valvetronic engine technology - IFET College of Engineering

Intake vale lift can be altered from aminimum of 0.25mm(!) to a maximumof 9.7mm, with the electric motoradjusting the eccentric shaft in 0.3seconds.Because the intake valves nowhave the ability to move from fullyclosed to fully open positions, andeverywhere in between, the primarymeans of engine load control istransferred from the throttle plate to theintake valve train. By eliminating thethrottle plate's "bottleneck" in the intaketrack, pumping losses are reduced, fueleconomy and responsiveness areimproved. Operating Parameters Valve lift is variable between 0and 9.7 mm.Adjustment of the worm gearfrom one extreme to the othertakes 300 milliseconds. Combined with double-vanosvalve timing technology, thecamshaft angle relative to thecrankshaft can be adjusted by upto 60°.The intermediate arm is finishedto a tolerance of 0.008 mm. The cams controlling theeccentric shaft are machined totolerances of a few hundredths ofa millimeter.ENGINE DESIGNASPECTS Basic engine design completelyrevisedNot only the cylinder head withBMW’s new Valvetronic technology,but also the complete four-cylinderpower unit featured in the BMW 316ti isan all-new development from the groundup. The new cross-flow cooling conceptwith its open deck crankcase reducescoolant flow resistance and thereforeallows use of a smaller water pump withjust 60 per cent of the usual poweruptake.Made of aluminum, the engineblock ends exactly on the centerline ofthe crankshaft bearings. A ladder framebetween the crankcase and the oil sumpconnects the lower halves of the bearingbridges to form one complete unit alsoaccommodating the balance shafthousing and the two-stage oil pump.This makes the entire drive unit very