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EI vs Magnetos

elippse

Well Known Member
I see a lot of discussion about how someone switched back to magnetos after installing some EI system and having problems with it. Can't say if I blamed someone for taking this action if they've had a lot of problems that haven't been adequately resolved. Magnetos have been around a long time and have done a grand job in providing ignition for an engine. But it should never be assumed that magnetos are without their own problems. A friend of mine at Santa Maria has just had his second magneto failure when the capacitor failed. Those who favor magnetos should be religious in overhauling them on a 500 hour basis. a friend of mine gave me the excellent book on magnetos put out by Sky Ranch and you should obtain a copy if you are going to maintain your magnetos yourself. When you read through this manual it will give you a new appreciation of how necessary frequent examination of a magneto and its mechanical parts is. There is a failure mode of the stop-pin for the impulse mechanism that will cause total annihilation of the gears in the accessory section! An EI will give automotive-like starting, but so will a shower-of-sparks-equipped magneto. Where the EI shines is in advancing the timing at the reduced manifold pressures at higher altitudes to give back some measure of performance;there are ample reports of 5% to 10% reduction in fuel flow. Another area that is seldom considered is that the timing of the magneto can vary +/- 5 degrees cycle-to-cycle due to cam wobble, points pitting, gear slop, and cam wear. This is why some prop makers restrict certain of their propellers from being used on an engine with EI; the excellent cycle-to-cycle timing precision of an EI can excite vibratory modes in the prop that are less present with the sloppier timing of the magneto. So to sum up, magnetos are good, and so are some EI systems!
 
Absolutely, Paul...

...I have a Lightspeed on one side on my -10 and starting is never a problem...hot, cold or indifferent:)

Best,
 
I recently removed a pair of P-Mags that had been installed about 40 hours. A lot of trouble and I didn't trust them, so the magnetos are back on. While perhaps not as efficient, they are time tested and reliable. YMMV.
 
EI and Magnetos

That true, some EI’s shine by advancing timing. The fact is, is that they are a “single spark system” they need to. Flame propagation is so slow at lower power settings, that advancing the timing is needed to obtain the most cylinder pressure @ the right time during the compression stroke.
On the other hand, plug.. Multi-spark EI’s (like our G3i system) burn the fuel more efficiently in the shorter window time (Crankshaft rotation degrees) so advancing the timing is not as crucial as the single spark EI systems to obtain the most cylinder pressure @ the right time. The multi-spark provides a complete fuel burn at all altitudes and MP settings, which results in fuel economy and more power. Also top & bottom spark plugs firing in perfect synchronization @ the same timing event play a big part in even flame propagation which also contributes to a more efficiency. Systems that are ½ EI & ½ Mag opperate out of sync. which can have its own issuses. If you think about it, who would set there mags at different timing degree marks (ex. 25 and 39 degrees). Last year at our booth a RV builder summed it up pretty good. Quote. "½ EI, ½ Mag, it’s like cooking pancakes and not flipping them, burned on one side and raw on the other”.
Left & Right magnetos originally timed properly, a timing variance of +/- 5 degrees is not common, but can happen. Mostly from poor quality control or knowledge from re-builder / inspector, and or excessive run time between simple inspections.

New trick ignition components coming.
See ya in KOSH
Thomas S.
www.g3ignition.com
 
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I recently removed a pair of P-Mags that had been installed about 40 hours. A lot of trouble and I didn't trust them, so the magnetos are back on. While perhaps not as efficient, they are time tested and reliable. YMMV.

I don't wish to hijack this thread, but Jim, I would be interested in the reasons why you have decided to revert back to magnetos. This decision seems to buck the trend of replacing magnetos with Pmags. You must have very good reasons and I would be grateful if you could share them with us.
 
Multi-spark ignition

The multi-spark provides a complete fuel burn at all altitudes and MP settings, which results in fuel economy and more power. Also top & bottom spark plugs firing in perfect synchronization @ the same timing event play a big part in even flame propagation which also contributes to a more efficiency. www.g3ignition.com

