How Much Fuel Used per Revolution of the Engine ???

[tpenfield]

Ever stop to wonder how much fuel is used for each revolution of your boat engine (assuming 4 stroke) or even the complete 2 revolution cycle of the engine? . . . and what that comes out to be for each firing of the piston? . . . maybe a drop or less???

I know, it is a slow day. . . and the kids are home from school, so I am not allowed to watch football. . . .

 

[Another retired guy]

Re: How Much Fuel Used per Revolution of the Engine ???

Wait until you're retired - then you'll experience a whole bunch of slow days!! Are you going to do the calculations

 

[HT32BSX115]

Re: How Much Fuel Used per Revolution of the Engine ???

Ever stop to wonder how much fuel is used for each revolution of your boat engine (assuming 4 stroke) or even the complete 2 revolution cycle of the engine? . . . and what that comes out to be for each firing of the piston? . . . maybe a drop or less???

I know, it is a slow day. . . and the kids are home from school, so I am not allowed to watch football. . . .

In so many words, the term is BSFC (Brake Specific Fuel Consumption)

Simple calculations can put it in terms of gal/ltrs/ml/fluid oz/ etc PER rev.

 

[Tail_Gunner]

Re: How Much Fuel Used per Revolution of the Engine ???

Ever stop to wonder how much fuel is used for each revolution of your boat engine (assuming 4 stroke) or even the complete 2 revolution cycle of the engine? . . . and what that comes out to be for each firing of the piston? . . . maybe a drop or less???

I know, it is a slow day. . . and the kids are home from school, so I am not allowed to watch football. . . .

You too huh...I have been banned to the cave with the volume at a certain level so the wife and girls can converse. Actually i am going to repaint my boat...that ought to get a few ohhh myy goddss

 

[Bondo]

Re: How Much Fuel Used per Revolution of the Engine ???

Ayuh,... I guess you guys don't burn wood for winter heat, huh,..??

Blacktop season ended last Wednesday, 'bout 3pm,...
I've been out back in the wood pile ever since,...
I've got 'bout 1/4, to 1/3 of what I'll burn for the season, put up...

Regardless how much fuel is burnt per piston stroke,...
There's been Toooo many times I've been a teaspoon Short...

 

[tpenfield]

Re: How Much Fuel Used per Revolution of the Engine ???

OK, let's see if I can figure this out . . . (still not allowed to watch any of the football games on the big TV) . . .

Fuel consumed per 2 revolutions (1 full cycle) of the engine while cruising. . . and also fuel consumed by each firing of a piston.

My Boat = Formula 330SS. . . Engines = 2 X Merc 7.4 LX MPI

According to BoatTest.com it gets about 1.5 mpg while cruising . . so let's say 30 mph and 2800 rpm. (I think that is about right)

each engine is getting 3.0 mpg while cruising 30 mph @ 2800 RPM. (So, I'll just do the calculations for 1 engine)


(30 miles/hour) / (3.0 miles/gallon) = 10 gallons / hour

(10 gallons / hour) / (60 minutes/hour) = 0.1666667 gallons/minute

(0.1666667 gallons/minute) X (128 ounces/gallon) = 21.333 ounces/minute

(21.333 ounces/minute)/(2800 revolutions/minute)X(2 revolutions/full cycle) = 0.015238 ounce/full cycle

(0.015238 ounce/full cycle) / (8 cylinders / full cycle) = 0.001905 ounce / cylinder

How many 'drops' per ounce ????

 

[tpenfield]

Re: How Much Fuel Used per Revolution of the Engine ???

Ayuh,... I guess you guys don't burn wood for winter heat, huh,..??

Blacktop season ended last Wednesday, 'bout 3pm,...
I've been out back in the wood pile ever since,...
I've got 'bout 1/4, to 1/3 of what I'll burn for the season, put up...

Regardless how much fuel is burnt per piston stroke,...
There's been Toooo many times I've been a teaspoon Short...

Is there a fair amount of marine repair work to do over the winter?

 

[tpenfield]

Re: How Much Fuel Used per Revolution of the Engine ???

Ayuh,... I guess you guys don't burn wood for winter heat, huh,..??

Regardless how much fuel is burnt per piston stroke,...
There's been Toooo many times I've been a teaspoon Short...

According to my calculations . . . a teaspoon would last about 1/2 second

 

[Bondo]

Re: How Much Fuel Used per Revolution of the Engine ???

Is there a fair amount of marine repair work to do over the winter?

