Below are some examples of parasitic loss and inertia values for various chassis roller and drive assemblies. These numbers represent the averages for each configuration.


“These are average values as of 5/4/2013.” Let us help you. If you are not sure which configuration applies to your system, contact technical support. Smoother roller-inertial-torque data is available, from DYNOmite-Pro board sets, by using one of our 0.1 RPM resolution modes (e.g. “RPM Pulses/Rev 4/1 x 0.1”). These modes provides finer resolution of the inertial acceleration power, […]

“These are average values as of 5/4/2013.”

Let us help you. If you are not sure which configuration applies to your system, contact technical support.

Smoother roller-inertial-torque data is available, from DYNOmite-Pro board sets, by using one of our 0.1 RPM resolution modes (e.g. “RPM Pulses/Rev 4/1 x 0.1”). These modes provides finer resolution of the inertial acceleration power, and are primarily for large-diameter and higher-inertia chassis-dyno assemblies – that will not be exceeding 6,535 RPM on Absorber (RPM-C).

Tip:  If you are using an inductive spark lead pickup on a signal source, that does not provide particularly clean Engine RPM  (RPM-A) data, it is suggested that you enter 0.000 as the inertia value for RPM A. This prevents small Engine RPM spikes form inducing large inertial torque values. 

This RPM for Hp Loss data was standardized at 5,252 (shaft) RPM simply for comparison convenience. It is this scaling, to 5,252 RPM, that makes these “Hp loss” values seem so large! Understand that, since they are exponentially applied, at lower “real-world” roll rpm’s their effective correction value is much smaller. DYNO-MAX “Pro” allows using any data entry RPM (and/or Exponent) when keying in your own experimental parasitic loss test result curve. However, do not change this data unless you understand the underlying principals and ramifications. We invite you to contact technical support for assistance.

There are two tables below (one for DYNO-MAX 2010 and the other for DYNO-MAX 2000). Each lists typical parasitic loss values and also the Vehicle Speed Factor calibration entry for various DYNOmite Dynamometer models.

Note: In DYNO-MAX 2010, the new “Driveline loss” values can only be entered from the Run Information screen’s – Vehicle tab (not from the Dyno tab). In DYNO-MAX 2010 (only) these Driveline loss values are used to drive the (chassis dynamometer) Estimated Flywheel Power and Torque formulas – these (approximate) sample entries do not effect the calculations for any of the other power or torque formulas. The new DYNO-MAX 2010 “Dyno loss” fields, which replace the old DYNO-MAX 2000 Driveline loss fields, must always be entered appropriately – to return precise power and torque formula results.

Entries for DYNO-MAX 2010 version 9.60 (and later)

Important: The table immediately below is only for use with DYNO-MAX 2010 versions 9.60 and later! For DYNO-MAX 2000 versions 9.38 (and earlier) use the second table – further down this page.

DYNOmite Dynamometer Model
(latest versions listed)
Driveline
Power
loss =
@ (shaft)
RPM of
Driveline
%
loss =
@ (shaft)
RPM of
to an
Exponent of
Dyno
Power
loss =
@ (shaft)
RPM of
to an
Exponent of
Dyno
%
loss =
@ (shaft)
RPM of
to an
Exponent of
Theoretical- Tire Vehicle Speed Factor
RPM-B/MPH
Deformed- Tire*** Vehicle Speed Factor
RPM-B/MPH
Average Inertias
(less absorber’s inertia if listed separately)*
5″ Kart roll + direct drive105,252105,25202.15,2522.005,252067.2365.46***0.269 (total)
               
8-1/2″ rolls + direct drive305,252105,252028.05,2522.005,252039.2637.82***3.279 (total)
               
12″ rolls + eddy-current absorber belt drive605,252105,252048.55,2522.025,252028.0127.25***12.600 (total)
12″ rolls + water-brake absorber belt drive605,252105,252032.05,2522.025,252028.0127.25***12.600 (total)
AWD 12″ rolls + dual eddy-current absorbers belt drive1205,252105,252097.05,2522.025,252028.0127.25***12.600 (per axle)**
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.200 (per absorber)
               
13″ rolls + eddy-current absorber belt drive705,252105,2520755,2522.025,252026.6325.93***4.587 (total)
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.215 (per absorber)
               
16″ x 25″w Bike (only) roll (inertia only – no drive)405,252105,25204.55,2522.005,252021.0120.50***4.700
16″ x 25″w Bike (only) roll  + eddy-current belt drive405,252105,25204.55,2522.025,252021.0120.50***4.900 (total)
add for absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.200 (per absorber)
               
