As of late I have been experimenting with ignition monitors. I finally have one that checks all my boxes. I have a hybrid ignition system on my plane. The right side has a Megajolt/EDiS system that was fun to make and test with the help of all the smart people here - I have several hundred trouble free hours on it now. The left side is a vintage 20+ yr old P-Mag (PM)that has been updated along the way and has given great service for almost 3300 hrs now. The MegaJolt (MJ) gave me one thing the P-Mag never really could - Control. I like to run LOP and my carbed O-320 needs a fair bit of advance to do that smoothly.
Big note of caution here - your engine is probably different and doing advance wrong can ruin your expensive engine
The MJ has a switch that allows moving b/t 2 independent timing curves - this is great for 2 situations 1) ROP climbs - lower advance (20- 24 deg) really helps keeps temps under control and 2) LOP cruise where more advance (30-40 deg) helps light off a slower burning lean mixture. The P-Mag has ground adjustable timing that in my experience is good for one or the other(for my engine).
Now for about the price of lunch at the burrito store - you can control the P-Mag and get the best of both worlds. More caveats - this is very experimental - there are commercial products that do the same - if you want a real product and support call them. if you like to build cool stuff - read on.... I have bench and flight tested this, but you will want to do the same. This is not a product - it is an idea, and a starting point. Be very careful here. All that said, it works pretty darn well.
What is it - It's an ignition monitor that also has a P-Mag control element. It's based on an ESP32 microcontroller, a small TFT screen, and an RS232 to TTL converter. You can buy that hardware for about $15. Code was written for ESP-IDF 5.4. It displays timing advance, timing correction(shift), ignition state (takeoff or cruise) and RPM for both the MJ and the PM. It has a switch input that lets you flip between 2 max advance limits on the PM. It wirelessly streams advance data for logging (I stream it to my GFT EFIS via another ESP32 to join engine and flight data). It also sets up a wireless hotspot you can log into and change P-Mag parameters on the ground eliminating the need for the sometimes futzy EiCad.
Less interesting to most people here is that the ESP32 acts as a USB host to ingest data from the MJ - that was the most challenging bit of code to get working. It still suffers data timeouts, but the recovery is pretty graceful. My coding skills are 40 years old and I'm not that smart - so Claude helped me(as did a few great guys here on the forums). I do finally have (nerdalert!) a Github if anyone is interested. Modifying this for a dual PMag setup would be pretty easy. I have no idea if this is of interest to anyone, but I enjoyed the process and the results.
My current setup for my carbed O-320 running mogas is: Curve shift = 5.6 deg, Takeoff mode = 21 deg advance limit, Cruise mode = 40 deg advance limit(but I only see about 35).
I take off ROP and climb to altitude - level off and start leaning the engine - I know at WOT and ~2250 rpm I am LOP at about 6GPH - when I get there, the engine will be a bit rough - flip the switches and the engine gets smooth. I have found that the advance gives me smooth ops and about 3kts TAS running LOP over the reduced timing. 3kts is great, but the big plus is the cooler climbs.
Big thanks to all the smart guys here that have done so much to educate us on ignition dynamics - Dan, Larry, Toolbuilder, Nigel and many others. My plane gained some utility here. If you are curious - try it, if you think i am crazy, my wife agrees with you
Here is a video of it in action.
Here is the web interface
Here is how put it in the panel for now
Flight test engineer with the post flight celly!
Big note of caution here - your engine is probably different and doing advance wrong can ruin your expensive engine
The MJ has a switch that allows moving b/t 2 independent timing curves - this is great for 2 situations 1) ROP climbs - lower advance (20- 24 deg) really helps keeps temps under control and 2) LOP cruise where more advance (30-40 deg) helps light off a slower burning lean mixture. The P-Mag has ground adjustable timing that in my experience is good for one or the other(for my engine).
Now for about the price of lunch at the burrito store - you can control the P-Mag and get the best of both worlds. More caveats - this is very experimental - there are commercial products that do the same - if you want a real product and support call them. if you like to build cool stuff - read on.... I have bench and flight tested this, but you will want to do the same. This is not a product - it is an idea, and a starting point. Be very careful here. All that said, it works pretty darn well.
What is it - It's an ignition monitor that also has a P-Mag control element. It's based on an ESP32 microcontroller, a small TFT screen, and an RS232 to TTL converter. You can buy that hardware for about $15. Code was written for ESP-IDF 5.4. It displays timing advance, timing correction(shift), ignition state (takeoff or cruise) and RPM for both the MJ and the PM. It has a switch input that lets you flip between 2 max advance limits on the PM. It wirelessly streams advance data for logging (I stream it to my GFT EFIS via another ESP32 to join engine and flight data). It also sets up a wireless hotspot you can log into and change P-Mag parameters on the ground eliminating the need for the sometimes futzy EiCad.
Less interesting to most people here is that the ESP32 acts as a USB host to ingest data from the MJ - that was the most challenging bit of code to get working. It still suffers data timeouts, but the recovery is pretty graceful. My coding skills are 40 years old and I'm not that smart - so Claude helped me(as did a few great guys here on the forums). I do finally have (nerdalert!) a Github if anyone is interested. Modifying this for a dual PMag setup would be pretty easy. I have no idea if this is of interest to anyone, but I enjoyed the process and the results.
My current setup for my carbed O-320 running mogas is: Curve shift = 5.6 deg, Takeoff mode = 21 deg advance limit, Cruise mode = 40 deg advance limit(but I only see about 35).
I take off ROP and climb to altitude - level off and start leaning the engine - I know at WOT and ~2250 rpm I am LOP at about 6GPH - when I get there, the engine will be a bit rough - flip the switches and the engine gets smooth. I have found that the advance gives me smooth ops and about 3kts TAS running LOP over the reduced timing. 3kts is great, but the big plus is the cooler climbs.
Big thanks to all the smart guys here that have done so much to educate us on ignition dynamics - Dan, Larry, Toolbuilder, Nigel and many others. My plane gained some utility here. If you are curious - try it, if you think i am crazy, my wife agrees with you
Here is a video of it in action.
Here is the web interface
Here is how put it in the panel for now
Flight test engineer with the post flight celly!
