Emission Test Cycles (ISO 8178)

The ISO 8178 is an international standard designed for a number of non-road engine applications. It is used for emission certification and/or type approval in many countries worldwide, including the USA, European Union and Japan. Depending on the legislation, the cycle can be defined by reference to the ISO 8178 standard, or else by specifying a test cycle equivalent to ISO 8178 in the national legislation (as it is the case with the U.S. EPA regulations).

The ISO 8178 is actually a collection of many steady-state test cycles (type C1, C2, D1, etc.) designed for different classes of engines and equipment. Each of these cycles represents a sequence of several steady-state modes with different weighting factors.

The particular engine modes and their weighting factors for B-type (11 mode) test cycles are listed in Table 1. The standard also includes an A-type 13-mode cycle, which is not listed in the table (ISO standards can be ordered through the ISO web site).

Table 1
Weighting Factors of B-Type ISO 8178 Test Cycles

Mode number	1	2	3	4	5	6	7	8	9	10	11
Torque, %	100	75	50	25	10	100	75	50	25	10	0
Speed	Rated speed					Intermediate speed					Low idle
Off-road vehicles
Type C1	0.15	0.15	0.15	-	0.10	0.10	0.10	0.10	-	-	0.15
Type C2	-	-	-	0.06	-	0.02	0.05	0.32	0.30	0.10	0.15
Constant speed
Type D1	0.30	0.50	0.20	-	-	-	-	-	-	-	-
Type D2	0.05	0.25	0.30	0.30	0.10	-	-	-	-	-	-
Locomotives
Type F	0.25	-	-	-	-	-	-	0.15	-	-	0.60
Utility, lawn and garden
Type G1	-	-	-	-	-	0.09	0.20	0.29	0.30	0.07	0.05
Type G2	0.09	0.20	0.29	0.30	0.07	-	-	-	-	-	0.05
Type G3	0.90	-	-	-	-	-	-	-	-	-	0.10
Marine application
Type E1	0.08	0.11	-	-	-	-	0.19	0.32	-	-	0.30
Type E2	0.20	0.50	0.15	0.15	-	-	-	-	-	-	-
Marine application propeller law
Type E3, Mode #	1		2		3		4
Power, %	100		75		50		25
Speed, %	100		91		80		63
Weighting factor	0.2		0.5		0.15		0.15
Type E4, Mode #	1		2		3		4		5
Power, %	100		80		60		40		0
Speed, %	100		71.6		46.5		25.3		Idle
Weighting factor	0.06		0.14		0.15		0.25		0.4
Type E5, Mode #	1		2		3		4		5
Power, %	100		75		50		25		0
Speed, %	100		91		80		63		Idle
Weighting factor	0.08		0.13		0.17		0.32		0.3
Notes: Engine torque is expressed in percent of the maximum available torque at a given engine speed Rated speed is the speed at which the manufacturer specifies the rated engine power Intermediate speed is the speed corresponding to the peak engine torque.