SH/T 0576-1993 L-ERC Two-Stroke Gasoline Engine Oil Evaluation Method

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Card type: Test method

1. Method number / full name / English name / replacement relationship

• Standard number: SH/T 0576-93
• Chinese name: L-ERC Two-Stroke Gasoline Engine Oil Evaluation Method
• English name: not provided in the available source
• Replacement relationship: not provided in the available source
• Approval/implementation: approved by China Petrochemical Corporation 1993-03-19, implemented on 1994-05-01
• Reference adoption: the American Society for Testing and Materials standard ASTM D02 committee's 1985 year publication "TSC-3 Evaluation of Two-Stroke Gasoline Engine Lubricating Oils" (see additional notes)

2. Scope of application and non-applicability

• This standard specifies the engine evaluation method for combustion cleanliness, high-temperature lubricity, and pre-ignition caused by carbon deposits of L-ERC two-stroke gasoline engine oils.
• Products that pass the evaluation of this standard are applicable to high-load (specific power output above 73kW/L), large-displacement (above 250mL) air-cooled two-stroke gasoline engines; such gasoline engines are mainly installed in highly reinforced motorcycles, snowmobiles, and various highly reinforced power devices.
• Not applicable: not provided in the available source.

3. Method principle

This standard includes three evaluation procedures:

• Procedure 1: Ring sticking and deposit test. A ROTAX503 two-cylinder air-cooled 500mL two-stroke gasoline engine is used; after operating under specified conditions, disassembly, inspection, and scoring comparison are carried out. One cylinder uses the test sample, and the other cylinder uses the standard reference oil, with cyclic operation for 20h. If the cleanliness score of the test sample is clearly better than that of the standard reference oil, the test may be stopped. If it is not clear, in order to eliminate the influence of the difference in thermal load between the two cylinders and improve the reliability of the evaluation, the mixed oil used in the two cylinders is exchanged and operation is continued for 20h, after which the average cleanliness scores of the two cylinders for each oil are compared.
• Procedure 2: Lubricity (tightening) test. A WY50 single-cylinder air-cooled 50mL two-stroke gasoline engine is used; during the test the speed is kept constant, the cooling air is cut off, and t₂ (spark plug gasket thermocouple temperature) is allowed to rise from 200℃ to 350℃ (or 330℃), and the torque decrease during that interval is measured; the magnitude of the value can indicate the quality of the oil's lubricity.
• Procedure 3: Pre-ignition test. The same two-stroke gasoline engine as in procedure 2 is used, operating at wide-open throttle maximum torque (4150r/min±20r/min) for 50h, and the time and number of occurrences of pre-ignition are measured under conditions of heavy carbon deposits and high thermal load.

4. Reagents and materials (purity / preparation)

• Test sample oil: provide test sample oil 25L for the evaluation test.
• Fuel oil: in order to eliminate the influence of differences in fuel composition on the evaluation of lubricating oil, standard fuel oil is used, see Appendix D. Standard fuel oil indicators (Table D1): density (20℃) 0.693～0.700 kg/m³ (GB/T 1884); distillation range initial boiling point >40℃, 50%<104℃, dry point <195℃ (GB/T 255); copper strip corrosion (50℃,3h) qualified (GB/T 378); Reid vapor pressure 34.3～48.0 kPa (GB/T 257); research octane number 93～94 (GB/T 5487).
• Reference oils: the standard reference oil used in evaluation procedures 1, 2, and 3 is C-301, the low reference oil for evaluation procedure 1 is C-302, and the low reference oil for evaluation procedure 2 is A-1030 (thus in the source text, suspected to be A-103, requires confirmation against the source standard (source-text extraction)).
• Cleaning liquid: engine cleaning is carried out according to Appendix I, and the cleaning liquid is prepared according to the appendix provisions to remove carbon deposits and sediments on parts and components. Cleaning agent formula (Appendix I): aluminum parts: 1L water, 18.5g sodium carbonate, 10g soap, 8.5g water glass, dissolve at 60～70℃, place the parts in the solution at 85～90℃ and keep for 2～3h, then scrub with a brush, rinse with clean water, and dry; steel and cast iron parts: prepared from 1L water, 33g sodium carbonate, 25g sodium hydroxide, 8.5g soap, cleaned and dried by the same method as above.
• Solvent oil: use GB 1922 190 solvent oil.
• Mixed oil preparation:
  • Procedure 1: standard reference oil C-301 and test sample oil are both mixed with fuel oil at 1:50(V/V), preparing 20L each time.
  • Procedure 2: standard reference oil C-301 and test sample oil are both mixed with fuel oil at 1:50(V/V), preparing 4L of each, and at the same time 4L standard fuel oil is also prepared and added to the third fuel tank.
  • Procedure 3: test sample oil is mixed with fuel oil at 1:33(V/V), preparing 4L each time; the standard reference oil for engine calibration (C-301) and the low reference oil (A-103) are mixed with fuel oil at the same mixing ratio to prepare mixed oil.

