(23 Mar 2014, 12:32 am)Andreos Constantopolous wrote A quick comparison of current Euro6 engines from Volvo http://www.volvobuses.com/bus/na/en-us/_...mId=130637&News.Language=en-gb
D5
• 240 hp 900 Nm (also available in biodiesel version)
D8
Three models:
• 280 hp 1050 Nm
• 320 hp 1200 Nm (also available in biodiesel version)
• 350 hp 1400 Nm
D11
Three models:
• 380 hp 1800 Nm
• 430 hp 2050 Nm
• 460 hp 2200 Nm
It's quite easy to see that the larger capacity engines offer higher torques (and, therefore, better 'pulling power'). Higher horsepower will result at the same engine revolutions (power is torque times revolutions).
Two different approaches to the same topic:-
http://www.largiader.com/articles/torque.html
http://www.epi-eng.com/piston_engine_tec...torque.htm
An engine with higher torque is capable of pulling longer gearing ratios, thereby giving the same roadspeed at lower engine revolutions.
The work done is the same (for equivalent roadspeed) but consumption will depend on the comparative economy of the engines at those revolutions.
The smaller capacity engine at higher engine revolutions might well be using more fuel to achieve this - but this will depend on the engine management system.
It is, perhaps, obvious that the components within the smaller capacity engine will 'run further' to achieve the same performance, and, therefore be expected to wear out sooner.
Conversely, if the gearing ratios are the same the larger capacity engine will probably use more fuel (again, depending on the engine management system). Throttle opening position will determine how much fuel is delivered (and how much performance is delivered) so judicious use of the pedal will reduce fuel consumption. A sophisticated 'drive by wire' control could optimise this.