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any P-mag pireps?

pa38112

Well Known Member
I am considering switching from Slick magnetos to P-mags. O-360-A1A with a FP prop. I am mainly interested in improving engine smoothness LOP. The cost savings of the 500hr maintenance on magnetos is a little addition justification. Has anyone done a similar conversion and like to share your impressions?
I am only interested in the P-mags because I don't want to add a redundant electrical system for other electronic ignition options.
 
4 years on dual Pmags. No problems, great factory support, straightforward install.

I operate LOP probably 75-80 percent of the time with an IO-320 and I can smoothly run as much as 70 degrees LOP.

With a carburetor maybe not so smooth LOP but you?ll still see savings by the ability to use auto plugs, smoother idle, easier starts and maybe a little less fuel burn at altitude ROP.
 
2.5 years, 330 hours. They work great.

IO-320 CS prop. I run LOP anytime I'm at cruise and burn about 6.2 GPH at 145knots TAS in the 10-14k range.

-Dan
 
One additional PIREP to add to the pile. First flight was on Sunday. 1 impulse-coupled Slick, one P-Mag. No problems. Even EGTs / CHTs across the board at break-in power. Smooth-running.
 
Will have a nice pair of trouble free P-mags going on the market just as soon as Ross releases the CPI-2.
 
We are very happy with our P-Mags. After talking to the owner at Sun-n-Fun (Brad I think?) we switched to automotive spark plugs and saw a real improvement in starting performance, especially when hot. We were also able to run about .5 gal/hr leaner of peak than with the aviation plugs.

We have had no problems with them whatsoever. Highly recommend.
 
Thank you for the links - very helpful. Do you know why I don't see these when I go to the Electronic Ignition Forum? There are only 4 or 5 post there.

You need to tell the search engine how far back to look - I think it defaults to 30 days. Set it all the way back, and you'll see way more information!
 
If you install P-mags, be sure to read and understand the manual and then install them accordingly.
 
If you install P-mags, be sure to read and understand the manual and then install them accordingly.

And...if you buy used, make sure to send them in to Brad if they don't have the latest software upgrade.

Very important that the latest version is installed.

I'll echo the other comments; easy starting and smooth running. One of the best upgrades I've done since I've been taking care of Whiskey-Victor...
 
And...if you buy used, make sure to send them in to Brad if they don't have the latest software upgrade.

Very important that the latest version is installed.

I'll echo the other comments; easy starting and smooth running. One of the best upgrades I've done since I've been taking care of Whiskey-Victor...

Good advice Rob.

The inspection isn't very expensive and worth every little dime.
 
Pmag experience

My recent experience for the the knowledge bank:
Doing my preflight mag check to verify my simple Mag switches powered down each mag, I got the standard 100 rpm drop on one but 200 rpm drop on the 2nd with some roughness. After 50 hours flying and checking, I knew this wasn?t normal. Emailed Brad at Emagair and he replied with some trouble shooting pointers as well as referring me to the manual. He also called me later that day to see if i understood his directions and if I had any additional questions or needed more help. Worked on it the next day and pinpointed the problem to the ignition coil of the 2nd mag. One of the 4 ?igniters? was no longer firing. So was running on only 7 plugs instead of 8. $110 and Fedex2day?s later had the new coil and installed it rather easily. Back to running on 8 plugs.
Totally happy with the manual instructions and especially with factory support. Who else would call to make sure your problem was resolved ???
 
One tip for everyone running autoplugs, regardless of the EI firing them.

Because our EICommander displays the condition of the spark intensity, we have noticed that the plugs start to deteriorate at around 100 to 130 hours. It is the insulators that start to break down, not the metal parts.

Buy the cheap plugs and just replace them every 100 hours.
 
Plugs

First pirep, they are good I run two with Bills EI commander. starts way hot or cold, one or two blades.

Bill does the spark plug comment carry for Iridiums?
 
Best Decision Ever!

Removed dual Slicks on my O-360 A1A with CS prop and installed P Mags with the EI Commander and auto plugs. Nothing but praise to Bill and Brad. Easier starts cold and hot, more power, smoother, less GPH and easy install and MX. Winner👍
 
EI Ignition

Failure modes are different from a mag

From experience, with an early system of EI on one side and a mag on the other. The EI lost its timing and was firing the charge at the wrong timing point therefore negating the good operating mag and the engine virtually stopped, we did not diagnose the fault quickly but luckily we were over an airfield so no real drama, if it had happed five minutes later we would have been swimming.

If we had switched off each ignition in turn them we would have been OK but we had just taken off and were at about 1000 ft, which did not leave enough thinking time.

