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Out with the Old, In with the New ? Upgrading to P-Mags

Ironflight

VAF Moderator / Line Boy
Mentor
Seven or eight years ago, when I was buying equipment for my RV-8 project, I was intrigued by the (then) new E-mag electronic ignition. Intended as a nearly “drop in” replacement for regular magnetos, I sure liked the clean design that did not require a separate “brain box”, crankshaft sensor, or extensive wiring. It seemed to me to be a great design concept – but I’ll be honest, I was a little nervous about anything that absolutely MUST work (to keep the airplane in the air) being that new. I decided to equip the airplane with tried and true Slick mags, and keep an eye on the E-mags. I watched as numerous people went with one, then two of the units, as well as the even newer P-Mag – an E-mag that had its own internal alternator so that once it was going, it was independent of ships power to keep the engine running. This really upped the interest, since it was pretty much as electrically independent as a traditional mag (except for starting – and take-offs are almost always optional).

After some early teething problems with temperatures and mechanical components, it appeared that folks who I have a lot of respect for were piling up hours on their P-Mag installations. Reports of difficulties became few and far between, and reports of improved customer service on the part of Emagair went up. I saw both of these as positive signs, so when it came time to have an engine built for our new RV-3, we pulled the trigger and went dual P-Mags to get the maximum benefit of EI all the time.

With 1430 hours on the RV-8’s engine, we suffered our first real Slick mag issue (I have had great luck with Slicks on a number of airplanes) when the left mag died on a long cross-country. Most likely a coil issue, we were able to borrow a mag from a friendly mechanic to get home, and then I started shopping for a pair of new Slicks. The price of coils and overhaul parts are such that it really makes about as much sense to buy a new one as it does to fix one that is malfunctioning, so I was looking at about $1600 for a set. P-Mags would cost more, but if I was ever going to make the switch, now was the time – and since I was committed (and happy) on the RV-3, I figured why not go ahead and bring the Valkyrie’s engine up to the same standard.

At the same time, it would allow me to see (and share) first-hand what was involved in making the swap. It turned out to be very straightforward and simple, with the greatest time spent in adding a couple of circuit breakers and determining where I wanted to run the wiring to supply ship’s power to the P-Mags. As always, making the installation look pretty takes a little extra time as well, but overall, this was a weekend project (if you don’t count the days I spent waiting on a couple of special parts and tools for my unique installation.

IMG_6203.JPG


Find an Album of Pictures (with captions) here: https://picasaweb.google.com/111407...0RV8PMagUpgrade?authkey=Gv1sRgCJCdopzF7f7zWQ#

I have been really impressed with the quick and easy starting on our RV-3, but I had nothing to compare it to - it came with P-Mags - so it has always started quickly. With the -8, I could get a direct comparison to the old Slicks – and it was like night and day. First off, I have always considered this to be a very nice-starting engine. Now, I was surprised at just how quick it lit off – like the proverbial one or two blades. Second, I have always had pilot passengers remark on how smooth the engine runs – with Mags. I was SHOCKED at how smooth it now started and idled with P-Mags, right out of the box. The ignition is obviously hotter and more powerful, and doesn’t misfire a single cylinder. After a little running on the ground, I cowled it back up and took it for a quick flight around the pattern. Leaning was incredible – even with a carburetor, you can lean it way, way down into the LOP region without misfiring – and I mean down to where the power is dropping off dramatically (but smoothly). It is going to be possible to run quite a bit leaner than before, and I was always able to run 50 LOP without a problem

Easy installation, a reasonable cost (when compared to a full-up Slick system), and few reported problems in the latest installations – I am sold. I fly lots of cross-countries, and cover lots of ground where I’d rather not land – but I am comfortable now that these have reached a level of maturity that I can trust. True – if I find myself with a dead P-Mag, I probably won’t find one on the field to get me home (like I might with an old Slick), but Fed Ex can reach us just about anywhere these days, and I won’t stuck for very long. Everything is a compromise, and you might find yourself stuck with a dead mag (and no replacement) at some out of the way refueling stop as well. But the past few years of demonstrated reliability, plus the smooth starts and potential for efficiency finally tipped the scales for us. We still have one Slick-equipped airplane, and when it needs ignition work, we’ll see what makes the most sense – but the P-Mags seem to be an easy and sensible direct replacement if you are looking at buying two new mags anyway.

