Thorp Air Command - T18.net

Just wondering thoughts on ignition for say an O-360

If starting fresh, what are the advantages/disadvantages of going with traditional mags, one traditional mag and an electronic unit or complete electronic ignition?

Weight, cost and reliability being the big three. Fuel savings is something to consider as well.

With complete electronic ignition along with say ipad or other electronic flight instrements, what about battery back up?

Seems like a lot of the weight savings of a complete electronic ignition and panel would be thrown out the window if a person would need some sort of isolated back up battery to keep the fan up front turning and the right side up in IMC for example. But it seems like the potential for smoothness of the engine and the ability to adjust timing and thus fuel savings would be a potential advantage.

I'm a LOOOOONG way off from this decision (As I'm just now ordering S-18 plans from Cubes), but just wanted to gather some thoughts of others.

I rode with Dave Reed at KY Dam last fall and I believe his thorp is 100% electronic and it was one smooth running engine!

You are correct, I have 2 P-mags on my 0-320. I would go with them again. As long as you keep the rpms above 8-900 in flight the internal alternator will power the ignition if you loose ships power. I have inadvertently made an entire flight with the ships power off and never had a clue until the engine died partway through rollout. (I turn off ships power for the mag check and forgot to turn it back on) My MGL panel has a small backup battery similar to what the emergency lights in buildings use that is supposed to power the panel for 2 hours. I have a switch that allows that battery to power the ignition in the event of a dead battery so I can hand prop it as well. I didn't get any mags with my engine so it was easier to decide to go with the new technology

Dave,

Any idea what the weight difference between traditional mags and the P-mags?

I was not aware because I have never really looked into this at all, that the P-mags have their own internal alternator for self power above what amounts to an idle.

Do you use traditional aircraft spark plugs or can you use automobile plugs or some other plugs?

Does the P-mag allow a timing change or is it pre-programmed to change timing versus the RPM or something?

Is your ship carb or injected?

IM gettin ready to do the p-mag David, recommendations you might have? Dan

I don't know the weight but I would guess they are some lighter. Installation is rediculously simple. Mount the mags in any convenient position, I think you need the engine at TDC but then you just blow into the MAP sensor tube and the timing is set. There are a couple of standard timing selections, mine advances the timing according to MAP. Look on their website but I think you can customize the timing with fadec controls if you wish. I'm not sure that is the proper terminology. You can use aviation plugs but I used their automotive harness and Autolite 386 plugs gapped to .030-.035 per their recommendations. These plugs do not require an adapter for the lycoming and are less then $2 each. Throw away and replace at annual. To quote Gary Green it starts like a Lexus. I use the MA-4 SPA carburetor, gravity fed. I had an issue with one of the first mags off of their production line but am completely satisfied with their changes and have always received good service from them. As I said I would buy another set, I have over 800 hours on my plane with them so far. David

Man I just put in all new plugs!!! How is it that the aviation plus are used? Sorry to be a pain asking probably what are dumb questions. And I will probably pester you some more. Dan

When you order you can choose either the standard harness or an automotive one. I imagine the only difference is the cap where they attach. The electronics makes a hotter spark than a regular mag, I think that is why the wider gap. I think they may recommend widening the gap on standard plugs. I am glad to share my thoughts, I just hate to sound like I am getting a commission. DR

I have installed the Pmag on 2 planes. I went with the auto plug harness on both. Auto plugs are cheaper than aircraft plugs, and have an excellent operating history, thanks to experimental aviation and web forums.
Before I installed the Pmag on my RV-8, I made up an auto plug harness for the Bendix 200 magneto.
I used MSD 8.5mm wire and MSD plug boots. I gapped the plugs to .016" the same called out for aircraft plugs.
That might have been a small gap, as I recently had the mags serviced for a Cessna 182, and they jumped a 1" spark from the speed provided by the impulse coupler!
Anyway, I am now an advocate for auto plugs. I run Autolite 386 18mm plugs in my T-18, which has an O-290 with 7:1 compression, and I use NGK BR8ES 14mm plugs with adapters in my RV-8 with an O-360 and 8.5:1 compression. both are fired by Pmags.
The auto plug conversion for Bendix mags is easiest if you use the old style magneto lead plate, which has a gland nut for each spark plug wire. These are often found on ebay. and are easily converted to 8.5mm MSD plug wire.
I am experimenting around with converting Ford EDIS ignition parts, and soon hope to remove the magnetos from both planes.