5. Instruments and equipment

• Test engines: ROTAX503 and WY50, see Appendix A.
  • WY50: number of cylinders 1, bore × stroke 40×39.6mm, displacement 49.8mL, rated power 2.06kW/5600r/min, fuel consumption rate 462g/kW·h(340g/PS·h), maximum torque 3.7N·m(0.38kgf·m)/4000～4500r/min, specific power output 41.2kW/L(45PS/L), idle speed 1300～1500r/min, total weight <4.5kg, compression ratio 7.5, spark plug model T4135J, CDI electronic ignition, carburetor PT-50A (the source text is TI'[unreadable separator]50A, requires confirmation against the source standard (source-text extraction)), fuel-to-oil mixing ratio 33:1 or 50:1, loop scavenging, chrome-plated aluminum alloy cylinder, high-silicon aluminum alloy piston, forged steel connecting rod, cast aluminum hemispherical cylinder head, tubular muffler exhaust system.
  • ROTAX503: number of cylinders 2, bore × stroke 72×61mm, displacement 494mL (the source text is [unreadable digit]94, requires confirmation against the source standard (source-text extraction)), rated power 22.0kW/5500r/min, fuel consumption rate 480g/kW·h(353g/PS·h), maximum torque 42～45N·m(4.3～4.6kgf·m)/4500～5000r/min (the source text is, 100, requires confirmation against the source standard (source-text extraction)), specific power output 44.5kW/L(60.5PS/L), idle speed 800～1000r/min, total weight <45kg, compression ratio 6.3, spark plug model 41973, CDI electronic ignition, carburetor PZ34J plunger type, fuel-to-oil mixing ratio 50:1, loop scavenging, cast aluminum cylinder body matched with special cast iron cylinder liner, high-silicon aluminum alloy piston, forged steel connecting rod, cast aluminum hemispherical cylinder head, exhaust manifold and cylindrical muffler exhaust system.
• Intake system: the original structure of ROTAX503 with two cylinders sharing one intake pipe is changed to one intake pipe and one carburetor per cylinder, and each is connected to the fuel supply system, fuel consumption measurement system, and throttle control system.
• Cooling system: the ROTAX503 engine uses its own fan cooling, and the intake and exhaust air volumes are adjusted with the fan inlet adjustment baffle and the hot air outlet adjustment baffle of each cylinder; the WY50 engine uses an external air source for cooling, with a 4 centrifugal blower driven by a 5.5kW motor, the blast volume controlled by a damper in the pipeline, the cooling air outlet size being 180mm×180mm, the wind speed adjustment range in front of the engine cylinder head being 0～20m/s, and the anemometer placed at a position about 1/2 between the air outlet and the cylinder head.
• Exhaust system: the exhaust pipes of the ROTAX503 and WY50 engines are respectively placed in an exhaust extraction system, in which a 4 axial-flow exhaust fan driven by a 0.6kW explosion-proof motor is installed. A K type armored thermocouple with length 150mm and φ3mm (the source text is [unreadable value]mm, requires confirmation against the source standard (source-text extraction)) is used to measure the exhaust temperature.
• Dynamometer equipment: the evaluation test bench for procedure 1 uses a CW 30 eddy current dynamometer, and the evaluation test benches for procedure 2 and procedure 3 use a ZDC-3B electric dynamometer, see Appendix B.
  • WY50 matched with ZDC-3B: maximum absorbed power counterclockwise 3.0kW/ clockwise 2.4kW, maximum power speed 4100～9000r/min, maximum torque counterclockwise 6.86N·m/ clockwise 5.49N·m, maximum electric power counterclockwise 1.3kW/ clockwise 1.8kW, excitation current 3.5A, main shaft bidirectional, center height from main shaft to ground 260mm, cooling water inlet temperature 25℃, outlet temperature 55℃, pressure 20～59kPa, flow rate 15～20L/min, torque measurement accuracy ±0.5%( electronic).
  • ROTAX503 matched with CW30: maximum absorbed power 30kW, maximum power speed 6100r/min (the source text is 61[garbled digits/unit]), requires confirmation against the source standard (source-text extraction)), maximum torque 114.7N·m, excitation current 2.8A, main shaft bidirectional, center height from main shaft to ground 410mm (the source text is 41[garbled digits/unit], requires confirmation against the source standard (source-text extraction)), torque measurement accuracy ±0.5%.
• Spark plug gasket thermocouple: install a K type thermocouple on the spark plug gasket, see Appendix C. The gasket material is made of copper, and the thermocouple material is nickel-chromium-nickel-silicon with diameter 0.3mm made into K type thermocouple wire, insulated with insulating material.
• Test instruments and meters: see Appendix H. Including four-channel penless recorder ST 4100 type (K type thermocouple, 0～600℃/0～800℃, ±1%), engine performance tester PXC-101 type, multi-channel digital thermometer DSI X-1-3A (±1%), single-channel multi-band digital thermometer YEl1 TYPE 2809 (±1%), fuel consumption meter S, -3 (0～10L/10～70mL, ±1%), tachometer SZ-2 (0～10000r/min, ±0.2%), torque meter SY (0～49N/0～97.9N, ±0.5%), digital display thermometer SIS2-101 (0～800℃/0～1200℃, ±1.0%), anemometer】】2M6 (0～30m/s, 0.2m/s), atmospheric pressure gauge moving-groove type (810～1100hPa, 0.1hPa), dry-and-wet thermometer DHW2 type (-55～55℃, ±0.2℃), cylinder pressure gauge Y】, -6 type (0～1.4MPa), throttle opening controller SD type, constant-speed setting device TNS type, high-speed printer M-1724 type, automatic plotter DXY-800 type, microcomputer IBM XT.