And the installation? Piece of cake!
 
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Notes

So here are a few notes to outline the project – one that even a non-builder should have no trouble following!

1) Pulling the old ignition was a piece of cake – the only things that are remarkable is that the hold-down studs for the left mag will most likely be too long for the P-Mags, since that mag usually has an impulse coupler, which requires a spacer – which requires longer studs. You’ll remove the spacer to install the P-Mag, and will probably want the shorter studs. Pulling the longer studs was easy with a special (expensive) Snap-On tool:

2) The P-Mags (like other mags) do not come with drive gears – they are engine parts. You can remove and re-use the one from the right mag, but the impulse-coupled mag has a different gear. Emagair was able to supply me with the correct gear (it was marked “used”, but looked great!) and that (to me) was an easy way to go.

3) The automotive ignition wires used by P-Mag are slightly larger in diameter than the aviation harness wire, so you’ll need some larger Adel clamps as replacements. Aside from that, everything is in the box with the P-mags – including a bag of microwave popcorn to keep you occupied while reading the manual.

4) Although I originally wanted aviation plugs just because I was comfortable with them, Brad (at Emagair) convinced me that not only were the automotive plug wires a much better fit (they are – the aviation caps are sort of Mickey Mouse, and he admits that), but the ignition was really designed to use auto plugs.

5) Installing the P-mags themselves took no time – and it was really nice to be able to orient them the way I wanted – with the side for the wiring harness plug facing outboard on the engine – this makes hooking things up and doing maintenance down the road SO much easier!

6) Attaching the power and control wires is pretty simple. If you decide to pick off the tach signal, you’ll have four wires to a P-Mag – Power, ground, the ignition switch “P-Lead”, and a Tach wire. While some have complained about the type of connector used on the P-Mag, I found that they were fairly simple to use, and look robust IF you follow instructions and use the supplied Adel clamp to restrain the wire bundle properly.

7) I supplied power to the two mags through separate 3 Amp circuit breakers that I added to the cockpit, and powered from my essential bus. Since the P-Mags will generate their own power once the engine is running more than 800 RPM, I was satisfied with a single power feed to each – considering that I have two different batteries and two alternators as a way to feed the essential bus. And if the airplane is really “dead-dead” when I go to start, I probably need to fix that before I go flying anyways.

8) You’ll have to look up the recommended connections for your particular tach (or EFIS) to see what it is expecting. In my case, I am using a Grand Rapids Technologies EIS – 4000 to collect the tach signal and feed it to my GRT EFIS. To hook it up to the old Slicks, it needed an inline resistor to work properly. Fortunately, I had planned ahead for a day like this, and put the resistor in with spade connectors – so it was a simple matter of pulling that out, and substituting a short wire with the appropriate lugs in it’s place. This took almost no time – but since I had an older EIS, I also had to go in to the box (using an excellent instruction sheet supplied by GRT) and clip two components – (a resistor and a capacitor) off of a circuit board. This took about ten minutes.

9) One other quick task was the addition of some cooling blast tubes – I have never used them for Mags (although many do – and if you do, then that job is done). P-Mag instructions specify blast tubes to cool the round “neck” portion of the units, and since they had early problems with temperatures, I think it is very wise to follow their instructions here.

10) The last thing I needed to do to hook things up was to add a manifold-pressure line to the two P-mags. The easiest way to do this is to route the two lines from the P-mags to a static-line Quick Disconnect “Y”-fitting. From there, a single line can be routed to a transducer manifold, or to a “T” in your manifold pressure sense line. Because of the way I had routed the lines on my RV-8, it was easier to add a “T” in the line going to the manifold pressure sensor, and secure the “T” to the engine mount. I really like having the QD in the sense line, because you set the timing with a blow into the hose – and you can pop it off quickly to accomplish this.

