Quote:
Originally Posted by CobraEd
Its smooth quiet idle is due to the cam. Too bad.
The gross duration on the lobes and the lobe separation angle between the lobes are what gives the lumpy "Cobra like" idle. This is an emissions engine and cannot have that.
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The 'lumpity-lump' of a high-performance cam comes from the overlap ground into the cam to optimize high RPM performance. Overlap is the amount of time both the intake and exhaust valves are open. At high RPM, it maximizes scavenging of the exhaust and filling the cylinder with the air-fuel mix. At low RPM, excessive overlap creates that 'lumpity-lump' idle we've all come to love. The Coyote has variable cam timing. At low RPM, the cams roll out to reduce overlap and create a smooth idle and manageable power delivery, not to mention an environmentally cleaner exhaust. At higher RPM, the cams roll in, increasing overlap which creates more horsepower. Without the variable cam timing, you would have the power the idle suggests. The beautiful thing about these new motors is with the mass flow and O2 sensors, you will have optimum fuel delivery to maximize efficiency and thus power. Want more power, just add air. The computer does the rest.
