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Duration, Lift, and Lobe Centers

I guess I'll start with the most difficult to grasp concept first: LBA, or lobe centers. Lobe centers work like this on the intake: degrees open before TDC plus degrees open after BDC plus 180; divide it all by 2, subtract the smaller of the the numbers before or after. For the exhaust, same story except before BDC to past TDC. Simple, huh?

I've been trying to find consistent information and keep running into conflicts. I've seen it defined as the distance in degrees between the center of the high part of the intake lobe and the center of lift of the exhaust lobe. Supercharger manufacturers tend to use this definition when recommending cams for forced aspiration. Wide LBA; short duration; minimal over-lap.

  • Valve Lift
  • Duration
  • Timing
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Last Modified:   Wednesday, 21st February, 2024, 10:24am PST
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