11) Timing was the easiest part. Set the prop at TDC (NOT 25 before TDC!!) – any cylinder, just line up the TDC mark on the starter alignment hole, or the seam case (which ever you have easy access to). Once there, power up the P-Mags with the ignition switch “off”. See the red lights? Blow in the tube until the lights blink, then blow again to confirm – and the lights turn green. BLOW HARD – it takes a little bit of pressure! Reconnect the line, and you’re done. An inspection mirror helps to see the LED’s – one will be easy, one will be tougher to get to.
 
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Nice write up

Paul,
Great to see the -8 isn't suffering from the 'new-kid-on-the-block' syndrome! I too have been curious about P-mags and my budget didn't allow it first go around, but a set of these is definitely on my wish list...
Thanks for sharing your experience both on the installation and operation!
 
Love the popcorn bag included. Its the small things sometimes that really makes it easy to connect with a company. Now they just need to get their 6-cylinder product to market!
 
This can be tough

So here are a few notes to outline the project ? one that even a non-builder should have no trouble following!

Pulling the longer studs was easy with a special (expensive) Snap-On tool:

.

The old standby of two locking nuts was not sufficient to overcome the incredibly sticky stuff that holds the studs in.

When the nuts started moving I picked up the mig welder and welded the top nut to the stud..then used a standard 6 sided socket.

I have used this trick many times and it works when other methods fail.

You have to have a mig welder handy of course.

Other folks have got them out sing vice grips..incredibly slow though.

A very nice write up Paul.

Frank
 
In your conversations with Emagair, did they happen to mention which year they would come out with their 6-cylinder system? Us Rocket guys have been waiting a long time. One more annual---and I'm going for another brand!

Thanks for the info on your swapout...


Lee...
 
Hi Paul,

I've never been a fan of the P mags...but time has gone by. Thank you for taking the time to share your experence. After reading your post I vow to consider this set up next time around. Well done and thanks again.
 
In your conversations with Emagair, did they happen to mention which year they would come out with their 6-cylinder system?
My IO540 is on delivery from AeroSport. I had hoped to have it shipped with the P200 but STILL not available. According to Aerosport, it is in Beta testing and should be out this month. Having said that, it was going to be last spring, summer, fall......... :rolleyes:

Sorry, Paul - bit off subject. Nice job and excellent write up!
 
Thanks for the write up, Paul.

Slicks have never let me down but I'm thinking the next engine will have one, maybe two EI's.

For best reliability Slicks should be overhauled or changed out every 500 hours and that is expensive. Operationally and financially, EI's make good sense.
 
For best reliability Slicks should be overhauled or changed out every 500 hours and that is expensive. Operationally and financially, EI's make good sense.

Exactly - when you consider the total "life cycle" cost of Slicks, the P-Mags are pretty much a wash when it comes to cost. Of course, I don't know anyone that has 2,000 hours on their P-Mags, so this is still a growing database (but one on which I was satisifed to make the leap).
 
P-Mag

I just replaced a Bendix with a P-mag on the left side during my conditional inspection. I have a Jeff Rose ignition on the right which has been flawless since 2004. P-mag installation was easy. Manifold press line was most challenging part. I have a 3-bladed Cato which is a light prop so I timed it just a little after TDC which makes it run better. I have only done ground runs, but notice that I have to lean it more than I used to during ground operations. Also get 50 more static RPM. I use the BR8EIX iridium auto plugs now on both ignitions. Will not fly until conditional is complete, but so far so good.
 
Leaning was incredible ? even with a carburetor, you can lean it way, way down into the LOP region without misfiring ? and I mean down to where the power is dropping off dramatically (but smoothly). It is going to be possible to run quite a bit leaner than before, and I was always able to run 50 LOP without a problem.

For best reliability Slicks should be overhauled or changed out every 500 hours and that is expensive. Operationally and financially, EI's make good sense.
Exactly - when you consider the total "life cycle" cost of Slicks, the P-Mags are pretty much a wash when it comes to cost. Of course, I don't know anyone that has 2,000 hours on their P-Mags, so this is still a growing database (but one on which I was satisifed to make the leap).

Not to mention the probable better fuel economy. Over 500 hours you might see fuel savings about equal to the whole cost of the P-Mag installation. With dual P-Mags I burn about 7.2 gph at or above 8000', and that seems to be a gallon or so less than others I know with the same engine set-up, but with traditional mags. I have less than 50 hours on mine though, so maybe I'm still in the honeymoon phase.