16″ x 50″w ATV / Bike roll (inertia only – no drive)405,252105,25206.55,2522.005,252021.0120.50***6.700 (total)
16″ x 50″w ATV / Bike roll + water-brake belt drive405,252105,252024.05,2522.025,252021.0120.50***6.920 (total)
16″ x 50″w ATV / Bike roll + eddy-current belt drive405,252105,252024.05,2522.025,252021.0120.50***6.920 (total)
add for absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.200 (per absorber)
               
16″ x 64″w Formula SAE roll + eddy-current belt drive405,252105,252026.05,2522.025,252021.0120.50***8.920 (total)
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.200 (per absorber)
               
16″ roll + single eddy-current absorber integral drive1005,252105,252.020.05,2522.005,252.021.0120.50***25.000 (total)
               
20″ roll + single eddy-current absorber integral drive1605,252105,252.020.05,2522.005,252.016.8716.51***35.850 (total)
               
20″ rolls (MR-12) + dual #400 eddy-current absorbers belt drive3205,252105,252.06255,2522.025,252.016.8716.51***79.900 (total)
20″ rolls (MR-12) + triple #650 eddy-current absorbers belt drive3205,252105,252.09405,2522.025,252.016.8716.51***79.900 (total)
24″ x 26″w rolls + eddy current-absorber belt drive2305,252105,2520240.05,2522.025,252014.0813.80***45.273 (total)
24″ x 26″w rolls + water-brake absorber belt drive2305,252105,2520134.05,2522.025,252014.0813.80***45.905
 (total)
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.632 (per absorber)
24″ x88″w single roll (inertia only – no drive)2305,252105,252050.05,2522.005,252014.0813.80***52.625
24″ roll + single eddy-current absorber belt drive2305,252105,2520160.05,2522.025,252014.0813.80***53.332
 (total)
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.707 (per absorber)
               
30″x96″ roll (inertia only – no drive)3605,252105,252060.05,2522.005,252011.2011.03***143.852
30″x96″w roll + single eddy-current absorber belt drive3605,252105,252.0210.05,2522.025,252.011.2011.03***144.561 (total)
AWD 30″x96″w roll + dual eddy-current absorbers belt drive3605,252105,2520420.05,2522.025,252011.2011.03***144.561 (per axle)**
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a0.709 (per absorber)
               
44″ x 26″w rolls + water-brake absorber belt drive7805,252105,2520275.05,2522.025,25207.667.57***208.000 (total)
44″ x 26″w rolls + single eddy-current absorber belt drive7805,252105,2520275.05,2522.025,25207.667.57***211.251 (total)
44″ x 26″w rolls + dual eddy-current absorbers belt drive7805,252105,2520300.05,2522.025,25207.667.57***211.251 (total)
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a3.251 (per absorber)
               
AWD 44″ x 26″w rolls + single eddy-current absorbers belt drive15605,252105,2520560.05,2522.025,25207.667.57***211.251  (total per axle)**
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a3.084 (per absorber)
               
AWD 44″ x 26″w  rolls + dual eddy-current absorbers belt drive15605,252105,2520600.05,2522.025,25207.667.57***211.251  (total per axle)**
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a3.084 (per absorber)
               
60″ x 26″w rolls + single eddy-current absorber belt drive11005,252105,2520320.05,2522.025,25205.605.54***215.000 (total)
absorber belt-drive system (only)n/a5,252n/a5,2520n/a5,2522.025,2520n/an/a6.103 (per absorber)
               
1000 axle-hub units (pair)55,252105,252045,2522.00.15,2520******4.480 (total)
1500 axle-hub units (pair)55,252105,252045,2522.00.15,2520******7.200 (total)
Tractor 100,000 (8-#650) axle-hub units (pair)505,25255,25201005,2522.025,2520******3.885 (total)
absorber belt-drive pulleys (only)n/a5,252n/a5,2520n/a5,2522.025,2520******26.328 (total)
2000 axle-hub AWD units (pair)55,252105,252085,2522.00.25,2520******4.480 (total per axle)**
3000 axle-hub AWD units (pair)55,252105,252065,2522.00.15,2520******7.200 (total per axle)**
               
Tractor PTO – single #650 eddy-current absorber drive505,25255,2520120.05,2522.025,2520******0.920 (total)
Tractor PTO – dual #650 eddy-current absorbers drive505,25255,2520220.05,2522.025,2520******1.145 (total)

*Tip:  Your rolls may have their individual component values stamped on each roll’s end edges (be sure to total up all the sub-components inertias before entering them into DYNO-MAX’s (e.g. as RPM B Inertia). You can also use the DYNO-MAX “Pro” Formulas and/or Pendulum Inertia Calculator to experimentally derive the calibration numbers for your own system.

