Al Gietzen wrote:

 WOT

RPM       Mixture   MAP ("Hg) Avg EGT (F)   HP     BSFC    mpg

5,100     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 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 miles/gal values were computed using the Velocity factory values

of

airspeed as a reference and adjusting it by the cube root of HP.

Al, At what altitude and temperature was the dyno? It appears you are
losing
MAP/power because of the air cleaner and or a pressure drop across the
butterfly
valves.

Paul Lamar

No air cleaner.  Only the first run was WOT; the rest partial throttle.
Altitude is about 1400'.  Baro pressure at the time of the first run was
28.87.  I double checked the MAP for that run; should actually be 26.8.
The HP is corrected to std press/temp.

The Map sensor ports are about 1/2" downstream of, and directly in line
with the butterfly shaft.  I wonder if high air velocity results a lower
pressure at the port (turbulence, vortices, and all that) than the true
static pressure in the free stream.

Al

I guess it is too late to measure it up stream from the throttle bodies.

Paul Lamar
 
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