Fuel Consumption 4-108

[bletso]

It's been too long. What can I expect for fuel consumption on a Perkins 4-108 either gals/hr or ltr/hr at say 1800-2200 rpm

[Downhill]

mine is using 0.5 gallons / hr at 1000 rpm

[model 10]

3/4 gph

[DeepFrz]

Try google custom search.

[CSY Man]

0.6 gallons per hour @ 2100 RPM with a proper wheel. (Not Over-Propped)

[hpeer]

Someone here once said .05 gal per hp per hour. Or .5 gal/10 hp/hr. That seems about right to me.

So what hp is your engine producing at that rpm?

[onestepcsy37]

37' cutter, 20000 lbs, full keel, 12x17 3 blade prop, perky 4-108. at 1700 rpm - my regular cruising speed - i get 3/4 gallon an hour at 6 knots.

been keeping a written engine log for the past ten years...

[Stu Jackson]

Originally Posted by hpeer

Someone here once said .05 gal per hp per hour. Or .5 gal/10 hp/hr. That seems about right to me.

So what hp is your engine producing at that rpm?

21 hp Universal - 0.5 gallons per hour NOT per 10 hp.

been keeping a written engine log for the past ten years...

Me, too.

Now that you've asked, start your own fuel log and keep track. That's how we did it for our boats and engines.

[hpeer]

I doubt you are running your engine WOT and at rated HP all the time.

What HP does your engine produce at your normal operating rpm?

[model 10]

Originally Posted by hpeer

Someone here once said .05 gal per hp per hour. Or .5 gal/10 hp/hr. That seems about right to me.

So what hp is your engine producing at that rpm?

I believe it was 1/2 LB per hour per hp. Deisel weighs about 7 lbs per gal so that says I'm making a tad under 11hp @1800rpm. I use a gallon per hour at 2400 rpm and that works out to about 35hp.

[onestepcsy37]

i'm sure that hull shape and weight of boat make a big difference. so even with the same engine and rpm, two different boats could get quite different fuel consumption.

i began keeping an engine log because i couldn't get the engine hour meter to work. so i just began recording place of arrival, hours run, and gallons of diesel loaded when at fuel dock. over the years it's averaged 3/4 gal an hour...

[Cheechako]

I kept records on my Tanton/CT44 during ownership. The perkins averaged .65 gal per hour on that 44 ft boat. I seldom idled for battery charging on that boat, so most of that is moving at least. We had a max prop and the best smooth cruising rpm was about 2300-2400 if I remember right.

[Jesse]

.8 gph. at 2600 rpm

[SV Windrush II]

I'm at about .75 gpr at 2000 rpm on a Mariner 40 ketch, 12 tons full keel doing 6.5 knots.

[a64pilot]

Originally Posted by onestepcsy37

i'm sure that hull shape and weight of boat make a big difference. so even with the same engine and rpm, two different boats could get quite different fuel consumption.
.

No, fuel mileage, yes of course, but you will get the same fuel burn tied to the dock. All that matters is the BSFC of that specific engine and the HP it's making as noted above. Even operating RPM won't make as big a difference as you might think, it does of course make some difference, but you don't markedly increase an engines efficiency by over propping it.