SH/T 0648-1997 Water-cooled two-stroke gasoline engine oil detergency and general performance evaluation method

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Card type: Test method

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

• Standard number: SH/T 0648-1997
• Chinese name: Water-cooled two-stroke gasoline engine oil detergency and general performance evaluation method
• English name (original text layer): Lubricants test method for evaluating detergence and general performance of water-cooled two-stroke gasoline engine
• Replacement relationship: not provided in the available source (the replaced standard number is not given)
• Adoption relationship: This standard is equivalent to the detergency and general performance test method in Section 6.2 NMMA of the National Marine Manufacturers Association NMMA—9—88 'Two-stroke gasoline engine lubricating oil TC—W I license test'
• Drafting organizations: Maoming Petrochemical Company Research Institute, Tianjin Internal Combustion Engine Research Institute
• Main drafters: Liang Qirui, Xie Shiwen, Wu Dawei, Chen Guanghui, Feng Xinping, Wang Xuehan
• Custodianship: Technical custodianship by the Petrochemical Science Research Institute of China Petrochemical Corporation
• Approval/implementation: Approved by China Petrochemical Corporation 1997-07-12, implemented on 1997-12-01

2. Scope of application and non-application

• This standard specifies the method for evaluating the detergency and general performance of lubricating oils used in water-cooled two-stroke gasoline engines such as outboard motors (Chapter 1).
• This standard applies to the evaluation of the detergency and general performance of water-cooled two-stroke gasoline engine oils (abbreviated as two-stroke oils) (Chapter 1).
• Non-application scope: not provided in the available source.

3. Method principle

Using a modified OMC 737 mL displacement two-stroke outboard motor, in a test water pool (tank), a reference oil and one or more candidate oils are simultaneously subjected to comparative tests on two or more outboard motors. If conditions do not permit, one engine may also be used to conduct comparative tests of the reference oil and the candidate oil sequentially. The engine is operated under specified operating conditions at full throttle 55 min, at idle 5 min for 7 h, followed by at least 1 h shutdown cooling time. This cycle is repeated 14 times to reach a total operating time of 98 h. By comparing the evaluation results of the reference oil and the candidate oil, the detergency and general performance of the candidate oil are evaluated (Chapter 4).

4. Reagents and materials (purity / preparation)

• 6.1 Test fuel: meets the requirements of Appendix B. The same batch of fuel must be used for the same series of tests. A complete test requires about 3200 L of gasoline.
• 6.2 Reference oil: a two-stroke oil produced by Citgo company with the designation 93738, approximately 19 L required for one test.
• Appendix B (standard appendix) Fuel properties (Table B1):
  • Actual gum, mg/100 mL, not greater than 4, test method GB/T 8019
  • Vapor pressure (37.8℃), kPa, not greater than 75, test method GB/T 8017
  • Tetraethyl lead, g/L, not greater than 0.001, test method GB/T 8020
  • Distillation range 10%, ℃ not higher than 70; 50%, ℃ not higher than 110; 90%, ℃ not higher than 167, test method GB/T 6536
  • Sulfur content, % (m/m), not greater than 0.03, test method GB/T 380
  • Octane number (research method) 89～93, test method GB/T 5487
  • Hydrocarbon types: olefins % (V/V) 5～20; aromatics % (V/V) 25～35, test method GB/T 11132
  • Note: Other measurement items meet the requirements of SH 0041.
• Mixing ratio: volume ratio of test fuel to two-stroke oil (3.5). For break-in, use 50:1 mixed fuel; for formal test, use 100:1 mixed fuel (8.1, 8.2.1).
• Purity/preparation details: not provided in the available source (other than the above mixing ratio and fuel specifications).