6. Recommended operating conditions

• Program 1 cyclic operation test procedure (Table 1): exhaust temperature (t₃-t₄) 540～580℃; temperature (t₁,t₂) 180～185℃; torque 24.1±1.0 N·m(23.1～25.1); balance among cylinders C₁-Cp<0.1kg/h, N₁-N₂<0.15kW(0.2PS), P₁-P₂<0.6N(0.06kg); dynamometer outlet water temperature 30～50℃. The engine runs one small cycle every half hour; after 5 small cycles of operation, shutdown 1h constitutes one large cycle; a total of 8 large cycles are carried out, operating 20h.
• Program 2 test conditions (Table 4): throttle fully open, torque (P) 19.6N±1.47N(2.0kgf±0.15kgf), speed at maximum torque point with throttle fully open 4150r/min±20r/min, power 1.54kW±0.15kW(2.1PS±0.2PS), fuel consumption 408～449g/kW·h(300～330g/PS·h), exhaust temperature 500℃±20℃, gasket temperature 180℃～350℃.
• Program 2 operating procedure (Table 5): carried out in 4 groups; each group performs 5 lubricity tests according to the 9.4 test steps. The standard reference oil and the sample oil are alternated.
• Program 3 test procedure is shown in Table 3 (the original table content source-text extraction is severely damaged and illegible, requires confirmation against the source standard (source-text extraction)).
• Program 3 test description: low temperature and high fuel consumption are favorable for carbon deposit formation; high temperature and low fuel consumption are favorable for carbon deposit surface ignition. According to actual engine calibration conditions, the high and low limit values may be taken within the given range. Before entering conditions 2 and 4 in Table 7, within 0.5～1.0h, adjust the mixture concentration by adjusting the air metering orifice and the air filter element. During the test, the power at the maximum torque point at the beginning is taken as the standard; when the power drops by 10%～15%, a new exhaust system must be replaced to restore power.

