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Note that the CIS 2.4TK heads don’t flow more then 150 CFM at .4 inches of lift. In general a camshaft that provides more then .4 inches of lift will not perform much better then a camshaft with .4 inches of lift in a TK head. The 2.2 S head on the other hand (also used in the 2.7RS) keeps flowing more air all the way up to .5 inches. If you were to use an E cam which only lifts to about .4 inches with an S head, you won’t even be using the last 25 CFM of flow that the cam and heads can provide. A chart of your heads’ flows such as this is very useful for comparing the valve lifts defined by the camshaft. Ideally you want a situation where the cam has opened far enough to allow maximum flow when the pistons are undergoing their maximum acceleration. Depending on the rod-stroke ratio, this generally occurs around 75-80 degrees of crank shaft angle. Now compare the head flows with the valve lift graph for the 911 S camshaft below.
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