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FS: Almost new dual e-Mag ignition

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MikeReinath

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I am selling my dual electronic e-Mag ignition. These e-Mags are model P114-L4 for Lycoming four-cylinder engines. They are the e-Mags with the internal backup alternator. I used them over a period of 18 months for 110 flight hours. I'll give a little background to explain the reason for selling. A couple of years ago, after 20 years of trouble-free flying with magnetos, I installed these e-Mags in my Lancair 360. I loved them. The engine started quicker. The engine idled smoother at a lower rpm. I ran the auto plugs that are only about $2 each, and I gained about 3 to 4 knots in cruise
above 11,000 feet. I loved them right up to the point when engine oil sprayed out of my prop hub at the blade roots after 110 hours of use. What happened? I experienced propeller resonance. This is a torsional resonance that you don't feel in the cockpit. I had only 380 hours on the prop since a major overhaul at the failure. Since then, I have had the prop overhauled again ($10K). Two prop overhaulers and MT in Germany agree that it was resonance. In addition to the engine oil leaking out the hub, the ball bearing separators had disintegrated, and ball bearings were found loose inside the hub. I have since reinstalled the prop and am flying again with my old magnetos. The e-Mags functioned flawlessly. I just had the bad luck of experiencing the resonance. My configuration (Lycoming IO360-B1B with 9:1 pistons and MTV-12B-175-59d) resonates with the e-Mag ignition. I tried selling on our LancairTalk forum, but there were no takers.


The kit includes everything you need to make the switch from magnetos:

Two P114-L4 e-Mags (SN 7407 and 7408).
Two sets of e-Mag harnesses for auto plugs.
Eight SR auto-plug adaptors and two spares.
One fitting to connect the vacuum tubing to a cylinder.
One certified Lycoming-style non-impulse-type drive gear from e-Mag.
One set of short studs, required when you replace the impulse-coupled magneto with an e-Mag.
One set of four new NGK BR8ES 5422 spark plugs.
Vacuum tubing and fittings.

The current 2024 price for these items is $4,471 on the e-Mag website.

I am selling the set for $3,400 plus shipping (or pick them up at 27AZ, if you are nearby, or I could possibly deliver if you are in Arizona).

Mike
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e_mags.jpg
 
I would be interested in Unit 7407 (the one without the gear) and one set of plug wires if you decide to separate.
Subject to agreeable pricing.
 
I would be interested in Unit 7407 (the one without the gear) and one set of plug wires if you decide to separate.
Subject to agreeable pricing.
Hello Jim,

Okay, but I am going to try to sell the whole thing for a while. If it does not sell, then I will consider separating.

Mike
 
Do not want any kind of thread drift with this classified ad, but am really interested (uneducated), on how the source of the spark can contribute
to resonance. Puzzling to me….
Maybe I could throw that up in General Discussion.
 
BravoAlphaRomeo,

Check out the following manual from Hartzell. You can find it with a search as a pdf. It explains the resonance problem. Basically, you don't want to be the first person to try an engine prop configuration with electronic ignition. You should look for examples of existing configurations the same as yours that are working. Then you know that yours will probably work. I did not do that.

Mike

Manual No. 193, Volume 1
61-03-93
Revision 2
April 2023
Information Manual
for Experimental Aircraft
Volume 1
Propeller Vibration Compatibility
on Reciprocating Engines
 
Do not want any kind of thread drift with this classified ad, but am really interested (uneducated), on how the source of the spark can contribute
to resonance. Puzzling to me….
Maybe I could throw that up in General Discussion.

Trying to avoid thread drift, but also provide relevant information, I'll try to keep it short.

Engines don't turn over smoothly, they accelerate and decelerate slightly as they are compressing the air/fuel or pulsing as the air/fuel combusts. This is called torsional vibration and when it acts on the tuning fork... I mean prop, it will cause the prop to vibrate. If the vibration is the resonance frequency (or perhaps a harmonic) of the prop then you get an amplification affect that will destroy things in sort order, also the frequency of this resonance can be high enough that it doesn't feel like vibration.

