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Fuel consumption discussed, with formulae and tables provided


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Your Detroit Diesel Specs

Basic specs are open to everyone and include images, displacement, dimensions and weight, essential bolt tightening torques, the characteristics of the engine like its power and torque.
Essential bolt tightening torques are the main bearing cap bolt torque, the connecting rod cap bolt torque and the cylinder head bolt torques.


Some Popular Engine Specs


Fuel consumption issues, formulae, tables

A correctly tuned diesel engine consumes fuel according to its power requirements.

Simple really, the more power you produce the more fuel you use.
Fuel consumption rate for many makes of Diesel Engines can be found in a range between  0.380 & 0.450 lbs/hp hour; 172 & 181 grams/hp hour; 231 & 243 grams/kW hour.
This does not represent a big difference in fuel consumption per power unit between most normal diesel engines.
Big Cam 400 engine Fuel consumption for diesel engines is normally more difficult to express than for petrol engines because of the vast variability in possible applications. Applications like stationary industrial, marine, automotive, and earthmoving are examples of this variability. So it is normal to express this fuel consumption as a rate in terms of the weight of fuel consumed per unit of power produced. A real headache for plant managers!

Now even if an engine operates for long periods at a constant speed it seldom operates at its full rated power. On a dynamometer, engines seem to operate best at about 70% of expected maximum power, they seem quite tireless when operating there.
Still, asset control may be critical for profitable operation so we trust the following formulae & tables may be of some use.


Diesel engine Fuel Consumption conversion table

Diesel engine Fuel Consumption conversions 
Basis: Specific Gravity of Diesel = 0.853 @ 15.5°C
Unit Multiply by to get
lbs / hp hour 0.533 liter  / hour
lbs / hp hour 0.1408 US gal / hour
US gal / hour 3.7854 liter  / hour
liter  / hour 0.2642 US gal / hour
kg  / hour 1.175 liters / hour
grams  / hour 0.001175 liters / hour
Regard all values as approximate

Diesel engine power to Fuel Consumption table 


Table based on fuel consumed at 0.400 lbs per hp hour.
Power Unit Fuel Consumption per hour expressed in
hp kW kVA lb kg liter US gal
1.00 0.75 0.93 0.40 0.18 0.213 0.056
1.07 0.80 1.00 0.43 0.19 0.228 0.060
1.34 1.00 1.25 0.54 0.24 0.286 0.076
5.00 3.73 4.66 2.00 0.90 1.066 0.282
7.00 5.22 6.52 2.80 1.30 1.492 0.394
hp kW kVA lb kg liter US gal
10 7.46 9.32 4.00 1.80 2.130 0.563
12 9 11 4.80 2.20 2.56 0.676
15 11 14 6.0 2.7 3.20 0.845
18 13 17 7.2 3.3 3.84 1.014
20 15 19 8.0 3.6 4.26 1.125
22 16 21 8.8 4.0 4.69 1.239
25 19 23 10.0 4.5 5.33 1.408
35 26 33 14.0 6.4 7.46 1.971
50 37 47 20 9.1 10.66 2.816
hp kW kVA lb kg liter US gal
55 41 51 22 10.0 11.7 3.09
60 45 56 24 10.9 12.8 3.81
65 48 61 26 11.8 13.9 3.67
75 56 70 30 13.6 16.0 4.23
80 60 75 32 14.5 17.1 4.52
100 75 93 40 18 21.3 5.63
hp kW kVA lb kg liter US gal
120 89 112 48 22 25.6 6.76
150 112 140 60 27 32.0 8.45
200 149 186 80 36 42.6 11.25
220 164 205 88 40 46.9 12.39
300 224 280 120 54 63.9 16.88
310 231 289 124 56 66.1 17.46
350 261 326 140 64 74.6 19.71
hp kW kVA lb kg liter US gal
400 298 373 160 73 85.3 22.53
450 336 419 180 82 95.9 25.33
500 373 466 200 91 106.6 28.16
600 447 559 240 109 128 33.8
750 559 699 300 136 160 42.3
1000 746 932 400 181 213 56.3
hp kW kVA lb kg liter US gal

Examples of Diesel Engine fuel consumption

Deutz Diesel F4L1011 fuel consumption
Detroit Diesel 4-71 fuel consumption

Abbreviations and Bodies related to diesel fuel, it's control, and emissions.

API - American Petroleum Industry
ARB - In California, the Air Resources Board
ASTM - American Society for Testing and Materials
ASTM D 975 - American standards for fuel and emissions. Fuel outside of this spec has poor atomization, which equates to less power, worse fuel economy and higher toxic emissions.
CARB - California Air Resources Board - Strict fuel and emission controls.
CEN - European Standards Organization
CS - California Standard
EN 590 - European diesel fuel standards
EPA - Environmental Protection Agency - Main US Body legislating the quality and usage of fuel oil and the reduction of emissions in the USA.
FS - US Federal Standard
EU - European Union Standard, EN 590 - European diesel fuel standards
JIS - Japanese Industrial Standard - JIS K 2204 - Japanese standards for fuel and emissions.
ULSD - Ultra Low Sulfur Diesel
WHO - World Health Organization

Fuel Consumption calculations

The above table is based on the following:
  • Diesel - Specific Gravity = 0.853 @ 15.6°C
    • i.e. 1 litre of diesel weighs 0.853 Kgs
    • & so 1 Kg of diesel is 1/0.853 = 1.172 liter  
  • kg = lbs ÷ 2.2
    • Kgs/hp hour = lbs/hp hour ÷ 2.2
    • & so liter  /hp hour = Kgs/hp hour * 0.853
    • & liter  /hp hour = lbs/hp hour ÷ (2.2 * 0.853)
    • & so liter  /hp hour = lbs/hp hour ÷ 1.8766
    • e.g. 0.40 lbs/hp hour = 0.40 ÷ 1.8766 = 0.2132 liter  /hp hour
Now to use the above data in practical examples:

An engine producing 310 hp at constant speed using 0.350 lbs of diesel per hp hour
uses the following amount of fuel:

310 x 0.350 = 108.5 lbs of diesel per hour
or
310 x 0.350 ÷ 1.8766 = 57.8 liter   per hour

An engine at constant speed producing 231 kW at that speed, & using 0.350 lbs of diesel per hp hour
uses the following amount of fuel:

231 x 1.341 x 0.350 ÷ 1.8766 = 57.8 liter   per hour


Questions on fuel consumption

Dinesh asks:
I am Dinesh & I have a question related calculation of how much L of diesel required for diesel engine. I have diesel engine with 8 cylinders of piston & 625 HP. I studied your page ...there it was written that 'fuel consumption rate for diesel engines is in range between 0.380 &0.450 lbs/hp hour.' My questions are:.... 1. Is the fuel consumption range of 0.380 & 0.450 lbs/hp hour independent of number of cylinders piston? 2. Why is the fuel consumption rate of diesel engines in the range between 0.380 & 0.450 lbs/hp hour?
Reply:
The number of cylinders does not matter, only the engine power. The 0.380 to 0.450 comes from engine spec sheets, but it can be regarded as 'argumentum ex silentio' that is good until we have more evidence to the contrary. I would love to get more evidence, can you provide any?
(Calculations: 453.59237*0.380= 172 grams per hp hour; 453.59237*0.400= 181 grams per hp hour; 453.59237*0.380*1.341= 231 grams per kW hour; 453.59237*0.400*1.341= 243 grams per kW hour;)


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email: steve@barringtondieselclub.co.za
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