160 RPM Delta between LS E/I and Slick Mag?

[twcroy]

Folks,

Is there an issue with a 160 RPM drop when turning off the Lightspeed E/I mag? The POH I was given when I bought the plane lists max of 125 RPM, so guess there is. Thinking of taking her to an A&P to have it checked.

Any thoughts or experiences in this area?

Thanks as always,
Tim

[Bob Axsom]

You are starting to gather intelligence about the system and I think that is the right way to go about the concern. When you do the mag check the other way - going from both to LS E/I only what is the drop? My guess is it will be something less. If you take your airplane to a mechanic without knowing the exact configuration of your non-standard system you are going to make the mechanic reverse engineer the system to determine what it is. I'm sure the people that have your kind of set up will chime in. I would not be surprised if the concept is that the LS E/I is primary system and the Slick mag is the backup though lower performing system and expecting the Slick mag to perform at the same level under all conditions is unrealistic. The mag check of the dissimilar systems under your test conditions shows the the backup drops 160 rpm but performs its backup roll nicely by providing ignition independent of an electrical power source.

Bob Axsom

[db1yg]

Hi Tim,

I have a LS PIII on the right and a Slick mag on the left on my O360 Eci engine. I do my mag check at 1600 rpm and see a 0 to 10 rpm drop when the mag is off and a 50-70 rpm drop when the EI is off. I found that the rpm at which you do the check makes a big difference but 70 drop is the max I have seen.

Hope this is of value.

Cheers,

db

[G3i Ignition]

Hi Tim,
On your 160 rpm drop, is this when you are cycling the ignition on your run-up? Is your engine still smooth, just sound lazy when going to the mag ? Excessive fuel mixture will cause this type of high delta when switching to just the mag. When doing your run-up, set the mixture a little leaner and see if that has any effect on your rpm drop when in the mag mode.
Thomas S.
www.g3ignition.com

[kentb]

On my IO-320 those have always been the drop since I started flying.
I do my test at 1700 rpm.

Kent

[Chino Tom]

I do my mag checks at 1800 rpm. When I first installed the LS PII i was
concerned about the larger than normal mag drop. I cleaned the plugs and
rechecked the mag timing. No change. I don't agressively lean on the ground
as I did with two mags and now with 1 EI, the plugs are much less prone
to foul.

[twcroy]

Thanks for everyones' response. After we leaned it 3-4 times on the ground we got it to about a 130-140 drop; and after landing and taking off 4 hours later it was a 130 drop from the start. My instructor and A&P want to check the timing on it, but I don't think that's a problem as mentioned by some folks. BTW, below is a response from another pilot of an RV-9A I received via email. Thanks again.

Blue skies, Tim

"So you should go out to this link (it's the online manual for your EI):

http://lightspeedengineering.com/Man...II_II+_III.htm

and do some reading.

If you search on your browser in the link above for "mag drop" you will
see well into the document under run up that the expected mag drop running
on the mag alone is "A large RPM drop will be noticed when the electronic
ignition is turned off."

I called Klaus Savier (the owner of the company) and he said that drops as
large as 200 rpm could be seen.

Since this is not a production aircraft, the specs are not as ridgid as
you would see on, say, a cessna. If your concerned about this, please
give Klaus a call, he can field your questions better than I can.

At the end of the day, you just need to make sure that when it's on mag
alone that it's running smoothly. If it's popping and missing, you
probably need to get the mag overhauled or timed. Once you give it a
chance to warm up (again running on mag alone) you can just retard the
throttle back to idol and get a pretty good impression of the state of the
mag. Remember that the more you run the mag, the better it will perform."