---
kind: "section"
citation: "40 C.F.R. § 86.1333"
title: "40"
number: "86.1333"
heading: "Transient test cycle generation."
url: "https://uscodex.org/cfr/40/86.1333"
---

# §86.1333. Transient test cycle generation.

- (a) **Generating transient test cycles.** The heavy-duty transient engine cycles for Otto-cycle and diesel engines are listed in appendix I((f) (1), (2) and (3)) to this part. These second-by-second listings represent torque and rpm maneuvers characteristic of heavy-duty engines. Both rpm and torque are normalized (expressed as a percentage of maximum) in these listings.
  - (1) **To unnormalize rpm, use the following equations—**
    - (i) **For diesel engines—**
  - (2) **Torque is normalized to the maximum torque at the rpm listed with it.** Therefore, to unnormalize the torque values in the cycle, the maximum torque curve for the engine in question must be used. The generation of the maximum torque curve is described in [40 CFR part 1065](/cfr/40/part1065.md).
- (b) **Example of the unnormalization procedure.** Unnormalize the following test point, given Maximum Test speed = 3800 rpm and Curb Idle Speed = 600 rpm.
  - (1) **Calculate actual rpm—**
  - (2) **Determine actual torque—** Determine the maximum observed torque at 1829 rpm from the maximum torque curve. Then multiply this value (e.g., 358 ft-lbs) by 0.82. This results in an actual torque of 294 ft-lbs.
- (c) **Clutch operation.** Manual transmission engines may be tested with a clutch. If used, the clutch shall be disengaged at all zero percent speeds, zero percent torque points, but may be engaged up to two points preceding a non-zero point, and may be engaged for time segments with zero percent speed and torque points of durations less than four seconds.
- (d) Determine idle speeds as specified in [40 CFR 1065.510](/cfr/40/1065.510.md).

## Notes

### Amendments

[70 FR 40438, July 13, 2005, as amended at 73 FR 37192, June 30, 2008; 79 FR 23704, Apr. 28, 2014]

### Authority

Authority: Secs. 202, 206, 207, 208, 301(a), Clean Air Act as amended 42 U.S.C. 7521, 7524, 7541, 7542, and 7601.

### Source

Source: 48 FR 52210, Nov. 16, 1983, unless otherwise noted.

### Authority

Authority: 42 U.S.C. 7401-7671q.

### Amendments

[70 FR 40438, July 13, 2005, as amended at 73 FR 37192, June 30, 2008; 79 FR 23704, Apr. 28, 2014]