ASTM D6201 Dynamometer Evaluation of Unleaded Spark-Ignition Engine Fuel
ASTM D6201 Standard Test Method for Dynamometer Evaluation of Unleaded Spark-Ignition Engine Fuel for Intake Valve Deposit Formation
13. Determination of Test Results
13.1 Post-Test Intake Valve Weighing Procedure - Prepare the intake valves for weighing using the following procedure. Remove carbon deposits from the combustion chamber side of the valve (valve face) and the valve margin using a bench grinder fitted with a fine steel brush as stated in 6.4.5. Perform the buffing process by rotating the valve and applying just sufficient pressure against the wire wheel to remove the deposits. Avoid removing deposits from any area not specified above.
13.1.1 Valve Rinse - Wash the valves gently with cyclohexane or n-hexane. Perform this procedure only once. Discharge the solvent from a hand squeeze bottle onto the valve. Gently rinse the valve starting at the top of the stem and proceeding towards the tulip section. While discharging the solvent, rotate the valve (which is held in gloved hand) to ensure removal of all oily residues. Continue the washing process until the solvent running off the valve is clear. Gently shake off any remaining solvent.

NOTE 6 - Precaution: In addition to other precautions, provide adequate ventilation and fire protection in areas where flammable or volatile, or both, liquids and solvents are used. Suitable protective clothing is recommended.

13.1.2 Removing the Rinse - Immediately after the wash is complete, place the intake valves inside an oven (see 6.4.4) for 5 min to remove any remaining solvent through vaporization. The oven temperature shall be 93 +/- 5°C (200 +/- 9°F).

13.1.3 Warm Valve Handling Technique - Use tongs to transfer the valves from the oven directly into a desiccator.

13.1.4 Desiccator - The valves shall remain in the desiccator for a minimum of 1 h and not more than 48 h while they cool to room temperature. Conduct a periodic check of the desiccant to ensure its proper functioning. Monitoring of color change is usually the method employed.

13.1.5 Weighing the Valves - After the valves have been dried and cooled in the desiccator, they are ready to be weighed. When the valves are transferred from the desiccator to the scale, wear clean gloves to eliminate contamination and the addition of weight to the valve due to oil or debris from skin contact. Hold valves by the stems. Weigh the valves to the nearest 0.0001 g using a calibrated balance and record the weights.
13.1.5.1 Confirm the repeatability of the balance between the start and the end of this procedure by weighing and recording the weight of a reference valve before and after weighing the four valves. The start and end valve weights shall not differ by more than 0.0010 g. If the absolute difference is greater than 0.0010 g, then repeat 13.1.5.

13.1.6 Calculating Deposit Weight - Calculate the deposit weight by subtracting the start-of-test clean valve weight (obtained in 10.4.5) from the end-of-test weight (obtained in 13.1.5) for each valve.
13.1.6.1 For deposit weights less than 0.0005 g (including negative values), clean valves as described in 10.4.4 and reweigh as described in 10.4.5. Substitute this end-of-test clean valve weight for start-of-test clean valve weight to calculate the deposit weight on these valves. Take photographs (see 13.2) before the valves are cleaned. Clean valves using a walnut shell blaster. Avoid using a wire brush. Rinse residue from the cleaning as described in 13.1.1. Place valves in oven as described in 13.1.2, and follow 13.1.3-13.1.5.

13.1.6.2 If using the end-of-test clean valve weight to calculate deposit weight (13.1.6.1), and the deposit weight is still found to be less than -0.0010 g, the valve weight will be invalid. Valves that have a deposit weight between -0.0010 g and 0.0000 g shall be noted and 0.0000 g shall be used to calculate average deposit weight. No negative valve weights may be used to calculate average deposit weight.

13.1.6.3 Outlier rejection criteria may not be used to omit deposit weights. Four valid intake valve deposit weights are necessary for a valid test.