I ran some tests of a multi-spark ignition, and here's what I saw on the 'scope: At up to 600 rpm it put out 5 sparks spaced 2 ms apart. The first coil input pulse was -510 V peak, the second -350V peak, and the succeeding ones were -330V peak. 2ms spacing at 600 rpm is 7.2 degrees spark-to-spark. From 600 to 1200 rpm, the unit put out 3 sparks at the same spacing and relative amplitudes. At 1200 rpm the sparks were 14.4 degrees apart. From 1200 rpm to 2400 rpm the unit put out 2 sparks, again at the same spacing and relative peak voltages, and at 2400 rpm 2 ms represents 28.8 degrees. From 2400 rpm to 3000 rpm the unit put out a single spark. With this unit, by the time you get above 1200 rpm, the additional delay from spark-to-spark is not going to do much good, if any. To be really effective, a multi-spark system would need to put out its second pulse within about 5 crank-angle degrees to aid combustion to any extent if not initiated on the first spark. That means at 2400 rpm the second spark would need to be no more than 350 micro-seconds after the first, or at 2700 rpm it would have to be delayed no more than 310 micro-seconds. It is well established that peak power is obtained when the peak pressure occurs at about 15 degrees after top-dead-center, with the power rolling off with the peak occuring later than this, so it is very important that the spark timing be very precise, and if additional sparks are necessary to initiate combustion, that there should be very little crank-angle delay from the first.
As far as a combined magneto-EI is concerned, if the EI spark is at, say 30 degrees BTDC and that from the magneto is at 25 degrees BTDC, at rich mixture the flame propagation speed will average about 100 ft/sec. At leaner mixtures and lower manifold pressure the propagation speed is even less. The bore of a Lycoming O-320 is 5 1/8". At 2700 rpm, 5 degrees, as noted before, represents 310 micro seconds, so that a second spark on the opposite side of the cylinder will start when the flame from the first has traveled about 0.37". It is hard to say exactly how far off-center the two flame-fronts will meet; that will depend on the exact flame-front speed relative to the time since its initiation, but at least they will meet somewhere off-center in the cylinder; it's not as if the magneto spark does no good as might be inferred from the 1/2-1/2 remarks!
 
EI and Mags

it's not as if the magneto spark does no good as might be inferred from the 1/2-1/2 remarks!

Impressed, excellent research data. We see similar findings in the lab also. On the flame front speed @ 100ft/sec. was that 100LL av-gas? Octane plays a big part. I will agree the mag does help some, how much though is questionable. It is just more efficient when the ignition timing is in sync. Another point is that cylinder pressures on the lagging ignition system are higher resulting in more KV to ionize. This makes the secondary ignition components to work harder. This is all great stuff.
Thomas S.
www.g3ignition.com
 
I don't wish to hijack this thread, but Jim, I would be interested in the reasons why you have decided to revert back to magnetos. This decision seems to buck the trend of replacing magnetos with Pmags. You must have very good reasons and I would be grateful if you could share them with us.

The ultimate decision to remove them came after a flying experience about a month ago. I had previous issues with occasional backfiring on engine start with the P-Mags (sometimes LOUD!!), but had learned how to manage that. The final straw was shortly after takeoff one day, I felt a split second surge, power loss, hiccup, whatever. It happened so fast and ended so quickly I'm not really sure what it was. The engine seemed OK, although I was following 2 buddies in RV-6's which I can normally out run, but this time I was having a hard time keeping up. Didn't think too much of that by itself, but what caught my attention was what appeared to be runaway CHT's on 1 and 3. They were taking off, and quickly climbed through 440. I reduced power from around 27" to around 14", and the CHT's came down. I advanced the throttle, and up they went. You could move the CHT's really easily by jacking around with the throttle. A little troubleshooting later and I found that the engine would perform just fine on the right mag, but if the left mag was in the picture the CHT's would climb on throttle advance. I was low to the ground when this happened, and it was exciting to say the least until I figured out the L/R mag solution. I returned to the airport uneventfully that day on the right mag and made a normal landing, although before I figured out the L/R mag solution I was considering an off airport landing since it seemed the engine was frying itself.

I had a 1,000 nm trip to Texas scheduled for the following weekend, so I made the decision to remove the P-Mags and reinstall the Slicks that had been removed for the P-Mag installation. The engine performed flawlessly on the 2,000 nm round trip. To be fair, Brad at P-Mag has offered to check them out for me, but I have just been too busy to send them back. The odd thing is when I got back to the airport that day I checked the timing and it was spot-on. I did do a power cycle before the timing check, so if it had jumped timing perhaps the power cycle fixed it. Or maybe something caused an instrumentation glitch (doubtful as I am using a bullet proof Dynon EMS) and the CHT's were really fine. Who knows. But in any event, I am 57 with 2,000 hours of trouble free flying. I don't need any more of that kind of excitement so I'm going to stick with the Slicks.
 
