PROFESSIONAL MOTORSPORT

SIMULATION SOFTWARE

Trying to make optimal use of the engine power

Printscreen of the LapSim GUI showing the listbox where one can select a 4,5,6 or 7 speed gearbox

LapSim enables 4 to 9 speed gearbox, with or without additional drop gear.

The left edit box is the amount of teeth of the ingoing gearwheel. The right the outgoing gearwheel.

LapSim subsequently calculates the ratio, which is shown just before the edit boxes.

Optimal shift points

Printscreen of the LapSim GUI where the shift points are specified in the gearbox figure

LapSim either changes gear at the rev limiter or at a rpm point where the traction force would increase by a gear change before the rev limiter.

Both the speeds as well as the revs for these “optimal” gear changes are specified in the figure.

Optimizing traction force

Printscreen of the LapSim GUI where the shift points are specified in the gearbox figure

LapSim combines the gearbox ratios with the specified engine characteristic to calculate the optimal gearshift points.

It tries to maximize the traction force as can be seen in the power plots behind the rev versus speed plots.

Providing the last step to accelerating force

Printscreen of the LapSim GUI showing the effective wheel radius and overal gearbox efficiency

Out of experience, we advise to take the size of the tire construction. So the tire diameter without the rubber running surface.

An appropriate value for gearbox efficiency would be between 83% - 87% for normal gearboxes. Straight cut racing gearboxes between 91% - 95%.

Compensation for gearshift time

Figures which show a comparison of the speed, rpm and throttle traces with or without a gearshift time in the simulation model

The specified gearshift time determines how long there will be no traction force during shifting.

As you can see in the figure, LapSim will increase the shifting point to compensate for the duration of the gearshift time, so the shifting point still results in the quickest laptime.