How the T-mount in your car dyno works

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How the T-mount works

The T-mount motor mounting system is a system created by Contrivance Engineering out of the desire to measure and collect torque and horsepower
data from an engine while it is in use. The T-mount system accomplishes this by creating a dynamometer in your car (or boat). Essentially the motor and
transmission assembly is cradled in a set of rollers which allow it to rotate freely with respect to the frame. Then a load sensor is placed between the motor
and frame to prevent that rotation and measure the load being exerted by the engine on the sensor. This is the torque output of the motor/transmission
assembly. Combining this information with driveshaft rpm gives horsepower. Vehicle dynamics(cornering, accellerating, going over bumps) do not affect
the measurements due to placement of the roller assemblies such that the engine rotates about its center of gravity. The total rotation is on the order of
.001 to .002 inch movement at the sensor. One form of the system is depicted in fig.1 and fig.2 The line drawn through the tailshaft mount and the pivotal
center of the motor plate passes through the CG(center of gravity) and is the axis about which the engine assembly rotates.
Measuring real time torque is the key to obtaining vital information such as drag coefficient and real altitude/air density/temperature affects on your
engine. This makes last minute dyno and engine tuning information available at the track during practice or warm up laps. When used in races where real
time measurement is not allowed during a race, the system can be quickly and easily disabled by removing the sensor and replacing it with a dummy pin
(see fig. 3 & 4).

Installation of the system requires the mounting of two plates for the attachment of the roller blocks at the front of the engine and the installation of a
single pivotal mount or equivalent at the rear of the transmission.
This is accomplished at the front of the engine by installing the T-mount assembly on the engine along with a positioning template (see fig.5). The
positioning template holds the roller blocks in the proper orientation while the engine is positioned. Once this is done, the weldments can be tack welded
into place. Fig. 6 shows a Bonneville car with a dummy engine block being used for positioning the mounts. Fig.7 is a close up of the plate welded into
place.
In this particular application, a standard rear transmission mount is used to provide the rear pivot.
Data collection can be done by any commonly available system. The sensor output is 0-5 volts with a 5-15 volt supply. Signal conditioning is provided
within the sensing unit itself. The system produces an accuracy better than 1% over a range of 09-2500ft.lb. of torque.