SH/T 0647-1997 Evaluation method for preignition tendency of water-cooled two-stroke gasoline engine oils

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Card type: Test method

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

• Standard number: SH/T 0647-1997
• Chinese title: Evaluation method for preignition tendency of water-cooled two-stroke gasoline engine oils
• English title: Lubricants test method for evaluating preignition tendency of water-cooled two-stroke gasoline engine (the source text source-text extraction reads “Lubricants test method for evaluating prei[unreadable characters]Lion tendency of water[unreadable separator]cooled tw[garbled characters]stroke gasoline engine”, English name requires confirmation against the source standard (source-text extraction))
• Replacement relationship: not provided in the available source
• Adoption relationship: equivalent adoption of United States ASTM D4858-92 “Standard Test Method for Measuring the Accelerated Preignition Tendency of Two-Stroke Gasoline Engine Lubricants”
• Approval/implementation: approved by China Petrochemical Corporation 1997-07-12, implemented on 1997-12-01
• Technical administration: under the technical administration of the Research Institute of Petroleum Processing, China Petrochemical Corporation
• Drafting organizations: Research Institute of Maoming Petrochemical Company, Tianjin Internal Combustion Engine Research Institute
• Main drafters: Liang Qirui, Chen Guanghui, Wu Dawei, Xie Shiwen, Liang Gaosheng, Feng Qiu

2. Scope of application and non-applicability

• This method specifies a test method for evaluating the preignition tendency of two-stroke gasoline engine lubricating oils (abbreviated as two-stroke oils).
• This standard is applicable to evaluating the performance of water-cooled two-stroke oils used for outboard motors and the like in reducing the occurrence of preignition.
• Not applicable: not provided in the available source.

3. Method principle

The test uses one 49 mL displacement single-cylinder air-cooled two-stroke gasoline engine. At a mixing ratio of 20:1, under the conditions of wide-open throttle and a speed of 4000 r/min, it is operated for 100 h, and the number of preignition occurrences is recorded by the sharp temperature rise of the combustion chamber.

4. Reagents and materials (purity / preparation)

• 6.1 Test fuel: use unleaded gasoline, meeting the requirements of Appendix B.
• 6.2 Calibration oil: use ASTM 601 and 605; each calibration engine test requires about 8 L; its main properties are given in Appendix C.
• 6.3 Reference oil: use ASTM 601 or NMMA 93738; each test requires about 8 L.
• 6.4 Oil to be evaluated: each test requires about 8 L.
• 6.5 For the assembly and running-in of each test, use ASTM 601 or the oil to be evaluated 0.4 L; the main properties of the ASTM 601 oil are given in Appendix C.
• 6.6 Solvent oil: GB 1922 190# solvent oil.
• Appendix B Fuel properties (Table B1):
  • Actual gum, mg/100 mL, not greater than 4, GB/T 8019
  • Vapor pressure (37.8℃), kPa, not greater than 75, GB/T 8017
  • Tetraethyl lead, g/L, not greater than 0.01, GB/T 8020
  • Distillation range 10%, ℃ not higher than 70; 50%, ℃ not higher than 110; 90%, ℃ not higher than 167, GB/T 6536
  • Sulfur content, %(m/m), not greater than 0.03, GB/T 380
  • Octane number (research method) 89～93, GB/T 5487
  • Hydrocarbon types: olefins %(V/V) 5～20; aromatics %(V/V) 25～35, GB/T 11132
  • Note: other test items meet the requirements of SH/T 0116.
• Appendix C Main properties of reference oil and calibration oil (Table C1): the source table source-text extraction is severely incomplete; only ASTM old numbers ASTM 601, ASTM 605, new numbers VT-D, VT-E, VT-N, 40℃ viscosity 107.9, 121～12? (requires confirmation against the source standard (source-text extraction)), 100℃ viscosity 34.2～38.2, 6.1～6.6, viscosity index 12.4, 106, 128～17 (requires confirmation against the source standard (source-text extraction)), total acid number, total base number, sulfate ash <0.005, 1.28, etc., can be discerned; the specific correspondences require confirmation against the source standard (source-text extraction).

