Originally posted by Travis:
1. As said before primary and secondary valve opening/durations mean NOTHING. They are there for emissions only and a possible 100 rpm longer power band in either direction.

2. Seat duration doesnt mean ANYTHING in the production of power either. Its the amount of meat under the seat that counts. A better number would be the 0.050 durations.


1. They uses separate lobe designs because the airflow to each valve is "completely" separate and therefore has different velocity, density, and cylinder filling ability.

They produce a tremendous change in the power curve when used together. It makes 2 complete different power curves and the IMRC point is put at were they cross to make the best power under the curve.
This was done to retain low speed drivability (TQ - Mainly for ATX's IMO) and still make & sustain good high rpm HP & TQ.
Definitely NOT done for emissions!

Why do you hold to this incorrect and very basic understanding of the cam & intake design?

2. I agree that Duration by itself is meaningless.
It is the valve timing points that play a large role in power production and when & where it will be produced. "Meat under the seat" as you put it is not the tell all either.

2000 SVT #674 13.47 @ 102 - All Motor! It was not broke; Yet I fixed it anyway.