One last thought in support of traditional mags though. I've never had a mental error of forgetting to turn traditional mags back "on" after the run-up. My engine quit on roll-out about 6 weeks back.:eek: The P-mag switch breakers were both off. Definitely an error I do not want to repeat, and I know someone else who did the exact same thing once.
 
...One last thought in support of traditional mags though. I've never had a mental error of forgetting to turn traditional mags back "on" after the run-up. My engine quit on roll-out about 6 weeks back.:eek: The P-mag switch breakers were both off. Definitely an error I do not want to repeat, and I know someone else who did the exact same thing once.


...Another very good reason to wire them up exactly like a conventional magneto installation...


Anyway... Anybody else experience the "zero" RPM drop at runup with dual P-mags? Even with 60+ hours on the plugs (burning 100LL), the RV still shows no change in RPM regardless of which side is firing. The only way I can tell is a slight change in tone and the obvious EGT rise.
 
Paul, after you fly some hours please let us know the effect of adding the blast tubes. Any change to CHT or oil temp?

I'm really curious about that as well Dan - having spent more than two decades with a marginally-cooled Grumman, I am loath to let ANY air leak out of the baffles except through the cylinder fins....so we'll see if anything changes with these two 3/4" holes!

Paul
 
... I have a 3-bladed Cato which is a light prop so I timed it just a little after TDC which makes it run better...
I hope you did this via the ICAD program provided by Emag.

Below 200 RPM the P-mag fires a few degrees (2, IIRC) past TDC to help with starting.

Your installation will make it fire well past TDC when in start-up mode.

FWIW, I have a Catto prop and dual P-mags and set both of them to TDC and have no starting issues of any kind.
 
Great write-up Paul, like always.

It's good to hear that you can go so LOP even with a carburetor when using P-mags. Answered some questions I had.
 
A Cave man could do it...

Nicely written Paul!
Sounds Like P-Mag has come a long way since introduction.

I installed a Jeff Rose "Electroair" system alongside a Magneto in my RV4 in 1996. At that time Jeff's groundbreaking system was leading edge and copied profusely by many others. Since then I have logged 3000 hours on three separate systems with not a single issue. I duplicated the same 1 Mag/1 E.I. system (Crank Trigger) in my HR2 and now operate Electroair's newer version in my current RVX. I wouldn't leave home without one. Why?

Of note:

1. 1 GPH reduction in FF. LOP operations.
2. Much easier starts (especially in the Rocket's IO-540)
3. Automotive spark 18MM plugs (cheap,plentiful) Autolite 386 is my favorite.
4. HP increase (Jeff Rose advertised 5HP, I concur)Much hotter spark and much longer duration burn across the piston than a Mag.
5. Improved High altitude operations (up to 40 degrees advance timing)

In my humble opinion Electroair's new system is every bit as good or better than anything else out there.www.electroair.net

V/R
Smokey


http://www.gofastforless.com/ignition/howig.htm
Best description of ignition I've read

http://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/19930091118_1993091118.pdf
Old NACA report on Mag Sparks

For those of you still operating Mags, make the quantum leap to Electronic ignition! The automotive industry did it 40 years ago...
 
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What happens below 800 RPM on dead battery...

If you have 2 p-mags, and unknowingly a dead battery, and the RPM drops below 800 RPM, what happens? Let's say you're practicing engine out approaches and you pull the power back to idle. I assume the engine quits and that you would not be able to get it started again.

Would you only install 2 p-mags in an airplane that had redundant backup battery of some sort?

I ask this because this happened to me in my C172 yesterday. I went flying for 2 hours. After the flight I fueled up, and when I went to restart, the battery was completely dead. I had to get a tow back to the hanger. This is a 1959 172 with a generator, rather than alternator. It is VFR only and has a single battery. Obviously old technology. I had no indication that the battery was drained.

Thanks for you thoughts in this,
Michael-
 
Michael,

I wouldn't worry about this as a "modern" personal aircraft such as an RV would have to have a lot of things going wrong. The buss voltage could only get low if the alternator was offline, and the battery was already discharged badly. At this point you would/should have a low voltage alarm, prompting you to head for home. The P-mags don't draw much current and can operate on a 9 volt battery so they don't take much. They would continue to operate long after your low voltage alarm.