5. Instruments and equipment

• 5.1 Test engine: YAMAHA CY50 engine; main technical parameters are given in Appendix A.
• 5.2 Modification of the engine:
  • 5.2.1 Remove the engine's power transmission components from the crankshaft to the rear axle so that the output power is directly output from the crankshaft; remove the engine's original cooling fan.
  • 5.2.2 Combustion chamber temperature: install a shielded thermocouple on the cylinder head as shown in Figure 1 to measure the combustion chamber temperature. The drilled hole diameter is about 3 mm, so as to fit closely a φ? mm thermocouple (the source text “[unreadable value]mm” requires confirmation against the source standard (source-text extraction)), and its contact point should be flush with the inner surface of the cylinder head. Install a ferrule threaded connector in the counterbore of the cylinder head to secure the thermocouple. The distance between the counterbore and the inner surface of the cylinder head shall not be less than 4 mm (the source text “4.m” requires confirmation against the source standard (source-text extraction)). The counterbore and thread dimensions depend on the ferrule threaded connector, but the thread diameter should be less than 14 mm. After the thermocouple is installed on the cylinder head, there should be no air leakage. It is generally required that the thermocouple temperature reading stabilizes after about 90 min of running-in operation (the source text “90.in” requires confirmation against the source standard (source-text extraction)).
  • 5.2.3 Spark plug temperature: use a copper spark plug gasket machined from red copper to replace the original spark plug gasket; the copper gasket thickness is 1.8～2.2 mm, outer diameter 20.8～21 mm, inner diameter 14.3～14.6 mm. Drill two holes of diameter 1 mm through the thickness in the diametrical direction, with a spacing between the two holes of 5～9 mm. Then insert the two poles of the thermocouple separately and fix them by silver brazing to measure the spark plug temperature.
  • 5.2.4 Exhaust temperature: install a thermocouple in the exhaust pipe at about 65 mm from the cylinder exhaust outlet to measure the exhaust temperature. The thermocouple contact point is located at the center of the exhaust pipe ±3 mm.
  • 5.2.5 Fuel system: install a pressure gauge at the carburetor inlet. The fuel pressure entering the carburetor should be maintained at 19～21 kPa.
• 5.3 External cooling fan: air volume 34.3 m³/min (the source text “34.3/mi n” requires confirmation against the source standard (source-text extraction)), and the flow rate can be adjusted. The fan outlet is connected to the engine intake by a duct.
• 5.4 Dynamometer: a dynamometer that satisfies absorbing power 2.5 kW at 4000～6000 r/min, with a torque measurement accuracy of ±0.5%. When the input power is changed, the speed can still be maintained at 4000 r/min±30 r/min. The dynamometer may be driven directly by the engine or by belt transmission.
• 5.5 Instruments and meters:
  • 5.5.1 Tachometer: accuracy ±25 r/min.
  • 5.5.2 Temperature recorder: a recorder using continuous recording, with a maximum interval of 2 s, a range of 40～750℃, and an accuracy of ±2℃.
  • 5.5.3 Flowmeter: various types of mass flowmeters accurate to ±0.01 kg/h at a flow rate of 1 kg/h. If a volumetric flowmeter is used, determine the relationship between temperature and density during operation, and convert between volume and mass.
  • 5.5.4 Pressure gauge: range 35 kPa, accuracy ±2%.
• 5.6 Shutdown device: the engine should be equipped with a shutdown device to prevent rapid temperature rise of the cylinder head inner surface (1 min or shorter) at 10℃ or greater (this indicates that a major preignition has occurred), and an automatic shutdown device should be used to stop the engine to reduce damage to the engine from preignition. If there is no automatic shutdown device, at least an alarm device should be provided to issue an alarm when the temperature rises by 6～7℃, so that the operator can perform manual shutdown when the temperature rise reaches 10℃.
• Appendix A Main technical parameters of the engine (Table A1):
  • Vehicle model: YAMAHA CY50
  • Engine model: the source text source-text extraction reads “3[unreadable character]”, requires confirmation against the source standard (source-text extraction)
  • Number of cylinders: 1
  • Cooling method: forced air cooling
  • Scavenging method: two-stroke loop scavenging
  • Bore × stroke, mm: 40.0×39.2
  • Displacement, mL: 49
  • Compression ratio: 7.0:1～8.0:1

