Hi all, I’m wondering of what the fuel consumption is for a common loco, let’s say models ranging from the seventies (SD40-2s, U-Boats) to the end of the nineties (SD70s, Dash9s), and then for the most modern types from GE and EMD, from Run 1 to Run 8.
Indeed I’m wondering what the fuel consumption is per ton carried, and per hundred of miles run, depending if the train is on level or slightly sloped track (ex BNSF sub between Daggett and Mojave), or in mountain area (ex Cajon Pass).
Is there a reliable link between horsepower and fuel consumption?
Modern locomotives, such as Dash9 and SD70 types, use about 0.210 kilograms of fuel per kilowatt hour. Assuming an SD70 at notch 8 is producing 4000 HP, say 3000 kW into the generator, in one hour it will use 3000 x 1 x 0.210 = 630 kg = 750 litres
For an older unit like an SD40 or SD40-2 you have
notch 8 = 650 l
notch 7 = 540 l
notch 6 = 430 l
notch 5 = 320 l
notch 4 = 220 l
notch 3 = 140 l
notch 2 = 75 l
notch 1 = 35 l
idle = 25 l
Remembering that an SD40 delivers 2240 kW to the alternator in notch 8.
If you can assume that the locomotive is working in a given notch climbing a grade such as the West face of Cajon, say is in notch 8, and you know how long it takes to get to Summit, you could estimate the fuel usage. Otherwise it is complicated, since you need to know the time spent in each notch setting during a trip to calculate fuel consumption.
EMD engines, particularly, have an uneven specific fuel consumption curve because in the lower throttle notches, the engine has to drive the intake air blower, while in higher notches, the exhaust turbine takes over and fuel consumption per delivered horsepower (or kW) reduces. A GE engine would not be affected in this way, but efficiency will still fall off slightly at lower power.
At idle, most engines use anywhere from 4-6 gallons per hour…at Run 8, figure an average between 165-240 gallons per hour with the 165 figure representing an SD40-2 and the 240 being an SD80/90MAC…most other models, SD60-70 and C40-8’s on through the ES series fall somewhere in between those two figures at Notch 8.
Here are some figures drawn from the SD80MAC thread!
Note that although the SD80MAC uses more fuel than the others, the fuel used per horsepower hour at notch 8 (SFC = specific fuel consumption) developed is less!
According to Metro-North, a GE Genisis gets about 3 gallons per mile, which the railroad’s spokesman told me is actualy considered efficient. But bare in mind, Metro-North is a comuter railroad, meaning frequent starts and stops. I wonder if fuel efficiency is affted by which direction the locomotive is running (M-N runs push-pull).
I always assumed the the fuel efficeincy between the 2nd Gen EMDs and the modern SD60/70/75 series had a bigger gap (just as many of today’s 6 cylinder cars are as powerful yet more fuel efficeint as some of the 1970s V8s—though not higher in torque)
But in looking at the figures, I now realize one has to take into account the higher horsepower per cylinder. This is one reason it’s surprising to me that there are still some 3,600 hp EMD 45 series running around, which are 20 cylinder fuel hogs.
The figures on Al Krug’s site suggest that the SD45 is, in fact slightly more economical than the contemporary sixteen cylinder locomotives, the SD40 at least on the basis of fuel used per horsepower delivered. This might be because the power per cylinder in the twenty cylinder engine is slightly lower in notch 8.
So the 20-cylinder is not a fuel hog, although there are maintenance problems due to torsional vibration in the long crankshaft. I wonder why it got that reputation?
Interesting that you mentioned the torsional vibration. I read a few years ago that Santa Fe suffered several crankshaft failures with their EMD 45 class units (20 cylinder).
From my understanding the shop techs overcame that problem by remachining and balancing.