What's new
Van's Air Force

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

Using EICAD to adjust PMAG timing

nigelspeedy

nigelspeedy

Well Known Member
G'day All,

I have a new engine with dual PMags. It has high compression and I want to be nice to it during the initial break in flights. Based on what I read I am probably better off with a little less advance than a little too much.

What I think I want to achieve is ~20 deg BTDC at high power, with no more than 30 deg BTDC at low power settings.

The Max Advance setting using the EICAD seems pretty easy and I've set that to 30.8 deg.

I've set the Max RPM to 3072 to help protect the prop if for some reason it wants to overspeed.

The Advance Shift I have set at -5.6 deg, which is based on my understanding that the timing at high power with 0 deg Advance Shift results in ~26 deg BTDC with mags timed at TDC. i.e. 26 deg - 5.6 deg would result in a new max power timing of 20.4 deg which is close to what I am aiming for.

Am I in the ball park here? I'd be happy to hear from those of you with more understanding of the PMAG default max power advance and use of the EICAD.

Cheers

Nigel
 
As you describe it, you have set it correctly.

One thing I would do and that is to set the max advance to as close to 26 degrees as you can. Run your engine this way for the first 10 to 15 hours until the cylinders break in. After that, set your max advance back up to 30* +/-.

That way your P-mags will act like a fixed magneto and eliminate timing as a source of high CHT's.

Feel free to call me, if you have any questions. (I've PM'ed you my number.)
 
One other thing, it is good you are playing with the rev limiter in the P-mags.

In the event of a prop governor problem, it will keep you from requiring an engine overhaul.

However, one thing you must know, unlike a car, this only cuts the ignition, not the fuel. Thus if you hit the rev limiter, the plugs stop firing and raw fuel will be pumped into your exhaust. When the prop slows down below 3072 and starts firing again, it will ignite the unburned fuel in the exhaust. This causes the pilot hit his head on the canopy as the ensuing BANG from the exhaust will frighten some fecal particles out of you!

(I tested this when we were developing the EICommander, and it does work.)
 
Thanks for the help.

Bill,

Thanks for the tips. I'll make the max advance timing change you recommend.

Once I had the engine broken in I was thinking that the EICAD would allow a simple experiment of running different advance shifts and max advance settings to see how it affects performance/engine running, allowing me to pick the best combination.

Regards
 
nigelspeedy said:
Bill,

Thanks for the tips. I'll make the max advance timing change you recommend.

Once I had the engine broken in I was thinking that the EICAD would allow a simple experiment of running different advance shifts and max advance settings to see how it affects performance/engine running, allowing me to pick the best combination.

Regards
Click to expand...
Yes, you can do that with the EICAD program but installing one of our EICommanders makes doing that much easier. One reason is that the EICAD program will not let you make changes on a running engine, like the EIC can. Also, the EIC can monitor your ignition while you are flying.

Even better is that the EIC can store up to five different configurations that you can send to the P-mags in flight. Thus, if you want to have one configuration for flying up high, you can send that to the ignitions, and have another for auto fuel, or one configuration for whatever you want.

That is in addition to making changes in flight and saving the configuration you like best.

Essentially, the EIC can do whatever the EICAD program can do but much more.

Even if you are going to stay with the EICAD program, I suggest you run all the wires into the cockpit that are required for the EIC and terminate them in DB9 connectors so you can run the EICAD program without removing your cowl. Then, if you ever decide to put in an EIC, you can make a simple harness that goes from both DB9 connectors to the twin row DB15 connector the EIC requires.

Sorry, I'm not trying to make this a "sales pitch", just trying to give you some options.
 
I am still getting familiar with the EICommander and like you I am about to begin the break in process on a new engine, mine is low compression..

I managed to change the "CCC" timing curve so that it will not advance the timing beyond 26 degrees. This way I can leave the vacuum lines in place, glad of that as one is very difficult to get to.

I love having the ability to monitor the health of the Pmags with the EIC and plan to have one program for Auto Fuel and one for 100LL after the break in process.

The EIC lets me choose what curve to run without messing with the jumpers.

One complaint I have about the PMags is their temperature sensors. The EIC can monitor the temperature which I feel is very important, but unfortunately the temperature data is not at all accurate. I get about 20F difference in temperature when I check it. Rather than having a blast tube just blow on one spot it seems like they should have a cooling shroud with provision to attach a 1" blast tube. Anyone done that?

I am happy with the EIC so far. Just takes a little learning curve to get familiar with the programming to get what you want out of it.

The manual could use some editing...

Randall in Sedona
RV7A, IO375 WW RV200
 
You must log in or register to reply here.
Back
Top