Common SIB engine WOT consumption?

Max... · 27 June 2013, 08:55

I cannot remember if I saw something on here once but does anyone have guideline fuel consumption figures for typical 3.5m SIBs' with common engines at WOT (say 16 to 20 kts) and 2/3 (12 - 14 kts) throttle or so in gallons per hour or whatever?

Tohatsu 9.8
Yam 15
Mariner 15 etc?

Glow · 27 June 2013, 09:14

I seem to recall the Tohatsu being 4.5l/h at WOT

AJ. · 27 June 2013, 09:19

Quote:

Originally Posted by Glow

I seem to recall the Tohatsu being 4.5l/h at WOT

+ 1 - Think Willk published that

Glow · 27 June 2013, 09:24

I think your right

Locozodiac · 27 June 2013, 15:24

For 2 strokes around 12% of it's rated HP per hour work at wot. A 15 HP will consume around 1.8 (3.80) gal/per hour and that's with lightly loaded boats.

For strokes probably 30-35% less...

Happy Boating

AJ. · 27 June 2013, 15:31

Quote:

Originally Posted by Locozodiac

For 2 strokes around 12% of it's rated HP per hour work at wot. A 15 HP will consume around 1.8 (3.80) gal/per hour and that's with lightly loaded boats.

For strokes probably 30-35% less...

Happy Boating

Hi Loco,

Sorry for the dumb question maths is never my strong point how did you get from 1.8 to 3.8 gph?

Max... · 27 June 2013, 15:40

Cheers guys, is there a formula for 1/2 or 2/3 throttle etc...?

Quote:

Originally Posted by AJ.

Hi Loco,

Sorry for the dumb question maths is never my strong point how did you get from 1.8 to 3.8 gph?

I think one US gallon is smaller (by 0.8)?

Locozodiac · 27 June 2013, 15:44

Sorry forgot to state, the engine consumption charts are based on US (3.80) Gal, if not mistaken you guys use 4.0 lt/gal right. Those are Tohatsu/Merc numbers, Yam probably slight more consumption.

Happy Boating

Max... · 27 June 2013, 15:52

Quote:

Originally Posted by Locozodiac

Sorry forgot to state, the engine consumption charts are based on US (3.80) Gal, if not mistaken you guys use 4.0 lt/gal right. Those are Tohatsu/Merc numbers, Yam probably slight more consumption.

Happy Boating

1 UK gallon = 4.55 EU litres

Or approx £6.20...

Locozodiac · 27 June 2013, 17:45

Quote:

Originally Posted by Max...

1 UK gallon = 4.55 EU litres

Or approx £6.20...

Is that a real bad fuel price, our local premium 95 octane E8 ethanol blended fuels are equivalent to US $ 5.60 per 3.8 Lt/Gal. Horrible numbers too, that's why not planning in a neart or distant future running engines passing 18 HP which are top for my boating applications.

Happy Boating

Max... · 15 July 2013, 19:03

Loco I never did work out exactly what you meant for the 15.

Anyone else running a yam or mariner 15 on a 3.5m or similar SIB give actual WOT consumption?

smitty477 · 15 July 2013, 19:14

"Loco I never did work out exactly what you meant for the 15."

What loco was saying is this....

15 HP times 12% of that is the fuel use at WOT in GPH for a two stroke.
15 X 0.12 = 1.8 GPH

Or sometimes its easier to think of it as 8.33 HP per gallon of fuel used per hour for uses of various HP motors and/or at partial throttle settings.

So with a 4 stroke that would be more like 12 HP per gallon of fuel used per hour.

Hope this helps

John Kennett · 15 July 2013, 21:58

Quote:

Originally Posted by smitty477

15 HP times 12% of that is the fuel use at WOT in GPH for a two stroke.
15 X 0.12 = 1.8 GPH

And those are US gallons of 3.8 litres each...

Another way to look at those figures is about half a litre per HP per hour for a 2-stroke running flat out.

prairie tuber · 16 July 2013, 05:48

Quote:

Originally Posted by John Kennett

And those are US gallons of 3.8 litres each...

Another way to look at those figures is about half a litre per HP per hour for a 2-stroke running flat out.

That sounds about right for my 2 stroke Yamaha 40.