6. Recommended operating conditions

• Formal test conditions (Table 4): speed 4000 r/min±30 r/min; throttle opening: wide open; load: record; spark plug temperature: 200℃±3℃ (the source text “20〕[unreadable sign]3” requires confirmation against the source standard (source-text extraction)).
• Adjustment operating conditions (Table 2): operating time 30 min; speed 4000 r/min±30 r/min; load 0.746 kW±0.07 kW; spark plug temperature 174℃±3℃.
• Warm-up operating conditions (Table 3): duration 2 min; speed 2000 r/min±200 r/min, throttle closed, load 0, spark plug temperature recorded; 2 min, 3000 r/min±50 r/min, throttle open 1/3, load recorded, spark plug temperature 125℃; 2 min, 3500 r/min±50 r/min, throttle open 2/3, load recorded, spark plug temperature 185℃; 2 min, 4000 r/min±50 r/min, throttle fully open, load recorded, spark plug temperature 200℃ (original "[garbled speed and sign]50" "2([unreadable character]" requires confirmation against the source standard (source-text extraction)).
• Break-in conditions (Table 1):
  • Stage one: 2 min, 2000 r/min±100 r/min, throttle closed, spark plug gasket temperature recorded, number of cycles 2; 2 min, 4000 r/min±50 r/min, open 1/3, maximum 125℃, 2; 2 min, 5500 r/min±50 r/min, open 1/3, maximum 125℃, 2; 2 min, 3500 r/min±50 r/min, open 1/3, maximum 125℃, 2; 2 min, 4500 r/min±50 r/min, open 1/3, maximum 125℃, 2.
  • Stage two: 2 min, 2000 r/min±100 r/min, closed, recorded, 4; 2 min, 4000 r/min±50 r/min, open 1/2, maximum 140℃, 2; 2 min, 5500 r/min±50 r/min, open 1/2, maximum 140℃, 2; 2 min, 3500 r/min±50 r/min, open 1/2, maximum 140℃, 2; 2 min, 4500 r/min±50 r/min, open 1/2, maximum 140℃, 2.
  • Stage three: 2 min, 2000 r/min±100 r/min, closed, recorded, 4; 2 min, 4000 r/min±50 r/min, open 3/4, maximum 155℃, 2; 2 min, 5500 r/min±50 r/min, open 3/4, maximum 155℃, 2; 2 min, 3500 r/min±50 r/min, open 3/4, maximum 155℃, 2; 2 min, 4500 r/min±50 r/min, open 3/4, maximum 155℃, 2.
  • Stage four: 2 min, 2000 r/min±100 r/min, closed, recorded, 2; 2 min, 4000 r/min±50 r/min, fully open, maximum 170℃, 2; 2 min, 5500 r/min±50 r/min, fully open, maximum 170℃, 2; 2 min, 3500 r/min±50 r/min, fully open, maximum 170℃, 2; 2 min, 4500 r/min±50 r/min, fully open, maximum 170℃, 2.
  • Note: In Table 1, some speeds source-text extraction are written as "[garbled speed and sign]50", "[unreadable character]D )[unreadable sign]50", "450)[unreadable sign]50", etc., requires confirmation against the source standard (source-text extraction).

