What is the maximum valve lift?, Is 0.650" possible? Options

[Beebo Kanelle]

What is the most extreme valve lift you've seen on a Type 4 engine?

Thanks in advance.

[barefoot]

For a flat faced poppet valve, that is with a 90 degree seat angle relative to the stem centerline, once the valve is lifted 1/4 of the throat diameter, there is no increase in opening area.
Valve throat area = Pi Dsquared/4
Area of the cylinder representing the lift area= Pi D H where H i the lift
Thus when Pi Dsquared/4=PiDH then when H=D/4 lift area equals throat area.

For a standard 2L head the intake throat diameter = 1.46". So once the valve lift exceeds .365, there is no further in crease in area. Remember to also subtract the area of the stem diameter for throat area for a more exact calculation. Also, since our valves are angled seats and not flat, the arithmetic is slightly different, but you get the picture.

In actual practice, there are dynamic effects of flow entering the combustion chamber that affect filling and combustion propagation that are dependent on the valve lift, so we cannot predict actual performance at lifts greater than .365".
That's for you guys that have developed cam profiles related to actual power produced