Also, through testing you may find that the engine will idle faster than 800 RPM in flight, leaving the P-mags in self-generating mode. Of course you will want to test this during your test program.

Bevan
 
No worries...

Michael,

With a dead battery and the 1 Mag/1 Electronic IGN setup, you always have battery out redundancy, ie: The single mag will still function. The current draw on the Electroair is .5 amps. Airborne with Alternator failure (been there) You have an easy hour with load shedding before you need to start looking for a piece of concrete (or grass). Lots of hours have proven the system (1 Mag/1 E.I.) worthy and safe.

Not the answer you were looking for but an alternative to P-Mag.

Smokey
 
If you have 2 p-mags, and unknowingly a dead battery, and the RPM drops below 800 RPM, what happens? Let's say you're practicing engine out approaches and you pull the power back to idle. I assume the engine quits and that you would not be able to get it started again...

Yes, it's possible - but you have a chain of very unlikely events all lined up to make it so:

Your alternator died and;
your battery is dead and;
you fail to notice the above and are doing touch and goes and;
the rpm drop below the cutoff RPM IN FLIGHT.

It's the last one that really is unlikely. In most cases, the only time you will drop below the cutoff RPM is when you are safely on the runway, well below flying speed. At that point it becomes merely inconvenient, rather than a safety issue.
 
I agree completely with Michael - extremely unlikely that you will get a complete engine cut-out in flight. Not impossible that you get stuck on the ground...but you CAN power the P-Mag with a 9 volt battery if you have to. In fact, I was going to build this into the harness on both airplanes (A little 9 volt connector) - just in case. But once I reviewed my redundancy, I figured it was just more unnecessary complication for an incredibly unlikely scenario.

Paul
 
Also, I believe the battery would have to be really low in order not to provide power to the pmag's.

Remember, on the ground you can start the engine using a little 9 volt battery, so one would think if the battery was less then 12v - if you had 9v say, then you would be providing power to the ignition.

I set my low voltage alarm at 12v, so if that comes on I will be load shedding and I'm now not going to pull the RPM's back below the internal alternator minimum operating speed.
 
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I also think the cutoff RPM than Brad lists is a bit on the conservative side. Mine will go down to 700 or so before giving up. In any case, I think you would have to work really hard to see less than 1000 RPM in flight, and it just isn't going to happen in a normal pattern.

I think the bottom line is that if you have flying speed and the propeller is turning, you are going to be well above cuttoff RPM.
 
we have a TMX-IO-360 with the Hartzell blended airfoil 2-blade prop and one P-Mag, we'll eventually swap the mag for a second pmag.

under normal circumstances (not below 65-70KIAS approach speed, no mechanical failure, haven't tried other than fine or almost fine pitch on the prop) flight idle will not or only slightly drop below 1000rpm until rollout on the runway...

different story on the ground / at runup obviously.

i was also wary about the 800rpm-self-power-limitation in case of an electrical fail before first flight, but now i am confident that this is a non-issue. and i can't see us dispatching without a working electrical system in the first place, so this isn't a consideration either.

someone with a fixed pitch prop have some rpm figures for short final?

rgds, bernie
 
Also, I believe the battery would have to be really low in order not to provide power to the pmag's.

Remember, on the ground you can start the engine using a little 9 volt battery, so one would think if the battery was less then 12v - if you had 9v say, then you would be providing power to the ignition.

I set my low voltage alarm at 12v, so if that comes on I will be load shedding and I'm now not going to pull the RPM's back below the internal alternator minimum operating speed.

With your low voltage set at 12v, your alternator has failed a long time ago and you have used your battery down to below 50%. Not a good place to be without a back-up battery.

I would set your low voltage alarm to 13 to 13.5 volts. Your alternator puts out 13.8 to 14.2 volts. Any reading of 13 volts and your alternator has failed and you are reading battery voltage less line loss to the gauge. And now is when you need to start your survival plan, not when your battery is below 50%.
 