7. Sampling and specimen preparation

• 7.1 Replacement of parts:
  • 7.1.1 For the first assembly, new piston, piston rings, cylinder, cylinder head and head gasket must be used.
  • 7.1.2 When reassembling the engine after the test, the cylinder head gasket, exhaust gasket, piston, piston rings and muffler are required to be replaced with new ones; other parts need not be replaced if they meet the requirements.
  • 7.1.3 After the engine has run for 100 h to 150 h, the cylinder usually needs to be replaced. After running for 1000 h to 1500 h, the entire engine needs to be replaced or completely reassembled.
• 7.2 Disassembly:
  • 7.2.1 Remove the engine shroud and spark plug. Remove the nuts and cylinder head, remove the intake pipe and reed valve assembly, and remove the cylinder. Use suitable pliers to remove the piston pin circlip. Using an auxiliary installer/remover, tap gently to press out the piston pin; if the pin is difficult to remove, the piston may be heated. Finally, take out the piston and piston rings.
  • 7.2.2 For disassembly of the crankcase, refer to the YAMAHA CY50 service manual.
• 7.3 Inspection of parts:
  • 7.3.1 Measurement of piston-to-cylinder clearance: the clearance between the piston diameter and the cylinder bore is 0.045 mm to 0.13 mm. Standard components will have tolerances. Record the piston-to-cylinder clearance. Minimum clearance = minimum bore diameter − maximum piston diameter; maximum clearance = maximum bore diameter − minimum piston diameter.
  • 7.3.2 Measurement of cylinder bore: measure and record the cylinder bore in both directions parallel to and perpendicular to the crankshaft at the following positions (accurate to 0.01 mm): below the top of the cylinder 7 mm; below the top of the cylinder 12 mm; below the top of the cylinder 43 mm. Record roundness and cylindricity.
  • 7.3.3 Measurement of piston outer diameter: measure and record the piston diameter in both directions parallel to and perpendicular to the piston pin hole at the following positions (accurate to 0.01 mm): middle of the top ring land; from the piston top downward 12 mm; from the piston top downward 43 mm.
  • 7.3.4 Measurement of piston ring clearance: place the piston ring horizontally at 15 mm from the top of the cylinder, measure the end gap, which is required to be 0.15 mm to 0.4 mm. Install the piston ring on the piston, measure its side clearance, which is required to be 0.03 mm to 0.05 mm.
  • 7.3.5 Check the piston pin hole for sharp edges or burrs; if present, lightly grind them away with sandpaper, but the hole must not be enlarged.
  • 7.3.6 Cylinder head: place the cylinder head on a surface plate; if a 0.05 mm feeler gauge can be inserted between the cylinder head surface and the surface plate, it must be corrected or replaced.
  • 7.3.7 Measurement of connecting rod and crank bearing clearance: clean the crankcase assembly with solvent naphtha, measure and record the clearance between the contact surfaces of the connecting rod and crank bearing. If the clearance exceeds 0.5 mm or the bearing shows fatigue, replace the relevant parts or the entire engine. After inspection, lubricate all parts with ASTM 601 oil to prevent rust.
  • 7.3.8 Intake system: check the intake system for cracks or deformation. Check the reed for cracks or peeling. Check the reed assembly against a light source for leakage. Replace any defective parts.
  • 7.3.9 Other parts: perform a general inspection of the air filter, carburetor and ignition circuit, and clean, repair or replace as necessary.
• 7.4 Engine assembly:
  • 7.4.1 Clean all parts with solvent naphtha and air dry, apply ASTM 601 oil to the piston assembly and cylinder. Install the piston and cylinder in order. The arrow on the top of the piston points toward the exhaust pipe side. Install the cylinder head, first tighten the nuts to 5～6 N·m, then to 10.5～11.5 N·m. For the first assembly of the crankcase, connecting rod, cylinder and cylinder head, the compression ratio must be checked and adjusted, see Appendix D, so that the compression ratio is between 7.0:1 and 8.0:1 (original "5.0:1" requires confirmation against the source standard (source-text extraction)).
  • 7.4.2 Check whether the ignition timing is between 17°～19° before top dead center.
  • 7.4.3 Apply a thin layer of sealant to both sides of the reed block gasket and install it on the cylinder. Install the reed assembly and intake pipe, and tighten the bolts to 0.7 N·m. Using a new gasket, install the carburetor and tighten to 0.7 N·m.
  • 7.4.4 Install a new NGK BP6HS or equivalent spark plug, with a torque of 20 N·m. The thermocouple of the spark plug gasket should be installed on the downstream side of the cooling air.
  • 7.4.5 Install the intake system, exhaust muffler and cooling air system.
  • 7.4.6 Install the fan shroud and connect the cooling air system.

