40 CFR § 1048.240 - How do I demonstrate that my engine family complies with exhaust emission standards?
(a) For purposes of certification, your engine family is considered in compliance with the applicable numerical emission standards in § 1048.101(a) and (b) if all emission-data engines representing that family have test results showing official emission results and deteriorated emission levels at or below these standards. This includes all test points over the course of the durability demonstration. This also applies for all test points for emission-data engines within the family used to establish deterioration factors. See paragraph (e) of this section for provisions related to demonstrating compliance with field-testing standards.
(b) Your engine family is deemed not to comply if any emission-data engine representing that family has test results showing an official emission result or a deteriorated emission level for any pollutant that is above an applicable emission standard from § 1048.101(a) and (b). Similarly, your engine family is deemed not to comply if any emission-data engine representing that family has test results showing any emission level above the applicable field-testing standard for any pollutant. This also applies for all test points for emission-data engines within the family used to establish deterioration factors.
(c) To compare emission levels from the emission-data engine with the applicable emission standards, apply deterioration factors to the measured emission levels for each pollutant. Specify the deterioration factors based on emission measurements using four significant figures, consistent with good engineering judgment. For example, your deterioration factors must take into account any available data from in-use testing with similar engines (see subpart E of this part). Small-volume engine manufacturers may use assigned deterioration factors that we establish. In addition, anyone may use assigned deterioration factors for engine families with a projected U.S.-directed production volume at or below 300 engines. Apply deterioration factors as follows:
(1) Multiplicative deterioration factor. Except as specified in paragraph (c)(2) of this section, use a multiplicative deterioration factor for exhaust emissions. A multiplicative deterioration factor is the ratio of exhaust emissions at the end of useful life to exhaust emissions at the low-hour test point. Adjust the official emission results for each tested engine at the selected test point by multiplying the measured emissions by the deterioration factor. If the factor is less than one, use one.
(2) Additive deterioration factor. Use an additive deterioration factor for exhaust emissions if engines do not use aftertreatment technology. Also, you may use an additive deterioration factor for exhaust emissions for a particular pollutant if all the emission-data engines in the engine family have low-hour emission levels at or below 0.3 g/kW-hr for HC + NOX or 0.5 g/kW-hr for CO, unless a multiplicative deterioration factor is more appropriate. For example, you should use a multiplicative deterioration factor if emission increases are best represented by the ratio of exhaust emissions at the end of the useful life to exhaust emissions at the low-hour test point. An additive deterioration factor is the difference between exhaust emissions at the end of useful life and exhaust emissions at the low-hour test point. Adjust the official emission results for each tested engine at the selected test point by adding the factor to the measured emissions. If the factor is less than zero, use zero.
(d) Collect emission data using measurements to one more decimal place than the applicable standard. Apply the deterioration factor to the official emission result, as described in paragraph (c) of this section, then round the adjusted figure to the same number of decimal places as the emission standard. Compare the rounded emission levels to the emission standard for each emission-data engine. In the case of HC + NOX standards, apply the deterioration factor to each pollutant and then add the results before rounding.
(e) Use good engineering judgment to demonstrate compliance with field-testing standards throughout the useful life. You may, but are not required to, apply the same deterioration factors used to show compliance with the applicable duty-cycle standards.