7. Sampling and sample preparation

• Sample oil: provide sample oil 25L for the evaluation test.
• For preparation of mixed oil, see Section 4.
• Cleaning of the engine: after running-in, the engine must be disassembled and cleaned. Carbon deposits on the piston, piston rings, muffler, cylinder head, etc. must be placed in cleaning liquid and boiled with heating. Carbon deposits and sediments in various holes, ports, and grooves must be cleaned thoroughly, and must not be scratched with sharp instruments. Before assembling the engine, the carburetor metering orifices and nozzles still need to be cleaned with solvent naphtha.
• Assembly conditions and preparation of the engine for the evaluation test: for the cleaned parts and components, measure and assemble the parts and components according to the assembly conditions given in Appendix E. During assembly, standard reference oil must be applied to mechanical surfaces that have friction. The tightening forces for spark plugs and various nuts and the preparation of the engine must be carried out according to the provisions of Appendix E.
• Assembly conditions (Table E1):
  • WY50: Cylinder liner-to-piston clearance: minimum clearance at 13mm upward from the skirt bottom 0.03±0.01mm (pre-ignition)/0.19±0.1mm (expansion tightness); piston ring end gap: place the ring in the cylinder liner and measure at 5～10mm from the top 0.2～0.4mm; piston ring side clearance 0.02～0.04mm (the ring positioning pin faces the exhaust side); spark plug electrode gap 0.6mm (with contact points)/0.8～1.0mm (without contact points); platinum gap or ignition advance angle 0.3mm±0.05mm, or contactless 18°18'CA.
  • ROTAX503: Cylinder liner-to-piston clearance: at 10mm upward from the skirt bottom (about 8～13mm), minimum clearance 0.092～0.112mm (deposits), service clearance 0.22mm; piston ring end gap: place the ring in the cylinder liner and measure at 16mm from the top 0.2～0.3mm (replace with a new ring when exceeding 1.2mm); piston ring side clearance 0.05～0.07mm (ring groove height 2.1⁺⁰·⁰⁷mm, ring height 2.1⁻⁰·⁰⁷mm, replace the ring or piston when the clearance exceeds 0.15mm); spark plug electrode gap 0.4～0.5mm; ignition advance angle 20°CA.
• WY50 engine tightening torques: cylinder head nuts M6 tightened in three stages (crosswise in two passes), M₁=9.8～11.8N·m; magneto flywheel fastening nut (M10×1.25), M₁=39.2～49N·m; spark plug (M14×1.5 thread), M₁=10.8～13.7N·m.
• ROTAX503 engine tightening torques: spark plug (M14×1.5 thread) M₁=10.8～13.7N·m; magneto fixing nut M₁=83N·m; cooling fan impeller nut M₁=64N·m; intake and exhaust manifold nuts M₁=20N·m; upper and lower crankcase body nuts M₁=20N·m; four stud nuts for cylinder block and crankcase M₁=20N·m.
• Running-in of the engine for the evaluation test: for a new engine or an engine reassembled after replacement of parts and components, before being put into the formal evaluation test, it must be run in according to the running-in specification specified in Appendix G.
  • WY50 engine (Program 2, Program 3) running-in: the first 1 stage of running-in is shown in Table G1, and the 2 stage of running-in is shown in Table G2. The expansion tightness test must undergo the 1 stage and the 2 stage of running-in. For the pre-ignition test, when the rated power 2.06kW±0.1kW/5600r/min can be reached after the 1 stage of running-in, the running-in may be ended.
  • ROTAX503 engine (Program 1) running-in: the first 1 stage of running-in (16h×2) is shown in Table G3, and the 2 stage of running-in (8h) is shown in Table G4. After 2 cycles of the 1 stage of running-in (total 32h), carry out Program 1 engine calibration. To achieve the full-power external characteristic, the 2 stage of running-in must be carried out.
• Preparation of dynamometer equipment, instruments, and meters: before the test, perform zero-point calibration of the mechanical system for the CW 30 dynamometer, and perform zero-point calibration of the pressure sensor for the ZDC-3B dynamometer. Before the test, all instruments and meters in the dynamometer control cabinet should have normal digital displays.

