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Posted for "Al Gietzen" <alventures@email.msn.com>:
Tracy wrote:
ran well below best power mixture in the
Sun 100 race (16.5 GPH) and stayed ahead of half the 180 HP RVs. BTW; Tracy, what EGTs were you showing at that point. What
do you get at best power?
Al
EGT during race was around 1650 (LOP). Best
power is around 1750.
Tracy
Hum-m-m; based on my results, these EGTs seem a bit on the high side. I
found best power EGTs (WOT) about as follows: 5000 rpm - 1560, 6000 rpm -
1630. What does it mean?
I finally have what little fuel consumption data we managed to get: here is
an excerpt from the dyno report I've written up: (hopefully this stays
formatted in the e-mail)
FUEL CONSUMPTION
The fuel consumption data was very limited because of a high degree of
scatter caused by poor flow meter performance. The computer logged data for
this parameter was essentially unusable. Some good data was measured by
doing timed runs, i.e.; set up a steady state engine operation and take
weight readings of a fuel supply container at one minute intervals for five
or more minutes. The number of these runs was limited to 4 as these were
the last tests we were doing and ran out of time. The results are as
follows:
RPM Mixture MAP ("Hg) Avg EGT (F) HP BSFC mpg
5,100 WOT Max pow 26.6 1,570 220 0.52 12.5
5,100 Leaned 23.8 1,556 155 0.49 16.9
5,000 Max pow 24.8 1,544 200 0.54 12.9
4,550 Max pow 21.8 1,488 150 0.55 15.6
The target operating points were 1.) 5000 rpm WOT, 2.) 5000 rpm, 24" MAP
about 150 lean of peak, 3.) 5000 rpm, 200 hp, and 4.) 4500 rpm, 22" MAP.
The max power mixture setting was approximate, and was typically with a
lambda of about 0.94, and maybe 100 - 150 degrees rich of peak EGT. The
"leaned" run was done at about the same amount lean of peak. The leaned run
may have no relevance in actual operation with a prop because rpm was held
as mixture was reduced by varying load while trying to maintain about 24"
MAP. Power dropped significantly, but estimated fuel economy is clearly
improved.
The BSFC values seem good; pretty much in line with expectations for a
rotary engine. The miles/gal values were computed using the Velocity
factory values of airspeed (given for 75% power with a 200 hp Lyc) as a
reference and adjusting it by the cube root of HP. AL
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