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Replace Plain Mag with E-Mag Option

rockitdoc

Well Known Member
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On the Thunderbolt order form there are lots of option choices for mags, impulse mags, e-mags, etc.

Std layout is one plain mag and one impulse mag.

One option is replacing the plain mag with an e-mag. This would leave an impulse mag and an e-mag.

I have searched a bit and am still somewhat confused. I understand the E-mag is electronic, so the engine has one conventional magneto and one electronic. What I don't understand is the difference between the 'plain' magneto and the 'impulse' mag. and why there is no option for a plain mag and an e-mag.
 
On the Thunderbolt order form there are lots of option choices for mags, impulse mags, e-mags, etc.

Std layout is one plain mag and one impulse mag.

One option is replacing the plain mag with an e-mag. This would leave an impulse mag and an e-mag.

I have searched a bit and am still somewhat confused. I understand the E-mag is electronic, so the engine has one conventional magneto and one electronic. What I don't understand is the difference between the 'plain' magneto and the 'impulse' mag. and why there is no option for a plain mag and an e-mag.

Figured it out. Impulse mag has a different drive gear. Replacing it is more complex.
 
I have a friend running one Slick and one pmag on his Glasair. He has around 1200 hrs on his setup and has only sent the pmag in for overhaul once, and the slick twice. I called emag and they said basically the slick is along for the ride and there as a backup.

I installed dual pmags on a friends skybolt. You’ll need the non impulse gear if you ever decide to change to dual pmags. I would call to get that mag changed to a non impulse on your order.
 
This is certainly rare but see this thread I started awhile back. Those impulse couplers have had multiple AD's over the years and I am certainly not the only person that has had one fail and cause damage to other parts of the engine. I won't ever put an impulse coupler back into any of my engines.
 
Impulse to Pmag

Figured it out. Impulse mag has a different drive gear. Replacing it is more complex.

I just swapped mine. The Impulse mag comes out just like the non impulse.
Difference is there is a spacer that comes off and the two studs have to be removed and replaced with shorter studs.
 
An impulse coupling is for starting your plane. Without it, the mag does not produce as much current at the low speed of cranking your engine with the starter. The impulse is a spring-loaded mechanism that speeds up the rotor just before it is time to fire. Once the engine is running there is a centrifugal force that disengages it. They are usually only installed on one magneto. Your ignition switch is wired to ground out the non impulse magneto during cranking. P-mags use battery power co create the spark. If you have one p-mag you do not need an impulse coupling on the magneto. The p-mag will start the engine and then the magneto will come up to speed.
When you run a P-mag, it advances the spark timing based on RMP and manifold pressure. Once it starts to advance it, it is then firing before the magneto (which is always firing at 25 degrees before top dead center). In that case, the fuel is already burning by the time the magneto fires. The magneto is not really helping your combustion, so it only there as a back-up incase the P-mag fails. It is better to have the fuel/air mixture begin to burn from both plugs for more complete and efficient combustion.
I run two P-mags. I feel that there is sufficient redundancy since each has a separate internal back-up power supply.
 
Ive decided to go full monty. Ordered engine with one emag and none on other side. I told lycoming the plan is to put on a second emag. Lycoming cant put second emag on at factory cuz of lawyers. So, they will prep engine for second emag. Btw, i emailed both emag and lycoming re this plan and they both got back to me immediately. Impressive.
 
Reference

I’m wondering if anybody can recommend a good book or other reference source that describes these things. I don’t know much about engines, and I’d like to learn, but find it difficult to piece the information together from multiple posts on forums. Is there a book about aircraft systems that anybody recommends which would include things like differences between ignition systems?
Thanks for the help.
 
I replaced my impulse mag (left side) with a SureFly SIM, as recommended by SureFly because of impulse coupling issues and AD’s. I start the engine on the SureFly. This setup is the same price as the non-impulse replacement, keeping the impulse mag spacer on the accessory case. If my right side Slick goes TU, I’ll install a second SureFly on the right, and then I could use either/both SIM’s for engine start.
 
why there is no option for a plain mag and an e-mag.

You can certainly use a plain mag and an e mag but you will have to start on the e mag only and have no option to hand crank if your battery is dead. You have to have an impulse mag to start.
 
What William says is true. But if you were forced to do that because of a problem with your impulse mag, would you really want to do that? The only way I would consider doing that would be to start the engine so I could taxi the airplane to some maintenance hangar when away from home - and I might not even do it then. What if the problem was with the impulse coupling on the mag? Well documented, hence the AD’s on Slick impulse couplings. I wouldn’t want to destroy my engine via chewed up metal in my accessory case because of the impulse failure for expediency reasons.
I guess you should ask yourself the question..... what is more reliable, an electronics ignition system, or an impulse-coupled tractor magneto. We know the answer on the tractor mag. We don’t have enough experience with most electronic ignition systems on airplane engines to make a valid comparison. We can’t really compare automotive ignition systems with their aircraft modified counterparts for the same reason, but usually advancement in these areas can be assumed to a certain degree. That’s why I have had electronic ignition on all five of the RV’s I’ve owned, and two eMags on my last RV8. However - getting rid of that impulse coupling, in my opinion, is a good move in terms of reliability, with no downside.
 
Starting on an e-mag alone

To those that start only via an electronic mag, is that working well for you? Any conditions where you wish you had a traditional impulse coupling?

George
 
To those that start only via an electronic mag, is that working well for you? Any conditions where you wish you had a traditional impulse coupling?

George

The short answer in #!*$ no.

Dual pMags - both on for engine start. Simple, easy, reliable.

