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DYNO
- Our facility houses a state of the art 2WD DASTEK
dynamometer. Unlike some other dynamometers, our unit
is capable of both acceleration run and loading run.
No matter what car, if it needs tuning or you just
want to know its power output and air fuel ratio we
can do it! A car is a car!! Knowing its air fuel ratio
is a good idea before you perfom any modifications to
your car. There is no point fitting and fiddling with
an S-AFC if your car's air fuel ratio is perfect!
Introduction
- A chassis dynamometer or also known as a rolling
road contains either one or two rollers. The purpose
of a chassis dynamometer is to measure engine output
either expressed in horsepower (hp), kilowatts (kW) or
Pferdestarke (ps). There is also a wideband O2 sensor
attached to the vehicle's exhaust to accurately
measure the air fuel ratio mixture of the engine. This
is important as incorrect air fuel ratio mixture at
high loads can lead to engine meltdown which is rather
costly and should be avoided. There is also a very
high flow fan blower placed in front of the vehicle to
keep the engine cool. This provides air flow
equivalent to driving on the motorways. This is
required since now the car is actually stationary
while the 'road' is moving.
Acceleration
run - or sometimes also known as inertia run is
best used to accurately obtain engine horsepower.
Power is measured by means of a heavy roller of a
known weight (usually 2 tonnes or so) where a vehicle
is strapped down. The vehicle is then accelerated
(usually in 3rd of 4th gear all the way to red line).
The system then measures the time taken to accelerate
the rollers. Since the mass (weight) of the roller
wheel is known, power and torque can then be
calculated using Newton's law. Force (torque) = mass x
distance traveled;. Power = torque over a specific
time (torque divide by time). So you can easily see
that the higher the power, the faster it takes to
accelerate a mass (weight). However this method is
only useful to accurately obtain hp figures and is not
suitable for engine tuning since the engine runs
freely on the roller wheel. Horsepower figures are
power at the wheels. A dyno sometimes also will
attempt to calculate the losses of the vehicle caused
by friction of the gears, bearings and sometimes due
to improper gearbox to shaft alignment etc. to obtain
the power at the flywheel. The flywheel horsepower is
not 100% accurate as the only way to get the exact
flywheel horsepower is to remove the engine from the
vehicle and bolt it on to an engine dynamometer in a
test cell.
Loading
run - is whereby a dynamometer has a second roller
known as the 'brake' hence the name brake horsepower (BHP).
This allows an engine to run at a steady state which
that the operator can hold the engine at any speed
that he dials into. The operator can then alter the
ignition timing while carefully listening for knock
and optimize air fuel ratio by monitoring a wideband
air fuel ratio display to tune for best power and
torque. So how does it calculate the horsepower. The
system applies torque to the rollers.When the torque
applies equals to the torque produced by the engine,
the dyno rollers will be held at a steady state. Power
is than calculated. Power = torque / speed.
Cost
- Single runs RM100, Club runs (minimum of 10 cars)
RM60/car
Unit
Conversion
1 hp = 0.7457 kW
1 hp = 550 ft-lbs/sec
If you can push a 250kg (550lbs) weight one feet in
one second, you are rated roughly one horsepower.
If you can push the same mass in ten seconds then you
are rated 0.1 hp!
Power (hp) = Torque (ft-lbs) x RPM / 5,252
Which means Power (hp) = Torque (ft-lbs) at exactly
5,252 RPM
Dyno
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