Primarily for general aviation discussion, but other aviation topics are also welcome.
By riverrock
What are the advantages of using automotive Spark plugs over the old aviation ones? Larger gap so larger spark (could we not just gap aviation ones wider)? Cheaper?

The 10+% fuel efficiency saving looks great on paper - do people actually get that?

I'm looking at whether to install a P-Mag in an AEIO-360 (PtoF SA Bulldog) since we have one Slick mag at its 500 hour limit and the other one potentially needing overhauled also due to service bulletin.
I understand early P-Mags had some issues but they are pretty reliable now, so should last longer than 500 hours.

Other disadvantages I can see is that manual says they need taken off every 100 hours to be checked, and they aren't self powered below 900RPM (or there-a-bouts) so would need to be careful when flaring to land if the other mag failed (and the power supply failed also - seems unlikely!).

Any other experiences?
By Duncan M
I’m afraid I am unable to add any knowledge to this, but would be very interested in any information.
I am at 500 hours on a continental c90 and would consider electronic ignition if the parts to rebuild the original Bendix mags are not available.
Upwards of £600 each mag for a recon does seem excessive to me.
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By GolfHotel
@riverrock I have an ex bulldog engine in my RV. I have one electronic ignition that uses automotive plugs. All I can say is no way would I have double mags again if I can avoid it. Far smoother, better performance, less fouling so whats not to like. Wish I had double electronic.
By riverrock
@GolfHotel - sounds good - I just need to convince my conservative group owner colleagues :)
I assume you have a P-Mag? Is it much bigger than the mag it replaces? I've struggled to find dimensions and we don't have a lot of space.
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By GolfHotel
It’s not a p mag. Can’t remember what it is. Can check if you like. It is not self sustaining and that’s why only one was fitted. The other is a conventional mag. That might give comfort to those worried about electronic ignition.

As for size it’s much smaller than a mag, but there is a box fitted in the cockpit.

Running on the mag the engine is just a normal lycoming. (Even if a bit more powerful than most, and a bit smoother with the balance doohickeys on the crank) but running on the EI most pilots comment on the smoothness. There is a very noticeable difference.
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By Ben Twings
I've flown with one P-mag with one (impulse) magneto.
It's a good arrangement. The automotive plugs mean you can use an Iridium tipped plug for about 1/3 the cost of an aircraft one. The more powerful spark can cope with a bigger gap than a mag can.
Starting becomes easier, ignition timing can be optimised and you can run a leaner mixture than before, especially with a carburetter system.
Performance and fuel improvements will depend somewhat on your leaning discipline, altitude etc.

Whe Jon Johansson stopped off in Santa Paula during his first RTW trip, he got a Lightspeed system installed which made the difference between him being able to complete the trip given his fuel capacity.

I'm now flying with a dual Lightspeed Plasma 3 system with a back-up battery to keep going after an alternator failure.
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By Trent772
We have dual P-Mags on our IO-360 in an RV7. 8 years of flawless operation so far on NGK BR9EIX plugs.


3rd blade start hot or cold
Plugs are $8 in O'Reilly's as opposed to $30 for Champion from Aircraft Spruce
Runs smooth, it has mapped ignition so the timing is optimised.
Probably gives more power and economy but how would you tell ?
Simple fit and timing - they can be oriented any way and timing takes about 5 minutes.
Same price or cheaper than a Slick Mag.



I would not hesitate to recommend them, Brad Dement has put a lot of time and effort into developing an excellent product.

Oh, btw.....

If your current mags are running fine, you don't have to do anything with them. It is a service bulletin only for 500hours and is not mandatory.
By simon32
4535jacks wrote:I think $1195 is for the single system whereas I intend to fit dual ignition which is $2395 + VAT and shipping and I don't think I would get much change out of £2k. But I would live to be proven wrong.

I would like like to see a system where the electronic ignition timing has two presets, power and economy which you could change between depending on what you are doing.

Would this be possible?

SDS in Galgary Canada has this. A switch with programmable advance.
You can also program the advance in 100 rpm steps.
It is a very well thought out system with Hall effect crank trigger like the Klaus Savier Lightspeed system but with coil pack ignition instead of capacitor discharge.
By riverrock
Trent772 wrote:If your current mags are running fine, you don't have to do anything with them. It is a service bulletin only for 500hours and is not mandatory.

Indeed - I think that has been a previous discussion on here.
We have had mag failures in the past, including failures while still under guarantee. Both of our mags (we think) are affected by the new SB too ... -bulletin/
We have a general policy in our group to abide by SBs and so decided to follow the 500hr SB for mags.