[Via Satellite 10-24-2014] SpaceX has completed the 100th Merlin 1D engine used to power the Falcon 9 rocket less than two years since beginning production. SpaceX currently manufactures four engines per week; by the end of the year, that number is projected to reach five per week.
The Merlin 1D engines are manufactured in California and tested individually in Texas before shipping back to California for integration into the Falcon 9 and then returning again to Texas for a simultaneous test firing of all nine engines. From there the Falcon 9 is transferred to its launch site where a full system test is conducted prior to launch.
SpaceX has launched 80 Merlin engines to date. The 100th engine will be used on an early 2015 mission.