ing determined and the engine preconditioned. (§ 85.127(c).)

(1) Idle mode. The engine is caused to idle for 5 minutes at the manufacturer's recommended low idle speed. The controls shall be set to provide minimum load by turning the load switch to the "off" position or by adjusting the controls to the minimum load position.

(2) Acceleration mode. (i) The engine speed shall be increased to 200±50 r.p.m. above the manufacturer's recommended low idle speed in 2 to 3 seconds.

(ii) The engine shall be accelerated at full-throttle against the inertia of the engine and dynamometer such that the engine speed reaches 85 to 90 percent of rated speed in 5±1.5 seconds.

(iii) When the engine reaches the speed required in subdivision (ii) of this subparagraph, the throttle shall be moved rapidly to the closed position and the preselected dynamometer load shall be applied. The engine speed shall be reduced to the speed of maximum torque or 60 percent of rated speed (whichever is higher), each within ±50 r.p.m. Smoke emissions during this transitional mode are not used in determining smoke emissions to compare with the standard.

(iv) The throttle shall be moved immediately to the full-throttle position so that the engine accelerates to 95 to 100 percent of rated speed in 10±2 seconds.

(3) Lugging mode. (i) Proceeding from the acceleration mode, the dynamometer controls and throttle shall be adjusted to permit the engine to develop maximum rated horsepower. Smoke emissions during this transitional mode are not used in determining smoke emissions to compare to the standard.

(ii) Without changing the throttle position, the dynamometer controls shall be gradually adjusted to slow the engine to the speed of maximum torque or to 60 percent of rated speed, whichever is higher. This engine lugging operation shall be performed smoothly over a period of 35±5 seconds. The rate of slowing of the engine shall be linear, within ±100 r.p.m.

(4) Engine unloading. After completion of the lugging mode in subparagraph (3) (ii) of this paragraph, take appropriate steps to return the dynamometer and engine to the idle condition described in subparagraph (1) of this paragraph. When this is accomplished, prepare to repeat the cycle.

(b) Repeat the procedures described in paragraph (a) (1) through (4) of this section until the entire cycle has been run three times. This will complete the test and the equipment is shut down. § 85.123 Dynamometer and engine

equipment.

The following equipment shall be used for smoke emission testing of engines on engine dynamometers.

(a) Engine dynamometer with adequate characteristics to perform the test cycle described in § 85.122.

(b) Engine cooling system having sufficient capacity to maintain the engine at normal operating temperatures during conduct of the prescribed engine tests.

(c) A noninsulated exhaust system extending 12+2 feet from the exhaust manifold of the engine and presenting an exhaust back pressure within ±0.2 inches Hg of the upper limit at maximum rated horsepower, as established by the engine manufacturer in his sales and service literature for vehicle application. A conventional automotive muffler of a size and type commonly used with the engine being tested shall be employed in the exhaust system during smoke emission testing. The terminal 2 feet of the exhaust pipe shall be of circular cross section and be free of elbows and bends. The end of the pipe shall be cut off squarely. The terminal 2 feet of the exhaust pipe shall have a diameter in accordance with the engine being tested, as specified below: Maximum rated horsepower

Less than 101. 101-200 201-300 301 or more..

Exhaust pipe size

2"

3"

4"

5"

(d) An engine air inlet system presenting an air inlet restriction within ±1 inch of water of the upper limit for the engine operating condition which results in maximum air flow, as established by the engine manufacturer in his sales and service literature, for the engine being tested.

§ 85.124 Smoke measurement system.

(a) Schematic drawing. The following figure (fig. 6) is a schematic drawing of the optical system of the light extinction meter. Figure 7 shows the meter with a means for adapting the optical unit to the engine exhaust system.

vergence of the collimated beam shall be within 4° included angle. A light detector, directly opposed to the light source, measures the amount of light blocked by the smoke in the exhaust. The detector sensitivity is restricted to the visual range and comparable to that of the human eye. A collimating tube with apertures equal to the beam diameter is attached to the detector. It restricts the viewing angle of the detector to within 16° included angle. An amplified signal corresponding to the amount of light blocked is recorded continuously on a remote recorder. An air curtain across the light source and detector window assemblies may be used to minimize deposition of smoke particles on those surfaces provided that it does not measurably affect the opacity of the plume. The meter consists of two units, an optical unit and a remote control unit. Light extinction meters employing substantially identical measurement principles and producing substantially equivalent results but which employ other electronic and optical techniques for zeroing, spanning, and calibration than those described, are deemed to be acceptable substitutes.

