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Old November 30th 2011, 10:21
Bruce. Bruce. is offline
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Join Date: Jan 2011
Posts: 83
more lift? well in the situation of Wally's stock 914 gaining significant HP with ratio rackers....
Even if the original peak lift exceeded the flow capacity of the port, adding ratio rackers increases the average lift during the cycle so has more flow for longer even if the peak flow might be unchanged.

more duration? perhaps not totally suited to turbo engines but a higher compression ratio means you can advance the exhaust openning point. That way you can get longer exhaust duration without increasing overlap. This is because with high compression ratios, the cylinder pressure falls faster as the piston moves away from the head on the detonation stoke.
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