Blue whales.
I'm soooooo glad that elReg didn't swallow NASA's tripe. Oh, sorry, that should read "hype".
According to Martin Burkey, of NASA’s Space Launch System team, RS-25 produces 512,000 pounds of thrust, that’s more than 12 million horsepower and "makes a modern jet engine look like a wind-up toy".
Unfortunately this also makes NASA look like a wind-up, because horsepower is, well, power, and power is distance moved per unit time (kinda like speed) multiplied by force (er, thrust) so it's back to school for Mr. Burkey and well done elReg for not falling into the bear trap.