I have repaired a fuel system fouling from last year and installed a flow meter to check fuel usage, we thought maybe someone was using the boat or stealing fuel but now I don't know. Anyways it is a 99 Tournament 192 with a 150 Yamaha SWS non fuel injected with a 4 blade prop fully loaded it runs 5000-5100rpm at 43mph and swallowing 22gpm if I reduce to 4000rpm at 33mph it drops to 12gpm. Does anyone have a similar set-up, I checked the Grady site but they list the boat with a 4 stroke at max fuel 14gpm. Gas is a little expensive up here to be burning through that fast but we gotta have fun. Thanks for any replies.
Fuel Consumption.
- Thread starter luvsno
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Something doesn't sound right....did you say 22 gallons per mile? Thats crazy....my sailfish with twin 150's burns about 1 gallon per mile at 22mph.....at 22gpm, you're basically throwing gas overboard with your bilge pump.....check those numbers or your gauge again.....maybe you mean 22 gallons per hour? That would be 2 gallons per mile roughly???
enfish
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Fuel burn seems high to me. On our 208 with a non-fuel injected 175 SWS Yamaha, 3-blade SS 15x17 prop, we get the following:
3600 RPM 8 GPH 21 MPH 2.6 MPG
4000 RPM 10 GPH 26 MPH 2.6 MPG
4400 RPM 12 GPH 31 MPH 2.6 MPG
5000 RPM 20 GPH 36 MPH 1.8 MPG
You can see our MPG curve is pretty flat until 4400 RPM, then it starts to suck fuel at a much higher rate, so we never run above 4400. I'd expect your numbers to be better than ours with a lighter hull and smaller motor.
3600 RPM 8 GPH 21 MPH 2.6 MPG
4000 RPM 10 GPH 26 MPH 2.6 MPG
4400 RPM 12 GPH 31 MPH 2.6 MPG
5000 RPM 20 GPH 36 MPH 1.8 MPG
You can see our MPG curve is pretty flat until 4400 RPM, then it starts to suck fuel at a much higher rate, so we never run above 4400. I'd expect your numbers to be better than ours with a lighter hull and smaller motor.
Two points:
1) I think you are a bit overpropped. You should reduce pitch by a couple of inches, or drop back to the recommended 3-blade prop.
2) Good rule-of-thumb for a 2-stroke engine is that WOT fuel burn will be aboiut 10% of the rated HP. That would be 15GPH for your engines, and despite your error with the units I think you were indicating 22GPH. Even for the old carbed SWS engines, that seems far too much.
NOTE: See point one about being overpropped and overloading the engine.
1) I think you are a bit overpropped. You should reduce pitch by a couple of inches, or drop back to the recommended 3-blade prop.
2) Good rule-of-thumb for a 2-stroke engine is that WOT fuel burn will be aboiut 10% of the rated HP. That would be 15GPH for your engines, and despite your error with the units I think you were indicating 22GPH. Even for the old carbed SWS engines, that seems far too much.
NOTE: See point one about being overpropped and overloading the engine.
Of course, we should all be aware that fuel consumption calculations done in the hot summer air will not be as good as calculations done in the winter..
my mistake
Yes thank you all, it was gallons per hour and yes it equated to 2.5 miles per gallon. I use the 4 blade because we have to load up and travel by boat to cabin on an island, the boat jumps out of the water and onto plane. We also have some narrow tight turns where with the 3 blade the boat would fall off and you have to start again. The 4 blade keeps us up down to about 22 mph. I am going to attach a 5 gallon can and do 1 run up empty and see how close the calibration is.
Yes thank you all, it was gallons per hour and yes it equated to 2.5 miles per gallon. I use the 4 blade because we have to load up and travel by boat to cabin on an island, the boat jumps out of the water and onto plane. We also have some narrow tight turns where with the 3 blade the boat would fall off and you have to start again. The 4 blade keeps us up down to about 22 mph. I am going to attach a 5 gallon can and do 1 run up empty and see how close the calibration is.