I'm a great fan of EI ignitions but like any lessons learned if we were in the same situation I would try each mag/ignition in turn. If our experience helps anybody else then it was worth hi-lighting our experience.


Rob
 
Lost timing

I expect Bill R to clarify that lost timing predates V40. If not, we should all be aware it can still happen
 
Failure modes are different from a mag

From experience, with an early system of EI on one side and a mag on the other. The EI lost its timing...

Rob

The key words here are EARLY SYSTEM. Many changes have come along since the early days. Many versions of P-Mag firmware have come along since the early days. Make sure you have the latest. V.40 is recommended as the oldest version which has the necessary built-in protections against timing loss.
 
First pirep, they are good I run two with Bills EI commander. starts way hot or cold, one or two blades.

Bill does the spark plug comment carry for Iridiums?
Steve, every plug manufacture is different. Since you have our EIC installed, keep an eye on the plug graphs. Once they consistently stay low, then replace your plugs.

We sent a set of eight BR8ES plugs with 130 hours on them of a PhD ME gear head college professor who performed a number of tests on them. He found the metal parts looked new but the insulation was starting to fail. Thus lower than new graph displays on the EIC. I assume, but do not know, that Iridium plugs may use the same insulating material.

If you are going to replace the plugs every year, then I simply recommend using the cheaper BR8ES plugs.

Failure modes are different from a mag

...

I'm a great fan of EI ignitions but like any lessons learned if we were in the same situation I would try each mag/ignition in turn. If our experience helps anybody else then it was worth hi-lighting our experience.

Rob
Yes, the failure modes are different than traditional Mag, but hopefully fewer and further between. Only additional experience will tell for sure.

I expect Bill R to clarify that lost timing predates V40. If not, we should all be aware it can still happen

Is there a newer rev than V.40 ? How are we supposed to know and how is different ?
Larry,

V41 is the new version. "V41: 9/19/17 Current production (and service to units with board versions 17 and 18) will get firmware V41. V41 does not alter operating instructions in any way. It simply smooths internal transition between internal and external power states."

Your P-mags should have a sticker on the outside, listing the current firmware version. If not, you can read the firmware version with either our EIC or the Emag EICAD program. There is a third option and that is to call Emag with your serial numbers.

I have not discussed this version either Brad or Tom, so I don't know if there is something else going on with it. However, I'm 100% confident it is a reliability improvement.

For those new to the Emag line of products. Early on there were both E and P-mag's. They were the same except the E-mag did not have an internal generator and required ship's power to fire the plugs.

Early failure modes were caused by both hardware and software issues. While there are still the occasional hardware failures, they are few and far between and of different nature than the early series P-mags. Also, The E-mag ignition is no longer in production.

When the 114 P-mag (113 P-mags can be upgraded with a board change) Emag added cooling fins to the neck of the ignition and the P-mags now switch to internal power as soon as the internal generator can support the ignition. This transition starts at about 800 RPM.

Additional software changes continued to improve the reliability. Version 40 solved two major issues; the first was that with V40, the ignitions fire the plugs at 4 degrees after TDC when in starting mode (below 200 RPM) and the second is that the software changed when the TDC mark can be set. This eliminated the possibility of a lost timing mark in aircraft equipped with independent grounding switches for their P-mags. These upgrades continue in Version 41, mentioned above.

Prior to version 40, it was not uncommon for people with lightweight props to "clock" their P-mag ignitions so they did not fire at or slightly before TDC, causing kickbacks, and breaking starters. With V40 or higher, it is recommended to set the timing to TDC. <-- Corrected the last sentence.
 
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What is the recommended setting now? I have a light weight prop (CATTO) and have always set my P-Mags somewhere around 1degree ATDC.

:cool:

Sorry, I had a type-o on that line.

If you have V40, then the recommended timing of TDC is all you should need.

At that timing setting, the ignitions will fire at 4 degrees after TDC when below 200 RPM, meaning during startup.
 
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Sorry, I had a type-o on that line.

If you have V40, then the recommended timing of TDC is all you should need.

At that timing setting, the ignitions will fire at 4 degrees after TDC when below 200 RPM, meaning during startup.
OK, THANKS!!!!

:cool:
 
To add a bit of info provided to me by Brad, and to counter some misinformation which has been quoted on this forum, V.40 will fire the plugs at 4 degrees After TDC every time the engine is spinning at less than 200RPM. Some thought the P-Mag had to go through a power-off cycle in order to reactivate this "engine start timing mode" but that, according to Brad, absolutely is not the case.
 