8. Analysis procedure

• 8.1 Break-in: before each test, break-in shall be carried out according to the provisions of Table 1 using ASTM 600 or a mixed fuel with a mixing ratio of 20:1 of the oil to be evaluated, for a duration of 2 h. After break-in, remove the piston and cylinder for inspection; if piston scuffing, ring sticking or other faults occur, replace the relevant parts and break in again.
• 8.2 Adjustment run: after break-in and final inspection of the engine, drain the fuel. Replace with new test fuel mixed at a mixing ratio of 20:1, restart the engine, and carry out the adjustment run according to Table 2.
• 8.3 Warm-up run: whenever the engine is stopped for any reason and restarted, it shall be run for warm-up according to the conditions listed in Table 3 for 8 min. The warm-up time is not counted in the total test time.
• 8.4 Formal test: after the engine is warmed up, operate according to the provisions of Table 4 for 100 h. The combustion chamber temperature and spark plug gasket temperature should be recorded continuously, and the interval between continuous records must not exceed 2 s. Every 30 min, record the fuel pressure, fuel flow rate, and intake air temperature. Every 2 h, record the atmospheric pressure and the relative humidity of the test room. Also pay attention to changes in the combustion chamber and spark plug gasket temperatures. Exhaust temperature is a monitoring item.
  • 8.4.1 Major pre-ignition: at any time when the throttle is fully open and the speed is 4000 r/min, if the combustion chamber temperature rises sharply, exceeding the stable temperature by 10℃ or more, then major pre-ignition has occurred; stop the machine immediately, record the time of occurrence, with timing accurate to 0.1 h. Usually when major pre-ignition occurs, the spark plug temperature rises and the torque decreases. After stopping the machine, the spark plug must not be removed immediately. Remove the exhaust pipe and cylinder head, and inspect the cylinder. If there is no mechanical damage, clean out the deposits in the combustion chamber, replace with a new cylinder head gasket and spark plug, and continue the test. Mark the total operating time (h) on the original spark plug. If scratching or seizure occurs, remove the cylinder and inspect the piston. If necessary, replace with a new piston and cylinder, repeat steps 8.1 to 8.2, and continue the test.
  • 8.4.2 Minor pre-ignition: if the recorder indicates that the combustion chamber temperature rises sharply by 7℃ or more but less than 10℃, record it as a minor pre-ignition phenomenon, and at the same time record the total engine operating time, the time of the last change in combustion chamber temperature (accurate to 0.1 h), and the decrease in torque accompanying the rise in combustion chamber temperature. When minor pre-ignition occurs, do not stop the machine.
• 8.5 Spark plug and other faults: if the engine speed decreases by 100 r/min or more and cannot return to the original speed within 2 min, while the combustion chamber temperature decreases, stop the machine to find the cause, and check whether the spark plug has electrode bridging or coking. If the problem is unrelated to the spark plug, continue using the original spark plug when restarting; otherwise, replace the spark plug, record the spark plug life and the reason for removal, and then continue the test.
• 8.6 Exhaust system blockage: at any time when the torque drops to 90% of the initial stable value, remove the deposits at the exhaust port and replace with a new muffler; if the power still cannot be restored, inspect and make appropriate repairs, and keep records.
• 9 Engine calibration: engines that are new or completely reassembled, or that have completed 10 tests, shall be calibrated. Use ASTM 605 as calibration oil for the test, and operate for 100 h like other samples. During operation, major pre-ignition phenomena shall occur at least 8 times and at most 20 times. If major pre-ignition occurs fewer than 8 times, check the problem and correct it, and recalibrate; if during the 605 oil test major pre-ignition occurs more than 20 times, and more than 180 days have passed since the most recent calibration, or after 50 runs (whichever comes first), operate for 100 h with ASTM 601 calibration oil. If major pre-ignition occurs no more than 1 times, no further measures are needed. Otherwise, find the cause and redo the calibration test.