Carl
 
I had one emag on my last RV, on the left and used for engine start. Then I replaced the right mag with a second emag and used both for engine start. Both ways worked very well.
I now have a SureFly on the left, mag right (RV4), and it also starts very well on the SureFly alone.
 
That’s very interesting I was going to call them on this Monday getting ready to pull the trigger on a RV14A Qbuild, Flying RV9A over 500 hrs with 2 p-mags, Love them! Doing the Thunderbolt was trying to decide on Lycoming E-Mags or what I know and love P-Mags. Mark
Ive decided to go full monty. Ordered engine with one emag and none on other side. I told lycoming the plan is to put on a second emag. Lycoming cant put second emag on at factory cuz of lawyers. So, they will prep engine for second emag. Btw, i emailed both emag and lycoming re this plan and they both got back to me immediately. Impressive.
 
No issues.

To those that start only via an electronic mag, is that working well for you? Any conditions where you wish you had a traditional impulse coupling?

I ran a single PMag for many years and eventually went to dual PMags. I never had an issue starting on a single PMag and now start with both. YMMV.

Cheers, Sean
 
You can certainly use a plain mag and an e mag but you will have to start on the e mag only and have no option to hand crank if your battery is dead. You have to have an impulse mag to start.

I wonder anyone has used the backup automotive battery to start airplane engine such as the one in the picture below.
 

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Mag

Scott,

I also decided to get rid of the impulse mag after reading a post here on the forum about a freshly rebuilt engine with an impulse mag. The impulse mag failed shortly after he got it back from rebuild and had to take the engine off to fix the issue (see below).

I have an Electroair ignition on one side and will have a non impulse Slick 4130 on the other side, exactly the configuration my buddy has with his RV-10. He starts on the Electroair then brings the non impulse Slick mag on line after engine start.

 
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That’s very interesting I was going to call them on this Monday getting ready to pull the trigger on a RV14A Qbuild, Flying RV9A over 500 hrs with 2 p-mags, Love them! Doing the Thunderbolt was trying to decide on Lycoming E-Mags or what I know and love P-Mags. Mark

Hold up- I believe when the order form says "E-mag" what it means is the P-mag 114 series manufactured By E-Mag Electronic Ignition. NOT the SureFly mag that is starting to show up on the certified engines, which still require a second old school magneto.

That may be a bad assumption on my part? I ordered a Thunderbolt with the 1 e-mag, delete second magneto option, expecting to add a second P-mag 114 when it shows up, but I went back and looked at my thunderbolt order form and it really doesn't specify whether the mag option is surefly or p-mag.

Can somebody verify one way or the other?
 
I wonder anyone has used the backup automotive battery to start airplane engine such as the one in the picture below.

The E-Mag manual recommends against powering the P-Mag up with a battery charger charging the battery because some chargers pulse the battery and can damage the P-Mag.
 
Hold up- I believe when the order form says "E-mag" what it means is the P-mag 114 series manufactured By E-Mag Electronic Ignition. NOT the SureFly mag that is starting to show up on the certified engines, which still require a second old school magneto.

That may be a bad assumption on my part? I ordered a Thunderbolt with the 1 e-mag, delete second magneto option, expecting to add a second P-mag 114 when it shows up, but I went back and looked at my thunderbolt order form and it really doesn't specify whether the mag option is surefly or p-mag.

Can somebody verify one way or the other?

I also ordered a Thunderbolt for my -14A. Lycoming told me the E-mag is the 114 P model from the Emag folks.
 
Hold up- I believe when the order form says "E-mag" what it means is the P-mag 114 series manufactured By E-Mag Electronic Ignition. NOT the SureFly mag that is starting to show up on the certified engines, which still require a second old school magneto.

That may be a bad assumption on my part? I ordered a Thunderbolt with the 1 e-mag, delete second magneto option, expecting to add a second P-mag 114 when it shows up, but I went back and looked at my thunderbolt order form and it really doesn't specify whether the mag option is surefly or p-mag.

Can somebody verify one way or the other?

A SureFly ignition only requires a second old school mag on certified installations. That’s because it requires an onboard operable electrical system to supply power to it. Electroair is the same. No other EI systems have been approved for certified installations. Most, if not all, experimental dual EI installations have a backup power supply to protect against a total main electrical system failure causing a failure of the engine ignition system and engine operation (except dual Emags).

Emagair used to produce an emag and a pmag. The Pmag was a POWERED mag, meaning it had its own internal alternator supplying independent power to sustain ignition operation. The original emag didn’t have this internal power supply, so it needed ships power to sustain operation. They no longer make the unpowered version of their ignition system. Now all EMags are self powered (as long as the engine RPM is enough to produce enough voltage - ~ 700-800 RPM).
 
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Right, I was just trying to verify which one came hanging off the back of the case when you tick the e-mag box on the order form. Somebody early up in the thread said something about the "Lycoming E-mag" vs. the "Pmag" To me, this sounded like they were talking about the Surefly.

Verified that you get the Pmag when you check that box, so all good.
 
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Scott,

I also decided to get rid of the impulse mag after reading a post here on the forum about a freshly rebuilt engine with an impulse mag. The impulse mag failed shortly after he got it back from rebuild and had to take the engine off to fix the issue (see below).

I have an Electroair ignition on one side and will have a non impulse Slick 4130 on the other side, exactly the configuration my buddy has with his RV-10. He starts on the Electroair then brings the non impulse Slick mag on line after engine start.


I am glad that my post has saved someone else from the possibility of a bad impulse coupler! :D

P.S. Pmags are now coming with black anodizing. I was surprised so I emailed Brad and he said it is their new color because the gold anodizing was becoming too inconsistent.
 
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