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Electronic ignition

bob888

Well Known Member
My -10 has an Electroair ignition on one side and a Slick mag on the other. Is there any benefit to adding a second electronic ignition, specifically a P mag so that a backup electrical bus won't be needed?
 
My -10 has an Electroair ignition on one side and a Slick mag on the other. Is there any benefit to adding a second electronic ignition, specifically a P mag so that a backup electrical bus won't be needed?

In all my many years on VansAirforce I've never read a single post by anyone claiming they could empirically calculate ANY performance gain or fuel improvement after adding a second EI. That means there might be some very very small improvement in adding a second EI but it is so small as to be immeasurable. The first EI is doing the trick. On the other hand a magneto is an extremely reliable ignition source (relatively speaking). So I think you already have the best combination. My vote is you keep the magneto.
 
My RV-6 IO-360 had a Lightspeed Plasma II on the right and Bendix mag on the left for about 15 years. Adding the Lightspeed definitely improved performance over dual Bendix. I could run LOP down to about 4.5 gph before #3 stopped firing with noticeable engine roughness. About 5 years ago I replaced both with P Mags. Now I can lean as low as 3.9 gph, and when #3 stops firing there is very little roughness. So a noticeable improvement at very low power settings. My only complaint with P Mags is the recurring inspection requirement. On my next plane I will install dual Lightspeeds with battery backup and a vacuum pump alternator or generator.
 
Allows starting on "Both", no impulse coupler.

And I don't have to rebuild them every 500 hours.

Those are your improvements for dual electronics.

If you are running standard fuel systems then yes keeping one mag offers reliable ignition should the electronic one fail. But if you are running an electron-dependent airplane anyway, such as many of us are doing now, there is no longer any advantage to keeping the mag - and there are arguably a few advantages for not keeping it.
 
Theoretically you may gain a little power back by eliminating a source of accessory loss. I wonder if anyone has ever measured that on a dyno…
 
Ignition

I have a p-mag and one impulse slick
I’m always worried that the impulse coupler spring will disintegrate so that’s why
I’m looking to add a second EI
Anyone have a Pmag or a Surefly for a 0-200 I’m looking.
Dave
 
Solid state

If you go with one of the solid state EI systems you can reduce lifetime maintenance cost. I have been flying 4 years (750 hours) and that would have me half way through my second magneto overhaul. So far my ignition maintenance has been zero.
 
I have dual Plasma III's and it's the easiest hot starting IO360 I have every had! no purge valve etc.

Are you saying that you had one magneto and one Lightspeed EI and that when you removed the mag and added the second Lightspeed EI your hot starting improved. Read the OP. That's the question here. We all know that one EI will improve starting, improve idling, and will provide other in-flight performance benefits. That's a given. But the real question is whether a second EI provides any measurable or worthwhile improvement over just one.
 
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Here's a thought exercise:

On a dual mag engine, both mags timed identically, when you turn off either mag, the rpm decreases.

Why?
And doesn't that mean - less power? Otherwise why the rpm drop?

One possible explanation - with a single plug igniting the mixture it takes longer to fully burn the mixture, and some of the mixture burns too late to be (as) useful.

If so, then ...
if you have a single electronic ignition
are flying at less than 75% power
and hence the electronic ignition is firing *earlier* than the magneto will (due to advance)

you could be in a situation where if the second ignition was electronic, and hence firing sooner... you might make more useful power.

Of course, there could be alternate explanations... like an electronic ignition makes a 'hotter' spark that makes the mag comparison incorrect.

An interesting test would be - for someone that has dual electronic ignition and has controllable advance on each electronic ignition:
1) climb to 10,000 DA (so at well less than 75% power)
2) presumably the ignitions will be running at around 30 degrees advance
3) record true speed
4) retard ONE of the ignitions to 25 degrees
5) record true speed

my wild hunch - you'll see a couple percent speed degradation.
Would LOVE for someone to try and post results. Lots of us would jump at gaining a few percent at the higher altitudes.

Of course, if you spend your time below 7500' DA, and at 75% power, I suspect there's no gain to be had.
 
My -10 has an Electroair ignition on one side and a Slick mag on the other. Is there any benefit to adding a second electronic ignition, specifically a P mag so that a backup electrical bus won't be needed?

We started out (in 2002) with a Jeff Rose (now ElectroAir) electronic ignition plus one mag on the RV6.

Later when the mag had issues, it was replaced with a P-MAG.
I am on the second engine with this combination now and have had no known problems.

