The recommended practice applies to the dynamometer test procedure which can be used to assess the smoke emission characteristics of vehicular diesel engines. In particular@ these procedures describe the smoke emissions test@ smoke test cycle@ equipment and instrumentation@ instrument checks@ and chart reading and calculation@ for evaluation of an engine's steady-state and transient smoke emission characteristics. A full-flow smoke opacimeter as opposed to other types of smoke-meters is required because the test is designed to monitor transient smoke. Sampling type instruments have an excessive and variable delay and do not provide an accurate measurement of the engine's transient smoke output. An appendix shows that the Beer-Lambert law can be used to correlate opacity measurements with different meter path lengths. Additional or modified test conditions may be requested when this recommended practice is cited in a request for a smoke assessment. These modified test conditions should be clearly stated whenever the results of the smoke assessments are reported. Similarly if the fuel is specified in the test request@ this should be stated when the results are reported. Sections-The procedure is divided into the following sections: 1. Definitions of Terms and Abbreviations 2. Smoke Emission Test 3. Smoke Test Cycle 4. Information to be Recorded 5. Equipment and Instrumentation 6. Instrument Checks 7. Chart Reading 8. Appendix Purpose-This SAE Recommended Practice provides a procedure for the assessment of transient and steady-state smoke emissions from vehicular diesel engines using an engine dynamometer cycle which stimulates normal operating conditions. While intended for engine development and evaluation@ it is similar to a procedure which has been used for regulatory approval by the United States government.