** Important: Although these AWD inertia specifications are per axle, do not double them when entering the RPM-B inertia into DYNO-MAX – its AWD aware Inertial Torque formulas already handle that.

** Important: RPM-B/MPH ratio is based on tire diameter – use DYNO-MAX’s “Define Dyno Configuration and Speed Factor” calculator screen.

***Tip: In most cases this factor can be set simply by comparing the vehicle’s speedometer reading to DYNO-MAX’s and then adjusting the factor up or down by the % of deviation. However, if the speed factor is calculated from the dynamometer roller’s diameter (e.g. via the Speed Factor Calculator) there can be a slight understating (-1% to -5%) of the real-world speed – due to tire deformation (particularly for small-diameter rolls). The exact deformation will vary with tire construction, inflation, strap-down forces, etc.

Entries for DYNO-MAX 2000 version 9.38 (and earlier)

 Important: The table immediately below is only for use with DYNO-MAX 2000 versions 9.38 and earlier! For DYNO-MAX 2010 versions 9.60 (and later) use the table above. Aslo, for all DYNO-MAX versions, the Vehicle Speed Factor and inertia data from the above shart should be used.

DYNOmite Dynamometer Model
(latest versions listed)
Driveline
Power
loss =
@ (shaft)
RPM of
Driveline
%
loss =
@ (shaft)
RPM of
to the
Exponent of
5″ Kart roll + direct drive2.15,25205,2520
      
8-1/2″ rolls + direct drive28.05,25205,2520
      
12″ rolls + eddy current absorber belt drive48.55,25225,2520
12″ rolls + water brake absorber belt drive32.05,25225,2520
AWD 12″ rolls + dual eddy current absorber belt drive97.05,25225,2520
absorber belt drive system (only)n/a5,25225,2520
      
16″ x 50″ ATV / Bike roll (inertia only – no drive)6.55,25205,2520
16″ x 50″ ATV / Bike roll + water brake belt drive24.05,25225,2520
16″ x 50″ ATV / Bike roll + eddy current belt drive24.05,25225,2520
absorber belt drive system (only)n/a5,25225,2520
      
16″ x 64″ Formula SAE roll + eddy current belt drive26.05,25225,2520
absorber belt drive system (only)n/a5,25225,2520
      
16″ x 25″ Bike (only) roll (inertia only – no drive)4.55,25205,2520
      
16″ roll + single eddy current absorber integral drive20.05,25205,252.0
      
24″ x 26″ rolls + eddy current absorber belt drive240.05,25225,2520
24″ x 26″ rolls + water brake absorber belt drive134.05,25225,2520
absorber belt drive system (only)n/a5,25225,2520
      
24″ single roll (inertia only – no drive)50.05,25205,2520
24″ roll + single eddy current absorber belt drive160.05,25225,2520
      
30″ roll (inertia only – no drive)60.05,25205,2520
30″ roll + single eddy current absorber belt drive210.05,25225,252.0
AWD 30″ roll + dual eddy current absorber belt drive420.05,25225,2520
absorber belt drive system (only)n/a5,25225,2520
      
44″ x 26″ rolls + water brake absorber belt drive275.05,25225,2520
44″ x 26″ rolls + single eddy current absorber belt drive275.05,25225,2520
44″ x 26″ rolls + dual eddy current absorber belt drive300.05,25225,2520
AWD 44″ x 26″ rolls + single eddy current absorber belt drive560.05,25225,2520
AWD 44″ x 26″ rolls + dual eddy current absorber belt drive600.05,25225,2520
absorber belt drive system (only)n/a5,25225,2520


*Tip:  Your rolls may have their individual component values stamped on each roll’s end edges (be sure to total up all the sub-components inertias before entering them into DYNO-MAX’s (e.g. as RPM B Inertia). You can also use the DYNO-MAX “Pro” Formulas and/or Pendulum Inertia Calculator to experimentally derive the calibration numbers for your own system.

** Important: Although these AWD inertia specifications are per axle, do not double them when entering the RPM-B inertia into DYNO-MAX (its AWD aware Inertial Torque formulas already handle that)!