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Gami's reply to my question. 300hp!
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Subject: RE: bsfc?
Author: "George Braly" <SMTP:gwbraly@gami.com>
Date: 8/2/2004 10:58 AM
Marc,
>> 17 hours of turbo-normalized operations in the last three days -
all
lean of peak TIT. Altitudes from 3000 MSL to 18,000 and everywhere in
between. ADH to ORL to PNE to ADH (55Kt headwind) ... headwinds on
two
of three legs. Average power? 92.5% of rated 300 HP continuous in
cruise.
Average torque? ~ 102% of rated torque; hottest CHT = ~ 378; TIT =~
1505
to 1525F; and normal BSFC = ~ 0.385 lbs/hp/hr.<<
That is the correct quote (note, 300 Hp, not 200). I made the flight
back in May. The cylinders on that engine have been operated that way
now for about 1400 hours.
The BSFC of 0.385 is the normal BSFC for that engine when operating at
high power and 50 to 80F LOP, which is where the observed BSFC(min)
for
that engine happens on a high power mixture sweep.
0.385 is pretty standard for a high compression (8.5:1) big bore TCM
engine, according to TCM's own published data which we have confirmed
on
our test stand.
And, yes, 0.385 is very good, and most people do not appreciate how
excellent our aircraft engines are in this regard when properly
operated
at high power while lean of peak. For example, the Porsche Mooney
(geared) engine would only do about 0.42 to 0.425, even when LOP. In
that case, the overall smaller size of the engine, the higher RPM,
and
the gear box are what makes the difference.
Regards, George
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