5. Instruments and equipment

• 5.1 Test engine: J40ELETB two-stroke outboard motor, main technical parameters see Appendix A.
• 5.2 Engine modifications:
  • 5.2.1 Remove the original propeller and replace it with a load wheel (OMC part number 382861) as the power absorption device. The load wheel must be machined to fit the power output shaft and meet the requirement of maintaining engine speed at full throttle 4500 r/min±100 r/min.
  • 5.2.2 Because premixed fuel is used, the oil pump suction inlet of the original engine must be blocked.
  • 5.2.3 Modify the engine cooling system. It is recommended that the cooling water for the power head part be directly supplied by a pump with a displacement of about 6 L/min circulating under a water pressure of about 69 kPa～83 kPa. The cooling water passes through a heat exchanger to adjust the water temperature to ensure the cylinder head water outlet temperature is within the specified range.
• 5.3 Test water pool (tank): The test should be conducted in a suitable outboard motor test water pool (tank) with sufficient ventilation. The pool (tank) should have sufficient volume and necessary buffers installed to avoid water flow affecting speed stability. The pool (tank) has a water inlet, a water outlet, and an overflow port set according to the outboard motor height to maintain the liquid level. An exhaust system is established to extract outboard motor exhaust gas to prevent exhaust gas from entering the carburetor and affecting the intake of fresh air.
• 5.4 Fuel system: Engine fuel is supplied by a fuel pump. To facilitate emptying and maintain relatively stable fuel inlet pressure, high-position fuel supply is used. The mixed fuel comes out of the fuel tank, passes through a filter, fuel consumption meter, outboard motor fuel connector, and then to the fuel pump. When stopped, the fuel pressure at the fuel pump suction inlet must not exceed 35 kPa.
• 5.5 Instruments and meters:
  • 5.5.1 Spark plug gasket: Made of copper, replacing the original spark plug gasket. Copper gasket thickness 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 in the middle of the thickness, and weld a temperature-measuring thermocouple with silver.
  • 5.5.2 Spark plug gasket temperature recorder: capable of continuous recording, maximum interval 2 s, accuracy ±1℃.
  • 5.5.3 Engine inlet and outlet water temperature recorder: continuous recording, maximum interval less than 2 min, accuracy ±1℃.
  • 5.5.4 Tachometer: electronic or vibration-type tachometer with accuracy ±25 r/min.
  • 5.5.5 Fuel flow meter: flow meter with accuracy ±0.23 kg/h under 11 kg/h.
  • 5.5.6 Ignition timing light: timing light with high-energy ignition system.
• Appendix A (standard appendix) Main technical parameters of test engine (Table A1):
  • Engine model: J40ELETB / J40E (original text source-text extraction unclear in the source text, requires confirmation against the source standard (source-text extraction))
  • Number of cylinders: 2
  • Scavenging method: two-stroke loop scavenging
  • Bore × stroke, mm: 80.96×71.63
  • Cooling method: forced water cooling
  • Displacement, L: 737
  • Number of carburetors: 2
  • Rated power, kW/r/min: 29.8/5000
  • Compression ratio: 7.0:1～7.2:1 (original text source-text extraction unclear in the source text, requires confirmation against the source standard (source-text extraction))
  • Full throttle speed range, r/min: 4500～5500 (original text source-text extraction unclear in the source text, requires confirmation against the source standard (source-text extraction))

6. Recommended operating conditions

• Table 1 Formal test conditions:
  • Speed, r/min: 4500±100
  • Throttle opening: full open
  • Fuel flow rate, kg/h: 9.5～10
  • Cylinder head cooling water outlet temperature, ℃: 77±3
  • Laboratory temperature, ℃: 14～43
  • Ignition timing: before top dead center 21° (original text source-text extraction unclear in the source text, requires confirmation against the source standard (source-text extraction))
• 8.2.2 Test cycle: idle (700 r/min～800 r/min) operation for 5 min, full throttle operation for 55 min. Repeat 7 times as one test cycle. Between two cycles, shut down for at least 1 h, and no more than 24 h. Repeat the cycle 14 times, total test time 98 h.
• 8.1 Break-in conditions: Prepare a mixed fuel of 50:1 using test fuel and test oil sample, partially open the throttle, operate at 3000 r/min for 1 h; operate at 4000 r/min for 1 h. After break-in, stop the engine, tighten the cylinder head bolts with a torque of 25.8 N·m～27.1 N·m, then drain the fuel from the tank, lines, and carburetor.

7. Sampling and sample preparation

• 7.1 Engine assembly:
  • 7.1.1 For each test, replace with new piston, piston rings, spark plug, connecting rod bearings, main bearings, and seal components. Clean parts with solvent naphtha, replace other damaged parts, and if necessary replace the entire short block or even the entire engine.
  • 7.1.2 Measure the cylinder diameter in the following positions in both directions parallel and perpendicular to the crankshaft: 19 mm below the top of the cylinder; above the exhaust port; above the bottom cutout. Roundness and cylindricity not greater than 0.05 mm, cylinder inner surface roughness 0.0005～0.001 mm.
  • 7.1.3 Measure the piston diameter at the top ring land and upper skirt in both directions parallel and perpendicular to the piston pin.
  • 7.1.4 The clearance between the piston and the cylinder must be ensured: the clearance between the top land of the piston and the cylinder at 19 mm below the top is 0.53～0.61 mm; the clearance between the upper part of the piston skirt and the upper part of the cylinder exhaust port is 0.41～0.48 mm.
  • 7.1.5 Place the piston ring horizontally into the cylinder at 19 mm below the top, measure the piston ring end gap, which is required to be 0.18～0.43 mm. The side clearance of the piston ring in the piston is 0.03～0.09 mm.
  • 7.1.6 Apply a thin layer of the sample to the relevant parts, reassemble the engine according to the OMC maintenance manual, and pay attention to the direction of coolant flow and sealing conditions. Block the exhaust auxiliary hole below the upper flange of the internal exhaust cavity to ensure that the cooling water supplied externally to the power head circulates without leaking out and that the cooling water supplied by the outboard motor cooling pump to the cooling exhaust cavity does not flow up into the power head.
• 7.2 Secure the assembled outboard motor in the test water pool (tank).
• Sample preparation (mixed fuel preparation): before the test, blend the test fuel with two-stroke oil according to the mixing ratio (3.6); use 50:1 for break-in, and use 100:1 for the formal test (8.1, 8.2.1).

