rough outboard consumption rates, 2 hp 4 stroke, (honda BF2B)

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TactilePaul

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hi, after using about 10 minutes of valuable laptop power I have been totally unable to get a rough figure here, in l/hr, gallons per minuite, ounces per mile, NOTHING!!!
I have scrolled through the manual, nothing, I eventually found a comprehensive review on an American boating site, got exited when i found the paragraph entitled, 'fuel usage', their statistic?; "it can get from one end of the Anderson reservoir to the other on one gallon!!"
please help me avoid measuring the flippin Anderson reservoir on google wherever that is, just a rough guide of range or l per hour for any 2hp 4 stroke will do, I have a day to kill in poole harbour and petrol that needs using up , as its 2 years old!!
thanks..
 
yes it does sound very un environmental, but without a petrol car to dilute this old fuel, i have no choice, I would like to make it up to wareham and back ideally..
 
goldcrest said:
yes it does sound very un environmental, but without a petrol car to dilute this old fuel, i have no choice, I would like to make it up to wareham and back ideally..
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If it's a post 99 2 hp Outboard with a centrifugal clutch do not use 2 year old fuel in it. There are no valve seats in this model and you will do damage
 
I am guessing your intention is to mix the old fuel in with some fresh fuel ?
I suggest you carry fresh fuel separately just in case the engine doesn't like the old fuel.
The fuel consumption will greatest if you run flat out ! Maybe two litres per hour?
 
If you guess 300g per kWh as typical petrol engine efficiency, 2hp flat out might be 450g/hr or so, density say .75 so maybe 0.6 litres/hr.
Maybe being such a small engine it's less efficient, may be need to add a % for gearbox loss?
But it will probably overheat if you drive it flat out for that long.
 
The good old Imperial rule of thumb is 15 bhp.hours per gallon for petrol 4 stroke, 10-12 for petrol 2 stroke and 20 for diesel. That's actual power generated. I would never run a Honda o/b at more than about half power (too noisy) so atthat rate it's 13 hours per gallon or 2.9 hours per litre. Allowing for the probably lower efficiency of such a small engine say 2.7 hours per litre.
 
At WOT - 1 litre per HP per hour.

At cruising speed - 1litre per NM

Typical values that apply to RIBs. Not sure how well that matches at low range. Hull will matter a bit.
 
We're 900NM into this season, not yet used 5l of NEW fuel this year, despite landing all over the outer hebrides. We have a Mariner 3.3 outboard- a replacement for a 2 HP Yamaha of 80s vintage. No appreciable change in consumption. We never run outboards at other than walking pace , so perhaps no surprise?
I would never use old petrol with an outboard- that's just asking for grief!
 
lw395 said:
If you guess 300g per kWh as typical petrol engine efficiency, 2hp flat out might be 450g/hr or so, density say .75 so maybe 0.6 litres/hr.
Maybe being such a small engine it's less efficient, may be need to add a % for gearbox loss?
But it will probably overheat if you drive it flat out for that long.
Click to expand...

Yet small outboards are designed to be run flat out.
 
Mikedefieslife said:
Yet small outboards are designed to be run flat out.
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In relatively short bursts, perhaps.
Thrashing an outboard just to get rid of fuel is pretty daft IMHO.
There's also a difference between 'flat out' as in 'at designed speed' and 'loaded to max power'.
 
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