8. Analysis steps

Program 1: Ring sticking and deposit test

• Engine calibration:
  • Both cylinders simultaneously use the standard reference oil. After operating according to the test procedure for 20h, disassemble and inspect. Score cleanliness for piston ring sticking, ring groove carbon deposits, ring land carbon deposits, cylinder head carbon deposits, piston skirt varnish, piston top and inner cavity deposits, and exhaust port blockage, and weigh the piston deposit mass.
  • After completing the above test evaluation, clean the parts and components, assemble the engine, and correct the two-cylinder balance according to Chapter 7. Both cylinders still simultaneously use the standard reference oil, operate again according to the standard test procedure for 20h, and then score and evaluate according to the items listed above.
  • After completing the above test evaluation, if between the two cylinders or between the average values of each cylinder from two runs, the difference in each score is less than 0.5 points, the difference in piston deposit mass is less than 0.05g, and the ring sticking score of each cylinder is above 9.5 points, then the test conditions of the two cylinders can be considered basically balanced and the evaluation method stable. During formal evaluation of the sample oil, the 20h repeat test of changing the mixed oil between the two cylinders is not required. If the above range is exceeded, then the 20h repeat test of changing the mixed oil must be carried out.
  • The calibration test of the standard reference oil is carried out once every 6 months.
• Operation test:
  • For an engine meeting the assembly conditions, before the formal evaluation test, a two-cylinder power balance test must be carried out. Through adjustment of the carburetor, throttle limiter, and throttle cable limit contact, the specified values in the cyclic operation test procedure are satisfied.
  • The cyclic operation test procedure is shown in Table 1. The engine runs one small cycle every half hour; after 5 small cycles of operation, shutdown 1h constitutes one large cycle; a total of 8 large cycles are carried out, operating 20h.
  • Explanation of the cyclic operation test: during operation, record the sudden increase of t₁. When Δt₁<10℃ and pre-ignition occurs, only record it and do not interrupt the test; when Δt₁≥10℃ and large pre-ignition occurs, immediately interrupt the test, replace spark plugs and other parts and components, and after troubleshooting continue operating the engine. For the accumulated time of the Program 1 evaluation test, start counting from 10min before the occurrence of large pre-ignition. During operation, when t₁ suddenly decreases and the power drops significantly, the spark plug must be checked and cleaned or replaced if necessary. For mechanical faults not caused by oil (including spark plugs) during operation, parts and components may be replaced or the engine adjusted. During operation, to ensure that parameters are within the specified range, necessary adjustments may be made to the engine.
• Disassembly inspection and evaluation:
  • After the test ends, disassembly inspection and evaluation must be carried out within 12h. The sequence is: remove the engine, wipe clean, score ring sticking, remove rings, photograph the main scoring locations, weigh the piston, and score the specified locations.
  • The main scoring and measurement items include: piston ring sticking, ring groove and ring land carbon deposits; piston skirt varnish, inner cavity carbon deposits; cylinder head carbon deposits; piston carbon deposits and carbon deposit mass measurement; percentage of exhaust port blockage area.
  • For the scoring method and criteria, refer to Appendix F. The carbon deposit description includes: type, thickness, hardness, location, etc. Calculate the total cleanliness score and the percentage of passing items.
  • Inspect for cylinder scuffing and scratching, record the number of spark plug replacements, and fill in Table 2 and Table 3.

