Outboard Motor Mileage

Approximate Fuel Consumption of an Outboard Motor

A number of factors influence outboard motor mileage; things like hull shape, weight and sea state. Generally speaking at Wide-Open Throttle, a gas outboard motor burns about 10-percent of its rated horsepower. So a 100-horsepower outboard motor would burn about 10-gallons per hour at Wide-Open Throttle. Naturally, at a lower rpm, less horsepower is generated and therefore less fuel is consumed.

Horsepower

max RPM

Gallons burned per Hour

Liters burned per Hour

2 (4-str)

5,000

0.24

0.9

2.5 (2-str)

4,500

0.4

1.4

3.5 (2-str)

4,750

0.5

1.7

3.5 (4-str)

5,500

0.4

1.4

4 (4-str)

5,000

0.4 1.5

5(2-str)

5,000

0.7

2.5

5(4-str)

5,000

0.5 1.7
(4-str)

5,500

0.5 2.0

8 (2-str)

5,000

1.1

4.3

8 (4-str)

5,500

0.85

3.2

9.8 (2-str)

5,500

1.3

4.9

9.8 (4-str)

5,500

1.0

3.8

9.9 (2-str)

4,900

1.5

5.5

9.9 (4-str)

5,000

1.1

4.0

15 (2-str)

5,500

1.9

7.3

15 (4-str)

5,500

1.5

5.5

18 (2-str)

5,500

2.2

8.5

18 (4-str)

5,500

1.5 5.7

25 (2-str)

5,500

3.3

12.5

25 (4-str)

5,500

2.3 8.7

30 (2-str)

5,500

3.4

13.0

30 (4-str)

5,500

2.6 9.8

40 (2 cyl)

5,500

4.5

17.0

40 (3 cyl)

5,350

4.5

17.0

40 (di)

5,500

4.0 15.2

50 (3 cyl)

5,500

5.2

21.0

50 (DI)

5,500

5.0 19.0

60 (2-str)

5,250

6.3

24.0

70 (2 cyl)

5,250

7.7

29.0

70 (3 cyl)

5,500

7.4

28.0

70 di

5,500

6.4 24.2

90 (2-str)

5,250

9.5

36.0

90 (di)

5,500

8.5 32.0

115  (2-str)

5,450

13.2

50.0

115 (di)

5,500

12.0

45.5

140 (2-str)

5,450

15.3

58.0

 

di = direct injected two-stroke.

2-str = conventional two=stroke