Any combination of things can change the frequency or amplitude of the torsional vibration: rpm, the timing advance, how precisely the timing fires (mags have gear lash that can make them wonder slightly), the compression ratio, the crank counterweights, the prop length, the prop weight, etc. Combine that with things that can change the resonance frequency of the prop such as the length, weight, material, shape, etc then you can see where one might intersect the other.

This is why certified airplanes have specific prop/engine combinations and Hartzell produces the document above that shows compatibility and ranges you must stay out of which are typically harmonics of the resonance frequency.

Another thing to point out is that this is why a gearbox is really hard to make. Many auto conversions have had vibration issues and without testing with specific engines, gearboxes, props, and support systems it's very difficult to know if it will last.
 
It seems there is more interest in just a single e_Mag and not the set, so I am splitting the set. Each set includes the following items.

One P114-L4 e-Mag
One set of e-Mag harnesses for auto plugs
Four SR auto-plug adaptors and one spare
Two new NGK BR8ES 5422 spark plugs (and four slightly used plugs)
Two ft of high-temp (450 deg F) vacuum tubing
About 1.5 ft of silicone vacuum tubing
Two herbie clamps
One pulse dampener for the vacuum line
One tach shift diode

The current e-Mag cost for the e-Mag, harness, and plug adapters is $2103.

I would like $1600 for each set.

The drive gear is $265 at e-Mag.

If you also want the drive gear, add $200.

Mike
 
Do not want any kind of thread drift with this classified ad, but am really interested (uneducated), on how the source of the spark can contribute
to resonance. Puzzling to me….
Maybe I could throw that up in General Discussion
I had the same issue in my CubCrafters Sport Cub. There was a notification bulletin issued by Sensenich for this same issue (Link Here). I replaced the original Bendix mags with Slicks. I could have swapped the propeller to fix the issue, too.
 
Do not want any kind of thread drift with this classified ad, but am really interested (uneducated), on how the source of the spark can contribute
to resonance. Puzzling to me….
Maybe I could throw that up in General Discussion.
Lots of things, but 9:1 pistons and maybe running too much advance. People do not seem to understand the crankshaft torsionals and peak pressures and then all the inertia stuff.

This may well have been set up at TDC and running 26+ degrees BTDC when it would have been far better at more like 20 degrees. Add to that the consistent spark event from digital precision and you do not get the same level of variability in every plug firing.
 
This may well have been set up at TDC and running 26+ degrees BTDC when it would have been far better at more like 20 degrees.
Indeed. There are some fairly sweeping conclusions in the OP. For the sake of the sale, it would be beneficial to understand the configuration the OP was running. Was the initial timing altered (housing or crank clocked) or was it straight up? Jumpers in or out? With altered compression, these details matter even more than usual.
 
Thread drift notwithstanding,
Resonance is always present in a reciprocating horizontally opposed gasoline engines with the spinning crankshaft transmitting pulses through the prop and hub. The electronic ignition spark advance rather than the fixed 25BTDC of a mag must be one factor. Like my Harmon Rocket and early RV4s, the Lancair has a crankshaft extension or in some cases a B hub which also adds resonance. There are several Hartzell B hub ADs for cracking caused by just such resonance.
In the VW world fixed pitch wood props are standard as they absorb rather than transmit or amplify the resonance which with their less robust crankshafts can cause failure. Several aftermarket VW rebuilders install a 5th bearing mod to reduce the stress but the wood prop solves a multitude of issues.
When I installed dual P Mags on my RVX, I told Craig Catto I wanted a 2 blade composite vice the three as I’d found with my Sonerai and RV4 the resonance issue was diminished with a 2 blade. I also spent quite a bit of time matching my pistons and rods as well as a crankshaft balancing during rebuild. Both my RV4 and RVX have dual electronic ignitions and FP composite/wood props. Never had a single issue with either but awareness is paramount.
Certified aircraft with metal 2 blade props aren’t immune either. The 0-360 powered Scout I towed banners with in my youth had a “yellow range” of RPM to avoid as it caused harmful resonance.

