Vehicle Engines - Decreasing Fuel Consumption and Exhaust Gas Emissions in Transportation - page 141

Table 9.8 (continued)
Operation modes Physical properties

Lubrication system Lubrication reduces the internal friction of engines and affects the fuel consumption. Pressure lubrication systems lubricate the whole

engine, meaning the crankshaft, the piston rod, the camshaft, the valves and the nozzles, the turbocharger, etc. Consumption of
lubricating oil depends on the load. Oil must be changed because it ages. Heavy trucks consume lubricating oil at the rate of 2-3 l
(1,000 km) -1 which equals to 0.53-0.78 gal (1,000 km) -1 , i.e., 0.85-1.30 gal (1,000 mi) -1 . Oil should be changed after 30,000-
60,000 km, i.e., 18,630-37,260 mi [ 52 ]
Synthetic engine oils with low viscosity may be slightly more expensive, but they can cut fuel consumption by much as 5% by
reducing the internal friction of the engine, particularly in cold starts in comparison with traditional oils [ 53 ]

Torque The force of the expanding air and fuel mixture which drives the piston together with the lever arm of the crankshaft downward is

converted into torque [ 54 ]. The torque depends on the average piston speed and operating pressure. The number of revolutions of
self ignition engines has been substantially increased since the beginning of the 1990s. Now car engines run up to 5,500 rpm;
heavy-duty vehicles usually run at lower rpm. Future injection systems with electronic speed regulation, e.g., an Electronic Diesel
Control (EDC) will deliver high engine torque with a smooth ride [ 55 ]

Performance The performance depends on the output, which is generated as a power per time interval. It increases with higher torque and higher

rpm. Modern self ignition engines of vans with fuel injection operate in a performance range between 80 kW (109 HP) and
100 kW (136 HP) [ 56 ]