Цитата(voroll @ 17.11.2009, 2:54)

Там написано Eng Power T WC, большая латинская буква "W" (wheels) как раз и означает что замер сделан с колес.
Литтеры WC означают Weather Correction, F=factor
Values Reported by a Chassis Dynamometer
A chassis dynamometer can directly measure the following values:
1. Roll shaft RPM/speed.
2. Torque/force applied to the dynamometer’s roll shaft(s).
All other values are based on these original 2 values. For example, acceleration is computed from
2 successive speed measurements, power are calculated based on the measured speed and torque
of the dynamometer’s rolls shaft(s), etc.
When a chassis dynamometer reports a “torque” value, the value reported is the torque measured
on the dynamometer’s rolls shaft(s), not on the vehicle’s drive axle or engine crankshaft.
A chassis dynamometer and the vehicle that is being tested on it effectively form a geared power
transfer system. While force is obviously not an engine-crankshaft relative term, and power values
do not scale (ignoring transmission losses) from shaft to shaft in a geared system, torque values do
scale from shaft to shaft in a geared system. So, in order for a chassis dynamometer to report
engine crankshaft relative torque values, the control software must know:
1. Dynamometer roll shaft torque.
2. Dynamometer roll shaft RPM.
3. Engine crankshaft RPM.
Using these 3 values, the control software can calculate the engine crankshaft torque that the
engine must be producing, using the formula below:
EngineTorque = ((DynoShaftTorque * DynoShaftRPM) / EngineRPM)
When engine RPM is not available, there is no way to report an engine crankshaft relative torque
value.
In Mustang Dynamometer chassis dynamometer software, when an engine-crankshaft relative
torque value is reported, it is simply a calculated value as described above. No “correction” factor
has been applied to account for drive-train losses. The overall gearing between the vehicle’s
engine and the
Dynamometer’s rolls has been calculated and used to scale the measured torque from a
dynamometer roll shaft value to an engine crankshaft value. So, just as power values will be lower
on a chassis dynamometer than on a test-stand dynamometer, any reported engine torque values
will be similarly lower.
Differences Between Chassis and Test-Stand Dynamometers
It is important to remember that a chassis dynamometer reports the power, force, and speed
experienced by the dynamometer’s roll shaft(s). A power figure obtained for an engine using a test
stand dynamometer will (and should) inevitably be higher than the power figure obtained using a
chassis dynamometer, for (among others) the following reasons:
1. On a test stand, there are no torque-converter/clutch, transmission, driveshaft,
differential or axle bearing losses.
2. On a test stand, there are no losses between the tires of the vehicle and the rolls of
the dynamometer.
3. On a test stand, some or all of the engine accessories may be disconnected.
4. On a test stand, the engine intake air, water and oil supplies may be externally
controlled.
5. On a test stand, the exhaust may be different than the exhaust system used on the
vehicle.
Differences in Reported Power Between Dynamometers
All of the following factors can influence the power measured by a chassis dynamometer:
1. Tire compound, pressure and temperature.
2. Engine, transmission and differential temperatures.
3. Lubricant types.
4. Method of vehicle restraint (downward pressure will waste power).
5. Type of testing performed: fast decelerating sweeps will generate the highest
values, steady state tests will generate intermediate values, and fast accelerating
sweeps will generate the lowest values, due to the internal power requirements of
the engine and drive-train in the vehicle under test.
6. Atmospheric condition corrections to different “standard” conditions.
7. Operator driving differences (can be very significant!).
8. Data acquisition options, particularly smoothing/averaging and clipping
functions.
While all chassis dynamometers should report the same power output for the same vehicle, this is
seldom the case. Most commonly, the difference in reported power values for the same vehicle on
different dynamometers can be traced to one or more of the factors listed above.