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The final straw was shortly after takeoff one day, I felt a split second surge, power loss, hiccup, whatever. It happened so fast and ended so quickly I'm not really sure what it was. The engine seemed OK, although I was following 2 buddies in RV-6's which I can normally out run, but this time I was having a hard time keeping up. Didn't think too much of that by itself, but what caught my attention was what appeared to be runaway CHT's on 1 and 3.

Jim can you confirm whether your pmags had all the latest firmware and hardware upgrades, or not?

--Paul
 
RAW

I'm running one mag and a Lightspeed Plasma II Plus... well I was running this combo. I got 108 hrs out of the Lightspeed Box and it crapped out. This was in about the first year of operation. Anyway the mag is still working good, and the Plasma II Plus was returned to Lightspeed for diag and repair. Good news, it's repaired and on the way back. The BAD news, Klaus did not warranty any part of the repair and refused to even identify the part he had to replace, then hit me with labor and shipping BOTH ways to boot. Yes, we feel a little RAW. It won't happen again! :mad:
 
I'm running one mag and a Lightspeed Plasma II Plus... well I was running this combo. I got 108 hrs out of the Lightspeed Box and it crapped out. This was in about the first year of operation. Anyway the mag is still working good, and the Plasma II Plus was returned to Lightspeed for diag and repair. Good news, it's repaired and on the way back. The BAD news, Klaus did not warranty any part of the repair and refused to even identify the part he had to replace, then hit me with labor and shipping BOTH ways to boot. Yes, we feel a little RAW. It won't happen again! :mad:

I just called ACSpruce and they said the warranty on a new Slick or Bendix magneto is six months from the time of purchase. If you're beyond warranty with a failure, will they fix it and ship it for free? 'Just wondering! There are several shops that specialize in the 500 hour magneto overhaul for $225. 'Don't know if that includes two-way shipping. The point is, both magnetos and EIs fail, sometimes sooner, sometimes later. It's too bad that you only got 108 hours. How mad and how bad would you feel if your impulse coupling arm had gone past a worn stop pin, bound up, then took out all the gears in your accessory section? Plenty, huh!
 
I just called ACSpruce and they said the warranty on a new Slick or Bendix magneto is six months from the time of purchase. If you're beyond warranty with a failure, will they fix it and ship it for free? 'Just wondering! There are several shops that specialize in the 500 hour magneto overhaul for $225. 'Don't know if that includes two-way shipping. The point is, both magnetos and EIs fail, sometimes sooner, sometimes later. It's too bad that you only got 108 hours. How mad and how bad would you feel if your impulse coupling arm had gone past a worn stop pin, bound up, then took out all the gears in your accessory section? Plenty, huh!

You apparently you missed the point. I was sold on reliability over Mags, not having to deal with the 500 hrs overhaul, cost savings, fuel savings etc... Everyone knows when building a plane, component are purchased a little ahead of flying the plane. To me... and now many others 108 hrs of flight time in a year for the LS EI product is not satisfactory service for the component. And... for Klaus to HIDE the fault part is a very poor business practice WHEN he is CHARGING you for the malfunction of his product in low time hours.
 
Rose

Paul

I read wih some interest your test data regarding multi spark duration. it may be antiquated and need a battery but i seem to recal that my old Jeff Rose system had something like 20 degrees of spark duration, depending on gap. Not sure at what RPM but I think it was actually more duration with higher RPM.

The longer I own them, the better I like them. Dead consistent, cheap plugs, vacuum and RPM advance, tuneable. All you need and nothing more for an aircraft. I dont mind carrying a small extra battery.

i can kill the advance on mine in the air. After i did that once, i will never go back to mags.
 