And yet, we have some credible reports of kickback events with v.40 and later. Should be absolutely impossible.

And yet, I have v.37 currently (just had my ignitions on the bench for their yearly checkup), and I've never had a kickback.
 
And yet, we have some credible reports of kickback events with v.40 and later. Should be absolutely impossible.

And yet, I have v.37 currently (just had my ignitions on the bench for their yearly checkup), and I've never had a kickback.

Sorry, I had a type-o on that line.

If you have V40, then the recommended timing of TDC is all you should need.

At that timing setting, the ignitions will fire at 4 degrees after TDC when below 200 RPM, meaning during startup.

To clarify...

Any time the RPM drops below 200 RPM's, the ignitions will fire at 4 degrees ATDC. This includes post startup. So if your engine starts and then the RPM's sags below 200 RPM's for some reason, the ignition will fire at 4 degrees ATDC until above 200 RPM's.

Above 200 RPM's, the ignition will start to step up to it's high power setting, wherever you have that set. It is not uncommon for me to see it down at 19.6 degrees when on low RPM idle (~600 RPM or so). At 1,000 RPM's it moves up to around 22.4. Full takeoff power sees mine stabilize at 25.2, which is where I have my P-mags configured.
 
Bill - my V.40 P-Mag is "stock out of the box", timed to TDC per manufacturer's instructions. Where should I be expecting it to be firing at 2700RPM takeoff power with a C/S prop in our naturally-aspirated, carb'd O-360?
 
Bill - my V.40 P-Mag is "stock out of the box", timed to TDC per manufacturer's instructions. Where should I be expecting it to be firing at 2700RPM takeoff power with a C/S prop in our naturally-aspirated, carb'd O-360?

Jumper in, it should fire at 26.6° BTDC for takeoff, assuming around 800' MSL.

Myself and others have had good luck moving the Advance Shift and Max Advance a -1.4°. This did two things, 1. It lowered the CHT's and 2. We gained a knot or two of speed. This is on engines parallel valve engines with the stock 8.5:1 compression ratio. If you have higher or lower competition ratio, you will have to find your engine's happy spot.

You can change these settings with the EICAD program available from Emag's website, if you don't have an EICommander. (We don't recommend changing any other settings.)
 
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Thanks for sharing this info, Bill. Can the same effect be had by simply timing the P-Mag at 1.4 degrees After TDC? I bought the P-Mag because I wanted an "install and forget" ignition system, rather than one which would need to have a computer attached to it.

BTW we're not seeing high CHT's but that's to be expected as a result of our low OAT - first flight was done with an ambient temperature on the ground of -15C and -20C in the air.
 
Thanks for sharing this info, Bill. Can the same effect be had by simply timing the P-Mag at 1.4 degrees After TDC? I bought the P-Mag because I wanted an "install and forget" ignition system, rather than one which would need to have a computer attached to it.

BTW we're not seeing high CHT's but that's to be expected as a result of our low OAT - first flight was done with an ambient temperature on the ground of -15C and -20C in the air.
I see no reason why that wouldn't work, as long as you have the jumper installed.

The timing configuration is way too advanced for our Lycoming engines without the jumper installed.

Check your PM's.
 
SNIP

The timing configuration is way too advanced for our Lycoming engines without the jumper installed.

Check your PM's.

I offer this is very dependent on what you are trying to achieve. At any rate this statement does not reflect my experience flying pMag over the last decade.

90% of my flying is LOP and the more aggressive curve works well. I do have a switch on the panel to select jumper in or jumper out and did some comparisons (and spent the first 20 hours or so after intial install using the less aggressive curve). If you tend to not mostly fly LOP, I can see staying with the less aggressive curve.

I recommend following the install manual, then decide if you want to mess with the timing or not. I offer the vast majority of users will be happy with the pMags as they are out of the box.

Carl
 
Myself and others have had good luck moving the Advance Shift and Max Advance a -1.4?. This did two things, 1. It lowered the CHT's and 2. We gained a knot or two of speed. This is on engines parallel valve engines with the stock 8.5:1 compression ratio.

I understands that -1.4 from the A curve may lower CHT's a bit, but more speed? Bill, Please explain...More speed requires more power, and I think Brad would say to increase the advance for more power.
 
I offer this is very dependent on what you are trying to achieve. At any rate this statement does not reflect my experience flying pMag over the last decade.

90% of my flying is LOP and the more aggressive curve works well. I do have a switch on the panel to select jumper in or jumper out and did some comparisons (and spent the first 20 hours or so after intial install using the less aggressive curve). If you tend to not mostly fly LOP, I can see staying with the less aggressive curve...