(3) Recorder-a continuous recorder, with variable chart speed over a minimal range of 0.5 to 8.0 inches per minute (or equivalent) shall be used for continuously recording the transient conditions of exhaust gas opacity and engine r.p.m. The recorder scale for opacity shall be linear and calibrated to read from 0 to 100 percent opacity full scale. The opacity trace shall have a resolution within 1 percent opacity. The recorder scale for engine r.p.m. shall be linear and calibrated in units to facilitate chart reading. The r.p.m. trace shall have a resolution within 30 r.p.m. Any means other than a strip chart recorder may be used provided it produces a permanent visual record of the data which is of equal or better quality as that described above.

(4) The recorder used with the smokemeter shall be capable of fullscale deflection in 0.5 second or less. The smokemeter-recorder combination may be damped so that signals with a frequency higher than 10 cycles per second are attenuated. A separate low-pass electronic filter with the following performance characteristics may be installed between the smokemeter and the recorder to achieve the high-frequency attenuation.

(i) 3 decibel point-10 cycles per second.

(ii) Insertion loss-zero ±0.5 decibels. (iii) Selectivity-12 decibels per octave above 10 cycles per second.

(iv) Attenuation-27 decibels down at 40 cycles per second minimum.

(c) Assembling equipment. (1) The optical unit of the smokemeter shall be mounted radially to the exhaust pipe so that the measurement will be made at right angles to the axis of the exhaust plume. The distance from the optical unit to the exhaust pipe outlet shall be 1.0 to 1.5 pipe diameters but never less than 4 inches. The full flow of the exhaust stream shall be contained within and be approximately centered about the light path of the unit in order for the test to be valid.

(2) Power shall be supplied to the control unit of the smokemeter in time to allow at least 15 minutes for stabilization prior to its use.

§ 85.125 Information to be recorded.

The following information shall be recorded with respect to each test: (a) Test number.

(b) Date and time of day.
(c) Instrument operator.
(d) Engine operator.

numbers.

(e) Engine identification Date of manufacture-Number of hours of operation accumulated on engine— Exhaust pipe diameter-Fuel injector type-Maximum fuel rate-Air aspiration system-Low idle r.p.m.-Maximum governed r.p.m.-Maximum rated horsepower and r.p.m.-Maximum torque and r.p.m.-Exhaust system back pressureand air inlet restriction.

(f) Smokemeter. Number-Zero control setting-Calibration control setting-Gain.

(g) Recorder chart. Identify zero traces-Calibration traces-Idle tracesAcceleration test traces-Lugging test traces Start and finish of each test. (h) Ambient temperature in dynamometer testing room.

(i) Engine intake air temperature.
(j) Barometric pressure.

§ 85.126 Instrument checks.

(a) The smokemeter shall be checked according to the following procedure prior to each test:

(1) The optical surfaces of the optical section shall be checked to verify that they are clean and free of foreign material and fingerprints. They shall be

cleaned if necessary; a fresh cotton swab and alcohol is useful for this purpose.

(2) The zero control shall be adjusted under conditions of "no smoke" to give a recorder trace of zero.

(3) Calibrated neutral density filters having approximately 20 percent and 40 percent opacity shall be employed to check the linearity of the instrument. The filter(s) is inserted in the light path perpendicular to the axis of the beam and adjacent to the opening from which the beam of light from the light source emanates, and the recorder response is noted. Deviations in excess of 1 percent opacity will necessitate corrective action.

(b) The instruments for measuring and recording engine rpm; air inlet restrictions; exhaust system back pressure etc., which are used in the tests prescribed herein shall be calibrated from time to time using techniques in accordance with good technical practice.

§ 85.127 Test run.

(a) The temperature of the air supplied to the engine shall be between 68° F. and 86° F. The observed barometric pressure shall be between 28.5 inches and 31 inches Hg. Higher air temperature or lower barometric pressure may be used, if desired, but no allowance will be made for possible increased smoke emissions because of such conditions.

(b) The governor and fuel system shall have been adjusted previously to limit engine performance at the levels specifiled by the engine manufacturer for maximum brake horsepower and maximum torque. These specifications shall be supplied with the data submitted under § 85.51.

(c) The following steps shall be taken for each test:

(1) Start cooling system.

(2) Starting with a warmed engine, determine by experimentation the dynamometer inertia and dynamometer load required to perform the accelerations in the dynamometer cycle for smoke emission tests (§ 85.122(a) (2)). In a manner appropriate for the dynamometer and controls being used, arrange to conduct the acceleration mode. Turn engine off or leave it on, as desired.

(3) Install smokemeter optical unit and connect it to the recorder. Connect the engine rpm sensing device to the recorder.

(4) Turn on purge air to the optical unit of the smokemeter, if such air is used.

36-099-70- -12

(5) Check and record zero and span settings of the smokemeter recorder at a chart speed of approximately 1 inch per minute. (The optical unit may be retracted from its position about the exhaust stream, if desired.)

(6) Start the engine, if necessary, and precondition it by operating it for 10 minutes at maximum rated horsepower.

