Hey Wayne, You may have included this in the past, I don't recall, but what sort of RPM are you turning at those fuel burn rates?
I assume your Mph figures are statue yes? For those who think in Nautical here's the conversion:
(.869 factor)
111 KTS on 8.4 GPH at 3500? MSL
123 KTS on 7/8 GPH at 12,500?
112 KTS at service ceiling of 17,800'