Id offer that your first paragraph contradicts your second, while also reinforces Bill's statement.

What we are "trying to achieve" with any ignition system is optimal timing. Period. Dot. The "jumper out" curve is indeed good for LOP, the flip side is that it is also "way too advanced" for high power settings. This is not a matter of opinion, its fact. Yes, there are work arounds which will allow the Pmag to give acceptable performance, but really, why in this day and age do we have to settle for a work around?
 
I understands that -1.4 from the A curve may lower CHT's a bit, but more speed? Bill, Please explain...More speed requires more power, and I think Brad would say to increase the advance for more power.

More Ignition advance does not equal more power. The ignition event is timed to allow the combustion event to reach maximum pressure at the most favorable crank angle. Because the combustion event burn rate does not vary with RPM, the START of the event must be varied to get the best pressure/crank angle. Combustion speed is greatly influenced by mixture however. Its real slow when high and lean; much faster low and rich.

The fact is, too much advance at takeoff power peaks the cylinder pressure before the optimal crank angle and reduces output while also building more heat in the heads. I have done testing where I flew at 100% power while RETARDING the timing to values well below the data plate value and saw no change in speed, but lower CHT. Pmags, even with the jumper in are "too advanced" in this power regime, so thats why you see reports of higher CHT compared to magnetos, and/or you hear about people mechanically retarding the timing a bit.

The problem with spoofing the timing in this way is that you then lose your advance up high and lean. You need to pick your poison- the Pmag curve is just not broad enough to cover it all.
 
I do have a switch on the panel to select jumper in or jumper out...

Carl,

I think I read somewhere that the P-Mag sensed the jumper state during power up and kept state regardless of any later change.

EDIT (from the install document): Note 2: The ignition looks at the jumper state at power-up only.
You cannot route these jumper terminals to a switch and go back and forth between curves while the
engine is running. EICAD does allow you to change timing (Advance Shift) while the
engine is running.
 
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Carl,

I think I read somewhere that the P-Mag sensed the jumper state during power up and kept state regardless of any later change.

Bill R?

This is correct. The only way to change the timing settings while running is with the EI Commander, EMag's EICAD software, or some other home brew device that can send serial commands to the Pmag.
 
I suppose I should ask Brad this, but I'm sure some of your know. What is the range for each main curve?

A: The manual says, up to 34 degrees advance, but what is it at max. power situations?

B: The manual says, up to 39 degrees advance, but what is it at max. power situations?
 
This is correct. The only way to change the timing settings while running is with the EI Commander, EMag's EICAD software, or some other home brew device that can send serial commands to the Pmag.

Except the EICAD program from EMAG will not let you change the timing, if the engine is running.
 
Carl,

I think I read somewhere that the P-Mag sensed the jumper state during power up and kept state regardless of any later change.

EDIT (from the install document): Note 2: The ignition looks at the jumper state at power-up only.
You cannot route these jumper terminals to a switch and go back and forth between curves while the
engine is running. EICAD does allow you to change timing (Advance Shift) while the
engine is running.
This is correct, however with the EICommander, you can move the timing curve in flight by adjusting the Advance Offset and Max Advance.

Upon power-up the P-mag sends its configuration out the serial port. If it receives the same thing back that it sent out, the jumper must be in, and it runs the A configuration. This only happens during power up. Once the engine is running, the internal electronics never stop getting power, and never perform that check again. Thus having an A / B switch in your cockpit will only work prior to engine startup.
 
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I understands that -1.4 from the A curve may lower CHT's a bit, but more speed? Bill, Please explain...More speed requires more power, and I think Brad would say to increase the advance for more power.

Setting the proper timing is kind of like balancing on top of a ball.

The idea is to start the fuel air mixture burning at a point before TDC that achieves maximum cylinder pressure after TDC and before the exhaust valve opens and lets the waste heat flush down the exhaust.

If your timing has too much advance (starting the fire further from TDC than optimal) then you have a lot of pressure in the cylinder as the piston comes up. This causes your CHT's to rise and wastes energy. As the piston crests TDC, there is less energy to drive the piston down. You see this as higher CHT's and lower EGT's.

If the timing has too little advance (starting the fire closer to TDC than optimal) then the pressure is starting to build and continues to build when the exhaust valve opens and allows the still burning and expanding fuel air mixture to exit the exhaust. You see this as lower CHT's and higher EGT's.

What we discovered, and I hope to do some more testing when I get the plane back together (I've been down since May with maintenance issues), is that by reducing the timing by 1.4 degrees, we are probably very close to the optimal timing for a parallel valve Lycoming with 8.5:1 compression.

