40 CFR 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; you may also choose between discrete-mode and ramped-modal testing. In all 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. If you submit certification test data using more than one duty cycle, any of the selected duty cycles may be used for any subsequent 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 described in 40 CFR Part 1065.
(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 | Weighting factors |
|---|---|---|---|
| 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. | Engine speed | 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) For full-load operating modes, operate the engine at wide-open throttle.