8. Analysis steps

• 8.1 Break-in: see Section 6.
• 8.2 Formal test:
  • 8.2.1 Formal test conditions: replace with the same sample mixed fuel at a mixing ratio of 100:1, start the engine and operate it according to the conditions in Table 1 (Table 1 see Section 6).
  • 8.2.2 Test cycle: see Section 6.
  • 8.2.3 If two or more engines are undergoing comparative testing simultaneously, when any one engine requires maintenance, the other engines must also be stopped. When the engine speed loss at full throttle is 200 r/min or more, stop the engine for inspection, find the cause, eliminate the fault, and then continue the test. If during the test it is necessary to replace the piston assembly, cylinder head, connecting rod bearings, or the entire short block due to a fault, the test results are invalid. If the test cannot continue due to sample quality problems, terminate the test and explain this in the test result report.
  • 8.2.4 Test records:
    • Engine coolant inlet and outlet temperatures: record continuously.
    • Spark plug gasket temperature: record continuously.
    • Engine speed: before and after each idle stage 5 min and before the end of idling.
    • Fuel flow rate, ignition timing, test room air temperature, pressure, and humidity: record once every 7 h.
  • 8.2.4.1 During the test, a sudden increase in spark plug gasket temperature of 10℃ or more is a sign of pre-ignition; record the time when pre-ignition occurs and stop the engine to replace the spark plug before continuing the test.
  • 8.2.4.2 When it is determined that the spark plug is not firing, remove it and record the spark plug condition and the time of the fault.
• 9.1 After the test ends, disassemble the engine within 2 h to 12 h for test result evaluation, in the following order: disassembly, piston ring scoring, piston ring removal, photographing of relevant parts, scoring and evaluation of specified parts. For the cleanliness and general performance scoring method, see Appendix C.

