86.1332-90—Engine mapping procedures.
(1) Otto-cycle engines.
(i)
For ungoverned engines using the transient operating cycle set forth in paragraph (f)(1) of appendix I to this part, the maximum mapping speed shall be no less than that calculated from the following equation:
or when a 3.0 percent drop in maximum horsepower occurs, whichever of the two is greater
(ii)
For ungoverned engines using the transient operating cycle set forth in paragraph (f)(3) of appendix I to this part, the maximum mapping shall be no less than that calculated from the following equation:
or when a 3.0 percent drop in maximum horsepower occurs, whichever of the two is greater
(iii)
For governed engines the maximum mapped speed shall be no less than either that speed at which the wide-open throttle torque drops off to zero, or the maximum speed as calculated for ungoverned engines (paragraph (c)(1)(i) of this section)
(2) Diesel engines.
(i)
For ungoverned engines, the maximum mapping speed shall be no less than that calculated from the following equation:
or when a 3.0 drop in horsepower occurs, whichever of the two is greater
(ii)
For governed engines, the maximum mapping speed shall be no less than either that speed at which wide-open throttle torque drops off to zero, or the maximum speed as calculated for ungoverned engines (paragraph (c)(2)(i) of this section).
(1)
During engine preparation or warm-up, the engine may be operated such that a preliminary estimate of measured rated rpm can be made.
(2) Otto-cycle engines.
(i)
For a cold engine, start the engine and operate at zero load in accordance with the manufacturer's start-up and warm-up procedures for 1 minute ±30 seconds.
(ii)
Operate the engine at a torque equivalent to 10±3 percent of the most recent determination of maximum torque for 4 minutes ±30 seconds at 2000 rpm.
(iii)
Operate the engine at a torque equivalent to 55±5 percent of the most recent determination of maximum torque for 35 minutes ±1 minute at 2000 rpm.
(vi)
While maintaining wide-open throttle and full-load, maintain minimum engine speed for at least 15 seconds. Record the average torque during the last 5 seconds.
(vii)
In no greater than 100±20 rpm increments, determine the maximum torque curve from minimum speed to maximum speed. Hold each test point for 15 seconds, and record the average torque over the last 5 seconds.
(viii) Alternate mapping technique.
In place of paragraphs (d)(2) (vi) and (vii) of this section, a continual sweep of rpm is allowed. While operating at wide-open throttle, the engine speed is increased at an average rate of 8 rpm/sec (±1 rpm/sec) from minimum speed to maximum speed. Speed and torque points shall be recorded at a sample rate of at least one point per second.
(ix)
Recalculate the maximum speed per paragraph (c)(1) (i) or (ii) of this section using the measured rated speed derived from the new maximum torque curve. If the new maximum speed lies outside the range of speeds encompassed by the actual map, then the map shall be considered void, and another map will need to be run using the newly derived measured rated speed in all calculations.
(x)
For warm engines, the entire warm-up procedure specified in paragraphs (d)(2) (i) through (iii) of this section need not be repeated. It is sufficient for an engine already at normal operating temperatures to be operated at the conditions specified in paragraph (d)(2)(iii) of this section until oil and water temperatures are stabilized, after which the procedures of paragraph (d)(2) (iv) through (vii) of this section may be performed. The oil and water temperatures are defined as stabilized if they are maintained within 2 percent of point for 2 minutes.
(ii)
Operate the engine at approximately 50 percent power at the peak torque speed for 5 to 7 minutes.
(iv) Option.
The engine may be pre-conditioned by operating at rated speed and maximum horsepower until the oil and water temperatures are stabilized. The temperatures are defined as stabilized if they are maintained within 2 percent of point for 2 minutes. This optional procedure may be substituted for paragraph (d)(3)(iii) of this section.
(vi)
Operate the engine at wide open throttle and minimum engine speed. Increase the engine speed at an average rate of 8 rpm/sec (±1 rpm/sec) from minimum to maximum speed. Engine speed and torque points shall be recorded at a sample rate of at least one point per second.
(vii)
Recalculate the maximum speed per paragraph (c)(2) (i) or (ii) of this section using the measured rated speed derived from the new maximum torque curve. If the new maximum speed lies outside the range of speeds encompassed by the actual map, then the map shall be considered void. The entire mapping procedure shall be repeated, using the newly derived measured rated speed in all calculations.
(viii)
For warm engines, the entire warm-up procedure specified in paragraphs (d)(3) (i) through (iv) of this section need not be repeated. It is sufficient for an engine already at normal operating temperatures to be operated per the requirements of paragraph (d)(3)(iv) of this section, after which the procedures of paragraph (d)(3) (v) through (vi) of this section may be performed.
(e) Mapping curve generation.
(1) Otto-cycle engines.
Fit all data points recorded under paragraphs (d)(2) (vi) and (vii) of this section (100 rpm increments) with a cubic spline, Akima, or other technique approved in advance by the Administrator. The resultant curve shall be accurate to within ±1.0 ft-lbs of all recorded engine torques.
(ii)
All points generated under the continuous rpm sweep by paragraphs (d)(2) (vi) and (viii) of this section shall be connected by linear interpolation between points.
(iii)
For governed engines, all points above the maximum speed (see paragraph (c)(1)(ii) of this section) shall be assigned maximum torque values of zero for purposes of cycle generation.
(iv)
For all engines, all speed points below the minimum speed shall be assigned a maximum torque value equal to that observed at minimum speed for purposes of cycle generation.
(v)
The torque curve resulting from paragraphs (e)(1) (i) through (iv) of this section is the mapping curve and will be used to convert the normalized torque values in the engine cycle (see paragraph (f)(1) of appendix I to this part) to actual torque values for the test cycle.
(2) Diesel engines.
(i)
Connect all data points recorded under paragraph (d)(3)(vi) of this section using linear interpolation between points.
(ii)
For governed engines, all points above the maximum speed (see paragraph (c)(2)(ii) of this section) shall be assigned maximum torque values of zero for purposes of cycle generation.
(iii)
For all engines, all speed points below the minimum speed shall be assigned a maximum torque value equal to that observed at the minimum speed for purposes of cycle generation.
(iv)
The torque curve resulting from paragraphs (e)(2) (i) through (iii) of this section is the mapping curve and will be used to convert the normalized torque values in the engine cycle (see paragraph (f)(2) of appendix I to this part) into actual torque values for the test cycle.
(f) Alternate mapping.
If a manufacturer believes that the above mapping techniques are unsafe or unrepresentative for any given engine or engine family, alternate mapping techniques may be used. These alternate techniques must 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 section for reasons of safety or representativeness shall be reported per § 86.1344(e)(6), along with the justification for their use. In no case, however, shall descending continual sweeps of rpm be used for governed or turbocharged engines.
(g) Replicate Tests.
An engine need not be mapped before each and every cold cycle test. An engine shall be remapped prior to a cold cycle test if:
(1)
An unreasonable amount of time has transpired since the last map, as determined by engineering judgment, or
(2)
The barometric pressure prior to the start of the cold cycle test has changed more than 1 in hg. from the average barometric pressure observed during the map, or
(3)
Physical changes or recalibrations have been made to the engine which may potentially affect engine performance.