Profile generator maximizes lift area

LapSim has its own camshaft profile generator, based by 9 parameters per camshaft. The profile generator maximizes lift area for the duration of the cam.

In our view this should enable you program any 'logical' camshaft you have or might want to use. The choice to go this route is based on our desire to keep the input simple for user-friendliness with little influence on the accuracy.

And perhaps most important, in this way we are not dependent on the availability of camshaft profiles.

LapSim has its own 'camshaft' model

LapSim figure showing camshaft lift curve, including lob centre and maximum lift

With the camshaft model in LapSim, both the duration as well as the lob centre values are the main indicators describing the camshaft.

Because both are influences by other factors you will need to check the actual values in the resulting graph.

The overall lift of the cam is the maximum lift, including the starting areas.

Necessary for smooth functioning of the valvetrain

LapSim figure showing the adjustable starting area of a camshaft profile as well as the valve lash

In order to create smooth functioning, camshafts have starting areas. In the acceleration graph one can judge how aggressive the opening and closing is.

Making them too long and high compared to the valve lash, will significantly reduce the fill rate at low rpm.

Checking if valve float will occur

LapSim figure showing valve acceleration curve

The camshaft model in LapSim assumes that the negative acceleration is linear dependent on the valve lift, similar to the valve spring force.

In this manner, the opening area of the valve is maximized for the given duration and lift.

You can specify the weight of the valve plus retainer and cam follower, together with valve spring stiffness and preload.

In the acceleration graph you subsequently see the spring force compared to the acceleration force at the rev limiter. So you can judge if valve float is likely.

Furthermore you can specify the positive acceleration of the cam in relation to the negative, opening part separated from the closing part.

Sometimes helpful for regulations or construction limits

LapSim figure showing the option to maintain the valve for a certain duration at maximum lift

There is the possibility the let the cam have an area where it stays at maximum lift.

This can be necessary to either meet certain regulations (old WTCC!) or because the construction does not allow more lift, or needs to be modified.