_________________
Scott Emery
EAA Chapter 326
T-18 N18TE

Hi, Scott. You may have seen some post by Karl (KWK) and me on light and simple T-18 builds and yours seems to one that fits that definition. I wonder if you could answer a few quick questions and provide a few specs on your plane? Here goes...

--Empty weight?
--Fuel capacity?
--Estimated power of your converted O-290?
--Speeds - 100%, 75%, 50%, stall flaps up, stall flaps down?
--Original or Sunderland airfoil?
--Stall strips, vortex generators?
--Anything you'd do differently if tackling a new T-18 project?

Also, I see that you have an RV-8 and put your T-18 up for sale last summer, but still have it. Did you just change your mind?

Cheers,

Matthew

_________________
Matthew Long, Editor
cluttonfred.info
A site for builders, owners and fans of Eric Clutton's FRED

« Voici ce que j'ai fait...vous pouvez en faire autant! »
"This is what I have done...you can do the same!"
--Henri Mignet (1893-1965)

I haven't talk to the folks at p-mag yet but it would appear that they have discontinued the aviation harness for their set up, at least that's what's in their Ops Manual. So, I guess the 2.00 rigs will be in order. Im goin to give em a call and see what the deal is on that, I'm going to assume that the auto plugs probably just flat beat out the aviation plug option due to cost and availability. Electronic Ignition will double and Somtimes tripple the voltage put out by a mag, but I am interested in the map timing advance as my old e-2d has a sweet spot at about 2350 rpm, I believe it just needs a few degrees of advance to have that sweet spot through the full 2700. I will Install the one p-mag, I do believe it wil probably just turn the one mag I have left into hole plug on the excessory case, so then I will probably change out the other one. Any comments? Dan

Dan,
I'll buy your old (new) plugs if they are REM 37BY.
Cubes

They are 40s Cubes, I have always used the 40s, I believe Ira has spoken for them. The ole lycasaurus had 40s in it when I got it so I continued with them. Blue skies!!! Dan

David , do you have to order your plugs from Summit? Who carries the crazy critters......Dan

I have most often bought them from summit but I believe I have ordered them through NAPA too. They are usually less than $2

Hi Dan,

I know David uses the 18mm auto plugs so there is no need for an adapter. The P-Mag installation manual has a few plugs listed that customers have used (they won't actually make a recommendation due to liability). If you read through their service notes they specifically warn against using the 18mm plugs. I put in the NGK BR8EIX plugs with the solid end (not the threaded ferrule). They were a little more expensive than the standard NGK plugs, but they are supposed to last a lot longer. I ordered them from Amazon.

http://www.emagair.com/service-notes/

The screw on ferrule is probably fine if you put a little locktite on it, but the solid ones cannot unscrew. The part number for the solid is #6747 and screw on is #5044. I think the iridium are about $7 or $8 each. The standard NGK plugs can be ordered either way also, #3961 (solid) and 5422 (screw on).

I run one Bendix mag and one P-mag. Better starts, smoother idle and maybe a little smoother at cruise. Both electronic would be better for efficiency, but still don't totally trust two of them. I may reconsider the next time the mag craps out and just put another P-mag on.

Hopefully David reads this and responds or I will contact him directly. Might be a good idea to call E-Mag and find out what the specific problem with the 18mm auto plugs.

_________________
Bernie Fried
N18XS