Chassis Dynamometer has become the industry standard in chassis
dynamometers worldwide because of its revolutionary ability
to measure horsepower/torque with repeatability, accuracy and
dynojet is accurate within 1% from Dynojet to Dynojet anywhere
in the world! This enabled the communication and sharing
of test data.
Isaac Newton said, (Force=Mass x Acceleration)
Force (horsepower) = Mass
(weight of drums) x Acceleration (provided
by the vehicle being tested)
of two laws of physics, force equals mass times acceleration
and work equals force times distance, gives us this equation:
W=m X a X d. "W" is the work, in pounds-feet, the rear wheels
are doing, "m" is mass equivalent (the drums), "a" is acceleration
(increasing drive wheel speed) and "d" is distance (drum circumference).
Once we have the work, we can find horsepower. One horsepower
is 550 pounds-feet of work done in one second so, we divide
the work number by the length of time measured, then divide
the number we get from that by 550. To simplify: we get horsepower
by multiplying the mass, acceleration and the distance, then
dividing that product by time multiplied by 550. This can be
expressed by: hp = (m X a X d) ÷ (t X 550).
can be figured by multiplying the horsepower by a constant,
5252, then dividing that product by the speed at which the thrust
force was measured. Generally, with rear wheel numbers, axle
ratio is not considered in the torque computation. For comparison
purposes, this makes more sense. The computer factors out the
axle ratio by using engine speed data in the torque derivation.
Since the only variable in the equation
is the vehicle, we can measure the amount of horsepower a vehicle
produces at the rear wheels with an extremely high level of
accuracy and repeatability. There are up to 4000 sample points
in a typical Dynojet horsepower test! Dynojets use the (SAE
J1349 rev. June 1990) correction factor, this is the lastest
correction factor in use today. Allowing our customers to compare
results with each other from over 600 Dynojets worldwide. Test
can also be measured using DIN, EEC, and STD correction factors.
The dynojet has become
the lie detector of the industry.
An inertia dyno
differs from a brake dyno in several ways:
1) it has no active
power absorption device
2) it's more accurate
3) it's easier on
the vehicles being tested
4) it's easier to
Another problem with
some brake-type chassis dynos is they lack the accuracy and
repeatability demanded by many performance-aftermarket manufacturers
Overheating the tires
and the tendency of cars to try and jump off the rollers are
also eliminated. Also, vehicles do not need to be loaded down
against the rollers which also reduces heat build up and increased
frictional losses through the tires.
why Dynojet is the chassis dyno of choice for names like:
BORLA, HENNESSEY, ROBERT YATES, KENNY BROWN, STEEDA, HKS, KENNE
BELL, PENSKE, ROUSCH, A.J. FOYT, JAVIER GUTIERREZ, NASCAR, ETC.
. . .
Competition Data Systems data acquisition we can simultaneously
map and plot RPM, time, and wheel speed.
-Wide Band Air to Fuel
-Horsepower and Torque
-We can also do speedometer calibrations
© 2003 DYNOSPORT. All rights reserved.
by Trenton Wilcox