fferentenginespeedandloadconditions.Considerableincreasesinfullloadtorquecanbeachievedwithvariableeventtiming,promised.Reductionsinpartloademissionsandfueleconomyarealsoachievablethroughfulloptimisationofhesystem.VariableLiftSystemsTherearetwomaintypesofvariableliftsystemcurrentlyunderinvestigation,thefirst"scales"thevalveliftsuchthatitsopeningdurationisunchangedwhilstthesecond"truncates^theliftprofilesuchthatthevalveopeningdurationreducesasliftreduces.binedwithaphasechangingdevice.Onemajorbenefitofvariableliftsystemsisthepotentialofthrottlingthecylinderbyreducingtheintakevalveliftthussavingthepumpinglossesassociatedwiththeconventionalthrottle(seeAppendixA).Thisrequiresveryclosecontroloflifttomatchchangesinenginespeedandloadconditionsandhasyettobefullyproven.Electro-icValveActuationSystems
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