Ad­vance vs. Re­tard

Chevy High Performance - - Vvt Is Your Friend -

Ad­vanced

Early in­take clos­ing cre­ates more cylin­der pres­sure at lower engine speeds

Ear­lier ex­haust open­ing re­duces pump­ing losses to im­prove fuel mileage

Builds more cylin­der pres­sure at lower engine speeds for bet­ter torque

De­creases in­take pis­ton-to-valve (P-V) clear­ance

In­creases ex­haust P-V clear­ance

Re­tarded

Later in­take clos­ing point de­lays max­i­mum cylin­der pres­sure to higher engine rpm

De­layed ex­haust open­ing al­lows longer cylin­der pres­sure push on the pis­ton

Builds more high-rpm power

In­creases in­take P-V

De­creases ex­haust P-V

Lobe Sep­a­ra­tion An­gle (LSA) does not change with ad­vance or re­tard

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