U.S. Code of Federal Regulations
Regulations most recently checked for updates: Jul 10, 2020
(a) The smoke standards in this section apply to all engines subject to emission standards under this part, except for the following engines:
(1) Single-cylinder engines.
(2) Constant-speed engines.
(3) Engines certified to a PM emission standard or FEL of 0.07 g/kW-hr or lower.
(b) Measure smoke as specified in § 1039.501(c). Smoke from your engines may not exceed the following standards:
(1) 20 percent during the acceleration mode.
(2) 15 percent during the lugging mode.
(3) 50 percent during the peaks in either the acceleration or lugging modes.