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@ this procedure describes the smoke test cycle@ equipment and instrumentation@ instrument checks@ chart reading and calculation for evaluation of an engine's transient smoke emission characteristic. In addition@ this procedure offers guidelines to be used in establishing correlation between full flow in-line and end-of-line opacimeters. Since the type of test described here is transient in nature@ a fast responding full flow opacimeter is required for the smoke measurements. Slow responding or sampling@ or both@ type instruments must not be used since they typically have excessive and variable response delays and do not provide an accurate measurement of an engine's transient smoke characteristics. Note: It is recommended that whenever this procedure is cited@ any additional or modified test conditions must be clearly reported. PURPOSE: This SAE Recommended Practice provides a procedure for the assessment of transient smoke emissions from vehicular on-highway operating conditions. While procedure which has been used for regulatory approval by the United States Government. In many areas@ additional recommendations to improve test precision are offered.