13.2 Photographs of Parts-General - In order to better document the test results, take photographs of engine test parts. Photographs shall be of sufficient clarity to accurately assess the deposit area. Reproduce the photographs in color, 216 mm wide by 279 mm high (8 1/2in. wide by 11 in. high) in size, except as noted. Take appropriate precautions so that the photography does not disrupt the deposits.
13.2.1 Intake Valves - Take photographs of valves after obtaining deposit weights. Take a photograph of all four valves grouped sequentially, and take individual photographs of each valve from directly above the valve stem. Mark the valves according to their position in the engine.

13.2.2 Intake Ports - Take photographs of all four ports, viewed from the combustion chamber side. Take individual photographs of each port from directly in front of that particular cylinder. Individual port photographs may be combined with the corresponding runner photograph.

13.2.3 Intake Runners - Take photographs of the four runners, viewed from the intake manifold side of the cylinder head. Take individual photographs of each runner from directly in front of that particular runner.

13.3 Induction System Rating - Rate the valves, intake runners, and intake ports visually using the CRC Manual 16. Clarification of the induction system rating procedure is as follows:
13.3.1 Intake Ports - Area defined by a cylindrical projection of the intake seat concentric with the valve guide and extending from valve seat to floor and including walls.

13.3.2 Runner Entrances - Area extending 25 mm into cylinder head runners from manifold to cylinder head interface.

13.3.3 Valve Tulips - Area from bottom end of travel to top of wear pattern on valve face. Rate valve tulips after valve faces are buffed.

13.4 Determination of Test Validity-Engine Conformance - During each test, strictly adhere to the specified operating conditions of the engine and monitor the conditions with data acquisition equipment capable of recording the following data as indicated in 12.3.3.
13.4.1 Engine Speed During Stages
13.4.1.1 Test Validation Criteria - For Stage 1, the engine speed averaged over the entire test shall be 2000 +/- 25 r/min. For Stage 2, the engine speed averaged over the entire test shall be 2800 +/- 10 r/min. If engine operation does not conform to this requirement, the test is invalid.

13.4.2 Manifold Absolute Pressure During Stages:
13.4.2.1 Test Validation Criteria - For Stage 1, the engine manifold absolute pressure averaged over the entire test shall be 30.6 +/- 1.3 kPa (230 +/- 10 mm Hg). For Stage 2, the engine manifold absolute pressure averaged over the entire test shall be 71.8 +/- 1.3 (540 +/- 10 mm Hg). If engine operation does not conform to this requirement, the test is invalid.

13.4.3 Engine Speed During Transitions:
13.4.3.1 Test Validation Criteria - Engine speed shall be 2400 +/- 75 r/min after 15 s into the transition between stabilized stages. If engine operation does not conform to this requirement, the test is invalid.

13.4.4 Manifold Absolute Pressure During Transition:
13.4.4.1 Test Validation Criteria - Manifold absolute pressure shall be 51.2 +/- 6.6 kPa (385 +/- 50 mm Hg) after 15 s into the transition between stabilized stages. If engine operation does not conform to this requirement, the test is invalid.

13.4.5 Total Engine Oil Consumption - Calculate the engine oil consumed per oil drain interval from the oil fill and drain weights as stated in 12.4.2.
13.4.5.1 Test Validation Criteria - Total engine oil consumption for the entire test shall be no more than 1.0 kg. A test will be invalid if oil consumption is greater than 1.0 kg.

13.4.6 Total Engine Test Duration:
13.4.6.1 Test Validation Criteria - Operate the engine for 100 h (approximately 462 cycles) using the same batch of test fuel.

13.4.7 Downtime - Once the engine begins operating according to this test method, complete the test with minimal downtime. Refer to 12.2 for specific downtime requirements.
13.4.7.1 Test Validation Criteria - Total engine-off time (or downtime) cannot exceed 10 h during any test. If engine operation does not conform to this requirement, the test is invalid. Four engine shutdowns are the maximum number allowed. If engine operation does not conform to this requirement, the test is invalid.

13.4.8 Engine Disassembly - Engine disassembly other than specified in the procedure shall not be permitted for a valid test. The engine shall not be disassembled for inspection during this test method.