Whats in a Dyno Graph
You’ve had it all checked and graphed but
“what really’ is in a Dyno graph”? More importantly “what should you be demanding” on
the report.
Some other very important information rarely
included in results is exhaust gas AFR (Air Fuel
Ratios) and Turbo boost if the engine is turbo
charged. The actual power results are pretty
Dyno graphs are still probably the most misuseless if the power gained was through inrepresented piece of paper received by a Vecorrect tuning. The AFR reading will show you
hicle owner.
how ‘rich or lean’ the mixture is. This will show
The most common Dyno used to date for cars, how ‘safe’ the results are. Particularly on a Die4WDs and Motor Homes would be a wheel
sel engine the engine may have been tuned
roller Dyno.
up 20% BUT may have had the fuel loadings
increased substantially to do this.
Simply put the vehicle is driven onto the Dyno
for testing. The steel rollers of the Dyno that
Seeing the AFR graph under the power graphs
the vehicles tyres will turn generally have a
will confirm if the power gain was obtained
large magnet attached to them. Electric curwithout turning up the fuel too much (rerent is sent to them to prevent the wheels
membering Fuel makes heat in a Diesel).
from accelerating away and is converted
by the Dyno computer to read a Power and
So many times I see what is excessive overTorque figure on the screen.
powering due to over-fuelling in a Diesel.
The Dyno graphs looked great until the AFR
This information will vary from Dyno to Dyno reading is taken only to show worrying overdue to various conditions including atmofuelling.
spheric conditions. Any good dyno operator
will do multiple runs to gain a repeatable avTurbo boost being graphed as well will make
erage of the dyno result graphs. Meaning the sure that the boost isn’t slow in responding or
first and 5th run may vary as much as 10% if
too high for sustained reliability.
the engine started off testing cool and was by
the 5th run well at operating temperature.
The key to your vehicles Dyno result is understanding the graphs and figures. Make sure
The old idea of paying for a ‘single power run’ you ask questions and feel comfortable with
may as well have been spent on something
the explanations and through this you will be
else. So my advice is to take the information
sure that your tow vehicle or Motor home is in
and use it more as a guide to what your vethe best condition to tow safely.
hicle or Motor Home obtain ed on that day.
Safe Driving
The Dyno operator should explain the results
to you. If you have just had the engine tuned Andrew
you should be able to see some power gains
as well.