These cam profiles are sometimes also called "inverted flank" or "inverted radius" cams.
As far as I know, they are only used with roller tappets.
The basic purpose of this profile is to increase the lift rates to a more aggressive intensity. The typical reason for it is to allow a cam to have shorter timing duration while still achieving the same lift as a conventional cam would need longer duration to do.
This generally has the result of higher torque in the lower rpms and midband.
However, this increased lift intensity results in very high accelerations to the valve gear, and can be very brutal on the valve train. They are often called "spring eaters" in the hot-rod world.
The very characteristics that allow them to have this lift rate, also limits the rpms that they can be effective at, because of these accelerations. Inverted flank cams are generally limited to engines of lower to medium rpm range(like ours, and Detroit muscle cars), because of the accelerations. They are sometimes/often used on hot-rod engines because of the extreme lift rates that they can give, but they have a somewhat "chequered" reputation because of the killer stress they can create.
How intense the accelerations become is dependent on how extreme the inverted flank is, and how high the rpms get. It is possible to just do a little of it, to keep things under less stress, but get a bit more torque.
So, they have their "goods and bads".
You can get a little more torque with less duration, and still get your high lift, as long as you keep the rpms within the limits, and you don't mind having very stiff valve springs with short lifetimes, and higher wear and stress on all your valve train parts. The more robust the valve train is, then the more aggressive you can get with the cams.
Topic: Question on cams ? (Read 1704 times)