9. Qualitative and Quantitative Determination and Calculation Formulas

• Pre-ignition determination:
  • Major pre-ignition: the combustion chamber temperature rises sharply, exceeding the stable temperature by 10℃ or more.
  • Minor pre-ignition: the combustion chamber temperature rises sharply by 7℃ or more but less than 10℃.
• Compression ratio calculation formula (Appendix D, Formula D1):
  • Compression ratio = (ESV + CV) / CV
  • Where: ESV— effective working volume, mL; CV— compression volume, mL.
• Appendix D Compression ratio measurement and adjustment:
  • D1 Determination of effective working volume:
    • D1.1 Place the piston at bottom dead center, and measure the distance from the top surface of the piston to the cylinder head mounting surface.
    • D1.2 Measure the distance from the top end of the exhaust port to the cylinder head mounting surface. The difference between the measurement result and D1.1 plus the depth of the piston ring groove is the effective exhaust port height.
    • D1.3 After determining the effective exhaust port height, place the piston at top dead center, and measure the distance from the top surface of the piston to the cylinder head mounting surface. The difference between D1.1 and the measured value D1.3 minus the effective exhaust port height is the effective stroke.
    • D1.4 Multiply the effective stroke (expressed as cm) by the cross-sectional area corresponding to the cylinder diameter (approximately 12.57 cm²) to obtain the effective working volume (expressed as mL).
  • D2 Determination of compression volume:
    • D2.1 Install the cylinder head, and adjust the engine position so that the spark plug hole seat plane faces upward and is horizontal.
    • D2.2 Remove the cylinder head, and place the piston at top dead center.
    • D2.3 Use a finger to press grease into the space between the piston and the cylinder wall, so that no gap appears around the piston. Wipe off excess oil on the top of the piston and the surface of the cylinder head gasket. Be careful not to move the piston during the operation.
    • D2.4 Install the cylinder head, and tighten to 10.5 N·m～11.5 N·m.
    • D2.5 Dilute 600 oil with solvent naphtha at a ratio of 5:1, inject it into the combustion chamber up to the top surface of the spark plug hole, slowly remove foam, and after the oil surface stabilizes, record the amount of oil used (accurate to ±0.1 mL); the normal amount used is about 5.0 mL. It is recommended to use a 10 mL burette to measure the oil amount.
    • D2.6 Subtract the volume occupied by the 1.1 mL spark plug from the oil volume, which is the compression volume.
  • D3 Calculation of compression ratio: see Formula D1.
  • D4 When the compression ratio is not within the range of 7.0:1～8.0:1, it should be achieved as much as possible by replacing the cylinder.

10. Precision

not provided in the available source.

11. Report

The test result report includes the test results of the oil to be evaluated and the reference oil. The content includes: test date, detailed test results, and necessary explanations.

12. Referenced Documents

• GB/T 260 Determination of Water in Petroleum Products
• GB/T 380 Determination of Sulfur Content in Petroleum Products (Lamp Method)
• GB 1922 Solvent Naphtha
• GB/T 5096 Copper Strip Corrosion Test Method for Petroleum Products
• GB/T 5487 Determination of Gasoline Octane Number (Research Method)
• GB/T 6536 Determination of Distillation of Petroleum Products
• GB/T 8017 Determination of Vapor Pressure of Petroleum Products (Reid Method)
• GB/T 8018 Determination of Oxidation Stability of Gasoline (Induction Period Method)
• GB/T 8019 Determination of Existent Gum in Automotive Gasoline and Aviation Fuels (Jet Evaporation Method)
• GB/T 8020 Determination of Lead Content in Gasoline (Atomic Absorption Spectrometry)
• SH/T 0116 Determination of Acidity of Gasoline Containing Ethyl Fluid
• Editor's note: the original standard number is SH/T 0116, the current standard number is SH/T 0116-92, and the current standard name is Determination of Acidity of Gasoline Containing Ethyl Fluid.
• Appendix A, Appendix B, Appendix C, and Appendix D are all normative appendices of the standard.

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.

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