valvetronic engine technology - IFET College of Engineering

Compact. In turn, the first representativeof this newly developed family ofengines was a four-cylinder four-valvespark-ignition power unit displacing 1.8litres, developing maximum torque of175 Newton meters (Nm) and maximumoutput of 85kW (see Figure 4). BMW’snew Valvetronic four-cylinder powerunits come with 1.8-litre and 2.0-litrecapacities.Some Experimental resultsDespite the reduction in enginesize by 100 cubic centimeters, comparedwith the former generation of powerunits, torque is up from 165Nm to175Nm, with output increasing from77kW to 85kW. With displacement ofthe 2.0-litre engine being increased by5%, torque was up by no less than 11%from 180Nm to 200Nm, engine outputincreasing from 87kW to 105kW,resulting in specific torque of100Nm/litre and specific output of52.5kW/litre.The driver senses this enhancedperformance through the more powerfultorque curve, the car’s dynamicbehaviour on the road clearly provingthe advantages of this extra torque. Morethan 90% of the engine’s torque comesat just 2,000 revolutions per minute(rpm), with torque peaking at 3,750rpm.Engine output, in turn, remainsconsistently at its near-maximumthroughout a wide speed range.The 4.4-litre power unit developsa maximum output of 245kW with a fuelconsumption of only 10.9 litres/100km(or 25.9 miles per gallon) and alreadycomplies with the EU4 standard, whichdoes not become obligatory until 2005.The oil service intervals, in turn, havebeen extended up to 40,000km or 25,000miles.One of the most importantobjectives from the start was to reducefuel consumption. These engines offer aparticular enhancement of fuel economyabove all at low loads. When idling, fuelconsumption is down by approximately25% and the overall improvement in theEuropean fuel consumption test cycle is12%. The customer will also experiencethis improved economy and fuelefficiency in everyday motoring on theroad. Using the power of the engine infull, on the other hand, the driver doesnot have greater fuel efficiency than witha conventional power unit. The reasonfor this is that, under these conditions,the engine runs like a throttle butterfly