ASTM D6891 Standard Test Method for Evaluation of Automotive Engine Oils in the Sequence IVA Spark-Ignition Engine
4. Summary of Test Method
4.1 Test Numbering Scheme - Use the test numbering scheme shown below:
AAAAA-BBBBB-CCCCC
AAAAA represents the stand number. BBBBB represents the number of tests since the last calibration test on that stand. CCCCC represents the total number of Sequence IVA tests conducted on that stand. For example, 6-10-175 represents the 175th Sequence IVA test conducted on test stand 6 and the tenth test since the last calibration test. Consecutively number all tests. Number the stand calibration tests beginning with zero for the BBBBB field. Multiple-length Sequence IVA tests are multiple runs for test numbering purposes, such as double-length tests which are counted as two runs and triple-length tests which are counted as three runs. For example, if test 1-3-28 is a doubled-length test, number the next test conducted on that stand 1-5-30.
4.2 Test Engine - This procedure uses a fired 1994 model Nissan KA24E, in-line 4-cylinder, 4-cycle, water-cooled, port fuel-injected gasoline engine with a displacement of 2.389 L. The engine features a single overhead camshaft with sliding follower rocker arms, with two intake valves and one exhaust valve per cylinder, and hydraulic lash adjusters. The camshaft is not phosphate-coated or lubrited.
4.3 Test Stand - Couple the test engine (devoid of alternator, cooling fan, water pump, clutch and transmission) to an eddy-current dynamometer for precise control of engine speed and torque. Specify the combined inertia of the driveline and dynamometer to ensure reproducible transient ramping of engine speed and torque. Control the intake air, provided to the engine air filter housing, for temperature, pressure, and humidity. Mount the engine similar to its vehicle orientation (tilted up 5.5° in front; sideways 10° up on intake manifold side; bottom of oil sump horizontal). Modify the engine ECM wiring harness, sensors, and actuators. The test stand plumbing shall conform to the diagrams shown in Annex A7. Install the engine on a test stand equipped with computer control of engine speed, torque, various temperatures, pressures, flows, and other parameters outlined in the test procedure (see Section 11).
4.4 Test Sequence - After engine break-in or after the completion of a previous test, install a new test camshaft and rocker arms. Charge the fresh test oil to the engine and conduct two flushes. After completing both flushes, drain the used oil, and weigh and install the fresh test oil and filter. Conduct the test for a total of 100 h, with no scheduled shutdowns. There are two operating conditions, Stage I and Stage II; Stage I for 50 min and Stage II for 10 min comprise one test cycle. The test length is 100 cycles.
4.5 Analyses Conducted - After test, measure the camshaft lobes using a surface profilometer. From these graphical profile measurements, determine the maximum wear at seven locations on the cam lobe. Determine individual cam lobe wear by summing the seven location wear measurements. Average the wear from the twelve cam lobes for the final, primary test result. After test completion, determine the oil consumption by the mass of used oil versus the fresh oil charged to the engine (including oil filter). Analyze the end of test used oil for fuel dilution, kinematic viscosity, and wear metals. Retain a final drain sample of 1 L for 90 days. Retain the camshaft and rocker arms for six months.
5. Significance and Use
5.1 This test method was developed to evaluate automotive lubricant's effect on controlling cam lobe wear for overhead valve-train equipped engines with sliding cam followers.
NOTE 1 - This test method may be used for engine oil specifications, such as Specification D4485, API 1509, SAE J183, and ILSC GF 3.
