I hope you will report back on your experience with the Pmags. ?I have liked them since they were introduced. ?I wanted to put at least one on my Midget Mustang, but they didn't have them for the O-200 at the time. ?Now I really want at least one on my Mustang 2.
I have spoke to a few people that have them and they all claim a 10% reduction in fuel burn, much easier starts, and smooth idle. ?One thing they also report is increased CHTs and oil temps and decreased EGT because more fuel is burned in the cylinders and less in the exhaust. Be sure to give us the details of what you see with them. -------------------- In fact, I maintain a GlasAir Super IIs with Pmags on an IO-360, so have been working with them for a few years. ?You have to have your cooling working correctly to accommodate the additional heat that comes with a more complete burn in the cylinders thanks to the timing advance. ?Since I am breaking in a new top end and have also modified my cowl to reduce the cooling, I am starting off with the more conservative timing curve that will limit itself to 34* advance. ?Once I have a few hours on the engine, I'll likely switch to the more aggressive timing curve that goes up to 39* advance. ?I did see some issues with the older Emag/Pmag in that the default timing routine wouldn't work, which I assume was due to our 7000' altitude here. ?I had to use the alternate timing methode, which was still easier than stabbing and timing regular magnetos. For those not familiar with them, the Emag/Pmag timing routine is all electronic. ?You mount the mag however it fits best for your engine, then turn the engine to #1 TDC. ?Power up the Pmag but leave the P-lead grounded. ?You should get a red LED. ?You blow into the manifold pressure (MAP) sense tube and the LED turns to flashing red. ?Wait 30 seconds and blow into the MAP tube again, and the LED will switch to flashing green, meaning it is now set for TDC on #1 cyl. ?Power down the Pmag. ?When you power it back up, you should have a green LED confirming #1 TDC. ?If you move the prop 1 degree either direction, the LED turns to red indicating that you are no longer at TDC. I recommend using the Automotive plugs and spark plug bushings, so my plane now has NGK BR8ES plugs in it. ?$2.50 per plug at the autoparts store. ?You start off with your plugs gapped around .030" rather than .015" as required for the massive elecrode aviation plugs. ?The tight gaps and multiple grounds on the massive electrode aviation plugs are there so you can maintain the tight gaps for the magnetos. ?As one gap starts to burn out, the spark will start arcing to the closer ground electrode. ?Your engine will run better with a bigger gap at the plugs, but a magneto that has to fire across a wide gap produces a lot of heat and often times fails the coil. ?The electronic ignition is perfectly happy to fire a wide gap on the plugs, which is why I recommend automotive plugs for the electronic ignitions. ?Emag is happy to supply a harness for either type of plug. While there are no moving parts in the Emag other than the shaft and bearing, they do still require inspections. ?Periodically, it is recommended to send them in to Emag for inspection and replacemenet of the bearing/seal. ?They charge a flat fee of $85 for service and inspection, which beats the socks off from paying the cost of a magneto overhaul. While I expect to see a reduction in fuel burn and will use a much cheaper spark plug, buying a pair of Pmags was not a cost saving move. ?Initial cost to replace both mags on an O-200 was $3000 plus you need a set of impulse coupled drive gears off the Slick mags. (Or NON-impluse gears for a Lycoming) ?I bought them for the expected improved performance at altitude since I start out on the ground above 7000' and usually cruise between 8500' and 13,500'. I'll report back on my experience with them, but the numbers may be a bit convoluded since I also modified my cooling and modified the engine with higher compression pistons at the same time. -Jeff Scott Los Alamos, NM
