The Ultimate Callout Challenge is an event for high-powered diesel trucks. The custom trucks compete in three events – drag racing, dyno testing, and sled pulling. the Dirty Hooker Diesel team barely made it to the event with their custom Chevy Silverado. The tuners assembled the final version of their turbocharged, 6.6-liter Duramax V8 engine just hours before the race.
Obviously, the thing makes unholy amounts of power. The 4,500+ lbs truck completed the 1/8th-mile drag run in 5.62 seconds at 136 miles per hour.
But when they got it on the dyno to test exactly how much power the Duramax makes, the turbocharger blew up, causing catastrophic damage to the engine bay. This resulted in a runaway reaction that can happen to diesel engines, causing them to operate beyond their limits and self-destruct.
The driver shut the fuel supply and engaged the brakes, but could not overcome the runaway engine. It was still hooked up on the dyno and figures showed it produced 2,053 hp and 2,572 lbs-ft of torque.
The UCC video is a great lesson in engineering and safety.
So, what about diesel engine runaway?
Diesel engine runaway can happen to very worn engines or engines under immense pressure, which is our case.
Unlike gasoline engines, which needs spark plugs to ignite the air-fuel mixture for the power stroke, diesel engines compress the mixture until it self-ignites. As long as you feed the engine fuel and air it will run itself mechanically. The more you feed it, the faster it will run, generating even more power and torque.
This simple principle is the backbone of the diesel’s efficiency and high torque. However, on rare occasions, it could lead to a catastrophic chain reaction.
Engine oil and diesel have similar chemical properties and energy density. Diesel engines will readily burn their own oil for fuel.
As they tested the truck on the dyno, the turbocharger failed. The compressor wheel exploded and propelled shards in every direction, decimating the air intake system. At the same time, the lubrication system continued pumping oil to the turbocharger which escaped through the blown housing and got sucked into the intake of the now free-breathing engine.
Feeding off of its own oil, the Duramax V8 revved up, pushing more oil into the turbocharger and causing a positive feedback loop.
At that point, the only thing they could do was clear the area and use fire extinguishers to try and suffocate the engine. The driver and dyno operators escaped unharmed, and the engine eventually tore itself to a halt.
It was a violent and horrifying scene.
It’s all about the sportsmanship
With the engine bay and rear end destroyed, it looked like game over for the DHD guys.
However, everybody at Ultimate Callout Challenge stepped up and organized spare parts and extra hands on deck to help save the Chevy. After 17 hours of arduous work, the truck received a new engine, new wiring harness, new plumbing, and rear end.
With everyone helping out Dirty Hooker Diesel rebuilt in time for the sled pulling competition, going 308 ft.
At the end of the day, the shared love for motorsports turned this disaster into a miracle.