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Old 03-19-2006, 04:07 PM
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Originally Posted by madamstn
I am goind to add another little comment. A engine is indivual everthing counts, Personally, because I like low end torque I want the rod to stroke ratio first. but it is only the beginning. Its all down hill after 1968. WANT to learn about air pulse, look ar the mopar crossram. mark

Yep, the 413 crossram intake ran dual quads on it and put the engine up over 100% volumetric efficiency. Mopar tuned the pulses so that the best VE (and thus torque) came at what they determined to be the car's cruising RPM at highway spees (which was in the mid 2000's of RPM range). The tradeoff, however, was that the manifold was twitchy to tune and had flat spots at other RPM ranges. Also because of the large runner length, pressure drops (dropping the throttle from idle to WOT) were laggy to respond to.

Rod to stroke ratio has very little to do with an engine's torque rating. Its really only an issue to think about in high RPM motors.

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