transmoto |
Camshaft duration is the measurement of the time one valve starts to open until it completes closing. Cam manufacturers always measure the cam rotation in degrees and list the 0.05" timing which records the 0.050 inches of lifter movement. The 0.05" duration closer to seat-to-seat duration usually boosts dyno performance in the red zone.
Measurement data, seat-to-seat duration: 283 degrees, LSA: 110 degrees |
To understand this phenomenon, let's take a look at the valve lift as a function of camshaft rotation. In comparison to the '236' case, the average valve lift in the '256' case is higher. Then more air is filled into the engine so that its output is stronger at high-rpm range.