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14.5 GPH...

mdmba

Active Member
just got a new GTN 650/345 installed...and i flew it today...and looked down and noticed i was 'burning 14.5gph at 2400/24 on the G3X...yikes. i sure hope its an error in the calibration...engine has 200hp...

looks like ill get to fly some more and see it thats real...

175K GS..

BTW..RV-8 is amazing...its new to me..and i LOVE LOVE LOVE it!
 
According to my calculations for a stock IO-360-A, -C, -D, -J, -K/AIO-360:

2400 RPM, 24.2 MP, 4500 Altitude, 46 F, Leaned for best power 75% = 12.2 GPH.

What was your TAS?

I also have an RV-8 and agree they are amazing airplanes.

Mine is a parallel valve IO-360 with high compression pistons. Those numbers seem pretty close, maybe slightly high for that power setting.

Got any pictures of your panel/plane you'd like to share?

Have fun, fly safe.
 
Ball park.

Yep, you are in the ball park with this. We run an IO-360 set-up to put out around 191-195 Hp. and these figures are very close to ours at 75%. If it is new to you it will take some time to get used to leaning for best power and LOP. I think you will like it even if you do burn a little more than you expected too. Hope this helps, Yours, R.E.A. III #80888

P.S. You may wish to keep in mind that no one of these RV's are a carbon copy of another. And that fuel systems and engine age also very a lot from aircraft to aircraft. You'll be fine, go have some fun.
 
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just got a new GTN 650/345 installed...and i flew it today...and looked down and noticed i was 'burning 14.5gph at 2400/24 on the G3X...yikes. i sure hope its an error in the calibration...engine has 200hp...

looks like ill get to fly some more and see it thats real...175K GS..

Marlon, we can help you get dialed in, if you supply the necessary information.

(1) Gallons per hour is a data point, but as the others have noted, we also need some idea of mixture state. That means referencing EGT to peak EGT in degreesF lean or rich of peak, or at least a notation of "Full Rich", or "Best Power" (ballpark 100~125 ROP).

(2) Calibrate the true airspeed indication on the GX3. That means flying some NTPS 3-leg runs to gather data. Download the "GPS PEC spreadsheet" at the link below. The inputs are groundspeed and track (not course or heading).

http://www.ntps.edu/information/downloads.html

(3) Need some idea of altitude. Generally max speed is found down low, max efficiency up high.

Is this stuff important? If we assume the reported groundspeed (175 knots) is your actual true airspeed, and 14.5 GPH is your best fuel burn to achieve that speed, well, your RV-8 looks like a pig.

Yes, I'm pulling your chain. However, there is room for improvement. Here's 70% on an IO-390, best power mixture (note EGT indications between 105 and 125 rich of peak). I had the power turned up more than usual, as we were bucking a 32 knot headwind, and I'd told friends a specific arrival time. True airspeed is 194 knots, on 12.4 gph, at near gross weight.



Here is roughly the same speed (175 vs 178) on roughly half the fuel burn, running up high and 25~30 LOP.

 
Question

Dan

It does not compute, left tank and right tank volumes do not add up to the combined total on your display.

Why or am I missing something

Rob
 
Dan

It does not compute, left tank and right tank volumes do not add up to the combined total on your display.

Why or am I missing something

Rob

The left and right levels come from the float gauges; the total comes from the fuel flow totalizer. The pink diamond on the Total column is the sum of the left and right floats, so you can easily compare the two measurements.
 
What Bob said. The totalizer is primary. The float sender values are not of much interest to me until less than 10 total, or if one dropped to a value below where it should be at that stage of the flight. Mostly I use them to make sure the tank selected for landing is the fullest.
 
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