BTW, if you don’t sell the whole 9 yards I’m interested :)
V/R
Smokey
 
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Do not want any kind of thread drift with this classified ad, but am really interested (uneducated), on how the source of the spark can contribute
to resonance. Puzzling to me….
Maybe I could throw that up in General Discussion.

THIS IS WELL KNOWN.... Hartzell to their credit did flight test (+20 yrs ago) with strain gauges and using electronic ignitions (not e_mag, p-mag, but electronic ignition). They found the vibrations, resonance at some RPM's were more than desired and more than magnetos.

So they recommended restricting the RPM range with typical HC-C2YK/F7666 props RV builders used with EI. The props already had stay out range. KEEP in mind thin props are fast props. However they put in "meat" to dampen vibrations. It is a balance act, like keeping weight of airframe down but strong. But EI with stronger spark and advanced timing was never tested.

This testing Hartzell did spawned their Blended Airfoil props that came out in 2002 I recall, that were made for RVs. They have since certified them for many certified planes. The older design is still good and have one with EI. I just have to not loiter or dwell at critical RPM's. Also when my prop gets to a certain hours they are toast, but that is more than I will likely ever get to.

WHY DO EI's cause this? The power pulse is stronger, with electronic ignition. This is an issue with METAL PROPS. I am surprised if a wood core, composite covered prop would have an issue. Also EI advance timing with lower power typical at high altitudes. I suspect the air density, TAS and engine pulse all conspire to make the stress on prop higher than magnetos. However the OP is also running higher compression than stock (9 to 1 vs 8:50 to 1).

So prop vibrations, fatigue is real.... Even if you put in a certified prop and engine combo (like mine which is similar to a Mooney or Piper Arrow) it will be experimental with electronic ignition and ram air intake (more power) and 4-into-1 tuned exhaust (more power). I have to stay out of certain RPM's.

Again this was to the credit of Hartzell they checked this out,. However they did not or can not test every combo. You change anything you affect the engine and prop. That is why we are experimental. The BA Hartzell is the way to go. As far as MT or other Prop brands, ask if they tested their props on your engine with Elect Ignition. I bet MT will say "NEIN".
 
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Indeed. There are some fairly sweeping conclusions in the OP. For the sake of the sale, it would be beneficial to understand the configuration the OP was running. Was the initial timing altered (housing or crank clocked) or was it straight up? Jumpers in or out? With altered compression, these details matter even more than usual.

I agree. I have P-Mags already but for the price I'd buy them in a second.

MikeReinath I frankly am not anti MT nor a fan. If MT props fall apart with EI so quickly I would be shocked it was all EI's fault. It is possible they failed all on their own, you were at worst MAP/RPM, your EI timing base and advanced were too aggressive? I have a German car and a German motorcycle. If anything breaks VW and BMW say it is the operators fault. German engineering is perfect. Ha ha.​

Seriously CALL BRAD at E-mag... As I wrote above EI does effect the prop... BUT the amount of damage and kind of damage sounds like a lot to blame on the EI. If it is such a sure thing why does MT not say not to use EI? Or do they?​

To be clear it is not a P-Mag issue any EI will do this. The P-Mag can be made to act like a mag (no timing advance). However the higher energy spark will still be there. Harmonics are very RPM dependent. Changing RPM and MAP slightly can make a big difference. Curious what MAP and RPM did you operate at? Also your engine sounds like it has higher compression? Should be 8:50 to 1 and you have 9:00 to 1. So all that is a factor, not just P-Mags. Again any EI (lightspeed, SDS-CPi, FlyEfi, Electroair) will have a stronger power pulse than a magneto.​

What BASE timing and jumper in or out, did you have on the P-Mag? I see the hose so the MAP connection was connected.​


