What's new
Van's Air Force

Don't miss anything! Register now for full access to the definitive RV support community.

SureFly Harness Aircraft Plugs or Automotive

gmcjetpilot

Well Known Member
Surefly is made for an aircraft harness and aircraft spark plugs. So you buy an aircraft harness plugs done. However you can modify or fabricate a harness to fit auto plugs. Which leads me to my questions:

Q: 1) How do you fabricate a harness to work with Surefly and auto plugs?
Do you start with automotive plug wires and modify them to work with surefly (how) or do you mod an aircraft harness to work with automotive plugs.

Q: 2) What Plug type and adaptor do you use?
Who makes best adaptor and what plug make / part number (NGK) do you recommend for Lyc O360 (180HP).
 
Last edited:
Not a direct answer but recognizing that Surefly uses a Slick harness/cap you can expand your query to anyone that uses auto plugs with Slick mags.
 
Go to G3i Ignition

G3i Ignition sells plans and parts to fabricate an ignition harness that uses auto plugs. IIRC, for $30 they will sell you the info to fabricate with your own parts or with parts you purchase from them.

Would then need to purchase spark plugs and adapters that other aftermarket ignition vendors sell and use.
 
I have one Slick and one SureFly on my IO-320. Not flying yet, but what are the benefits swapping over the SureFly harness from massive plugs to auto plugs?
 
I have one Slick and one SureFly on my IO-320. Not flying yet, but what are the benefits swapping over the SureFly harness from massive plugs to auto plugs?

Working off my inconsistent memory....so check your SureFly docs. I think I recall them stating that even though the SureFly will work with auto plugs they didn't see any advantage to using them.
 
I have one Slick and one SureFly on my IO-320. Not flying yet, but what are the benefits swapping over the SureFly harness from massive plugs to auto plugs?

Plug gap dictates spark energy. Aviation plugs are made for mags and the gap is small to accomodate the weak coil in the mag. I assume (don't know for sure) that the surefly has a bigger coil and can deliver a stronger spark with a bigger gap. Have never tried to gap a massive plug at .030 or .035, so don't know how easy or difficult that easy. The other benefit is cost. Auto plugs are about 90% cheaper.

Larry
 
I have one Slick and one SureFly on my IO-320. Not flying yet, but what are the benefits swapping over the SureFly harness from massive plugs to auto plugs?
You can buy 8 NGK plugs for the price of one Champion.

Working off my inconsistent memory....so check your SureFly docs. I think I recall them stating that even though the SureFly will work with auto plugs they didn't see any advantage to using them.
I called Surefly and the nice Gent I talked to has a RV6 and uses Automotive plugs. He just replaces them every 12 mo condition inspection. It is not about extra performance, however the NGK's perform well. There is a few decades of experience using NGK's in Lycoming's. The reason to go from aircraft plugs to NGK is cost.

So what is better mean? Genuine NGK** Vs. standard Champion REM40E, RHM38E - The Champions are $40 each or $320 for a set of 8. NGK is $24 for a set of 8. So 1/13th the cost. You can afford to replace them every year. We milk our expensive Aircraft plugs with cleaning, testing and reuse, over and over. Right? The resistance of Aircraft engines does increase over time, They can be out Spec in as short as 3 to 5 years. However people will keep using old plugs as long as "they work". However high plug resistance can damage magnetos, burn points or overheat coil. So just chucking your NGK's every year is cheap and easy.

It is thought that the NGK gives a better spark than a MASSIVE dual electrode Champion. Why. The electrodes block the spark. The electrodes are huge for longevity. You say, "Hey Smarty Pants, there are fine wire Aircraft plugs like EARHM38SE." Yep $120 each. Again it is not performance but similar or same performance for much lower cost. Also with EI putting out a very hot long duration you can open up the NGK gap more and get a bigger spark.

So to answer my own question NGK BR9ES is a good starting point I read. Correct me if wrong. If you want a hotter plug go to an 8. If you want cooler go to a 10. Cost? $3 each. WARNING** NGK's are favorites to be counterfeit. So make sure you get genuine NGK. If the price is too good to be true it's likely fake. There are ways to tell if you have the real deal (web has some guides for authenticity). Just be aware. The counterfeits work but I read they are not as good as genuine NGK?

Thanks for the replies they are all great. Appreciate the perspective. IF YOU HAVE INSIGHT TO USING NGK'S AND HARNESS KEEP THE COMMENTS COMING.
 
Last edited:
Yes, but you have to replace them roughly 5X as often.

While many do, I don't believe it is required. An auto plug will go 30K miles (~1000 hours) in a car easy. Fancy alloys will go 100K. I have run them for over 400 hours in my 320 and they still spark just fine with resistance in spec, but the gap may need to be adjusted sooner, just like an aviation plug. My REM37by's were significantly footballed and unusable (too difficult to get a good gap when that happens) by about 750 hours.

A failed plug is easy to spot if you watch EGTs and the consequences of losing one plug out of 8 or 12 is quite negligable, so see no need to replace more often than necessary.

Larry
 
Last edited:
Not a direct answer but recognizing that Surefly uses a Slick harness/cap you can expand your query to anyone that uses auto plugs with Slick mags.

Has anybody purchased the Surefly cap and harness for their slick mags and had luck with auto plugs? Perhaps close up the spark plug gaps a little for the mags..
 
Has anybody purchased the Surefly cap and harness for their slick mags and had luck with auto plugs? Perhaps close up the spark plug gaps a little for the mags..



SureFly doesn't sell a proprietary harness. Their devices use either the same harness designed for the Slick mags with aviation plugs or a "magneto" harness that has been converted for use with auto plugs.
 
Back
Top