- Upgraded version of the Merlin 1A
- Mainly upgraded the Turbopumps
- Sea Level Stats
- Thrust: 380 kN (85,000 lbf)
- Isp: 261 Seconds
- Vacuum Stats
- Thrust: 420 kN (95,000 lbf)
- Isp: 303 Seconds
- First intended to be used on the Falcon 9 but development was moved towards the Merlin 1C engine
- This engine was never used on a launch vehicle