Twin-Turbocharged 12-Valve Cummins Engine - Engine Builder Magazine

Twin-Turbocharged 12-Valve Cummins Engine

Life-sized Hot Wheels? Say less. Sean Smith and his wife built this rat rod from scratch and it was a contender in last year's Hot Wheels Legends Tour. But it's not only for show – thanks to a twin-turbo'd 12-valve Cummins under the hood, this ride makes quite a bit of power too!

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Automotive enthusiasts and professionals often gain their interest for the industry early in life. That could come from helping a parent wrench around in the garage or pulling the car/truck up and down the driveway – but even earlier than that, automotive enthusiasts tend to form their passions through toys.

Matchbox and Hot Wheels diecast cars are a staple of the American household, bringing children joy since the late ’60s. Some people collect these cars late into adulthood, some build their own miniature toy cars, and some people even build life-sized versions.

Enter Sean Smith, a man we met at the Ultimate Callout Challenge this year who built an impressive rat rod and entered it in the Hot Wheels Legends Tour last year. Essentially, Hot Wheels tours the world searching for custom vehicles worthy of the ultimate claim to fame: becoming a Hot Wheels diecast car.

Smith explained that he won his first judging competition in Detroit and even flew out to California, where he was able to meet Jay Leno, see his famed garage, and show the celebrity his build. He didn’t end up winning the tour, but he proved the creative ingenuity involved in his build to a world stage.

“I built this with my wife,” Smith says. “It’s all handmade from the chassis and the two-by-four frame to all the plumbing and the body. It’s completely one-off and it gets a lot of attention because it’s different.”

A lot of other unique additions make the car perfect for auto shows where spectators can take a closer look. We noticed a radiator overflow tank made from a moonshine bottle, a keg for a fuel tank, and seats out of an airplane. It also has an air suspension system that allows it to touch the ground when stationary and lift up when driving.

Front and center of the build is a 12-valve Cummins engine that Smith dropped into the rat rod.

“700 or 800 horsepower is about what we’re making right now,” Smith says. “We upgraded the camshaft, head studs, added 4,500 rpm valve springs and governor springs – all of it. The pump is all turned up and it has twin turbos – a 68mm and an 88mm. It makes like 90 lbs. of boost.”

We couldn’t stop looking at this one-off build and we were glad we got a chance to speak with Sean about the car and its Cummins diesel engine during UCC 2023.

Diesel of the Week is sponsored by AMSOIL. If you have an engine you’d like to highlight in this series, please email Engine Builder Editor Greg Jones at [email protected].

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