Document ID: chunk:federal_register_of_legislation:F2023L00129:reg:13:p2
Version: federal_register_of_legislation:F2023L00129
Segment Type: reg
Provision Reference: reg 13 (pt 2/56)
Character Range: 301598–304409

rate of at least one point per second.

 When selecting option (b) in paragraph 7.4.7. for determining negative reference torque, the mapping curve may directly continue with minimum operator demand from maximum to minimum mapping speed.

7.4.4. Alternate mapping

 If a manufacturer believes that the above mapping techniques are unsafe or unrepresentative for any given engine, alternate mapping techniques may be used. These alternate techniques shall satisfy the intent of the specified mapping procedures to determine the maximum available torque at all engine speeds achieved during the test cycles. Deviations from the mapping techniques specified in this paragraph for reasons of safety or representativeness shall be approved by the Type Approval Authority along with the justification for their use. In no case, however, the torque curve shall be run by descending engine speeds for governed or turbocharged engines.

7.4.5. Replicate tests

 An engine need not be mapped before each and every test cycle. An engine shall be remapped prior to a test cycle if:
(a) An unreasonable amount of time has transpired since the last map, as determined by engineering judgement; or
(b) Physical changes or recalibrations have been made to the engine which potentially affect engine performance.

7.4.6. Denormalization of engine speed

 For generating the reference cycles, the normalized speeds of Appendix 1 (WHTC) and Table 1 (WHSC) shall be denormalized using the following equation:
 nref = nnorm x (0.45 x nlo + 0.45 x npref + 0.1 x nhi − nidle) x 2.0327 + nidle (9)

 For determination of npref, the integral of the maximum torque shall be calculated from nidle to n95h from the engine mapping curve, as determined in accordance with paragraph 7.4.3.

 The engine speeds in Figures 4 and 5 are defined, as follows:

                  nnorm is the normalized speed in Appendix 1 and Table 1 divided by 100

nlo is the lowest speed where the power is 55 per cent of maximum power

                  npref is the engine speed where the integral of max. mapped torque is 51 per cent of the whole integral between nidle and n95h

                  nhi is the highest speed where the power is 70 per cent of maximum power

 nidle is the idle speed

                  n95h is the highest speed where the power is 95 per cent of maximum power

 For engines (mainly positive ignition engines) with a steep governor droop curve, where fuel cut off does not permit to operate the engine up to nhi or n95h, the following provisions apply:

 nhi in equation 9 is replaced with nPmax  1.02

 n95h is replaced with nPmax  1.02
       Figure 4:
       Definition of test speeds

       Figure 5
       Definition of npref

7.4.7. Denormalization of engine torque

 The torque values in the engine dynamometer schedule