9. Qualitative and quantitative and calculation formulas

• 9.2 Test result report: compare the test results of the oil to be evaluated with the reference oil, issue the test result report according to Appendix D, and attach photographs of the relevant parts.
• Appendix C (standard appendix) Scoring method for cleanliness and general performance results of water-cooled two-stroke gasoline engine oil:
  • C1 Scope: This method is only applicable to evaluating the results of outboard motor tests for water-cooled two-stroke gasoline engine oil.
  • C2 Scoring environment: C2.1 The scoring work should be carried out in a scoring box. C2.2 The inner surface of the scoring box is coated with white blended paint. Two cool white fluorescent lamps of 15 W each are installed in the box. The color temperature of the lamps is about 4500 K, and the illuminance is 210 lx～5400 lx.
  • C3 Piston ring scoring: C3.1 After the piston is removed from the cylinder, immediately score the flexibility of each piston ring. Take the average score of four rings from two cylinders. C3.2 Relationship between piston ring condition and score:
    • Free ring: 10
    • Dull ring: 9.5
    • Spot-stuck ring: 9.0
    • Cold-stuck ring: 4.5×cold stickiness number/3 (original text source-text extraction unclear in the source text, requires confirmation against the source standard (source-text extraction))
    • Hot-stuck ring: 4.5×(2−hot stickiness number/3) (original text source-text extraction unclear in the source text, requires confirmation against the source standard (source-text extraction))
  • C4 Piston cleanliness scoring:
    • C4.1 Remove the piston rings, carefully wipe the piston surface with fine fleece until there is no lubricating oil or sludge on the piston surface.
    • C4.2 Score the four areas of the piston skirt, top land, second land, and piston inner top separately. Take the average score of eight areas from two cylinders.
    • C4.3 Scoring method:
      • C4.3.1 Using the merit scoring method, a surface not covered by any lacquer film is scored 10 points; one fully covered with black lacquer film is scored 0 points. When between the two, multiply the lacquer film severity coefficient by the respective corresponding lacquer film coverage area percentage, and add the products to obtain the lacquer film score for that area.
      • C4.3.2 The piston ring land is evenly divided into 10 areas, each with an area of 10%. The division of the piston skirt area and the area percentage of each region are shown in Figure C1. The division of the piston inner top is shown in Figure C2.
      • C4.3.3 The lacquer film severity coefficient is expressed by the corresponding color plate grade in the SH/T 0510 lacquer film color standard color plates.
      • C4.3.4 All carbon deposits are treated as black lacquer film.
      • C4.3.5 Before the test, inspect the four areas to be scored. If the original surface cleanliness is lower than grade 10 of the standard color plate, then corrections should be made when scoring after the test. After determining the various lacquer film severity coefficients, add the original difference in grades to each lacquer film severity coefficient. For example, if the severity coefficient of a certain area before the test is 9, the severity coefficient of this area after the test must increase by one grade; that is, if the determined lacquer film severity coefficient is 5, the corrected lacquer film severity coefficient should be 6.
      • C4.3.6 Examples of scoring are shown in Table C2 and Table C3.
  • C5 Evaluation of exhaust port blockage: the degree of exhaust port blockage is expressed by the percentage of the exhaust port cross-sectional area occupied by exhaust port deposits. It must be evaluated when the parts are carefully removed.
  • C6 Determination of spark plug faults: state in the test result report the number of shutdowns caused by spark plug coking and electrode bridging due to the test oil sample, but excluding spark plug faults caused by mechanical problems.
  • C7 Component evaluation:
    • C7.1 Visually evaluate the corrosion, scuffing, damage, and other conditions of the piston skirt, cylinder liner, bearings, and main journals, and directly compare the component conditions of the oil to be evaluated and the reference oil, expressing them as better than, worse than, or the same as.
    • C7.2 Combustion chamber deposits are evaluated using the scoring method. Only the cylinder head and piston outer top are scored, and the average score of four areas from two cylinders is taken.
      • C7.2.1 A surface not covered by any deposit is scored 10 points; a coverage thickness of 12.8 mm or more is scored 0 points. When between the two, multiply the deposit severity coefficient by the respective corresponding deposit coverage area percentage, and add the products to obtain the deposit score for that area.
      • C7.2.2 Deposit severity coefficients are shown in Table C1:
        • 10: clean
        • 9.9～9.0: lacquer film deposits are graded according to C4.3.3, deposit severity coefficient = 9.0 + lacquer film severity coefficient/10
        • 9.0: carbon deposit with thickness less than 0.1 mm
        • 8.0: carbon deposit with 0.1≤ thickness < 0.2 mm
        • 7.0: carbon deposit with 0.2≤ thickness < 0.3 mm
        • 6.0: carbon deposit with 0.3≤ thickness < 0.4 mm
        • 5.0: carbon deposit with 0.4≤ thickness < 0.8 mm
        • 4.0: carbon deposit with 0.8≤ thickness < 1.6 mm
        • 3.0: carbon deposit with 1.6≤ thickness < 3.2 mm
        • 2.0: carbon deposit with 3.2≤ thickness < 6.4 mm
        • 1.0: carbon deposit with 6.4≤ thickness < 12.8 mm
        • 0: carbon deposit with thickness of 12.8 mm or more
      • C7.2.3 Examples of cylinder head and piston outer top deposit scoring are shown in Table C4.
  • C8 The average score in the test result report is taken to one decimal place.
• Appendix D (standard appendix) Water-cooled two-stroke gasoline engine oil cleanliness and general performance test result report (Table D1) columns: sample name, NMMA93738#, comparison of oil to be evaluated with reference oil, submitting unit, test method, test date, cleanliness score (cylinder one/cylinder two/average), piston ring score (top ring/second ring/subtotal/total), piston deposit score (top land/second land/piston inner top/skirt/subtotal/total), component evaluation (piston outer top/cylinder head/cylinder liner/bearing/other), spark plug faults (times), exhaust port blockage (%), pre-ignition (times), conclusion, remarks, scorer, report, reviewer.

10. Precision

not provided in the available source.

11. Report

• 9.2 Test result report: compare the test results of the oil to be evaluated with the reference oil, issue the test result report according to Appendix D, and attach photographs of the relevant parts.
• Appendix D Table D1 report format see Section 9.
• C8 The average score in the test result report is taken to one decimal place.
• 8.2.3 If the test cannot continue due to sample quality problems, terminate the test and explain this in the test result report.
• C6 State in the test result report the number of shutdowns caused by spark plug coking and electrode bridging due to the test oil sample.

12. Reference documents

• GB/T 380 Determination of sulfur content in petroleum products (lamp method)
• GB/T 5487 Determination of gasoline octane number (research method)
• GB/T 6536 Determination of distillation of petroleum products
• GB/T 8017 Petroleum products — Determination of vapor pressure (Reid 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)
• GB/T 11132 Determination of hydrocarbon types in liquid petroleum products (fluorescent indicator adsorption method)
• SH 0041 Unleaded automotive gasoline
• SH/T 0510 Rating method for engine tests of gasoline engine oils
• Editor's note: original standard number SH 0041, current standard number SH 0041-93, current standard name Unleaded automotive gasoline

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