sent a true evaluation of engine condi-
sories not considered on the basic
tions.
engine.
1. Oil pressure gage installed in one of
In situations where other than basic en-
the engine main oil galleries.
gine equipment is used during the test,
proper record of this fact should be
2. Oil temperature gage installed in the
made on the Engine Test Report. The
oil pan, or thermometer installed in the
effects of this additional equipment on
dipstick hole in the oil pan.
engine performance should then be con-
sidered when evaluating test results.
3. Adaptor for connecting a pressure
gage or mercury manometer to the engine
DYNAMOMETER. The function of the
air box.
dynamometer is to absorb and measure
the engine output. It's basic components
4. Water. temperature gage installed in
are a frame, engine mounts, the absorp-
tion unit, a heat exchanger, and a tor-
the thermostat housing or water outlet
manifold.
que loading and measuring device.
5. Adaptor for connecting a pressure
The engine is connected through a uni-
gage or water manometer to the crank-
versal coupling to the absorption unit.
case.
The amount of power absorbed in a water
brake type dynamometer as an example,
6. Adaptor for connecting a pressure
is governed by the volume of fluid within
the working system. The fluid offers
gage or mercury manometer to the ex-
haust manifold at the flange.
resistance to a rotating motion. By con-
trolling the volume of water in the
absorption unit, the load may be in-
7. Adaptor for connecting a vacuum gage
creased or decreased as required.
or water manometer to the blower inlet.
The power absorbed is generally meas-
8. Adaptor for connecting a fuel pres-
ured in torque (lb-ft) on a suitable
sure gage to the fuel manifold inlet pas-
scale. The values for a given engine
sage.
speed will show the brake horsepower
developed in the engine by the following
9. Adaptor for connecting a pressure
formula:
gage or mercury manometer to the turbo-
charger.
BHP=(T x RPM)/5250
In some cases, gages reading in pounds
Where:
per square inch are used for determining
pressures while standard characteristics
BHP= brake horsepower
are given in inches of mercury or inches
of water. It is extremely important that
T- torque in lb-ft
RPM= revolutions per minute
the scale of such a gage be of low range
and finely divided if accuracy is desired.
This is especially turn of a gage reading
in psi, the reading of which is to be
Some dynamometers indicate direct brake
converted to inches of water. The fol-
horsepower readings. Therefore the use
lowing conversion factors may be
of the formula is not required when us-
helpful.
ing these units.
Inches of water =psi x 27.7"
During the actual operation, all data tak-
Inches of mercury =psi x 2.04"
en should be recorded immediately on an
Engine Test Report, shown at the end of
this subsection.
NOTE
INSTRUMENTATION. Certain instrumen-
Before starting the Run-In or
tation is necessary so that data required
starting the engine for any reason
to complete the Engine Test Report may
following an overhaul, it is of ex-
be obtained. The following list contains
treme importance to observe the
both the minimum amount of instruments
instructions of Preparation for
and the proper location of the fittings on
Starting Engine First Time in this
the engine so that the readings repre-
subsection.
Engine Tune-Up
11H-9
