1048.505—How do I test engines using steady-state duty cycles, including ramped-modal testing?

This section describes how to test engines under steady-state conditions. In some cases, we allow you to choose the appropriate steady-state duty cycle for an engine. In these cases, you must use the duty cycle you select in your application for certification for all testing you perform for that engine family. If we test your engines to confirm that they meet emission standards, we will use the duty cycles you select for your own testing. We may also perform other testing as allowed by the Clean Air Act.

(a) You may perform steady-state testing with either discrete-mode or ramped-modal cycles, as follows:

(1) For discrete-mode testing, sample emissions separately for each mode, then calculate an average emission level for the whole cycle using the weighting factors specified for each mode. Calculate cycle statistics and compare with the established criteria as specified in 40 CFR 1065.514 to confirm that the test is valid. Operate the engine and sampling system as follows:

(i) Engines with lean NO X aftertreatment. For lean-burn engines that depend on aftertreatment to meet the NOX emission standard, operate the engine for 5-6 minutes, then sample emissions for 1-3 minutes in each mode.

(ii) Engines without lean NO X aftertreatment. For other engines, operate the engine for at least 5 minutes, then sample emissions for at least 1 minute in each mode.

(2) For ramped-modal testing, start sampling at the beginning of the first mode and continue sampling until the end of the last mode. Calculate emissions and cycle statistics the same as for transient testing as specified in 40 CFR part 1065, subpart G.

(b) Measure emissions by testing the engine on a dynamometer with one or more of the following sets of duty cycles to determine whether it meets the steady-state emission standards in § 1048.101(b) :

(1) For engines from an engine family that will be used only in variable-speed applications, use one of the following duty cycles:

(i) The following duty cycle applies for discrete-mode testing:

Table 1 of § 1048.505

C2 mode No.	Engine speed 1	Torque(percent) 2	Weightingfactors
1	Maximum test speed	25	0.06
2	Intermediate test	100	0.02
3	Intermediate test	75	0.05
4	Intermediate test	50	0.32
5	Intermediate test	25	0.30
6	Intermediate test	10	0.10
7	Warm idle	0	0.15
1 Speed terms are defined in 40 CFR part 1065 .
2 The percent torque is relative to the maximum torque at the given engine speed.

(ii) The following duty cycle applies for ramped-modal testing:

Table 2 of § 1048.505

RMC mode	Time in mode(seconds)	Engine speed 1,2	Torque(percent) 2,3
1a Steady-state	119	Warm idle	0
1b Transition	20	Linear transition	Linear transition.
2a Steady-state	29	Intermediate speed	100
2b Transition	20	Intermediate speed	Linear transition.
3a Steady-state	150	Intermediate speed	10
3b Transition	20	Intermediate speed	Linear transition.
4a Steady-state	80	Intermediate speed	75
4b Transition	20	Intermediate speed	Linear transition.
5a Steady-state	513	Intermediate speed	25
5b Transition	20	Intermediate speed	Linear transition.
6a Steady-state	549	Intermediate speed	50
6b Transition	20	Linear transition	Linear transition.
7a Steady-state	96	Maximum test speed	25
7b Transition	20	Linear transition	Linear transition.
8 Steady-state	124	Warm idle	0
1 Speed terms are defined in 40 CFR part 1065 .
2 Advance from one mode to the next within a 20-second transition phase. During the transition phase, command a linear progression from the torque setting of the current mode to the torque setting of the next mode.
3 The percent torque is relative to maximum torque at the commanded engine speed.

(2) For engines from an engine family that will be used only at a single, rated speed, use the 5-mode duty cycle or the corresponding ramped-modal cycle described in 40 CFR part 1039, Appendix II, paragraph (a).

(3) Use a duty cycle from both paragraphs (b)(1) and (b)(2) of this section if you will not restrict an engine family to constant-speed or variable-speed applications.

(4) Use a duty cycle specified in paragraph (b)(2) of this section for all severe-duty engines.

(5) For high-load engines, use one of the following duty cycles:

(i) The following duty cycle applies for discrete-mode testing:

Table 3 of § 1048.505

Mode No.	Enginespeed	Torque(percent) 1	Minimum time in mode (minutes)	Weighting factors
1	Maximum test speed	100	3.0	0.50
2	Maximum test speed	75	3.0	0.50
1 The percent torque is relative to the maximum torque at maximum test speed.

(ii) The following duty cycle applies for discrete-mode testing:

Table 4 of § 1048.505

RMC modes	Time in mode(seconds)	Engine speed(percent)	Torque(percent) 1,2
1a Steady-state	290	Engine governed	100
1b Transition	20	Engine governed	Linear transition.
2 Steady-state	290	Engine governed	75
1 The percent torque is relative to maximum test torque.
2 Advance from one mode to the next within a 20-second transition phase. During the transition phase, command a linear progression from the torque setting of the current mode to the torque setting of the next mode.

(c) If we test an engine to confirm that it meets the duty-cycle emission standards, we will use the steady-state duty cycles that apply for that engine family.

(d) During idle mode, operate the engine at its warm idle speed as described in 40 CFR 1065.510.

(e) For full-load operating modes, operate the engine at wide-open throttle.

(f) See 40 CFR part 1065 for detailed specifications of tolerances and calculations.

(g) For those cases where steady-state testing does not directly follow a transient test, perform the steady-state test according to this section after an appropriate warm-up period, consistent with 40 CFR part 1065, subpart F.

Code of Federal Regulations

[73 FR 59239, Oct 8, 2008, as amended at 75 FR 23022, Apr. 30, 2010]