Chapter II Technical Information of Engine
Great Wall Baoding Internal Combustion Engine
Manufacturing Company Limited
17
Section III Main Performance Indexes of Engine
The indexes used to evaluate and analyze the engine performance mainly include the power
performance, economical efficiency, applicability, low public hazard, etc.; every index contains several
items, and here we only introduce the indexes that are commonly used:
1. Power Performance Index
(1) Effective torque: refers to the torque that is output through the engine flywheel; it is balanced to the
external resistance moment which is exerted on the power output end of engine. It is represented by M
e
,
and the unit is N•m.
(2) Effective power: refers to the power output by the engine. It is represented by P
e
, and the unit is kW.
It is calculated by multiplying the effective torque by the crankshaft rotation speed:
Where, M
e
——Effective torque (N·m).
n
——Crankshaft rotation speed (r/min).
The effective torque and the crankshaft rotation speed are usually measured with a hydraulic or electric
dynamometer directly; the effective power is calculated by Pe=M
e
·
n/9550 (kW), which indicates the
effective power under the tested working condition.
The effective power and corresponding rotation speed under the calibrated working condition indicated
on the engine nameplate are called the calibrated power and calibrated rotation speed. Presently, the
calibrated power of engine is divided into four grades according to the national standards:
(1) 15min power: the Max. effective power of engine when the engine constantly rotates for 15 minutes
under the standard environmental condition.
(2) 1h power: the Max. effective power of engine when the engine constantly rotates for 1 hour under the
standard environmental condition.
(3) 12h power: the Max. effective power of engine when the engine constantly rotates for 12 hours under
the standard environmental condition.
(4) Continuous power: the Max. effective power of engine when the engine continuously rotates at the
calibrated rotation speed under the standard environmental condition,.
Generally speaking, the 15min power is applied to the power calibration of vehicle, motorcycle,
motorboat, etc.; 1h power is applied to the industrial tractor, engineering machinery, diesel locomotive,
etc.; 12h power is applied to the agricultural tractor, agricultural irrigation and drainage machinery, and
river vessel, etc.; continuous power is applied to the power station, vessel, and agricultural irrigation and
drainage machinery, etc.
2. Economical Efficiency Index
Currently, the frequently used comparative evaluation index is the fuel consumption rate which refers to
the fuel mass consumed by the engine in an hour. It is represented by g
e
, and the unit is g/kW·
h:
ge=G/P.·
10
3
(g/kW·
h)
Where, G
——Fuel consumption per hour (kz/h) obtained by testing.
P
——Effective power of engine (kW).
Attention has always been taking for the reduction of fuel consumption since it has great significance for
decreasing engine application costs, promoting rational use of resources, improving the ecological
environment, etc., and the fuel consumption is decreasing year by year.
