writes "Through a remarkable confluence of backyard engineering and external requirements, NASA has been "hot firing" 40-year old parts of F-1 rocket engines, pulled from storage and museums. The process of resurrecting the old engines has been complex, including a total 3D scan inside and out of the rockets to produce modern CAD files. NASA is considering using a brand new, redesigned version of the F-1, called the F-1B, as booster rockets for its upcoming SLS launch vehicle. I was on-hand for one round of F-1 gas generator test firings and I've written up the story of how a group of young engineers drove the engineering effort to bring the giant back to life.
The F-1 is the most powerful single-chamber liquid rocket engine to ever have existed; putting out 1.5M lbs of thrust, five of these engines powered one Saturn V moon rocket, each gulping 3 tons of fuel per second. The new F-1B would modify the F-1's uprated F-1A variant (extensively tested but never flown) to make it simpler and easier to manufacture, and at the same time even more powerful: 1.8M lbs of thrust per second."Link to Original Source