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The VALC profile allows the valves to open faster and for longer. This translates to faster lift and increased area under the 'lift curve' (see fig. ①) which in turn generates more power. (Greater area under the 'lift curve' = greater air intake)
① |
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| CAM ACCELERATION | CAM ACCELERATION | |
| LOW |
HIGH |
|
| LIFT | LIFT | |
| LOW |
HIGH |
|
| AIR INTAKE | AIR INTAKE | |
| LOW |
HIGH |
|
Unlike the valve opening, the VALC profile ensures that the valves close at a slower rate, helping to prevent common valve train related issues.
With a conventional direct-acting valve train, the maximum lift is usually determined by the size/diameter of the valve lifter. Selecting a high-lift camshaft without taking this into consideration often results in the camshaft lobes travelling beyond the surface of the valve lifter. This causes the lobe to make contact with the edge of the lifter, damaging both components over time. （see fig. ②）
Therefore, the ideal performance orientated high-lift camshaft needs to have a profile that maximizes lobe travel on the lifter without exceeding the outer edge.
VALC profile camshafts have achieved this ideal by deliberately reducing the maximum cam velocity to limit lobe travel on the lifter surface. （Maximum cam velocity = lobe travel distance on lifter)
② |
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| High lift profile without taking lifter size/radius into account. |
Compared to standard profile camshafts of the same lift, VALC profile camshafts are able to then then off-set the difference for even greater lift/performance gains
