I can speak to this, owning a Jabiru and having flown it coast to coast. The Jabiru has a bing carb, which is altitude compensating with no mixture control in the cockpit. It uses a tapered draw-needle for metering. The taper on this needle has been modified by jabiru over time. Early ones provided very rich mixture at full throttle for take-off to prevent detonation. The extra-rich region has been toned down over time as, reportedly, was deemed safe. But yes the stock Jab carb goes rich at WOT. Come back just off WOT and you get normal EGT's. I burned just over 5GPH using high cruise throttle settings and the old style needle (and was going 100MPH, the Avid is a draggy airplane). Others in my user group see under well under 4GPH in cruise. Now, if I left it at WOT and looked at fuel flow, could that extra rich region use 7GPH? I would say that is not impossible at all, but never measured it as I dont have a fuel totalizer unit.
> CC: ml at n56ml.com > > Colin Hales wrote: > > >>My 75 hp 2.2 Jabiru Powered KR2 does 148 mph flat out burning shed > loads of fuel. 7 Gallons an hour. << > > Don't Jabirus have a mixture control? Apparently not. My bone-stock KR2 > with a 75 hp VW 2180 burns 4.0 US gph (3.33 UK gph) at 148 mph, > throttled back a bit to conserve fuel, turning 3150 rpm. Whether you > are talking US or UK gallons, the Jabiru appears to be wasting a lot of > unburned fuel out the tailpipe. Perhaps your KR2 is draggier than > mine, but double the fuel consumption at the same speed seems extreme. > I'm talking true airspeed at lower medium (maybe 4500') altitudes. You > may be talking about some other kind of airspeed. > > Mark Langford
