Plasma 11 vs Plasma 111

Captain Avgas · #1 02-06-2007, 06:28 AM

I have been told by some-one who has very extensive field experience with experimental electronic ignitions that the Lightspeed Plasma 111 has not proven to be as reliable or robust as the Plasma 11. As he puts it....the Plasma 111 is still more reliable than a magneto, but not as reliable as a Plasma 11. He considers that the crank sensor is also considerably more reliable than the Hall Effect sensor.

Has anyone out there had any experiences that would either substantiate or refute these claims.

Initially I fancied the Plasma 111 because I am interested in lean of peak operations and the Plasma 111s long hot spark would seem to be better for igniting very lean mixtures. But for me reliability is absolutely paramount because I intend to fly long distances over water so I'm now eyeing the Plasma 11.

Any comments.

Incidentally, I love the P-Mag concept..but it's just too early for me at this stage given the type of flying I plan. I need track record.

Walt · #2 02-06-2007, 02:03 PM

I ran a LSII for 2 years and 500 hrs when I decided to add the second and dump the mag I went with a LSIII. I asked the same question but the answer I got was there is no difference in reliability. I stuck with the one of each concept though for a couple of reasons: the LSII has been around longer and has more of a proven track record than the LSIII and my LSII unit has been flawless since installing. The LSIII gives me the advantages of that unit with the higher output which is a good thing, but with higher output comes the associated electronics to drive it beyond what is in the LSII (higer output/higher parts count/higher current all mean lower MTBF in my book). No compatibility issues with running one of each so I kept my "proven" LSII and added the LSIII when I upgraded to dual EI. BTW, noticable improvement in smoothness with the second unit and I can run lean of peak now with no problem or roughness with my old fashioned bonehead reliable carb. I am all about reliability and only fly with components that have a proven track record, so when it came to electronic ignition Lightspeed was the obvious choice!

Captain Avgas · #3 02-06-2007, 05:36 PM

Quote:

Originally Posted by Walt

I ran a LSII for 2 years and 500 hrs when I decided to add the second and dump the mag I went with a LSIII.

Walt, thank you very much for your considered and helpful comments. I spoke to Klaus at Oshkosh last year and he said the 111 was as reliable as the 11 (of course he would)...but that's not what some other people say. Your comments about the additional complexity of the the 111 makes sense to me.

Any other comments out there.

TX7A · #4 02-06-2007, 06:36 PM

"He considers that the crank sensor is also considerably more reliable than the Hall Effect sensor."

I'd like to see some comments on this. I'll be using the LS system & have wondered what the differences were.

Thanks,
Sam

Captain Avgas · #5 02-06-2007, 08:03 PM

Quote:

Originally Posted by Walt

BTW, noticable improvement in smoothness with the second unit and I can run lean of peak now with no problem or roughness with my old fashioned bonehead reliable carb.

Walt, have you switched between the Plasma 11 and the Plasma 111 while you're running lean of peak. I am imagining that the Plasma 111 might run just a bit smoother due to its longer duration spark and perhaps superior ability to ignite the leaner mixture....but maybe not. You're the only person I know with a 11 on one side and a 111 on the other who runs LOP so your feedback would be very valued.

I know you said the engine runs better with EI on both sides (rather than one MAG) but can you now ascertain if one EI performs better than the other, particularly LOP.

Walt · #6 02-07-2007, 12:23 AM

to see if there is a difference LOP between the II and III. I do know that with the mag and the LSII running I could run LOP but it would not be as smooth as at peak. Now with both II and III running I can go LOP with no noticable change in engine smoothness. Overall engine operation seems a little smoother as well with dual LSI vs the single and a mag. In ref to the reliability of the crank pick up vs the hall effect, I ran the hall effect for a few hundred hours but started having trouble with oil seeping past the seal in the sensor which I could not get fixed so I switched over to the crank sensor, other than that it worked perfect. The hall effect was certainly easier to install than the crank sensor was though (thank you ECI for drilling and tapping the case for the crank seal retainer so the pickup bolted up with relatively little hassle).

AlexPeterson · #7 02-07-2007, 07:41 AM

I have two Plasma III's with direct crank pickup. I typically run fairly low power (~55%) LOP in cruise.

What is interesting, and seemingly pertinent to this thread, is that it could be difficult to notice if one ignition failed in flight. When running at the above conditions, there is a subtle change in the engine sound when one ignition is shut down, but if I were talking on the radio I'm not sure I would detect it. When running richer, it really is difficult to detect. I have the interconnect, which advances the remaining ignition 5 degrees should the other go off line or is switched off.

I believe that I need some sort of annunciator system to notify me that one ignition has failed. I haven't looked at the schematics, perhaps there is an output which could be used.

dan · #8 02-07-2007, 09:02 AM

Quote:

Originally Posted by AlexPeterson

I believe that I need some sort of annunciator system to notify me that one ignition has failed. I haven't looked at the schematics, perhaps there is an output which could be used.

Alex,

I'm sure you're like me in that you "know your EGTs." You get familiar with the range in which your EGTs end up running for a given condition & power setting.

If an ignition fails, expect to see those EGTs rise. That alone is a great indicator imho of an ignition failure.

Gotta love contemporary engine monitors.

For what it's worth...on my AF-2500 you can configure "yellow" and "red" limits for most parameters. On the EGT, I believe I set it up so that it goes into the yellow pretty close to where I typically see normal peak EGT.

The net result is...if an EGT goes on the rise due to some issue, the bar is likely to turn yellow, indicating the abnormal condition.

AlexPeterson · #9 02-07-2007, 06:26 PM

Dan, you are right on with regard to egt's. Once set up in LOP cruise, I will usually see about 1380 or so, and when I kill one ignition, it will rise to about 1460.

Captain Avgas · #10 02-08-2007, 04:56 AM

Quote:

Originally Posted by dan

If an ignition fails, expect to see those EGTs rise. That alone is a great indicator imho of an ignition failure.

Dan, I believe that you have Plasma 11 on one side and a slick mag on the other.

Can you technically explain why turning off the mag in medium power cruise would result in an EGT increase.