dtec DYNertia3 - Losses System; What Are the Effects of Mechanical Losses; What Does Measured Mechanical Loss Correction Do; Are These Losses Worth Worrying about

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Chapter 17: Losses Correction
’Losses’ System
Any mechanical system will have Power losses - your Engine, Transmission, Tires and the Dyno itself are no exception.
Within DYNertia3 we refer to these as Mechanical Losses (sometimes described elsewhere as ‘Parasitic’ Losses).
Every bearing, gear, chain, belt or other component of the system under test and in the Dyno itself is increasing these
mechanical losses. Even with good design, it is not possible to eliminate them and of course transmission and tire losses
on the system under test can be VERY significant.
What are the effects of Mechanical Losses?
Put simply, your Dyno will not give you the correct Power or Torque readings, even assuming you have an appropriately
sized and calibrated Inertial Mass or Brake Unit. In many applications this may not be a concern as the Dyno is used to
compare modifications / tuning changes - but if you really want accurate ”numbers” or work on a variety of systems then
losses need to be considered.
What does Measured Mechanical Loss Correction do?
‘Mechanical Losses Correction’ systems allows you to compensate for the measurable mechanical losses of your Dyno
system and Driveline. This is not a guess as sometimes included in other systems - but actual measurement of the
losses through the Dyno’s operating range. These losses are then automatically corrected for and ‘Loss’ information is
stored with each run file for later user analysis.
MEASURED Mechanical Loss Correction-
Ideal for Engine Dynamometers, where the System Under Test is directly connected to the Dyno. This enables
Mechanical Losses within the Dyno to be automatically and predictably corrected based on a “Correction File” (multiple
files allowed) created during the one off Losses Calibration process.
USER ESTIMATED Mechanical Loss Correction-
This is not a measured loss calculation, it is just an estimate. The result will depend on how well the loss percentage has
been researched, many users have their own idea of the losses they expect from manual and automatic drivelines.
Are these “Losses” worth worrying about?
That depends on the complexity, quality and maintenance of your system. We have tested losses from a small chassis
dyno system which has a worst case power loss of 1.141kW and 12.424 NM. - it's a very basic mechanical system ( 4
bearings and a disc brake ).
However other systems use multiple belts, numerous bearings, “run in” fans etc. and are a very different matter. Vee belt
losses range from 4% to 10%. Roller chain is commonly assumed to be around 98% efficient, non linear devices like
fans are even more troublesome and complex...... the losses all add up. So depending on your dyno’s construction and
your application - losses could be significant.