Ayuh,.... Eric pulled 2 of his own Highliners yesterday, 'n dropped 'em off here in the yard for drainin',...
I'll move 'em to a warehouse later,...

The lower gear case on 1 of 'em looks like it's been rubbin' on a rock the last few weeks,...
Not through, as the oil is still oil, but she's darn thin... flat sided by the bullet nose...

He's had a good season on the SEI I bolted on earlier, on the other Highliner, so I'll talk 'im into another 1 for this boat,...
Good thing anyways,...
The drive on it is for a V6....
The right ratio, 'n smaller prop will make it a nicer runnin' hull...

Some of the projects will move forward,... Heat is the issue for some of it,...

 

[HT32BSX115]

Re: How Much Fuel Used per Revolution of the Engine ???

Ayuh,... I guess you guys don't burn wood for winter heat, huh,..??

Blacktop season ended last Wednesday, 'bout 3pm,...
I've been out back in the wood pile ever since,...
I've got 'bout 1/4, to 1/3 of what I'll burn for the season, put up...

Regardless how much fuel is burnt per piston stroke,...
There's been Toooo many times I've been a teaspoon Short...

cutting/splitting your own wood warms you twice!

My neighbor brought me some used oil a few days ago for my shop furnace (Lanair HL-140 waste oil furnace) My 200 gallon tank is almost full! I just LOVE that thing!

 

[Bondo]

Re: How Much Fuel Used per Revolution of the Engine ???

cutting/splitting your own wood warms you twice!

My neighbor brought me some used oil a few days ago for my shop furnace (Lanair HL-140 waste oil furnace) My 200 gallon tank is almost full! I just LOVE that thing!

Ayuh,... I've got 3, 55 gallon drums fulla used oil, 2 of which are reasonably clean used Hyd. oil...

You can have 'em, if ya wanta come get 'em,...

I was gonna mix it into my #2 boiler oil to stretch the expensive stuff, but don't wanta deal with the added burner cleanin'...
Especially that I'm now burnin' Free wood...

Well,... maybe not Free, but inexpensively bartered for....
'n the sweat spent blockin', splittin', 'n movin' to the front backyard, from the back 40...

 

[HT32BSX115]

Re: How Much Fuel Used per Revolution of the Engine ???

Ayuh,... I've got 3, 55 gallon drums fulla used oil, 2 of which are reasonably clean used Hyd. oil...

You can have 'em, if ya wanta come get 'em,...

I was gonna mix it into my #2 boiler oil to stretch the expensive stuff, but don't wanta deal with the added burner cleanin'...

I'll be right over!!!!

You could probably mix it with #2 diesel but in that type of burner, you run the risk of plugging the nozzle eventually.
Hydraulic oil produces a "clinker" from the additives they put in it. (always amazes me that people with diesels think it's ok to run ATF/hydraulic fluid in a diesel engine!!......That stuff was never intended to run in a combustion chamber!)


All kiddn aside....If you lived close, I would absolutely be over to scrounge that oil. These waste oil furnaces run particularly well on lighter oils like hydraulic and auto-trans fluids etc. I am always looking for people who are getting rid of an oil fired furnace and want to get rid of the oil left over. They usually have to pay someone to haul it away!

My Lanair burns about 1gal per hour when it's fired. I heat a 3000 sq-ft airplane hanger/shop with it. (with the oil that everybody brings me!!)

 

[tpenfield]

Re: How Much Fuel Used per Revolution of the Engine ???

In so many words, the term is BSFC (Brake Specific Fuel Consumption)

Simple calculations can put it in terms of gal/ltrs/ml/fluid oz/ etc PER rev.

It seems that I would also need the output power of the engine that is being generated from the fuel consumption (21 ounces/minute, 0.015 ounce/full cycle, etc.) in order to figure the BSFC. I have no way of knowing for sure how much torque the engine is generating at the 30 mph cruise. So, it looks like I cannot figure the BSFC without it ???

 

[Scott Danforth]

Re: How Much Fuel Used per Revolution of the Engine ???

yes, BSFC is dependent on engine load. for example, my experience with diesels would be .325 - .335 #/HP-Hr as the typical rating that we would see (no mater which engine size). so the actual consumption per revolution is dependent on the load of the engine, as well as the efficiencies within the engine.

your best bet to determine what your fuel consumption is would be either install a fuel flow meter, or look at boattest.com and see what they got for fuel consumption on your hull and engine combination.