What is important to ME is that IF I have TOTAL electrical failure, I still have a smooth-running engine. I probably would not notice the loss. If you assume 400-500 hours per mag before overhaul or replacement, then the EI has been paid for. And that is NOT counting better fuel consumption.
 
If you assume 400-500 hours per mag before overhaul or replacement, then the EI has been paid for. And that is NOT counting better fuel consumption.

P-Mag, about $1900 (plus mag gear, plugs, switches, breaker, wiring, etc).
Mag Ovhl, avg $400.

So you can Ovhl the mag about 5 times for the cost of the Pmag install (assuming no labor charge).

The Pmag needs R&R every 100hrs/CI for inspection, and generally returned every few years for SW updating and/or repairs. If you do this yourself great, if a maint shop does it add labor. Pmag service at factory usually runs around $200.
 
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On a dual mag engine, both mags timed identically, when you turn off either mag, the rpm decreases. Why?

Peak pressure is delayed.

One possible explanation - with a single plug igniting the mixture it takes longer to fully burn the mixture, and some of the mixture burns too late to be (as) useful.

Not sure "useful" is the best term. "...too late to be optimum" is closer.

you could be in a situation where if the second ignition was electronic, and hence firing sooner... you might make more useful power.

You're suggesting moving peak pressure closer to TDC would result in more power, which is not necessarily true. Both too early and too late make less power. The problem with too early is it's also very hard on the engine structure.

"Electronic, and hence firing sooner" is likewise not always true. Let's not conflate how the spark is generated (EI) with when it is delivered (timing advance). EI's come in both fixed and variable timing versions, often as options for the same product

Of course, there could be alternate explanations... like an electronic ignition makes a 'hotter' spark that makes the mag comparison incorrect.

"Hotter spark" claims appear to be bad advertising. Is the plasma temperature in the ionized gap actually higher? So far I've not found any such evidence, and I'd be delighted if someone could provide a reference.

An interesting test would be - for someone that has dual electronic ignition and has controllable advance on each electronic ignition:
1) climb to 10,000 DA (so at well less than 75% power)
2) presumably the ignitions will be running at around 30 degrees advance
3) record true speed
4) retard ONE of the ignitions to 25 degrees
5) record true speed

my wild hunch - you'll see a couple percent speed degradation.

The proposal assumes the dual 30 degree timing resulted in optimum point of peak pressure. While close for an angle valve running LOP, it would be too much advance if somewhere in the ROP to peak EGT range. A parallel valve has different timing needs. I've seen dyno charts showing 30 as near optimum for max power with a hot rodded parallel valve, meaning the combustion chamber and port design is not as good. Point is, the result would depend on much more than just a 5 degree timing retard on one ignition. The two largest variables appear to be combustion chamber design and mixture.
 
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P-Mag, about $1900 (plus mag gear, plugs, switches, breaker, wiring, etc).
Mag Ovhl, avg $400.

So you can Ovhl the mag about 5 times for the cost of the Pmag install (assuming no labor charge).

The Pmag needs R&R every 100hrs/CI for inspection, and generally returned every few years for SW updating and/or repairs. If you do this yourself great, if a maint shop does it add labor. Pmag service at factory usually runs around $200.

Walt, you are correct, BUT ...

I was assuming that all mag work was farmed out. P-Mag prices have gone up! (As everything else). I have over 2000 hours with the plane so my math, based on prices I paid, still works out. Also, Iridium "aircraft" plugs all around are a small mortgage payment :) (Put some of those expensive plugs on a Piper I owned years ago.). All around Iridium "auto" plugs is the cost of dinner. :)

In short, people have choices here and either way can be made to work.
 
Peak pressure is delayed.



Not sure "useful" is the best term. "...too late to be optimum" is closer.



You're suggesting moving peak pressure closer to TDC would result in more power, which is not necessarily true. Both too early and too late make less power. The problem with too early is it's also very hard on the engine structure.

"Electronic, and hence firing sooner" is likewise not always true. Let's not conflate how the spark is generated (EI) with when it is delivered (timing advance). EI's come in both fixed and variable timing versions, often as options for the same product



"Hotter spark" claims appear to be bad advertising. Is the plasma temperature in the ionized gap actually higher? So far I've not found any such evidence, and I'd be delighted if someone could provide a reference.



