found this reply from vans when asked about projected fuel burn of the RV-14, on the vansairforce site.
"Since there are no owner built 14s flying yet, there aren't a lot of real world numbers. I've
flown the airplane on one 1400 mile trip and a lot of shorter trips, and generally plan on 10
gph overall. In cruise, at altitude we can do a bit less -- around 9 gph for 155-160 KTAS. IT'll
give you 170 KTAS, but the fuel burn will be about 12 -- so we rarely push it that hard. With
the injected IO-390 and good instrumentation, we're quite happy running it lean of peak at
altitude.
For the same 155-160 speed the smaller RV-9 burns about 7.5 and the RV-7 about 8 at
altitude. The 9, with no need for aerobatic roll rates, has a higher aspect ratio wing and it's
efficient cruise altitude is a bit higher, resulting in better economy.
Understand that these numbers are very general. The pilot has ultimate control and one
person's figures can easily be different by 15% -- or more.