More on EI-Mag

You apparently you missed the point. I was sold on reliability over Mags, not having to deal with the 500 hrs overhaul, cost savings, fuel savings etc... Everyone knows when building a plane, component are purchased a little ahead of flying the plane. To me... and now many others 108 hrs of flight time in a year for the LS EI product is not satisfactory service for the component. And... for Klaus to HIDE the fault part is a very poor business practice WHEN he is CHARGING you for the malfunction of his product in low time hours.
I think that maybe you, too, missed the point. The LSE EI is warranted for 1 year whereas magnetos are warranted for only 6 months, both from day of sale. The 108 hours of flying in one year seemed like a lot. With the speed of your plane you would probably have averaged at least 170 mph on a trip, which means for 108 hours you would have gone about 18,000 miles. Quite a bit of flying! So in 108 hours at an average of 7 gph and $4/gal and 5% fuel-burn savings you already saved $151.20! But you had the EI for 2 1/2 years, not the 1 year you said in your post, which was well past the 1 year warranty. Plus Klaus only charged you $95 for the repair, which in this day and age is next to nothing, and got it out to you the next day; seems to me like pretty good turn-around time. If you take your car into the shop with the "check engine" light on, they will charge you over $100 just to hook up to your car's computer. I know, 'cause a friend of mine paid $120 just to find out she hadn't tightened her gas cap. If the ignition fails on your car, you'll wish you only had to pay a $95 bill! You said you have some familiarity with electronics, so that you are probably aware that relative to reliability, the first 100 hours is the time when you have the most likelihood of failure, what is referred to as infant mortality. Generally once you get past that point, if the equipment isn't subjected to conditions of voltage, heat, short circuits or other mal-appropriate operation for which it wasn't intended, there should be many hundreds or thousands of hours of trouble-free operation. I guess I'm not sure why you think Klaus owed you an explanation of what the trouble was or how he fixed it, or why you think he is hiding the fault. Again, the unit was well past its warranty period, he fixed it, charged you just a nominal fee for his time, and got it out the next day after he received it. 'Seems to me you got plenty of value for your money! I sincerely hope the unit works trouble-free for the rest of the time you have it, and if any other piece of equipment on your airplane fails after its warranty period is up that you will be treated as quickly and fairly!
 
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Paul

I read wih some interest your test data regarding multi spark duration. it may be antiquated and need a battery but i seem to recal that my old Jeff Rose system had something like 20 degrees of spark duration, depending on gap. Not sure at what RPM but I think it was actually more duration with higher RPM.

QUOTE]

I've never run tests on a Jeff Rose system, so I really can't comment on it. With the very popular multi-spark system I tested, the primary voltage went to zero in 50 micro-seconds and the secondary, to the plugs, went to zero in about 200 microseconds. Since time-per-revolution is a function of rpm, this means the time-per-degree is rpm related also. At 2700 rpm the engine is rotating 45 times-per-second. That would yield 16,200 degrees/sec. or 60 microseconds-per-degree; that means that for the spark to last for 20 degrees at 2700 rpm it would have to last for 1.23 milliseconds. Perhaps with an inductive system that is possible, but definitely not at a much lower rpm, where the spark would have to last for inordinately long periods of time. The LSE Plasma I and III have a very unusual spark pattern. It puts out a series of up to eight sparks of alternating polarity that are 80 microseconds apart; that's 25 times closer together than the other unit. Because of the opposite polarity on each spark in the plug gap, the gas in the gap gets extremely hot and ionized, truly becoming a plasma, thus the name! The spark also does not look the same as a typical spark. Whereas a typical spark is bright blue, the Plasma spark is very pale violet, almost transparent. And where a typical spark system will burn holes in a piece of paper placed in the gap, the Plasma will immediately set it on fire! It's HOT!
 
I think that maybe you, too, missed the point. The LSE EI is warranted for 1 year whereas magnetos are warranted for only 6 months, both from day of sale. The 108 hours of flying in one year seemed like a lot. With the speed of your plane you would probably have averaged at least 170 mph on a trip, which means for 108 hours you would have gone about 18,000 miles. Quite a bit of flying! So in 108 hours at an average of 7 gph and $4/gal and 5% fuel-burn savings you already saved $151.20! But you had the EI for 2 1/2 years, not the 1 year you said in your post, which was well past the 1 year warranty. Plus Klaus only charged you $95 for the repair, which in this day and age is next to nothing, and got it out to you the next day; seems to me like pretty good turn-around time. If you take your car into the shop with the "check engine" light on, they will charge you over $100 just to hook up to your car's computer. I know, 'cause a friend of mine paid $120 just to find out she hadn't tightened her gas cap. If the ignition fails on your car, you'll wish you only had to pay a $95 bill! You said you have some familiarity with electronics, so that you are probably aware that relative to reliability, the first 100 hours is the time when you have the most likelihood of failure, what is referred to as infant mortality. Generally once you get past that point, if the equipment isn't subjected to conditions of voltage, heat, short circuits or other mal-appropriate operation for which it wasn't intended, there should be many hundreds or thousands of hours of trouble-free operation. I guess I'm not sure why you think Klaus owed you an explanation of what the trouble was or how he fixed it, or why you think he is hiding the fault. Again, the unit was well past its warranty period, he fixed it, charged you just a nominal fee for his time, and got it out the next day after he received it. 'Seems to me you got plenty of value for your money! I sincerely hope the unit works trouble-free for the rest of the time you have it, and if any other piece of equipment on your airplane fails after its warranty period is up that you will be treated as quickly and fairly!

