- Honda Car Owner's Manual

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74
VTEC-ESYSTEM
TheHondaInsight'sengineemploysanewlydesignedVTECsystem.Inthissystem,thecamfollowers
oftheintakeprimaryrockerarmsarefittedwithrollersthatminimizefrictiononthecam'scontactsurfaces.
(Eachrollerturnsonaneedlerollerbearing.)
TheVTECrockerarmsareanew,compact,low-frictiondesign,adaptedfromtheS2000roadster,with
the VTEC switching mechanism (pistons) located coaxially with the roller elements. This new design
reducesthereciprocatingmassofthevalvetrain,for morereliable high-rpmoperation,andalso allowed
Hondaengineerstoreducevalve-springloadby30percent.
Duringacceleration,whenenginespeedreaches2500 -3200rpmtheprimaryandsecondaryrocker
armsarelockedtogetherbytheVTECpistons.Duringdeceleration,whenenginespeeddropsto2300rpm
theprimaryandsecondaryrockerarmsseparate.Theexhaustrockerarmsaremadeofaluminum.
TheIMAengine'ssingleoverheadcamshaft(SOHC)cylinderheadusesacompactchaindriveinplace
ofatoothedbelt,andfeaturesanewcompact,low-frictionVTECvalvetrainthatusesacommonshaftfor
boththeintakeandexhaustrockerarms.Placingalltherockerarmsononeshafteliminatestheneedfora
secondrocker-armshaft,sothevalvemechanismcanbemorecompact.
Anadditionaladvantageofthisdesignisitsnarrowerincludedvalveanglethatbettercentralizesthe
stratifiedair-fuelchargearoundthesparkplugforquicklight-offandmorecompletecombustion.
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