Use EDIS without MJLJ - Fixed timing for aircraft 28*

markhuebbe · Post by **markhuebbe** » Wed Apr 15, 2009 1:17 am

Can I use the EDIS-4 setup without the MJLJ (aircooled vw engine for an experimental airplane) and run the timing at 28* fixed?

I would like to install the coil pack, trigger wheel, sensor and module but not the MJLJ box. Similar VW conversion aircraft engines run fixed timing of 28* all the time. I don't need TPS sensors or MAP sensors or advance curves as the engine will be operating from 2800-3200 rpm all the time.

Can I run the EDIS in limp mode and mount the sensor to give me 28* fixed? If limp mode gives me 10* how do I get 28*?

Post by **brentp** » Wed Apr 15, 2009 2:50 am

This would certainly work. To get 28 degrees you would simply offset the sensor mounting position (or offset trigger wheel) by 18 degrees. It would be helpful to make some sort of mechanical adjustment mechanism for either the trigger wheel or sensor.

markhuebbe · Post by **markhuebbe** » Wed Apr 15, 2009 1:52 pm

So if the sensor is 90* BTDC and the gap in the wheel is at TDC, would I move the sensor to be at 108* BTDC to get 28* static timing in limp mode?

markhuebbe · Post by **markhuebbe** » Wed Apr 15, 2009 2:33 pm

How many amps does the stock coil normally draw?

Post by **brentp** » Wed Apr 15, 2009 4:51 pm

That woud seem correct.

Going off of memory- for a 4 cylinder configuration, count on the coil packs consuming about 8-10A at max RPM.

markhuebbe · Post by **markhuebbe** » Wed Apr 15, 2009 5:01 pm

But what is max rpm? I've seen some people bench test an EDIS and only see 1 amp at 3000 rpm. Or I've seen figures such as 1 amp per 1000 rpm.

Has anyone bench tested their EDIS setup and found the current draw?

Post by **brentp** » Wed Apr 15, 2009 6:26 pm

The MAX rpm I was referring to was about 8000 RPM, driven on the bench. How much current are you able to supply to the system?

markhuebbe · Post by **markhuebbe** » Wed Apr 15, 2009 6:49 pm

I believe the manufacture uses a simple Harley alternator, which is a fixed stator and a rotating drum-like thing with magnets inside. It's 20 amps total power, but I need the ignition to be around 8 amps max so I can run a radio, gagues, etc... I wanted to run dual EDIS-4 modules, dual sensors, and dual coils for redundancy. So I'm looking for 4 amps max for each coil. Engine RPM will be between 2800 & 3200 cruising and 3300-3400 takeoff.

Post by **brentp** » Wed Apr 15, 2009 6:52 pm

Your redundancy plans warms the cockles of my heart, on your behalf.

Keep us updated on your progress!

markhuebbe · Post by **markhuebbe** » Wed Apr 15, 2009 7:26 pm

brentp wrote:Your redundancy plans warms the cockles of my heart, on your behalf.

Yes, redundant systems is a priority for me.

So, has anyone bench tested their EDIS setup and found the current draw at various RPMs?

DannyP · Post by **DannyP** » Fri Apr 17, 2009 3:24 am

Mark, have you heard of this?

http://www.aeroconversions.com/

They use dual redundant electronic ignition to run their twin-plug motor. I don't think they sell the ignition separately, though. Are you building your own engine? I have a little interest in type1 VW, one powers my 550 Spyder replica.

If my engine has more that 15 degrees advance, it kicks back and won't want to start. Admittedly, it has almost 10:1 compression and lots of valve overlap! I didn'y know you could start an engine with 28 degrees of advance.

markhuebbe · Post by **markhuebbe** » Mon Apr 20, 2009 6:02 pm

I don't want to buy my engine from them but build my own. It's $2500 cheaper that way.

One ignition on the Aerovee is magneto and one is electronic. Both are timed at 28* and the engine starts just fine. (8:1 CR)

DannyP · Post by **DannyP** » Mon Apr 20, 2009 11:58 pm

I understand about the money issue. Thanks for the timing info.

What plane is this going in??