Thanks for your concern... With my aircraft on the ground (AOG), I overnighted the box and insured it. It came back GROUND due to the cost I incurred getting the box to Klaus and then the unexpected repair charge. Total I have now invested 20% of what I paid for the system with this component failure. The sad think is, I had just talked to Klaus a couple of weeks before the failure issue about purchasing a second Plasma II system to run dual. I guess one good thing came out of this failure, it saved me from jumping in for another dose. We will identify the failed part(s) this weekend.
 
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More on EI failure

We will identify the failed part(s) this weekend.

If you open up the unit then you immediately void any warranty on it. I guess I'm not up to speed on why identifying which component or connection that failed is so important to you. It could have been something as simple as a cold solder joint that occured in the solder bath during the production run. This kind of failure is insidious since a unit will often go through test with no problems only to show-up at a later time when engine vibration shakes it loose. How will you be able to determine if that was the cause? I had two problems at Vandenberg that only showed up in the morning for a brief period of time when the equipment was cold and then went away after it warmed up. One of them was due to the plating on a through-the-board pin that opened up a circular gap that must have been measured in the millionths of an inch! I have run two Plasma Is since 2001; one of them had been previously installed on a Lancair 235/320 that I was a partner in before mine was completed. That unit has about 650 hours and the other about 400. I had one failure of my own doing when I modified a trigger input circuit and didn't lock down a component properly. I was racing at Wendover, Utah, and near Salt Lake I hit a sharp bump. That shock knocked the part loose. It stopped working after I departed for home, and I had to complete the trip on the other unit. That's where the 5 degree advance that takes place when you shut off one unit really comes in handy.
 
Things break

Dear Reiley
I run a mag and a LSE ignition, I need both because sometimes things fail, when they do I need a backup, it's come in handy. When the mag needs parts when it does not work right I buy them....it's a big company we don't complain we pay. I think we sometimes feel a bit different when its a single person we are dealing with. Maybe a bit unfair. Sounds like you received some fast turnaround service....pretty good. My LSE makes my RV6 go faster, run smoother and hot start way better (FI). I guess it may break one day but that's why I have 2 Ignitions ( Mag and LSE) and I do love the performance with the EI . Just my thoughts
 
Dear Reiley
I run a mag and a LSE ignition, I need both because sometimes things fail, when they do I need a backup, it's come in handy. When the mag needs parts when it does not work right I buy them....it's a big company we don't complain we pay. I think we sometimes feel a bit different when its a single person we are dealing with. Maybe a bit unfair. Sounds like you received some fast turnaround service....pretty good. My LSE makes my RV6 go faster, run smoother and hot start way better (FI). I guess it may break one day but that's why I have 2 Ignitions ( Mag and LSE) and I do love the performance with the EI . Just my thoughts

Hi Peter,

We are together on the idea that things break, just how soon they should break is the separation. I have a Ford diesel with a quarter million miles and still to date have not replaced the computer... same with some 5-6 other vehicles I've owned in the last 15-20 years or so that were computer operated ignition systems. I'm really done with this issue and I hope the issue in the brain unit is solved. I don't know if the repair Klaus made is cover by a warranty or not, he doesn't reply to the email when I requested this info.
 
Attitude

I have a freind here in Victoria, Australia that is selecting ignition systems for their -10.

So after talking to him I started to look more deeply into EIs.

I have to say no matter how well the Lightspeeds work Klaus's attitude is enough to make me not want to do business with the man.

Something breaks, that I own, and the repair for it, costs money that I pay, the technician has no right what-so-ever to say "no I am not going to tell you what broke, I do the work and I hold that information a secret"

Imagine owning an oven in your kitchen, paying for a technican from the manufacturer to come out and fix it and he won't tell you what broke.

Would you stand for it?

And that is an oven, your life is not depending on it.

That had just made me deeply interesed in Pmags and the G3i system.
 
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