Rotax 503 fuel burn?

I am planning to use a rotax 503 on my plane. I have been reserching what to expect for fuel burn. Ive found anywhere from 4.5 to over 6 us gallons an hour. Those with time flying a 503 powered plane what did you average?

 

http://www.ecotrons.com/products/400cc_to_800cc_engine_fuel_injection_kit/

 

I average about 4.5 to 6 gal per hour depending on power setting.

 

Each and every Engine is going to be a little different account there is so many different Types of Aircraft Weights, as well as Pilot Weights, are different as Props used are different, as well as different People Fly at different Speeds/Rpms.

So don't be so vague in your Question, what Plane, what Prop, your approximate Weight? IF, your Plane of choice is under powered with a 503(50hp) it will have to work harder, IF it's Over Powered, it can turn lower rpms which usually mean better gph. Using EFI usually means a better gph. Just like Reducing Drag on your Airplane usually means a better GPH.

Here is the Dyno results of the Stock 503UL with Rotaxs UL Muffler and a 503UL with an R&D Tuned Pipe. Notice 49.8hp@6250rpms vs 62.3hp@6500rpms. IF, you don't need the extra 12.5hp, with the Tuned Pipe, use MAX 5250rpms for 51hp!
http://www.rotaxservices.com/dyno.html

 

Just like here is a Stock 277UL HP Comparison. Notice Stock made Max 25.4hp@6000rpms with Rotaxs Muffler vs 30.5hp@6250rpms with R&D's Tuned Pipe! At only 20% Increase that is even a Mild Tuned Pipe. Notice Fuel Flow didn't really change. With just a Muffler your losing a Percentage of Fuel right out the Exhuast! IF, you don't need that extra 5.1hp you could still make MAX 26.2hp@5500rpms!

 

Just like here is a Stock 582UL HP Comparison. Notice Stock 582UL made Max 64.7hp@6250rpms with Rotaxs Muffler vs 80.7hp@6500rpms with R&D's Tuned Pipe! At only 25% Increase that is even still a Mid Range Tuned Pipe. With just a Muffler your losing a Percentage of Fuel right out the Exhuast! IF, you don't need that extra 16hp you could still make MAX 64.1hp@5750rpms! Probably a True 65hp at 5800rpms.