As I wrote above Hartzell found higher blade stresses with EI (when EI was new). However it is 20,000 hours before there was a theoretical issue (and by issue I mean not meeting their certified criteria, fatigue margins of safety). I assume you have composite covered wood core? So the blades are fatigue resistant and resonance because wood and composite is dampened (but not wear resistant), You are saying the HUB ate itself? WOW. I am sorry about that...​

I am having a hard time understanding how a high end prop shook itself apart with EI and high compression pistons so soon. Again if this is "a thing" with MT props and EI it should be out there, like Hartzell did +20 yrs ago. However Hartzell hubs were not the issue. Metal (aluminum) blades can vibrate. They are designed for it. EI did cause more vibrations at resonance at some (not all) RPM's. Hartzell never suffered an EI related hub or prop failure.​

Hartzell's have failed over a half century and millions of hours, on certified planes with magnetos. However often is corrosion pitting and dis-use and lack of maintenance. In the day kit plane builders use to cut metal props down and re-twist them. They failed, A LOT, even with magnetos.... Wood fixed props ruled for kit planes through the early 80's. Then builders started using Hartzell CS props and Sensenich made a metal fixed pitch prop for fast homebuilts that was safe. On the other hand strong 180 HP and 200 HP Lycs were too hard on WOOD props... Most kit planes (including the RV3, RV4, RV6) were made for 160HP or less. Then 180/200HP was the go to, and transition to CS props and metal fixed pitch props happened, despite increase weight and cost. A super light RV3/4/6 with wood prop is a delight to fly.​


CALL BRAD AT E-MAG....
 
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It is interesting that I had a very similar experience just a couple of months ago. Angle vavle Io-360, 10:1 compression, not an RV. One pmag configured to fire at 21 BTDC with max advance limited at 26. The other mag is Slick times at 21*, too. I was using a two-blade MT prop. The bearings fell aparts after 250 hours in that configuration, broken races found in the hub, the propeller was scrapped by MT-Prop USA in Florida. I'm thinking of making a precautionary sale of mmy pmag, too, though a crappy batch of MT prop bearings cannot be completely ruled out.
 
Resonance is always present in a reciprocating horizontally opposed gasoline engines with the spinning crankshaft transmitting pulses through the prop and hub.

noun: resonance

MECHANICS
the condition in which an object or system is subjected to an oscillating force having a frequency close to its own natural frequency.


In Smokey's description above, power pulses are the primary oscillating force (aka driving or forcing frequency). The forcing oscillation is always there, but note it does no harm at all...until it matches the natural frequency of some component. When a natural frequency is matched by a forcing frequency (or an integer multiple of the forcing frequency), the amplitude of vibration increases dramatically. That's resonance. The unfortunate detail with propellers is that a blade has multiple natural frequencies, each having its own mode of vibration. Here are 1st, 2nd, and 3rd mode examples.

Propeller Vibratory Modes.JPG


Instrumenting a blade with strain gauges and flying it allows a skilled engineer to find resonant modes, and more important, determine amplitude. An amplitude which exceeds a fatigue limit results in a prohibited RPM and/or manifold pressure.

Hartzell Instrumented Prop.jpg



Like my Harmon Rocket and early RV4s, the Lancair has a crankshaft extension or in some cases a B hub which also adds resonance.

Actually, its primary effect is to lower the fundamental natural frequency of the crankshaft. In effect, it might move a resonant RPM down the scale, but it does not in itself cause resonant behavior.

In the VW world fixed pitch wood props are standard as they absorb rather than transmit or amplify the resonance which with their less robust crankshafts can cause failure. Several aftermarket VW rebuilders install a 5th bearing mod to reduce the stress but the wood prop solves a multitude of issues.

Although a better bet when behavior is unknown, a wood propeller can most definitely resonate. And even if not strictly a blade resonance, a resonant crank-propeller system can push prop loads beyond a safe level.

