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Description of the Configuration File
Volume 2, Rev 2 6/28/04
Section 9 - Page 17
Channel 37 - RwAbPw HP = C2*C123/5252.113
kW = C2*C123/9549
Used only on AWD
Channel 37 is used to calculate the power absorbed by the strain gage
attached to the rear differential. It uses the power absorber torque from
Channel 2 times the roll RPM from Channel 123, and divides by a
constant to determine the power absorbed. This value is combined with
channels 43 and 44 in channel 42 to calculate rear wheel power. When
the eddy current absorber is loaded during a test, this channel will
contribute a larger portion to the rear wheel power calculation in channel
42. When using the AWD dyno in 2WD mode, by not placing the vehicle
front wheels on the front rollset, this channel will also calculate all losses
due to the rear drive wheels now spinning the front rollset. Thus, no front
rollset losses or inertia calculations are necessary. This also enables use
of the dyno without the front rollset connected via its driveshaft.
Channel 38 - FwRlPw C39+C40+C41
Used only on AWD
Channel 38 is used to calculate the measured wheel power delivered to
the front dynamometer roll. Channel 41, the eddy current absorber power,
is added to Channel 39, the inertia power due to acceleration, and
Channel 40, the dynamometer parasitic power loss.
Some inertia only
dynamometers use only the inertia power, leading to measurement
errors.
This channel and channel 42 are added together to derive total
wheel power.
Channel 39 - FwInPw HP = (1651+C90)*C122*C10/375
kW = ((1651*0.454)+C90)*9.91*C122*C10/3600
Used only on AWD
Channel 39 is used to calculate the front rollset inertia power during a
transient test. When the vehicle is accelerating or decelerating, additional
power is developed by the engine to accelerate the inertia of the roll, the
absorber, and the rotating components of the vehicle. Inertia power is
calculated from the front rollset inertia of the dynamometer (1651 lbs), the
rotating inertia of the front wheels of the vehicle (channel 90), the rate of
acceleration in G's from Channel 122, and the actual road speed from
Channel 10. The inertia power is used by Channel 38 to determine the
total front wheel power. The default value of 1651 is the inertia value for a
typical front rollset. Individual customer systems will require their specific
rollset value to be entered into this channel. This will be done during initial
testing at SuperFlow and can be verified by the customer calibration data
sheet shipped with the system. The value is equivalent vehicle mass in
pounds. This value should match the calibration sheet shipped with your
system.
DO NOT CHANGE THIS VALUE. Doing so will severely alter all
power readings from the system. The constant 375 comes from the
standard horsepower equation constant that uses 33,000 lbs-ft/min. By
dividing 33,000 by 5280 and then multiplying by 60, you get 375. This
converts to lbs-miles/hour, which works with the MPH value from channel
10.