Slick vs. Bendix Magnetos

captain_john · Post by **captain_john** » Mon Oct 29, 2007 9:12 pm

Hey all, I am gonna use an electronic ignition and one of these old fashioned mags. Dunno which one yet. (IO-390 engine)

I need to make a decision for Advanced Flight Systems t make my EFIS/EMS display so I can give them the information.

I called Mattituck today, but Mahlon wasn't in. Mahlon, you didn't check with me before taking the day off! Work on that, would you?

Anyways, I am sure Mahlon will read this and respond soon. (Much apreciated!)

All, what is the deal with mags? Why one over the other?

Should I put an impulse coupling on>

Mag top or bottom?

Auto plugs or finewire?

Anything I missed?

CJ

svanarts · Post by **svanarts** » Tue Oct 30, 2007 12:01 am

Why not an emag/pmag combo?

captain_john · Post by **captain_john** » Tue Oct 30, 2007 2:47 pm

Well, I like the Electro-Air stuff for the time being. It seem like a nice, lean system that is simple and durable.

The P-Mag is a real close second.

I want the reliability of a second "mag", hence this decision.

...I think.

CJ

jim_geo · Post by **jim_geo** » Wed Oct 31, 2007 1:47 am

Why not go for reliability all the way around. My own opinion, but it never made any sense to me that anyone would want to mix ignition (read that to mean timming) sources. Here's why I say that. If the spark set off the charge on one side of the cylinder there's a shock front that begins to move across the top of the piston. If at some later moment another spark is set off it causes a second shock front to move across the top of the piston. When the two fronts meet they are perhaps not going to be symetrical and and to my way of thinking possibly cause any number problems such as lower power or possible hot spots. Usually an aweful lot of care is given to get the ignition to go off at the same moment. Like I said, just my opinion.

captain_john · Post by **captain_john** » Wed Oct 31, 2007 5:51 am

Ummmmm, naw...

Once the fire is lit, the fire is lit. The mixture can only light once. You can't cook a chicken twice.

I want the EI so I can have an accurate burn. The mag is there only for the redundancy and backup. I am expecting the EI to pretty much run the show.

I do appreciate your input, though!

...at least that is the way I am justifying it now in my own mind's eye.

CJ

cjensen · Post by **cjensen** » Wed Oct 31, 2007 9:08 am

Have you looked at LASAR CJ? Expensive, but I think it's the best overall combo. I probably won't use it because of cost, but Jack has it in his 7, and it has worked flawlessly. Just another option...

jim_geo · Post by **jim_geo** » Wed Oct 31, 2007 1:00 pm

I draw a lot of information from my ol Dad. His credentials as a graduate of M.I.T. And Purdue made me pay attention. He was a Lockheed flight test Engineer for most of his career his specialty being power plants. Internal combustion and turbine, from the Vega to the L-1011 with the P-2's and 3's along with a few other projects thrown in. I'm not trying to argue, I did say it was just my opinion but that opinion was based on some very informative conversations with him. I can't help but think that there are some very smart people designing our engines and doing what they do for some very good reasons.

svanarts · Post by **svanarts** » Wed Oct 31, 2007 2:08 pm

I've also heard people smarter than me say it is a flame front that propagates from the spark outward (within the cylinder.) That's to agree with Jim.

To agree with CJ, I don't think fractions of a second matter much. If two explosions were meeting in the middle of the cylinder I could see it being a problem, but I can't see two flame fronts interfering with each other that much. Once they meet they stop moving because there is nowhere else to go.

As long as the EI is designed to work with a Mag the smart guys that invented it have designed their EI such that the spark will work around the magneto's spark in such a way as to achieve best performance for a given situation.

Or else I don't understand how they work. Which could very well be.

TomC · Post by **TomC** » Wed Oct 31, 2007 3:15 pm

Here is what I learned a couple of years ago when I installed my engine.

Should I put an impulse coupling on

On my Mattituck TMX-360 engine, they put one Lightspeed ignition and one impulse coupled mag. They recommend that the engine be started with the mag on and elect ignition off, something to do with the starter drawing the battery voltage down to a level that the electronic ignition might misfire, causing damage (Mahlon, can you expound?)

Mag top or bottom?

My engine has the electronic ignition on the top set of plugs. Why? I don't know.

Auto plugs or finewire?

My electronic ignition uses auto plugs and the mag uses aircraft.

I hope this helps. I have not had any trouble with my engine or ignition systems. One downside to the electronic ignition is that Mahlon does not recommend running auto fuel in an engine with electronic ignition. The thought is that the spark is advanced to a degree that might cause detonation without the higher octane/leaded mixture

Good Luck,

captain_john · Post by **captain_john** » Wed Oct 31, 2007 4:09 pm

Guys, thanks for the replies.

Chad, ummmm no. Not until now. I just figured that due to the fact that it is certified it would be inferior and costly. As I read the propaganda on the web, I see that it may not be either!

What do you know about it?