Here's one split on the engine stand right at the predicted RPM. Technically this is a glue line failure, but that's just a weak link..
GlueFailure1.jpg


Background to the above. The diagram below plots predicted resonant RPM for firing frequency and two multiples. Amateur work, but it turned out to be accurate. Nine cylinder radial, so the drivers of interest are 4.5, 9th, and 13.5 orders. The above prop split right around 2000 RPM. The engine/propeller system's natural frequency was calculated to be 296 hz, which would be matched by the first integer multiple of the 4.5 order firing frequency at 1973 RPM. Theory meets practice.

For a 4-stroke, firing frequency is (RPM x #cyls) / 120 = hz. The angled lines are plots of frequency across the RPM range. It means that there is always a full spectrum of possible forcing frequencies.

A much more robust propeller increased natural frequency to 314 hz. Not optimum, as it might result in a prohibited RPM range centered on 2100. Sound familiar?

Order and Frequency Plot.JPG


I've long taken the position that slapping any prop on any engine is playing with fire, but hey, I'm just an old homebuilder.
 
It is interesting that I had a very similar experience just a couple of months ago. Angle vavle Io-360, 10:1 compression, not an RV. One pmag configured to fire at 21 BTDC with max advance limited at 26. The other mag is Slick times at 21*, too. I was using a two-blade MT prop. The bearings fell aparts after 250 hours in that configuration, broken races found in the hub, the propeller was scrapped by MT-Prop USA in Florida. I'm thinking of making a precautionary sale of mmy pmag, too, though a crappy batch of MT prop bearings cannot be completely ruled out.
You think it could be a bad batch of bearings? So are you going back to all Magnetos.

Not a BASH of MT.... but ALL companies tend to deny any responsibility, at first unless they have proof (are caught). I had a VW diesel have a weird problem I won't get into. They tried to deny warranty. I had to (1st time in my life and hope the last) get a lawyer. We settled. All is well still have care and LOVE IT...

I have a BMW motorcycle that has been flawless for me, 50,000 miles, but a batch of this model in the early 2000's had some engine/transmission cases machined wrong, so clutch alignment was affected. The clutch splines wore out, failed, outside of warranty like clockwork at 30,000 miles. They denied it. Fortunately I did not get one of the bad ones. There is no fixing this problem if you are unlucky. I don't think BMW ever admitted fault. To fix it would be new engine and/or transmission cases and lots of labor.

I have NO CLUE what would case prop bearings to disintegrate. I find "torsional resonance" to be suspect. I find blaming it on the EI, especially a specific brand suspect as well. Hartzell's have been flying with EI for about 30 years of all brands, including P-Mags. Never heard of a hub or bearings failing, and that is swinging BIG METAL BLADES... However may be the lighter WOOD CORE composite blades are subject to this problem? Wood based props tend to be great in damping vibration. Being lighter would also seem easy on bearings. It really is an unfounded fact EI is causing this. Could be? But it would be true of any EI... ALSO in ALL CASES from reading post High Compression Pistons were used. I think you all should compare serial numbers and alert the community. They may fail regardless of magnetos or stock compression...

Again P-Mag and ALL EI's basically do the same thing the same way and produce similar results...
That is why there is no legit claim of super superior performance (fuel econ, power) between brands of EI's. There are claims of super hot spark energy... but it is Ad copy not, really important after a threshold of "hot spark" is reached. How much spark energy do you need? Diminishing returns after you reach a threshold. You end up with high coil temperatures and power requirements. with no gain.

Some people run dual EI's of different brands. They find little difference between them when flying single ignition, switching back and forth. Form, fit, function is different. P-Mag is the only self powered EI on the market. That distinguishes the P-Mag. IE's get most of their benefit from spark advance at low power and some from a slightly higher spark energy, which allows slight larger gaps, which is a bigger spark, which burns fuel better. Magnetos at high RPM are no slouch, but the timing is fixed. They don't start as easy. They have wear parts, points, nylon gears, rotor, cap.... Timing is fixed and not as efficient at high altitude low power. If you go to real high altitudes magnetos can internally arc.

There are difference when comparing Magnetos vs EI. Typically people claim 4% to 10% increase in economy with EI from magnetos. There is no significant power gain despite any claim. The better fuel econ (at low power), easier starting, smoother running are the Pros of EI.

