These are the massive diesel engines that power NASA’s 6.6 million-pound crawler-transporter

The largest and heaviest self-driving ground vehicle in the world, per Guinnessis located at NASA’s Kennedy Space Center in Florida. This monstrosity, creatively named Crawler-Transporter 2, is the size of a baseball diamond, and although it is more than 50 years old, it is expected to continue to dutifully serve the national space program for decades to come. NASA says it has a maximum speed of just 2 miles per hour, slower when loaded with a launch payload. Even at those low speeds, the CT-2 has over 3,300 kilometers on the odometer, powered by a pair of massive ALCO 251C V16 diesel engines that deliver a combined 5,500 horsepower.

CT-2 has been upgraded to Super Crawler specifications so it can handle the extra weight of the Space Launch System rockets, ahead of the Artemis project that means returning humans to the moon (as well as massive budget cuts that Congress may not make). While the machine itself weighs a whopping 6.6 million pounds, an SLS rocket weighs another 5.8 million pounds. To carry so much weight, the two diesel engines work together with sixteen electric traction motors with a combined power of 6,000 hp and directly variable torque. When the CT-2 was built in 1965, it required the equivalent of twenty Hi-Po V8 Mustangs to get around, but by 2026 this machine could theoretically be propelled with the equivalent of just four Lucid Air Sapphires in horsepower.

Did ALCO build these engines specifically for the space program to use as diesel generators for ground transporters? No, of course not. ALCO is the abbreviation for American Locomotive Company and these engines started production ten years earlier in Schenectady, New York. The original use, intended use, of the ALCO 251C was to power trains across the American, Mexican and Australian countryside.

It’s probably not yet fully realized how big this engine is (although its power is dwarfed by the enormous engines that made the SS United States the fastest ocean liner). To put it in perspective, each cylinder has a diameter of 9 inches and a stroke of 10.5 inches, or about 10.95 liters per cylinder. Multiply that by 16 cylinders and two engines, and NASA’s load mover has more or less the same displacement as a 175 Kia Seltos.

Using only 32 feet per gallon of fuel, the Crawler-Transporter 2 is quite inefficient for a hybrid. That equates to approximately 165 liters of fuel burned to travel one kilometer. Forget miles per gallon!

When you watch the launch sequences for NASA’s upcoming manned lunar missions, you’ll see the CT-2 doing what it does best, what it was built to do 61 years ago. I hope I still have this kind of athletic ability when I’m 61 years old.