In early June I wrote an email trying to get the answers to power/speed related questions.  I asked these questions because I was trying to get answers without much additional effort on my part.  The LML was posted with some answers and I got a few privately – all of which only raised more questions.  Over time I will try to expand on many of those, but only after the Kitty Hawk to OSH race is over.

 

This e-mail is the first of probably several on the LASAR ignition.  As advertised, LASAR claims CHTs will be 20 or so degrees hotter and EGTs about 80 degrees cooler.  They also claim better “gas mileage” or greater power.  Installed in the fall of 2001, over a period of about a month, I have said that I experienced “sprightlier take-off runs” and “exuberant climb rates”.  I also “felt” I had more power but this may have been cooler outside temperatures and psychological effects of new product afterglow.  In the spring of 2002 I ran a timed 202 Kts in the Sun 100 race, but in June of that year, I had my engine completely re-built (another long story) and did not fly it again until September of last year.  It seemed like a dog.  Finally, I replaced and calibrated the Pitot and OAT probes and, along with other cleanups, I was getting close to my prior indicated/true speeds – but not quite there.  Note that just recently, I solved a problem with the fuel flow sensor and it is now very accurate.

 

Recently, in preparation for the Cup race, I have been doing high power runs at different altitudes with unsatisfactory results and cooling problems.  Not dangerous cooling, but just hotter than it should be.  Finally, I had 60 hours on the engine and stable oil usage, a strong indication that it was broken in.  Still, I was fooling with cooling (rhyme unintended).  Anyway, it was these many puzzles that prompted my list of questions.

 

George Braly’s LASAR response was mainly correct, but did not make me “feel” any better.  In summary, he said

1. Hotter sparks (higher voltage, longer duration)…. Is marketing hype.
2. CHT/EGT effect is from advanced timing.
3. Most engines are over timed on takeoff with factory timing.
4. Advancing the timing further (sea level, std day) is probably counter productive with respect to HP and it is guaranteed to substantially increase the peak internal cylinder pressures in an undesirable way.
5. Spark advance at altitude can improve HP (running LOP).

 

A call to LASAR confirmed that the spark is from a higher voltage only at start (like Slick-Start) but is about the same as produced by magneto when the engine is running.  The representative would not reveal any timing information as it is “proprietary”, but the specs note that spark duration is 40 degrees and advance may be as much as 41 degrees.

 

 

So, last week I decided to start from scratch with some comparisons of running with either the LASAR or the mags and I wired a panel switch to do just that testing.  Also, I am not going to test takeoff or climb effects because collecting comparable data, by hand, in smooth air, in the summer is close to impossible.  For now, I want to report on some preliminary observations – before I talk to LASAR again.

 

                 &n bsp;  June 9         June 12 - BKL -> ARR

…LASAR  OFF    ON    OFF     ON

Barometer  29.87 same 29.97  same

P Altitude  8550   same 4500   same

D Altitude  9940   same 5500   same

Temp in C  26     same   19      same

…….MAP  23.1   same  24.8    same

…….RPM  2660  same 2480   same

.Oil Temp  176      ?      174      180

…….GPH  9.9     10.1   10.1      9.8

.Avg CHT  380    405    375      400

.Avg EGT 1340  1290   1310   1300

Deg ROP  100     100     90     Not releaned 

……..IAS  173    169     177      173

…….TAS  200    195     191      185

 

The preliminary says that I have harmed my performance in ways that George outlined above.  I will try to find the altitude at which the LASAR has some positive effect when running best power.  Maybe my ram air is confounding the LASAR?  Maybe it is not seeing the same sensor data I am (I can check this with my laptop)? The LASAR people said that there is a detonation buffer built in – maybe this is a negative effect?  I thought more power = more heat but, apparently, more heat does not equal more power.

 

More on this later.  If you are considering LASAR, wait a bit.  I chose LASAR for the benefits of an electronic ignition (timing advance) with the very straight forward backup of mags.  Well, I got the mags with an electronic ignition backup to keep my oil warm on cold days.