The proposal assumes the dual 30 degree timing resulted in optimum point of peak pressure. While close for an angle valve running LOP, it would be too much advance if somewhere in the ROP to peak EGT range. A parallel valve has different timing needs. I've seen dyno charts showing 30 as near optimum for max power with a hot rodded parallel valve, meaning the combustion chamber and port design is not as good. Point is, the result would depend on much more than just a 5 degree timing retard on one ignition. The two largest variables appear to be combustion chamber design and mixture.

I was assuming that any electronic ignition being considered would have ignition advance. I actually wasn't aware that there are electronic ignitions (commonly available) that don't provide advance at lower power settings.

From my Lightspeed manual - advance at sea level pressure is 22 degrees +/- 2 degrees, and advance is 1 degree per 1000'. So presumably the advance at 10,000' DA would be around 32 degrees. This is on a (parallel valve) engine that calls for 25 degree mag timing. My proposal of 10,000' test and running 30 degrees both vs. 30 degrees on one and 25 on the other was based on an engine with a 25 degree normal mag timing.

Interesting that you feel that 30 degrees on stock parallel valve engine, running ROP, at 10,000' DA is too much. Lots of Lightspeeds out there... apparently running at 32 degree advance in this scenario. Maybe I should wire up the timing adjustment and try retarding mine.
 
Walt, you're at it again.

P-Mag, about $1900 (plus mag gear, plugs, switches, breaker, wiring, etc).
Mag Ovhl, avg $400.

So you can Ovhl the mag about 5 times for the cost of the Pmag install (assuming no labor charge).

The Pmag needs R&R every 100hrs/CI for inspection, and generally returned every few years for SW updating and/or repairs. If you do this yourself great, if a maint shop does it add labor. Pmag service at factory usually runs around $200.

That's the problem with you Walt....you're always raising inconvenient FACTS. :D

Why can't you just be like most other people and simply base your product opinions on defence of purchase choice (wink wink) ;)
 
Thanks all. For Dave “do the time” worried about his impulse coupler…do you need it if you have a p-mag? What about removing the impulse coupler, keep the mag and start with the p-mag?
 
I have a p-mag and one impulse slick
I’m always worried that the impulse coupler spring will disintegrate so that’s why
I’m looking to add a second EI
Anyone have a Pmag or a Surefly for a 0-200 I’m looking.
Dave

I'd look at this from a different perspective. One of the big advantages of a Slick Magneto is that you can probably get service on it, or a quick replacement or loaner, just about anywhere....even in remote locations. I wouldn't underestimate the advantage of that. That is certainly not true of a PMag. So from that perspective alone it could be argued that there might be an advantage to keeping one Magneto. I wouldn't be worried about the impulse coupler "disintegrating". There's many tens of thousands of them flying. Just make sure it's properly maintained in accordance with the manufacturer's specifications. It's a homebuilt plane, you've probably got bigger things to worry about.
 
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I just installed two PMags and pulled out two very reliable Bendix mags that were up for 500 hr inspection. I haven't flow with them enough to form an opinion as to if the cost was worth it yet. The cost was 4350 with the complete kit with sales tax, harnesses, 1 gear, and plug adapters, all said and done and I did all the work....Two advantages to Pmags I have realized quickly is blow thru a tube timing, and the savings of 6lbs of weight!.... Unfortunately I am a little tail heavy so now working on that problem! :(
 
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Is the an SB behind this? I didn’t see anything on the emagair site, but I may have missed it.

Step 6 below:

Maintenance: Condition Inspection (annual)

1) Confirm Setup reference positions (TC, MIN, MAX) prior to removal. Look for discrepancies (if any) from prior settings.

2) Check E-MAG web site for the most recent Manual (www.emagair.com/downloads), Service Notes (www.emagair.com/service-notes), and verify equipment is current with all updates.

3) Ignitions come with a thermal sticker that will trip (turn from a light eggshell white color to gray or gray/black) as case temperatures exceed 200 degrees (F). Dark gray or solid black indicates a period of significant over-temp. If tripped, review blast cooling and/or other cooling impediments. Operating temperatures should be kept below 200 degrees.

4) Ohm Check all plug wires and examine for evidence of wear or chafing. Lead resistance should be roughly 180 ohms per foot of wire.

5) Remove and inspect spark plugs for signs of unusual wear or build-up. Replace plugs at 125 hrs. Re-gap plugs per instructions. When re-installing auto style plugs with auto plug adapters, review plug/adapter installation guidelines. Ref. Appendix 1.

6) Remove ignition and examine shaft for bearing play - disassembly is not necessary. Look for excessive radial and axial play. Shaft rotation should be free, with no catching, flat spots, or grinding. While you have access, inspect the ignition drive cushions which can get hard over time.