Procedure 2: Lubricity (tightening) test

• Engine calibration:
  • If the interval between two tests exceeds 3 months, before the formal evaluation of the sample oil, a calibration test must be conducted with A-103 low reference oil.
  • According to the test steps specified in this procedure, calculate the difference in average torque drop between the standard reference oil and the low reference oil. If the difference can clearly distinguish the quality of the oils, it indicates that the engine operating conditions and assembly conditions produce moderate severity for the oil, which can ensure normal evaluation of the sample oil; otherwise, the engine must be readjusted.
• Lubricity (tightening) test procedure: Conduct in 4 groups as shown in Table 4 and Table 5. Each group must undergo 5 lubricity tests according to the 9.4 test steps. ΔM₁ and ΔM₂ respectively represent the engine output torque drop of the test oil and the standard reference oil between 200℃ and 350℃ (330℃) during t₂. ΔM₁ and ΔM₂ respectively represent the average torque drop measured in 10 lubricity tests for each lubricating oil.
• Lubricity (tightening) test steps:
  • Start the machine and warm up, with the throttle fully open, 4150r/min±20r/min, so that t₂ = about 170℃, and run at thermal equilibrium for 1h.
  • Adjust the cooling air so that t₂ = 180℃. At this time, the throttle is fully open, the speed remains unchanged, and the laboratory ambient temperature is maintained at 23～27℃.
  • After stable operation for 3min, cut off the cooling air source. Start the tightening test according to Table 4 and Table 5. To reduce the rate of increase of t₂ at the beginning, do not remove the cooling drum air opening until t₂ reaches 200℃. During the tightening process, reduce the excitation at any time to lower the load and maintain a constant speed. Prevent interference from various external air sources during the test.
  • During the period when t₂ rises from 180℃ to 350℃, collect data every 10℃. For each tightening data, use a computer for data processing and a X-Y instrument for plotting.
  • When t₂ reaches 350℃ (or 330℃), immediately start the cooling air source, reduce the throttle opening to lower the output power by about 1/2, and restore the gasket temperature to 160～170℃.
  • Fully open the throttle, adjust the cooling air so that t₂ reaches 180℃, and after stabilizing for 3min, repeat the above process.
  • For each oil, conduct 5 consecutive tightening tests. 5 tests form one group, and two groups are conducted in total. According to equations (1)～Equation (4), calculate the average torque drop ΔM₁ and ΔM₂ for each oil from 200℃ to 350℃ (330℃).
  • Oil change: After the tightening test of one mixed oil is completed, drain the residual oil in the carburetor, then use fuel oil to run at idle for 5min to flush the oil circuit, then change to another mixed oil, fully open the throttle, bring the speed to 4150r/min±20r/min, run for 20～30min, and then repeat the above process.
  • The tightening test of Procedure 2 must be completed continuously. Cylinder seizure is not allowed during the test. After disassembly, there should be no cylinder scuffing, ring sticking, or severe scratching. Fill the recorded data and calculated data into Table 6.

Procedure 3: Pre-ignition test

• Engine calibration:
  • Low reference oil calibration: After a test interval of 3 months or after conducting 10 pre-ignition tests, before the formal evaluation test, a pre-ignition test must be conducted with low reference oil according to this operating procedure. During operation, large pre-ignition must occur 1～3 times. If large pre-ignition does not occur, the engine operating conditions must be adjusted within the range specified in Table 3.
  • Standard reference oil calibration: After an interval of half a year or after conducting 50 pre-ignition tests, or when the number of large pre-ignitions during low reference oil calibration exceeds 3 times, a pre-ignition test must be conducted with standard reference oil according to the procedure in Table 3. Record the time and number of occurrences of large pre-ignition.
• Running test:
  • Start the engine and gradually fully open the throttle. Adjust the operating parameters according to item 2 in Table 7. After stable operation for 20min, enter the operating procedure.
  • The test procedure is shown in Table 3 (the original table content source-text extraction is severely damaged and illegible, requires confirmation against the source standard (source-text extraction)).
  • Test description: Low temperature and high fuel consumption are conducive to carbon deposit formation; high temperature and low fuel consumption are conducive to carbon deposit surface ignition. According to the actual calibration conditions, high and low limit values can be taken within the given range. Before entering the 2 and 4 operating conditions in Table 7, within 0.5～1.0h, adjust the mixture concentration by adjusting the air metering orifice and the air filter element. During the test, the maximum torque point power at the beginning shall prevail. When the power drops by 10%～15%, a new exhaust system must be replaced to restore power. During 50h operation, the sample oil must not exhibit large pre-ignition. When large pre-ignition occurs, the engine must be disassembled, and the inspection situation must be reported, including: whether there is ring sticking, cylinder scuffing, or scratching; report the spark plug carbon deposit situation and replacement situation (faults caused by carbon deposit-induced pre-ignition cannot be replaced). After the evaluation test of Procedure 3 is completed, fill the collected data into Table 8.