Many things impact the optimal timing, such as; cylinder head design, compression ratio, piston diameter, RPM, manifold pressure, etc.

With a reduction in manifold pressure, the fuel-air molecules are further apart and it takes longer for the flame front to propagate across our large cylinders than at high MAP. Thus, when you climb, a variable timed ignition can allow the sparkplugs to fire further before TDC and still achieve maximum pressure at that magical 12 to 15 degrees after TDC.

Does that help?
 
Id offer that your first paragraph contradicts your second, while also reinforces Bill's statement.

What we are "trying to achieve" with any ignition system is optimal timing. Period. Dot. The "jumper out" curve is indeed good for LOP, the flip side is that it is also "way too advanced" for high power settings. This is not a matter of opinion, its fact. Yes, there are work arounds which will allow the Pmag to give acceptable performance, but really, why in this day and age do we have to settle for a work around?

More Ignition advance does not equal more power. The ignition event is timed to allow the combustion event to reach maximum pressure at the most favorable crank angle. Because the combustion event burn rate does not vary with RPM, the START of the event must be varied to get the best pressure/crank angle. Combustion speed is greatly influenced by mixture however. Its real slow when high and lean; much faster low and rich.

The fact is, too much advance at takeoff power peaks the cylinder pressure before the optimal crank angle and reduces output while also building more heat in the heads. I have done testing where I flew at 100% power while RETARDING the timing to values well below the data plate value and saw no change in speed, but lower CHT. Pmags, even with the jumper in are "too advanced" in this power regime, so thats why you see reports of higher CHT compared to magnetos, and/or you hear about people mechanically retarding the timing a bit.

The problem with spoofing the timing in this way is that you then lose your advance up high and lean. You need to pick your poison- the Pmag curve is just not broad enough to cover it all.

Michael is correct on both posts.

The trick with any automated ignition is setting the timing for the current flight conditions, which continually change, and not endanger the cylinder head & piston with too much pressure and heat.

See my post above for an explanation.
 
I've been happy with dual pmags for almost 700 hours on my parallel valve, ECI-360, with 8.5 pistons (with squirters) and vertical AFP injection. I use EICAD (no jumper), but haven't varied from advance shift of "0", which provides the "A" curve.

I'm based in Tucson, AZ, so I'm rarely taking off below 2500 density altitude, and much of time considerably higher. I fly mostly LOP in high DA cruise. It's only sometimes in the summer that I'm flying near sea level, in the pacific northwest.

When I hear that the A curve may be too far advanced, it makes me wonder if I should make a change. Perhaps I'll try the -1.4 advance shift setting just for grins, but I don't expect to notice the difference.

What's your advice?
 
...

When I hear that the A curve may be too far advanced, it makes me wonder if I should make a change. Perhaps I'll try the -1.4 advance shift setting just for grins, but I don't expect to notice the difference.

What's your advice?
It won't hurt and will probably only help. If it is easy to make the change, give it a shot.
 
Without EICAD, retarding the timing by 1.4 degrees would be approximately 1/2 tooth on the ring gear? Ring gear is 149 teeth. Is this an acceptable method?

Bevan
 
Without EICAD, retarding the timing by 1.4 degrees would be approximately 1/2 tooth on the ring gear? Ring gear is 149 teeth. Is this an acceptable method?

Bevan

About as accurate as setting it any other way.
 
The reason P-mags work in 1.4 degree increments

In order for the P-mags to calculate the firing angle as efficiently as possible, they operate at the bite level. Thus 360 degrees divided by 256 bites equals 1.40625, which we shorten to 1.4 degrees.


Timing in increments of 1.4 degrees does not appear to degrade engine performance, so there is little to no need for the ignitions to operate in 360 degree increments.
 
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In order for the P-mags to calculate the firing angle as efficiently as possible, they operate at the byte level. Thus 360 degrees divided by 256 bytes equals 1.40625, which we shorten to 1.4 degrees.


Timing in increments of 1.4 degrees does not appear to degrade engine performance, so there is little to no need for the ignitions to operate in 360 degree increments.

As Bill says, the processors used inside the Pmag are low resolution or at least they use a low resolution 1 byte register for the firing angle (have no idea what the actual processor is). Its actually 360/256 "bits" instead of "bytes" but you get the idea.
 
As Bill says, the processors used inside the Pmag are low resolution or at least they use a low resolution 1 byte register for the firing angle (have no idea what the actual processor is). Its actually 360/256 "bits" instead of "bytes" but you get the idea.

Yep, transposition error on my part. Corrected above.

Thanks for pointing that out!
 
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