Dynojet WinPEP 7 - Manual (Page 62)

WinPEP 7 User Guide
C H A P T E R 4
Making a Run—Negative Horsepower
4-8
N EGATIVE H ORSEPOWER T EST —D RIVE T RAIN
Performing the test in this example may exceed some vehicle’s design
specifications. Check with the vehicle manufacturer before performing
negative horsepower tests such as this one. This test could result in severe
damage to your vehicle.
Negative horsepower can measure how much power is absorbed by your drive train
and other parasitic losses (transmission, drive shaft, and tire friction). To graph drive
train loss simply perform a roll-on test.
1
Follow steps 1-8 for “Making a Run” on page 4-3.
2 At redline, push the clutch in (manual transmission) or put the vehicle in neutral
(automatic transmission). Allow the vehicle to coast to a stop.
3 When the drums are no longer, turning press the green sample button.
4 View the graph with negative horsepower enabled. This will display a positive and
negative horsepower graph.
The amount of horsepower displayed below zero is how much power is being
absorbed by the drive train at a given speed. Drive train losses can be visualized as the
negative horsepower area of the graph shown in Figure 4-6.
Figure 4-6: Negative Horsepower Graph Showing Drive Train Losses
zero
negative area of
graph