Perry, just wondering if you know fuel burn at full throttle.  If the engine
is tuned well (good Ve), it can burn double the fuel rate you mentioned at
5000 - 5300 at full throttle.  I'm assuming that you are well below WOT at
5300?

Tracy Crook

No I don't, I guess that's where a fuel flow monitor be a nice thing to
have.  No, not well below WOT at 5300.
WOT was 5500 before the recent mods, down to about 5400 now.  The mods
are going well to shorten the runners, so we'll see if I can get some of
that back. I mainly want the power back for climb.  Climb RPM at 90
knots decreased from 5200 to 5100 and it is noticable.

--
Perry Mick

Tracy I might add that Perry is using the stock computer and mass airflow
sensor so he has no direct control over the mixture in case you were thinking
of an conventional aircraft system. Is that still correct Perry?

Paul Lamar

Yes it's true, I have a fake FADEC. Also, if the engine was capable of
large fuel consumption, wouldn't that also indicate it would be capable
of high HP output?  My engine just isn't putting out that much HP.  If I
did the calcs right 6.5 gph is 87 HP and 7.5 gph is 100 HP.  If my
engine is capable of 120 HP max, that would be a max burn rate of 9 gph
- consistent with observations.

If it was actually burning double-rate WOT, 15 gph --> 200 HP, that's
not what I'm experiencing!

--
Perry Mick
Custom Composite Props
mick@bridgingworlds.com
http://www.ductedfan.com

What numbers are you using for BSFC Perry?

Lets see 15 GPH is  90 pounds per hour so 200 HP at 90 pounds is
0.45 I don't think it is that good. Lets try 0.5 so 6.5 GPH is 39 pounds divided
bu 0.5 is 78 HP. 7.5 GPH is 90 HP. Something wrong there somewhere.

Perhaps your computer is keeping it too lean. We need more data
like MAP, EGT and O2 sensor data. 

If you assume the torque curve is flat, as Al 
noticed on the dyno, the HP will be a straight line function 
of RPM. If you had 185 HP at 6000 RPM you should 
have 154 HP at 5000 RPM. If it were 170 HP at 6000 RPM it should
be 141 HP at 5000 RPM. All at wide open throttle and best power
mixture.

Have you checked the tach for accuracy?

 
Paul Lamar
 
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