Originally Posted by RallyBob
Certainly you will lose some of the benefit, but not all of it. You can compensate somewhat by increasing the valve lift but retaining the same duration. This way you'll have more lift area under the curve where it counts the most for racing....at peak airflow. Normally the peak flow is only momentary...when you hit maximum lift for a microsecond you have peak flow, but as soon as the valve starts to close again the flow drops. With higher valve lift you can his this peak flow while the valve is still opening, retain it for numerous degrees of rotation as it passes peak lift, and then retain the same peak flow until the valve has closed below the head's peak airflow numbers. So you will have more cam duration at the maximum airflow level.
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I get the idea,
but this probably means high lifts of 14-15mm with potential coil bind issues?
as your flow data say that the 2.2 & 2.4 heads reach max flow at about 13mm,
I was wondering if we could "chop off" the tip of a big cam profile,
in such a way that the total duration under 13mm lift would be as long as a normal 14-15mm lift cam,
in other terms the cam profile would be very round just at the tip of the peak.
sorry I'm not very clear without a plot to show,
this weird idea would allow for an optimal duration under max flow without coil bind problem.
Hiro