Reciprocating Engines To reduce the power output of an engine equipped with a constant-speed propeller and operating near maximum BMEP, the a. manifold pressure is reduced with the throttle control before the RPM is reduced with the propeller control. b. manifold pressure is reduced with the propeller control before the RPM is reduced with the throttle control. c. RPM is reduced with the propeller control before the manifold pressure is reduced with the throttle control.