# 40 CFR § 86.1333 - Transient test cycle generation.

§ 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:

$\text{Actual rpm}=\frac{%\phantom{\rule{0ex}{0ex}}\mathrm{rpm}·\left(\text{Max Test Speed}-\text{Curb Idle Speed}\right)}{112}+\text{Curb Idle Speed}$

Where:
Max Test Speed = the maximum test speed as calculated in 40 CFR part 1065.

(ii) For Otto-cycle engines:

$\text{Actual rpm}=\frac{%\phantom{\rule{0ex}{0ex}}\mathrm{rpm}·\left(\text{Max Test Speed}-\text{Curb Idle Speed}\right)}{112}+\text{Curb Idle Speed}$

Where:
Max Test Speed = the maximum test speed as calculated in 40 CFR part 1065.

(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.

(b) Example of the unnormalization procedure. Unnormalize the following test point, given Maximum Test speed = 3800 rpm and Curb Idle Speed = 600 rpm.

$\frac{\text{PercentRPM}}{43}\frac{\phantom{\rule{0ex}{0ex}}\text{PercentTorque}}{82}$

(1) Calculate actual rpm:

$\mathrm{Actualrpm}=\frac{43·\left(3800-600\right)}{112}+600=1,829\mathrm{rpm}$

(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.

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