7) Reinstall the ignition - see Setup instructions.

8) Verify proper operation including:

a) Perform Ignition Checks on each ignition – see Ignition Check section for guidelines:

i) Basic internal alternator Ramp Check.
ii) Internal alternator Cut-Out test – record results in logbook for L, R, Both.
iii) Mode Switch Check, if installed.
 
Interesting that you feel that 30 degrees on stock parallel valve engine, running ROP, at 10,000' DA is too much.

Too much for an angle valve:

The proposal assumes the dual 30 degree timing resulted in optimum point of peak pressure. While close for an angle valve running LOP, it would be too much advance if somewhere in the ROP to peak EGT range. A parallel valve has different timing needs. I've seen dyno charts showing 30 as near optimum for max power with a hot rodded parallel valve, meaning the combustion chamber and port design is not as good.

30 BTDC is spot on for a parallel valve running ROP at altitude. Photo below from Nigel Speedy's excellent testing.

One timing map does not fit all.
.
 

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If I replace one of my two magnetos (Bendix) with an electronic ignition, which mag (L or R) would I get rid of? And why.....

Thanks!
 
...
30 BTDC is spot on for a parallel valve running ROP at altitude. Photo below from Nigel Speedy's excellent testing.

...
Interesting timing - I was putting along with my io-360 parallel valve at about 140ktas, 8700 DA, FF 6.3 GPH and the EICommander was showing 30.1 degrees advance on my pmags.
 
If I replace one of my two magnetos (Bendix) with an electronic ignition, which mag (L or R) would I get rid of? And why.....

Depends on how much you value the impulse coupler. An impulse mag on a serious bush plane could be valuable, as the owner might need to hand prop it one day. Practically no one will ever hand prop the IO-390 in a RV-14, so keeping the impulse coupler seems worthless. Parts not on the airplane never fail.
 
Too much for an angle valve:

The proposal assumes the dual 30 degree timing resulted in optimum point of peak pressure. While close for an angle valve running LOP, it would be too much advance if somewhere in the ROP to peak EGT range. A parallel valve has different timing needs. I've seen dyno charts showing 30 as near optimum for max power with a hot rodded parallel valve, meaning the combustion chamber and port design is not as good.

30 BTDC is spot on for a parallel valve running ROP at altitude. Photo below from Nigel Speedy's excellent testing.

One timing map does not fit all.
.

That's interesting. On the 10, my EI does 23* down low and starts to advance around 25". During ROP climbs, once I got to around 8000' my CHTs would start to rise aggressively and by 14,000 I was hitting 425. I put in a knob to manually adjust advance and by dropping the advance closer to 26 or 27 throughout the climb, I was able to keep the temps around 400 or so all the way to 14K'. In LOP cruise, I am seeing around 32* for both ignition's is optimal. I dial it back a couple of degrees when running closer to peak at higher altitudes.

30* may be optimal for my PV when ROP up high, but it seems the 10 cowl doesn't allow enough heat shedding in the thinner air to deal with the CHTs that come with optimal advance. 30 may work well for ROP cruise up high, with it's high air flow rates, but I don't ever cruise ROP so never tested it.

Larry
 
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30* may be optimal for my PV when ROP up high, but it seems the 10 cowl doesn't allow enough heat shedding in the thinner air to deal with the CHTs that come with optimal advance.

Optimal for power comes with a CHT penalty. Nigel noted an average of +2.5F for every additional degree BTDC.

As for the 10 cowl, make some pressure measurements. I don't have any good data for a stock install, but I'd bet it's not one of the great ones.
 
That's interesting. On the 10, my EI does 23* down low and starts to advance around 25". During ROP climbs, once I got to around 8000' my CHTs would start to rise aggressively and by 14,000 I was hitting 425. I put in a knob to manually adjust advance and by dropping the advance closer to 26 or 27 throughout the climb, I was able to keep the temps around 400 or so all the way to 14K'. In LOP cruise, I am seeing around 32* for both ignition's is optimal. I dial it back a couple of degrees when running closer to peak at higher altitudes.

I'm running SDS so it's not apples to apples, but the ignition timing lessons still apply. When I was testing on 100LL, I found my results very similar to Larry's above - but when running 91E10 I could put the engine into detonation at 32 degrees, and occasionally at 31 degrees. Since the evil E-gas is my fuel of choice for most flying I limited my max advance to 29 degrees. I do have retard built in for high manifold pressure, down to 22 degrees at sea level.
 
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