T&T: Diesel fuel consumption

[Rock Bradford]

It really depends on the engine, doesn't it?  I have a Gardner 8LXB, 170 hp
@ 1150 rpm and at cruise speed, 8.5 kts. it burns 3.5 gph.  The engine is
also pulling a 8 kw cruise generator (belt driven), a 100 amp Electrodyne
alternator and hydrostatic hydraulic pump for the windlass and bow
thruster.  The Gardner is turning a 42" wheel.  Since the equations
proffered here, when applied to the Gardner, give a figure of 9+/- gph, the
only way I found out for certain was to install a Floscan , which answered
the question once and for all.   Wish all of you a happy new year.

Rock Bradford
44' Cygnus / "Magpie"
Georgetown, SC

On 12/31/06, LRZeitlin@aol.com <LRZeitlin@aol.com> wrote:
>
> It is hard to come up with a precise formula for the amount of fuel a
> diesel
> burns per horsepower per hour. The specific fuel consumption varies with
> engine size, rpm, loading, and the energy content of the fuel. Typically
> larger
> engines are more efficient than smaller ones because of lower heat losses.
> The 4
> cylinder, 54 hp Yanmar diesel burns .055 gal/hr per hp output while the
> one
> cylinder, 9 hp Yanmar requires .066 gal/hr per hp. This is a 20%
> difference in
> favor of the larger engine. Bigger engines are a bit more eficient.
>
> Engines are also most efficient near the middle of their operating range.
> Engines burn more fuel per hp at low output because of frictional losses
> and more
> fuel at the top end because of breathing and air pumping losses.
>
> The best formula is no formula at all. Just assume that the average diesel
> burns .06 gal/hr per horsepower output. That should be close enough for
> most
> purposes.
>
> Happy New Year to all.
>
> Larry Z
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