The reason I haven't been updating my fuel logs:

[bestclimb]

Originally Posted by Old Tele man

...yeah, but it makes for real simple mathematics: 1 MPG =1 gallon per mile (GPM)!

...which is basically what the oiriginal Chrysler Abrahms turbine-engined tank got! Back during the Carter administration, I instrumented and measured its fuel-consumption tests at the Yuma Army Proving Ground...300 gallon fuel tank = 300 mile range...which was virtually same as the GM variable-compression ratio diesel tank.

I usto run boats with 4 420 hp turbo diesels. Each would burn 15 gallons per hour. The total fuel burn was 60 gallons per hour or 1 gallon per minute going 25-30 knots.

[Christ]

4x420 = 1680HP available engine capacity

1 gallon of diesel fuel contains 138,690 BTU/gal

138,690 / 3413 = 40.64 KW/gal content for middle grade (road) diesel

40.64*60 (GPM) = 2,438.4 kW/Min available energy content in the diesel fuel that was burned.

2,438 kW = 3,269.4 HP.

1680 / 3,269.4 = 0.514 (about 51% efficient).

Not bad for huge oil-burners, eh? I would have to assume they were purpose built and run steady-state (at a specific RPM), right?

[Clev]

I throw out anything where the wife drives more than 30% of the time; she really kills the mileage. I also threw out one where the gas pump shut off very early (but I didn't figure it out until I was already out on the road.) It would have shown over 50 mpg, which would have skewed the results more than I would have liked!

As for the fuel log, I requested the extra digit back in the "report problems in this thread" thread, but got shot down. Interestingly, the problem is that the field is simply too short. If your fillup is less than 10 gallons, there'll be room for three decimal places. Seems like a very easy change in the code to me.

[Christ]

Clev - the next fill up would have negated the skewed result.

I'm working with this right now, because the first entry into Cara's work log will actually be more gallons than the tank holds. There was a partial fill in there because my Father had to take her to work w/ the bike still in the back, and she was running on E by the time I got back from upstate NY.

[Clev]

Originally Posted by Christ

Clev - the next fill up would have negated the skewed result.

I'm working with this right now, because the first entry into Cara's work log will actually be more gallons than the tank holds. There was a partial fill in there because my Father had to take her to work w/ the bike still in the back, and she was running on E by the time I got back from upstate NY.

True, and I also could have combined the numbers from that fillup with the next one and averaged them out. I just like that the "best fillup" and "worst fillup" numbers are legitimate, and not 10 mpg high or low because of the gas pump.

[Christ]

Originally Posted by Clev

True, and I also could have combined the numbers from that fillup with the next one and averaged them out. I just like that the "best fillup" and "worst fillup" numbers are legitimate, and not 10 mpg high or low because of the gas pump.

Good point.

I ended up giving my dad a $20 the other day to put gas in Cara to take her to work, because that's all I had. Between that, and the running I had to do today before filling up completely, I ended up using 20.4 gallons of fuel, and going 575.5 miles, for a figure of 28-ish MPG, which is not bad considering the crap I've been hauling and the stupid little trips I've been making across town and such for that tank.

I'll update the fuel log as soon as I find the receipts again.

[bestclimb]

Originally Posted by Christ

Not bad for huge oil-burners, eh? I would have to assume they were purpose built and run steady-state (at a specific RPM), right?

The engines are off the shelf as it were for marine diesels. Pretty small actually not much bigger than a tractor engine.

Typically idle, for 15 to 30 minuets looking at wild life, then running full governed power to the next spot for 30 minutes. Up to 150 passengers. Very similar to some of the high speed twin haul ferries in new york.