Good point Warren,

As I read your post I see the need to adjust.

I have my AFS set to 12v and my VP100 Set to 13.5v.

Probably a good idea to set them both to 13.5v like you said.

The nice thing is its only a 2 min fix and since it's only 17.7F degrees out today :eek: that is the ONLY Maintenance I am going to do! :D
 
One or two p-mags...

I'm about ready to pull the trigger on my engine order. I've decided to go with p-mags but haven't decided whether to do 1 p-mag and a slick, or two p-mags. 1 p-mag and a slick feels like the more conservative approach.

For anyone that has operated both these configurations, would I notice a difference in the way the engine operates between 1 p-mag, 1 slick and two p-mags? e.g. starting, idle, leaning, efficiency

Thanks for all the responses to my earlier questions.

Michael-
 
I would expect the maintenance to be far less on the P-mag. But that will come at the 500 hour inspection on the slick. Some day you will dump the slick. Why not use that value towards a modern ignition system now. As long as you trust the system that you choose.
 
I decided to go dual P-mags before this thread started. I'm not flying yet so I can't answer your question based on "personal" experience BUT after reading Paul's experiences and this thread, I'm glad I have not bothered with the old style mags.

Bevan
 
Differences

I'm about ready to pull the trigger on my engine order. I've decided to go with p-mags but haven't decided whether to do 1 p-mag and a slick, or two p-mags. 1 p-mag and a slick feels like the more conservative approach.

For anyone that has operated both these configurations, would I notice a difference in the way the engine operates between 1 p-mag, 1 slick and two p-mags? e.g. starting, idle, leaning, efficiency

Thanks for all the responses to my earlier questions.

Michael-

I started with slicks for about 100hrs, then 1 pMag for 300hrs, then 2 pMags for 65 hrs. It is hard to notice the differences, but it starts easier, no plug fouling on run up, and it feels more powerful on take off. The take off power was most noticable when i went with two pmags. In the air I can not tell a difference. At the gas pump I notice I burn less fuel on cross country flights. It seems to run smoother too. Sorry, I don't have data to back up my feelings.
 
LOP

Paul, I am also carburated and don't run LOP. Sounds like maybe I could with dual pmags. I have about 150 degrees delta on my egts and that always bothers me. Can you comment on your egt delta when you go LOP? Does it get better (smaller) or worse?
 
Paul, I am also carburated and don't run LOP. Sounds like maybe I could with dual pmags. I have about 150 degrees delta on my egts and that always bothers me. Can you comment on your egt delta when you go LOP? Does it get better (smaller) or worse?

The spread of my EGT's have always ben the best (almost zero) right at Peak. They tend to splay out when I go LOP (one alwasy peaks first). The worst spread is when it is way rich. I run LOP almost all the time, and see great economy, I have not had the chance to really test if it has gotten better with P-Mags.

Paul
 
update please?

I read your excellent and informative initial write up of your pmag installation back in January and am wondering after 9 months or so of flying if you would mind updating us on the performance of your new ignition? Any maintenance issues? I am on the fence about switching out my left side Slick mag soon and have to admit seeing posts titled "Another Pmag failure" or "Pmag troubleshooting" and than reading and finding out the pilot was charged $425.00 because a internal magnet disintegrated have made the decision problematic for me.


VAF check is in the mail. No really.
 
I read your excellent and informative initial write up of your pmag installation back in January and am wondering after 9 months or so of flying if you would mind updating us on the performance of your new ignition? Any maintenance issues? I am on the fence about switching out my left side Slick mag soon and have to admit seeing posts titled "Another Pmag failure" or "Pmag troubleshooting" and than reading and finding out the pilot was charged $425.00 because a internal magnet disintegrated have made the decision problematic for me.
.

Zero P-Mag issues - probably 100 hours of flying on them in the -8 (and another 160 hours on a pair in the -3). We're sitting in Oregon right now, over 1600 miles from home - have also done Oshkosh and a quick Pensacola trip in the past couple of months without a lick of ignition trouble.

Now .... we had to replace a starter relay today (it helps to be in the Mothership's hangar when you need a part....)....but I would call that expected maintenance after almost eight years and 1600 hours of flying!
 
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