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PMAG w/ 10:1 compression?

K

kcameron

Well Known Member
I've decided to replace one of my mags with an electronic ignition. At the moment, I'm leaning toward a PMAG even though, like every other electronic ignition provider I know of, they don't publish their advance curves. At least they give the operator some control over the advance (shift up/down and max). It would also help to see optimal timing advance curves published somewhere for Lycoming engines. I don't guess it will ever happen, though.

Anyone here using a PMAG with 10:1 compression? Any problems? What timing settings work best?

Thx.
 
Apparently, no one here has run this configuration. That doesn't fill me with confidence. I'll can them tomorrow and report my findings.

Kev
 
I purchased a aircraft built by Robby Attaway. It has dual lightspeeds with 10 to 1 pistons. I do have a advance digital readout in the cockpit but really have no idea what its telling me. If you google Robby Attaway you will find his website. If you email him I suspect he will be glad to give you some advice. He was a authorized ECI engine builder.

George
 
Why would it matter what ignition you have? The spark doesn't care about the compression ratio. For 10:1 you retard the timing to 20 degrees and it should work fine. The advance curve only applies at low MP so I doubt there will be an real effects due to the compression ratio increase.
 
rocketbob said:
Why would it matter what ignition you have? The spark doesn't care about the compression ratio. For 10:1 you retard the timing to 20 degrees and it should work fine. The advance curve only applies at low MP so I doubt there will be an real effects due to the compression ratio increase.
Click to expand...

C'mon, RB. You guys and your logical approaches to a problem. You eliminate all of the worry and hand wringing! Can't we be at least a little concerned?
 
Pmag and 10:1

I ran across your post about the Pmag and 10:1 compression. I'm currently running 10:1 with the Bendix dual mag that I'm pretty sick of at this point. I've lost count of how many times I've opened it up now. The Pmag guys have been stringing me along for the last several years now on the dual mag replacement, but in the meanwhile I've once again lost the left side ignition. I'm looking at everyone (electronic ignition) at this point. Just wondering what you found in regard to the Pmag?
 
EFII ignition

Hi David,
Our ignition will light off a 10:1 motor very well.
It is a high energy inductive ignition.
Available in either single or dual mag replacement versions.
Out billet crank trigger is part of the kit.
It is a robust piece that bolts to the front of the engine.
The timing curve is also programmable with the optional programmer.
More info at www.flyefii.com
Robert Paisley
 
While the shape of the P-mag timing curve cannot be changed, the degrees BTC and max advance can be changed using the free EICAD program available on the E-mag web site.

Or, you can buy an EICommander and manage one or two P-mags from the cockpit and monitor them at the same time.
 
I just finished a Top End overhaul with Combustion Technologies 10:1 pistons. I have a P-Mag and one Magneto. After lots of research, the 20 degrees BTDC seems like the way to go, and what Lycoming sets for the helicopter O-360's with 10:1 compression....and a 2000 hr TBO.

I've done 5 hrs of break in so far and it has run beautifully. I set the mag at 20 degrees, and set the p-mag to 5 degrees AFTER TDC to lower the possibility of kick back on start (wood prop) and left the manifold pressure hook-up off which puts the ignition at 26 degrees BTDC (minus the 5 from clocking it late gives 21 degrees BTDC.

My initial intention after talking with the P-Mag folks was to program the ignition using their software for a 25 degree max advance (with the 5 degree late clocking), to ensure 20 degrees BTDC.....I have yet to be able to get the software to connect using a USB-Serial adapter, but am still trying. He recommends programming over leaving the manifold pressure tube loose as their is no guarantee that the air by the carburator is ambient due to pressure fluctuations from airspeed, cooling air, etc.

Hope that helps
Eric
 
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As a +1....

I've never been able to talk to my ignitions using the USB to Serial adapter either. I've been told that not all adapters are created equal, but this one sure doesn't work.
 
I have a IO360/CS with 10:1 and I am using a Mag and Lightspeed.
I really enjoy the combination. I start the engine on the Mag and then turn on the lightspeed. The engine smooths out and purrrrrrs.
I only have 14 hr on the fly-off. I checked the fuel consumption for two hours at 24 square and it was 7.5 gal/hr. I could not believe it. I ran at PK toward LOP.
I do not know about the other brands of Electric Ignitions.
Dave
 
Keep in mind that a standard magneto has "fixed" ignition timing, while P Mag is managed (varies as required., In essence your engine would not get the full benifit of total timing management. In addition, P Mags has a longer spark duration, and constant intensity, while the old mag has short duration and variable in intensity commong with standard magnetos.
PMags have built in timing curve choice.
Whatever you decide, don't waste time with two timings, get 2 P Mags not one, especially with higher compression.
 
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