9. Qualitative and Quantitative and Calculation Formulas

• Procedure 1 acceptance criteria:
  • The main scoring items of the sample oil (shown in Table 4) are all not lower than the standard reference oil by 0.5 points, and the sum of the main scoring items is not lower than the standard reference oil by 5.5 points.
  • Piston deposits do not exceed the standard reference oil by 0.25g.
  • The number of spark plug failures does not exceed the standard reference oil by 2 times, and there is no piston scuffing.
  • The difference in exhaust port blockage rate between the sample oil and the standard reference oil does not exceed 10%.
  • If the test results do not meet the above provisions, the test may be repeated once. If the repeated test passes, the evaluation is passed.
• Procedure 2 data processing:
  • Calculate the average torque drop ΔM₁ and ΔM₂ of the standard reference oil and sample oil according to the following formulas, and calculate the standard deviation S₁ and S₂ of the average torque drop for each oil:
    • ΔM₁ = (1/n)ΣΔM₁ᵢ (Equation 1)
    • ΔM₂ = (1/n)ΣΔM₂ᵢ (Equation 2)
    • S₁ = √[Σ(ΔM₁ᵢ - ΔM₁)²/(n-1)] (Equation 3)
    • S₂ = √[Σ(ΔM₂ᵢ - ΔM₂)²/(n-1)] (Equation 4)
    • Where: ΔM₁—average torque drop of the sample oil; ΔM₂—average torque drop of the standard reference oil; i=1,2,3……n; n— number of tightening tests, n=10.
  • Calculate the outlier identification values B₁ and B₂ according to Appendix J, and discard the outliers B₁ and B₂ from the 10 torque data points of each oil, then recalculate ΔM₁, ΔM₂ and S₁, S₂.
  • Calculate the average torque drop equivalence identification value t' and the combined standard deviation S- according to Appendix J. When t' < t critical, it can be considered that the average torque drop measured values and accuracy of the two oils are equivalent.
  • The deviations of S₁ and S₂ should be basically the same. A large deviation is caused by large differences between the torque drop data points of that oil, which is due to abnormal engine operation (misfire) during the tightening process, and outlier identification must be performed.
• Procedure 2 acceptance criteria:
  • ΔM₁ ≥ ΔM₂ (original text is 4M, } - OM,, requires confirmation against the source standard (source-text extraction)).
  • When calculating ΔM₁ and ΔM₂, outlier identification and equivalence identification must be performed on the collected data in advance, discarding outliers in the data and ensuring t' < t critical. The confidence level for outlier identification is 90%, and the confidence level for equivalence identification is 95%.
  • If the test results of the sample oil do not meet the acceptance criteria, the test may be repeated once. If the repeated test meets the acceptance criteria, the sample oil evaluation is passed.
• Procedure 3 acceptance criteria:
  • During 50h operation, if the number of large pre-ignition occurrences of the sample oil is not more than that of the standard reference oil, or the time of the 1th large pre-ignition is greater than or equal to that of the standard reference oil, the sample is considered to pass the evaluation.
  • If the sample oil fails, one repeat test may be conducted. If the repeat test passes, the evaluation is passed.
• Appendix J data processing:
  • Outlier identification value B*: B* = Δ/σ, where Δ=|ΔMᵢ - ΔM|, σ=√[Σ(ΔMᵢ - ΔM)²/(n-1)]. When B* > B critical value, the data point for calculating that Δ value should be discarded; this torque drop is an outlier, often caused by intermittent engine misfire. After discarding the outlier, the degrees of freedom n change from 10 to 9. Recalculate the average torque drop and standard deviation of the sample oil and standard reference oil according to n=9. The B critical value is often taken at 90% confidence level, obtained by looking up Table J1.
  • Equivalence identification value t': t' = S- / |ΔM₁ - ΔM₂| × √(n₁n₂/(n₁+n₂)) (the original formula source-text extraction is damaged, requires confirmation against the source standard (source-text extraction)). n=n₁+n₂-2. S- is the combined standard deviation, S- = √[(n₁S₁²+n₂S₂²)/(n₁+n₂)]. Where n₁ and n₂ are the tightening times of the standard reference oil and sample oil respectively; S₁ and S₂ are the standard deviations of the standard reference oil and sample oil respectively. The degrees of freedom n equal the total number of data points (20) minus the number of samples (two types: reference oil and sample oil, so subtract 2)). The number of discarded outliers should be subtracted from the total number of data points. Table J2 gives the critical identification value t critical, generally taken at 95% confidence level. When t' < t critical, it can be considered that the average torque drop and precision of the two oils are equivalent. The unit of torque drop is N·m.
• Appendix F cleanliness scoring method:
  • For carbon deposits and various colored deposits, the defect scoring coefficient is 10.
  • Paint film demerit rating coefficient (Table F1): black 10.0; dark brown (with black) 7.5; brown (with red) 5.0; yellow 2.5; slight coloration 1.0; bare metal color 0.
  • Scuffing: if cylinder seizure or cylinder scoring occurs due to the oil, the evaluation test is declared failed. If scuffing occurs due to the oil, scoring is required. Demerit rating coefficient for slight scuffing felt by hand 5.0; obvious scuffing felt by hand 10.0.
  • Piston ring rating (Table F3): free ring 0; blunt ring 0.5; stuck ring, stuck 30° 1.0, stuck 330° 5.0; cold stuck ring 6.0; hot stuck ring 10.0.
  • Rating: for deposits, paint film, and scuffing separately, calculate the percentage of the rated area occupied; multiply this value by the demerit rating coefficient to obtain the demerit rating; then calculate the merit rating of the rated area as merit rating = 10- demerit rating coefficient × area percentage.

