M

Mike Ice

Well Known Member
Hello,

I currently have an electronic ignition set up and I am going to switch back to traditional mags. The why isn't that important.

I am guessing there are more RV's running around with traditional mags then electronic mags and I never hear about them. That must be good news.

What I would like to know from any traditional mag users is the performance your getting from them.

Do you have any suggestions how to set them up?

Slick VS Bendix?

Type of plugs?

Thanks,

Mike Ice
 
Bendix cost more, weigh more, are an older design, but parts are cheaper.
Slick cost less, weigh less, are a newer design, but parts are much more expensive. IMHO, Slick parts plus A&P labor can cost more than Slick replacement mags. In other words, if you are going to have someone else overhaul your mags, it would be cheaper to just get new Slick mags. If you can work on them yourself, the cost of the parts is very close to the replacement mag. Bendix has lots of ADs against them but once you put in the newest parts, the run well for a long time.

I ran Bendix mags for over 2,000 hours and recently switched to Unison LASAR that have a special SLICK mag. I have the paperwork / manuals to work on both and know how and have worked on both. I have worked on more Bendix but have more tools and manuals for the Unison stuff. I will be overhauling my two old Bendix mags again to have sitting on the shelf in case I have problems with the Lasar and cannot fix it myself.

The LASAR will burn 1 gallon per hour less fuel than the Bendix but that one gallon fuel saving (leaner mixture) does reduce speed. It will save about 1/2 gallon per hour over the Bendix at the same speed. I did use the same OLD spark plugs as I was using with the Bendix mags.

I like Aerotronic harness with 90 degree spark plug ends.

Champion plugs are very good and last a long time.
Unison Autolite plugs are the new kid on the block and have stainless steel bodies so they do not rust.

Many guys run REM40E or UREM40E but I kind of like the REM37BY or UREM37BY better. I have a new set of UREM37BY to install. The set of REM40E that I am removing have over 1,100 hours. They still pass the go / no go gauge test but I am going to replace them with new as I now have over 2,159 hours on the airplane / engine.

This is my opinion and others will may have different opinions.
 
I like Bendix myself, they seem like a more robust design, but as noted, they weigh more and cost more.

Of course Slick has an open SB against the carbon brush and cam right now.

Whichever you choose, most likely in the long run the costs will be about the same. If you go high often, probably should run Bendix 1200 series mags (BIG and HEAVY) they deal with altitude better than slicks.
 
osxuser said:
Of course Slick has an open SB against the carbon brush and cam right now.
Click to expand...
This is true for a relatively few set of mags with numbers starting with a couple different prefixes. By no means are all Slick mags affecte by this SB. I know this only because I had to check my new Slicks against the SB. Dodged the bullet this time!:)
 
magnificent mag info

Folks,

Ask and you will receive. Just the info I was looking for.

oxuser, When you say high,could you please be more specific. How high do you mean? I have heard this before but did not get a specific number. Why do traditional mags loose performance at higher altitudes?

RV6 flyer,

Great info, I am printing these pages and will use this data in my new purchase.

Thanks everyone for the help.

anyone want to buy an e or a p mag?

Mike Ice
 
Experiment

Maybe you could buy one mag and fly with your pmag? Work out the issue with more testing and research...
I would probably stick with the Slick Mag, you can make a set of good brushes if necessary. I do also have Bendix on the shelf.
 
Last edited:
Or somebody on the list can buy his Pmags and do the testing. I think he's done with them.
 
Mike Ice said:
oxuser, When you say high,could you please be more specific. How high do you mean? I have heard this before but did not get a specific number. Why do traditional mags loose performance at higher altitudes?
Click to expand...

It's my understanding (and I'm sure I'll be corrected quickly on here if this is incorrect) that mags CAN have issues (not DO, but CAN) at altitude due to the difference in the breakdown potential of air at different pressures. As air pressure changes, it requires more (or less) voltage to jump a spark across a gap. We only want to jump the spark in the combustion chamber across the spark plug, no where else. In some cases as you climb, you may develop a spark jumping internally in the mag instead of the combustion chamber, as the ambient air pressure drops and decreases the required breakdown potential of the gap in the mag between high-voltage parts and the surrounding grounded parts. I have seen many pilots choose "pressurized" mags (unknown mfr) for high altitude flight to avoid this. If you can keep a minimum air pressure in the mag to keep the breakdown potential high enough so that the preferred spark gap is the one in the combustion chamber, then you're golden. I've heard it repeated many times that the low teens (cruising altitude) will show you quickly if your mags will have an issue with this.
 
You must log in or register to reply here.