A carbureted outboard usually consumes approximately 10% of its horsepower
in gallons. So your 115 horsepower engine would burn roughly 11.5 U.S.
gallons at full throttle.

The four stroke usually burns about 30% less than that and same with the
direct fuel injection like FICHT would burn equal to 4 stroke. The savings
is the stroke no longer allows the unburned fuels to exhaust out and pollute
while it evacuates the cylinder.






"RB" wrote in message
...
What is a good GPH fuel consumption number for my 4 cyl 115hp Johnson o/b
for sizing a fuel/water separator? I have a choice of either 30 or 60. I
think the 30 should be more than adequate, but not certain. The good
news
is they're only $5 apart in price, so I'll probably get the big one just
to
have it if I ever need to put it on a bigger engine.