§ 89.407-96 - Engine dynamometer test run.

(a) Measure and record the temperature of the air supplied to the engine, the fuel temperature at the pump inlet, and the observed barometric pressure.

(b) The governor and fuel system shall have been adjusted to provide engine performance at the levels reported in the application for certification required under § 89.115-96.

(c) The following steps are taken for each test:

(1) Install instrumentation and sample probes as required.

(2) Perform the pre-test procedure as specified in § 89.406-96.

(3) Read and record the general test data as specified in § 89.405-96(c).

(4) Start cooling system.

(5) Precondition (warm up) the engine in the following manner:

(i) Operate the engine at idle for 2 to 3 minutes;

(ii) Operate the engine at approximately 50 percent power at the peak torque speed for 5 to 7 minutes;

(iii) Operate the engine at rated speed and maximum horsepower for 25 to 30 minutes;

(iv) Optional. It is permitted to precondition the engine 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 °C for 2 minutes. The engine must be operated a minimum of 10 minutes for this option. This optional procedure may be substituted for the procedure in paragraph (c)(5)(iii) of this section;

(v) Optional. If the engine has been operating on service accumulation for a minimum of 40 minutes, the service accumulation may be substituted for the procedure in paragraphs (c)(5)(i) through (iii) of this section.

(6) Read and record all pre-test data specified in § 89.405-96(d).

(7) Start the test cycle (see § 89.410-96) within 20 minutes of the end of the warmup. (See paragraph (c)(13) of this section.)

(8) During the first mode calculate the torque corresponding to 75, 50, and 10 percent of the maximum observed torque for the rated speed.

(9) During the fifth mode calculate the torque corresponding to 75 and 50 percent of the maximum observed torque for the intermediate speed.

(10) Record all modal data specified in § 89.405-96(e) during a minimum of the last 60 seconds of each mode.

(11) Record the analyzer(s) response to the exhaust gas during the a minimum of the last 60 seconds of each mode.

(12) Test modes may be repeated, as long as the engine is preconditioned by running the previous mode.

(13) If a delay of more than 20 minutes occurs between the end of one mode and the beginning of another mode, the test is void. If the delay is under four hours, the test may be restarted without preconditioning (begin at the point in the procedure described at paragraph (c)(6) of this section). If the delay exceeds 4 hours, the test shall include preconditioning (begin at paragraph (c)(2) of this section).

(14) The engine speed and torque must be measured within the accuracy requirements of Table 3 (in appendix A to subpart D), and maintained within the requirements of Table 1 (in appendix B to this subpart) during a minimum of the last 60 seconds of each mode.

(15) If at any time during a test mode, the test equipment malfunctions or the specifications in paragraph (c)(14) of this section are not met, the test mode is void and may be aborted. The test mode may be restarted without preconditioning (begin with paragraph (c)(6) of this section).

(16) Fuel flow and air flow during the idle load condition may be determined just prior to or immediately following the dynamometer sequence, if longer times are required for accurate measurements.

(d) Exhaust gas measurements. (1) Measure HC, CO, CO2, and NOX concentration in the exhaust sample.

(2) Each analyzer range that may be used during a test mode must have the zero and span responses recorded prior to the execution of that test mode. Only the zero and span for the range(s) used to measure the emissions during a test mode are required to be recorded after the completion of the test mode.

(3) It is permissible to change filter elements between test modes.

(4) A leak check is permitted between test segments.

(5) A hangup check is permitted between test segments.

(6) If, during the emission measurement portion of a test segment, the value of the gauges downstream of the NDIR analyzer(s) G3 or G4 (see Figure 1 in appendix B to subpart D) differs by more than ±0.5 kPa from the pretest value, the test segment is void.