lml@lancaironline.net Mailing List Archive

George,

Darn, this is fun when we address more esoteric issues. Hopefully, we can all learn more. After all, I was finally convinced that there is a place and time for operating LOP.

See my posted reply to "RE Relative Temps?" for basic info about my experimental aircraft operation. Then,

Jumping to your conclusion:

<<<<<<Frankly, at high power and rpm, properly maintained magnetos do a pretty good job in terms of the "quality" of the spark, and most electronic ignition systems don't do much better in terms of the quality of the spark. >>>>>>>

My system is not "most", therefore the argument is categorically rejected for lack of experience specifically with LASAR, unless you know something about it that I don't. Note that "a pretty good job" is not good enough, 'cept for spam cans.

Unison states that their magnetos do not produce consistent sparks. If that is so, only one plug may initiate the the burn with a less than optimal double flame front. This is exactly why the one Electronic Ignition (EI) - one magneto sytem may perform better than two mags, but not better than two EIs.

Before that you said:

<<<<<There is ONLY one explanation that is consistent with all of the data that I have seen. The EFFECTIVE timing, as measured by the location of the peak of combustion pressure after TDC *IS* changing significantly.>>>>>>

Well, maybe that's how you want to explain it. All things being equal (sure!) if the EI always sparks and the mags mostly spark, the EI is more often going to burn the gas in the right place. Ergo, the temperature patterns can be different. Maybe this does alter the peak pressure point. Maybe 4-cylinder engines are just built tougher. Maybe mine is going to blow up tomorrow because it is working harder? Maybe we will learn more when I get more data as outlined in my post "RE Relative temps." Maybe other alien ignition system users will add to the data.

George, the rest of your reply completely befuddles me. Since I can't provide a URL for the PRISM page, hopefully, the reader can get thru this copy off that page (assuming LML does not scramble it):

PRISM™
(Pressure Reactive Intelligent Spark Management)

Features:
•Optimized Spark Timing to achieve maximum brake torque

•Simple, fewer moving parts, fiber optic design

•Increased horsepower at all power settings

•Smoother engine operation- reduces coefficient of variation of combustion- even on lean mixtures

•More efficient engine operation-CDI produces larger spark at optimized time BTDC

•Replaces both magnetos- no overhaul required prior to TBO

•Fully redundant design- proven electronic durability with quad redundant ignition

•Includes GAMI's Supplenator™ Supplemental Alternator- back-up power to primary alternator and battery and GAMI's PDU™ Panel Display Unit

•Automatic detection/prevention of detonation

•Maintains lower peak cylinder pressures- reduced loads on power train components, longer engine life

•Allows for the future use of lower octane, unleaded fuels. This is the only system on the millennial horizon that is inherently compatible with lower octane, unleaded fuels.

•Champion® ignition components (spark plugs, wires, coils)

•Optional panel display of actual real-time horsepower and torque

•Optional digital tachometer

•Optional extensive on-board engine diagnostic capability

•Improved fuel economy- lower BSFCs than previously possible

•Significantly lower EGTs/TITs for reduced exhaust system maintenance

FAA STC certification expected soon!

It sure sounds better than LASAR since I can't get any real onboard diagostics.

Let's see, more HP, reduces variation of combustion, larger spark, improved fuel economy, lower EGTs -- Gee it must be an EI. Of course, yours does more than LASAR, but some of the fundamental concepts are similar.

So, when you say:

<<<>> 1. You mean the PRISM system doesn't use modern electronic ignition components and controls, including timing? <<

I am a bit confused by this comment, and I don't know what the reference was to this.

The issue is NOT how the spark is generated - - it can be a big box of quick matches set off by Santa's little helpers, for all I care - - but the issue is what is the effect of the nature and timing of the event that initiates combustion on the resulting important stuff that happens in the combustion chamber after the combustion event is started.>>>>>

I asked that question tongue-in-cheek. PRISM is clearly an EI. Unless you are the ghost writer for Richard Clarke, I find the "box of matches" comment to be disingenuous. You already know that a consistently presented and timed spark is crucial for combustion events better than "pretty good."

Later, you reply thusly:

<<<<<>> 3. Do you mean that the spark energy, shape, duration and consistency is of the same quality for electronic ignitions and magnetos? <<

No. In some cases, it is worse for electronic ignitions !!

But, properly done, electronic ignitions can improve on the important aspects of the initiating sparks that start the combustion events. It just requires that the electronic stuff be originally designed with a really thorough understanding of what is important about the combustion events. From what I have observed, this is not always the case. >>>>>>>>

Again, the "NO" would have been adequate. Of course, you have to qualify it with "some cases", fixed later with "Properly done" and deflated later with "this is not always the case. Frankly, I am only presently concerned with my case and the data which I am capable of collecting. I am trying to learn but there is no learning when you try to tell me only how things fail to work.

Then, you replied:

<<<<<<>> 4. Are you telling me that our excess fuel delivery systems are so good that no combustion is occurring in the exhaust pipe near the EGT probe? <<

No. Not sure how that plays into this discussion. Later effective combustion ignition events will result in higher EGTs. Earlier effective combustion ignition events will result in lower EGTS, assuming nobody has changed the camshaft in the mean time!>>>>>>>>

Uh, "Not sure how this plays into the discussion." It seems to me that it is critical to part of this discussion. I guess "later combustion ignition events" could be where one of the flame fronts doesn't get started at all. "In some cases," this could even be from timing mismatches between magnetos, not to mention the occasional failure to fire at all. Anyway, "No" is helpful.

Finally:

<<<<<>> 5. Do you mean that magnetos deliver a consistent spark (time, duration and strength) 100% of the time when one manufacturer states that there can be magneto spark impairments of up to 10% of the time? And, that this deficient combustion in the cylinder might lead to some combustion completion in the pipe? <<

No. ..........There is some variability in the magneto spark events and the electronic spark events. However, on properly maintained magnetos, it does not result in anything like the kinds of changes in EGTs that you are reporting.>>>>>>>>

Well, we shall see from the tests that I am going to run. BTW, what kind of EGT drops are seen with PRISM? I know they occur because PRISM claims a "significant" drop. Unison predicts 70-90 degrees on the LASAR (if I remember correctly). Maybe this is what Cy meant by "relative."

I look forward to the duel between my mags and the EI. Each slugging it out in the bowels of my wee cylinders, head studs struggling to restrain piston and pin from separating -- with fuel, spark and air combined properly to constrain the potential runaway chain-reaction from endangering any planet earth species that happen to be in the vicinity. Carpe Diem!

Scott Krueger

PS, Yes, Walter was a bit cryptic. "Most" people probably wish I were, too.

PPS I do hope that the EI and electronic injection systems on my 1800cc twin-v motorcycle are OK - I don't like where one of the jugs is aimed. Of course, the CU utilizes at least the MAP, RPM, Induction air temp and an O2 sensor in the exhaust to optimize HP and Torque through a wide range of throttle positions, especially when twisted to WOT.