AFS needs to know which brand of mag I have in order to configure an RPM sensor for the EMS. I chose Unison/Slick because they won the toss, pretty much. It looks like I got lucky and they seem like a good choice!

I guess that I could rephrase my question now.

Q. Does anyone have any commentary on Unison/Slick mags? Have you ever used the Slickstart or LASAR products?

CJ

P.S. Jim and Scott, as you can see, I am new to all these ignition products and I am feeling around in the dark for the switch! I am not too smart to be open minded. If you find anything that substantiates the combination of systems to be bad, lemme know. I know there are many planes out there flying doing just that.

cjensen · Post by **cjensen** » Wed Oct 31, 2007 4:40 pm

Not a whole lot, but here is a base to start from. Maybe Mahlon could chime in...

The standard LASAR system consists of a pair of standard Slick magnetos, that have been modified with a movable plate on the points to allow the timing to be both retarded for starting, and advanced for cruise operation. The timing is controlled by a "brain box" typically mounted on the firewall, that senses RPM and manifold pressure, and modulates the timing according to a pre-programmed timing map. If the "brain" should fail, or if battery power is lost, the timing is returned to the baseline value that is set for the particular engine. If a magneto should fail in the normal sense, the other magneto will power the engine as usual, and the working magneto will revert to baseline timing.

I know some have had some issues with it, but Jack's has been flawless for nearly three years. Hope I didn't just jinx something...

captain_john · Post by **captain_john** » Wed Oct 31, 2007 4:55 pm

Tom, Thanks!

I looked at the Lightspeed. They want the "brain" if you will to be located inside the PAX compartment. I suppose I could do that, but I have some sort of personal feeling that all engine components should be in the engine compartment. It looks like a good system and am really considering it.

I am getting the feeling that you really can't go "wrong" with any system. I suppose it is like a good gun or golf club. If you like it, you will use it well!

Chad, I saw that info on the Unison website. I couldn't tell if the Slickstart could be used with the LASAR system or if isn't advised?

I think I have questions for my questions at this point!

CJ

cjensen · Post by **cjensen** » Wed Oct 31, 2007 5:01 pm

Don't know the answer to that one.

If I go EI, it'll be dual LSI Plasma III Direct Crank Sensor, if anyone cares...

Mahlon · Post by **Mahlon** » Thu Nov 01, 2007 5:51 am

captain_john wrote:Tom, Thanks!
Chad, I saw that info on the Unison website. I couldn't tell if the Slickstart could be used with the LASAR system or if isn't advised?

I think I have questions for my questions at this point!

CJ

Slick Start is not necessary with LASAR ignition.
Good Luck,
Mahlon
“The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

Mahlon · Post by **Mahlon** » Thu Nov 01, 2007 7:54 am

TomC wrote:
On my Mattituck TMX-360 engine, they put one Lightspeed ignition and one impulse coupled mag. They recommend that the engine be started with the mag on and elect ignition off, something to do with the starter drawing the battery voltage down to a level that the electronic ignition might misfire, causing damage (Mahlon, can you expound?)

Yes, that is the reason. But Lightspeed has redesigned their system to have a lower threshold voltage, so that kickback can't happen from low system voltage. We are testing that now and may remove the warning to start on the mag when using Lightspeed.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

Mahlon · Post by **Mahlon** » Thu Nov 01, 2007 7:59 am

captain_john wrote:
Should I put an impulse coupling on>

Mag top or bottom?

Auto plugs or finewire?

Anything I missed?

CJ

I would use an impulse mag if going 1/2 EI and 1/2 mag. EI fires the top plugs and the mag fires the bottom. Auto plugs on the EI is fine and fine wires on the mag are the best, but massive electrode plugs will work well too, just will wear out sooner.
Good Luck,
Mahlon
"The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

captain_john · Post by **captain_john** » Thu Nov 01, 2007 3:15 pm

Mahlon, thanks!

I am sure you were digging out of a mountain of stuff from your 3 day absence.

What do you think about the Electro-Air stuff?

CJ

Mahlon · Post by **Mahlon** » Thu Nov 01, 2007 5:24 pm

captain_john wrote: What do you think about the Electro-Air stuff?

CJ

Honestly, I don't have a lot of experience with the system. Word on the street is it is fine but I don't know that for fact.
Good Luck,
Mahlon
“The opinions and information provided in this and all of my posts are hopefully helpful to you. Please use the information provided responsibly and at your own risk."

Speed3Guy · Post by **Speed3Guy** » Thu Nov 01, 2007 5:31 pm

I could be wrong about this, but I believe Mr. Bowen http://www.bowenaero.com used Electo-air for awhile. After a long list of problems and failures, he wound up abandoning it. I can't check his website from work, so I may be talking smack. Check into it.

Guy

captain_john · Post by **captain_john** » Thu Nov 01, 2007 8:57 pm

Hmmm, okaaaay...

Mebbe P-Mag then?

CJ

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Slick vs. Bendix Magnetos

Slick vs. Bendix Magnetos

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