Profile
The base or shortest duration profile of the helical camshaft system is almost identical to a standard production engine profile. The helical camshaft base profile belongs to the general group of lobe shapes which are used with pivoting cam followers, especially those with a fairly high rocker ratio, around 2:1.
This family of lobe profiles is characterised primarily by having a short lobe lift. Because of this the lobe has a very rounded-off (or “snub-nosed”) appearance. The radius of curvature of the nose region (about the axis of rotation of the camshaft) is often very close to being a constant radius over an angular extent of about 20 degrees or so. A helical camshaft requires this region to be a true constant radius. In some cases this requires as little as 0.25 mm (or less) to be removed from the nose. When measured, the rates of acceleration and jerk in the nose region are slightly higher than standard.
The lobe nose typically can have about 150° added to it, for extra duration. The lift surface geometry remains unchanged. Because of this extended duration the lift rate and total lift do not have to be as extreme as a racing cam to achieve maximum high end power.
Read more about this topic: Helical Camshaft
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