Hartzell found out by test the Pwr pulse with EI's (I think they used a Jeff Rose ignition?) is stronger, and with VERY precise timing, this triggers resonance at certain RPMS, that a magneto might not, with weaker spark and with timing having some hysteresis, due to the mechanical nature, points, rotor, etc. If the timing is jumping around slightly the "exciting" impulse or vibration frequency resonance is not as pronounced. It is complex and why testing is always used to verify the math.
 
Wow, educated opinions on a valid subject matter!
Awesome…

“I’d love to shoot at an educated man at least once in my life”

Ranger Capt Augustus McCrae speaking to Ranger Woodrow F. Call.
Lonesome Dove

:)
Smokey
 
You’re absolutely correct sir, sound engineering presented in a constructive manner is timely, valid and appreciated!
V/R
Smokey
 
Ok, so why this opinion...
Why are you even commenting on my comment. You said nothing. WHY did I say that? Read what I wrote. Context. I said it is possible. My opinion is really shock... So literally 10 seconds of google I found MT has a Service Bulletin on EI and High Compression pistons.

There are other forums all over that discuss this... It does not change my point... P-Mag is not the problem. DanH what ever EI you love, whatever brand that is, would do the same thing to this MT prop (apparently). That was my point. I know you like to petulantly rag on my comments and dislike P-mags. Don't care. I am fine with your options. We just often disagree.

So to clarify. IT IS torsional (apparently) and the design of MT props and it's limitations. Again to be clear I AM SHOCKED... My Hartzell with P-Mag over 1000 hours. Pretty sure can x 10 those hours without issue with normal maintenance, and it is tested by Hartzell with EI. I do have stay out yellow band RPM's.

MT are light props. and they have real RPM (service bulletin) restrictions. When ever mix and match some new combo of engine, compression, ignition, airframe you are a test pilot....

My Vibrations Prof in undergrad worked for NASA... Vibration of a prop is a whole system, everything can change the system response even the accessory case, engine mount, airframe it self, exhaust, intake... all changes the system. . The best way to test a prop is stain gauge and flight test. Not cheap, but can be done.
 
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Why are you even commenting on my comment.

Your comment was...

I have NO CLUE what would case prop bearings to disintegrate. I find "torsional resonance" to be suspect. I find blaming it on the EI, especially a specific brand suspect as well.

Today we have...

So to clarify. IT IS torsional (apparently) and the design of MT props and it's limitations...

So after examining the "other forums all over that discuss this", you now accept torsional issues, but you're willing to blame a specific brand.

Here's reality. The OP's IO-360-B1B was running no pendulum absorbers, a compression ratio increase, and ignition advance. All these factors (and a few more) contribute to increased propeller stress, for any propeller. Arguably Brand A may withstand the stress better than Brand B, but we should not blame a manufacturer when we use the product in some way they did not intend.

My Hartzell with P-Mag over 1000 hours. Pretty sure can x 10 those hours without issue with normal maintenance, and it is tested by Hartzell with EI. I do have stay out yellow band RPM's.

You mention flying a Hartzell with P-Mag over 1000 hours. Lots of folks can say that, and I believe them, although with a caveat..."Hartzell" is not a specific propeller, and engine configurations vary widely. Could you share your specific engine configuration and propeller model? Had the prop apart recently?

Approved Hartzell combinations as of April 2023: https://hartzellprop.com/EXP-AIRCRAFT/Man-193-Vol-01.pdf

Two notes...

Ignition brand is not really relevant here. The method of spark generation and the crankshaft timing at which it is delivered are relevant, but separate issues. Good comments, posts 14 and 15 above.

MT representatives insist their product is a wood prop with a non-structural fiberglass sheath. As before, a wood prop can be subject to vibratory issues. Another wood/glass prop with different mass distribution and stiffness may be fine on the same engine.
 
Gentlemen - this was a Classified Ad, not a place to beat out the detailed engineering of EI.
 
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