ongoing testing is any indication, the timing is relativily insensitive to mixtures richer than peak. Yes, it would be neat if the timing map could follow the jump to LOP ops, but I suspect that people who operate LOP have one primary setting they go to, so a discrete switch which adds the preselected advance gets you there with very little effort. That said, you do need to do the testing to see what that advance value is for your particular engine. The ability to plug in a custom number (like the CPI does) is a huge benefit.

[lr172]

Originally Posted by Toobuilder

If my ongoing testing is any indication, the timing is relativily insensitive to mixtures richer than peak. Yes, it would be neat if the timing map could follow the jump to LOP ops, but I suspect that people who operate LOP have one primary setting they go to, so a discrete switch which adds the preselected advance gets you there with very little effort. That said, you do need to do the testing to see what that advance value is for your particular engine. The ability to plug in a custom number (like the CPI does) is a huge benefit.

Michael,

Your testing and results have been VERY helpful for me in setting up my initial advance map and I thank you for your generous sharing. I intend to run increased advance starting in the 24-25" MAP range. In my case, with an FP prop, much of my climb is in the 24-25" range with power levels in the 80-85% range. I will run ROP here and want a lower advance (am planning high 20's or 30). However, when I hit cruise, I am turning 2700 and still pulling 24". In this case, I am at 70-75% power and want 35* of advance as I will run LOP. In this case, the table switching is very convenient, as I would otherwise have to have some fine resolution in the RPM side of table to produce a 75% line and use it for increasing advance. Although, as I am thinking about this now that may be a better approach. I'll have to play with this.

Compiling your results across your tests, it was good to see a confirmation that the desired advance reduced as you went to dual ignition. It seemed that your optimum advance dropped by almost 5 degrees when you went from a single to dual setup, which is in the range that I was expecting. I mention this for the benefit of others leveraging that data. Optimum advance figures for a dual setup are not the same as those for a single EI setup. With advance, we are really try to optimize the timing of peak cyl pressure and with dual spark, that will be based upon a blend of two different spark events and there subsequent advance settings.

I hope to finish my install on Saturday and will try to post results after testing.

Larry

[Toobuilder]

I did mention that the timing is "insensitive" if ROP - but thinking about it more I don't mean to imply there is no benefit to having the "correct" timing. Variable timing is a big benefit over a fixed magneto even if you operate at the relatively rich and relatively low altitude "sweet spot" for magnetos. As we've known for decades, the ABILITY to light off a fat mixture in thick air is essentially the same for mags or EI, but the TIMING of that event is where EI's should have the advantage. I say "should" because as my testing indicates, there is a big disparity between engine characteristics and yes, whether one EI is used or two. It is clear to me that one size does NOT fit all. EI's with fixed or limited adjustable maps certainly have their appeal, but their limitations are exposed after testing the infinitely adjustable CPI product.

That said, I think that we foot stomp one more time that "more" advance is not "better" - you are looking for the "right" advance. It is noteworthy that based on my 100% power testing that I have tweaked my map and am now RETARDING timing at high MP. I'm pulling out 3 degrees from the data plate timing (and remember, this is a low compression, bone stock 260) because the performance is the same, and it will buy me more detonation margin.

Also keep in mind that the above is discussing ROP ops and thick air. The other discussion is when LOP and high - where the power of the hot EI spark positively influences the "ability" to light the fire (and yes, the variable timing) really blows the magnetos away.

[Mike S]

Mike, sent you a PM.

[Mike S]

Heads up for anyone considering using a flywheel mounted trigger wheel like in the photo below.



There are at least two flywheel designs with different diameters of "V" belt pulleys out there.

If the "V" belt pulley is too big, there is no room to mount the pickup as the teeth are hidden behind the pulley.



No, I do not know the right size, I do however know the wrong size......

[Toobuilder]

Yep, good catch. That "small" pulley is the early version... Getting kind of rare.

This is exactly the opposite situation with the CPI pickup - no design yet for this small pulley.

[gasman]

That small pulley would work great with an automotive alternator.... These were found on 150 hp Warrior's

[Mike S]

Originally Posted by Toobuilder

Yep, good catch.

Too bad I did not catch it before having the water jet folks make the wheel.

I just wanted to let others out there who might be pondering this setup know that there could be an issue with the large pulley.

[airtractor8]

Please be sure to protect the wiring harness on flywheel triggered systems. Alternator belt failures can and do happen. This terrible accident would seem to be a direct result of that. http://www.atsb.gov.au/media/5341498/AO-2013-221%20Final.pdf