10. Precision

• Procedure 1 calibration run: if between two cylinders or between the per-cylinder averages of two runs, the difference in each rating is less than 0.5 points, the difference in piston deposit weight is less than 0.05g, and the stuck ring rating of each cylinder is above 9.5 points, then the test conditions of the two cylinders can be considered basically balanced and the evaluation method stable.
• Procedure 2: confidence level for outlier identification is 90%, confidence level for equivalence identification is 95%.
• Other precision indicators: not provided in the available source.

11. Report

• Procedure 1: fill in Table 2, Table 3 (original table content source-text extraction severely damaged, illegible, requires confirmation against the source standard (source-text extraction)).
• Procedure 2: fill the recorded data and calculated data into Table 6 (L-ERC two-stroke gasoline engine oil evaluation procedure 2: tightening test table). Table 6 includes: engine model, dynamometer model, fuel oil grade, sample oil grade, mixing ratio, assembly conditions (minimum cylinder-piston clearance, ring end gap, ring side clearance, spark plug electrode gap, ignition advance angle, ambient temperature, atmospheric pressure, relative humidity), tightening test operating conditions (wide-open throttle torque, speed at maximum torque point at wide-open throttle, power, exhaust temperature, gasket temperature), test data (torque of standard reference oil and sample oil, outlier identification, torque drop of each group), average torque drop of standard reference oil, standard deviation of average torque drop of standard reference oil, average torque drop of sample oil, standard deviation of average torque drop of sample oil, conclusion, evaluation unit official seal, evaluator, responsible person, remarks.
• Procedure 3: fill the collected data into Table 8 (original table content source-text extraction severely damaged, illegible, requires confirmation against the source standard (source-text extraction)).
• Other reporting requirements: not provided in the available source.

12. Normative References

• GB/T 255 Petroleum products distillation range determination method
• GB/T 257 Engine fuel saturated vapor pressure determination method (Reid method)
• GB/T 259 Petroleum products water-soluble acid and alkali test method
• GB/T 378 Engine fuel copper strip corrosion test method
• GB 1883 Reciprocating piston internal combustion engine
• GB/T 1884 Petroleum and liquid products density determination method
• GB 1922 Solvent naphtha
• GB 5360 General technical conditions for motorcycle gasoline engines
• GB 5363 Bench test methods for motorcycle gasoline engines
• GB/T 5487 Gasoline octane number determination method (research method)
• SH/T 0269 Determination method for detergency of internal combustion engine lubricating oil
• ZB J90 003 Endurance test method for general small gasoline engines
• ZB J91 012 Bench performance test method for small gasoline engines
• Editor's note: the standard numbers and standard names of the referenced standards in this standard have changed as follows:
  • Original standard number GB 1883 → current standard number GB/T 1883, current standard name Terminology for reciprocating piston internal combustion engines
  • Original standard number GB/T 1884 → current standard number GB/T 1884, current standard name Laboratory determination of density of crude oil and liquid petroleum products (hydrometer method)
  • Original standard number GB 5360 → current standard number GB 5360-85, current standard name General technical conditions for motorcycle gasoline engines
  • Original standard number GB 5363 → current standard number GB/T 5363, current standard name Bench test methods for engines of motorcycles and mopeds

13. Source and verification

This page is an AI translation of the available Chinese method card. Human verification is pending. It is not an official translation of the standard. Check the source standard and product certificate before use.

14. Quick Reference Q&A