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CUSTOM FAST CARS |
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Useful car information |
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> Car Performance Tests |
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Car
Performance Tests |
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Learn what tests to do on your car in order to
evaluate its performance. |
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| Breaking Horse Power
(BHP) |
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See what horsepower your car
has with a dynamometer, the dynamometer applies
various loads on the engine and measures the
engine's ability to move the load. The
dynamometer may be connected to a computer which
calculates the output of the engine. The engine
is run from idle to its maximum RPM and the
output is measured and plotted on a graph.
Nearly all aspects of engine operation are
measured during a dyno run.
An engine dynamometer measures power and torque
directly from the engine's crankshaft (or
flywheel), when the engine is removed from the
vehicle. These dynos do not account for power
losses in the drivetrain, such as the gearbox,
transmission or differential etc.
A chassis dynamometer measures power from the
engine through the wheels. The vehicle is parked
on rollers which the car then turns and the
output is measured. These dynos can be fixed or
portable.
Because of frictional and mechanical losses in
the various drivetrain components, the measured
horsepower is generally 15-20 percent less than
the brake horsepower measured at the crankshaft
or flywheel on an engine dynamometer.
Horsepower and torque figures are a strong
predictor but do not guarantee a specific 0-60
MPH or 1/4 mile E.T. (elapsed time). An engine
accelerating in a vehicle experiences different
conditions than on a dyno. G forces and
different temperatures as well as different
modes of vibration in a vehicle can cause
significant differences in power output. |
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Compression Ratio |
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The compression ratio is a
single number that can be used to predict the
performance of any internal-combustion engine.
It is a ratio between the volume of a combustion
chamber and cylinder when the piston is at the
bottom of its stroke, and the volume when the
piston is at the top of its stroke. The higher
the compression ratio, the more mechanical
energy an engine can squeeze from its air-fuel
mixture. Higher compression ratios, however,
also make detonation more likely. Due to pinging
(detonation), the CR in a gasoline/petrol or LPG
or CNG-powered engine will usually not be much
higher than 10:1.
In engines with a ping or knock sensor and an
electronic control unit, the CR can be as high
as 13:1 (2005 BMW K1200S)
In a turbo charged or super charged engine the
CR will be around 8.5:1
In a diesel engine the CR will be 14:1 and
higher. |
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1/4 Mile or
Quarter Mile |
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The Quarter Mile (402 meters,
440 yards, or 1,320 feet) is a distance
generally used for racing two objects, and it an
excellent way to compare the speed and
acceleration of two objects. The race is
generally begun with a standing start which
allows three factors to affect the outcome of
the race: reaction time, acceleration and speed.
The most common example use of this distance is
in automobile Drag Racing. |
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0-60 mph |
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0 to 60 is how to measure the
acceleration of your vehicle it is the time it takes
your vehicle to get from standing to 60 mph. |
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