(7) Proceed with the sequence of smoke emission measurements on the engine dynamometer as described in § 85.122. of

(8) During the test sequence § 85.122, continuously record smoke measurements and engine rpm at a chart speed of approximately 1 inch per minute minimum during the idle mode and transitional modes and 8 inches per minute minimum during the acceleration and lugging modes.

(9) Turn off engine.

(10) Check zero and reset if necessary and check span of the smokemeter recorder. If either zero or span drift is in excess of 3 percent opacity, the test results shall be invalidated.

§ 85.128 Chart reading.

(a) The following procedure shall be employed in reading the smokemeter recorder chart.

(1) Locate the acceleration mode (§ 85.122(a) (2)) and the lugging mode (§ 85.122 (a) (3)) on the chart. Divide each mode into 2-second intervals beginning at the start of each mode. Determine the average smoke reading during each 2-second interval except those recorded during the transitional portions of the acceleration mode (§ 85.122(a) (2) (iii)) and the lugging mode (§ 85.122(a) (3) (i)).

(2) Locate and note the 15 highest 2-second readings during the acceleration mode of each dynamometer cycle.

(3) Locate and note the five highest 12-second readings during the lugging mode of each dynamometer cycle. [34 F.R. 11097, July 1, 1969]

of engine design features. These features include: Combustion cycle (2 cycle and 4 cycle): cylinder configuration and dimensions; and method of air aspiration (natural, turbocharged, and

supercharged).

(b) Emission data engines: Two engines of each family shall be run for smoke emission data as prescribed in § 85.132(b). Within each engine family, the engines that feature the highest fuel feed per stroke, primarily at the speed of maximum torque and secondarily at rated speed, will be selected.

(c) Durability data engines:

(1) One engine from each family shall be tested for lifetime smoke emission data as prescribed in § 85.132(c). Within each family, the engine which features the highest fuel feed per stroke, primarily at rated speed and secondarily at the speed of maximum torque, will be selected for durability testing.

(2) Whenever a manufacturer's total latest full calendar year sales in the United States of engines subject to this part represents less than 5 percent of all domestic sales of engines subject to this subpart, such manufacturer shall not be required to test more than four engines for durability data. These four engines will be selected from the several families of engines in order of expected sales volume and will represent as many families as possible and shall include at least one engine using each combustion cycle and one engine using each method of air aspiration included in the manufacturer's expected production.

§ 85.131 Test conditions.

(a) Maintenance:

(1) A complete record of all pertinent maintenance performed on the test engines shall be supplied with the application for certification.

(2) Maintenance on the durability engines may be performed only as a result of part failure or gross engine malfunction with the following exceptions:

(i) Only one major engine tuneup may be performed, at approximately 500 hours of dynamometer operation.

(ii) Normal lubrication services (engine and transmission oil change and oil, fuel, and air filter servicing) will be allowed at recommended intervals.

(b) Complete dynamometer - exhaust emission tests (see §§ 85.120 through 85.129) shall be run before and after any engine maintenance which can be expected to affect emissions.

§ 85.132 Durability testing and emission

measurements.

(a) Durability testing shall be simulated by operation of an engine on a dynamometer.

(b) Emission data engines: Each engine shall be operated on a dynamometer for 125 hours with the dynamometer and engine adjusted so that the engine is operating at 95-100 percent of rated speed and at 95-100 percent of maximum rated horsepower. The results of all exhaust smoke tests conducted after 125 hours of operation will be supplied with the application for certification to establish the low-use emission level of each engine.

(c) Durability data engines: Each engine shall be operated on a dynamometer for 1,000 hours with the dynamometer and engine adjusted so that the engine is operating at 95-100 percent of rated speed and at 95-100 percent of maximum rated horsepower. Exhaust smoke measurements shall be made at least every 125 hours of operation. The results shall be supplied with the application for certification and shall be used to establish the deterioration factors (see § 85.133). § 85.133 Compliance with emission

standards.

(a) The emission standards in the regulations in this part apply to the lifetime emission of equipped engines. Prior to certification, lifetime emissions can be obtained by projection of test data to lifetime normal service. Lifetime normal service or its equivalent is taken to be 2,000 hours of prescribed dynamometer operation.

(b) It is expected that the opacity of exhaust emissions will change with use of the engine. It is assumed that emissions corresponding to 1,000 hours of prescribed dynamometer operation is the average emission of engines over their lifetime.

(c) The basic procedure for determining compliance with exhaust smoke emission standards in diesel-powered engines, is as follows:

(1) Emission deterioration factors for the acceleration mode (designated as "A") and the lugging mode (designated as "B") will be established separately for each durability data engine. They shall be determined from the emission results "a" and "b," respectively, of the durability data engines.

(i) All smoke test "a" and "b" results will be plotted separately as functions of