The Jerk Curve

The jerk curve is probably the least talked about part of a lobe profile. You wouldn't design or analyze a lobe profile without looking at the jerk curve associated with that profile. Although, many people do completely ignore the jerk curve when analyzing a lobe profile. Mainly because their lobe profile machine does such a lousy job of producing both an acceleration and a jerk curve. The resolution of the encoders used in these machines is just not good enough. Acceleration is the change in velocity and jerk is the change in acceleration. Eight decimal places are necessary to produce these curves.

Jerk can be replicated in your vehicle by speeding up and slowing down quickly. That "jerky" back and fourth motion. You can imagine the negative effects that would have on the valve train and yet many people don't even look at the jerk.

Not to knock these lobe profile machines, but someone that really understands camshafts and lobe profiles can manually get better data with a degree wheel and a dial indicator. Like everything, much more knowledge is necessary to do something manually instead of electronically with a computer. That explains one of the major problems with society today.