Utah man installing gigantic diesel engine into his monster truck and it’s about to get wild
Published on Feb 22, 2026 at 12:30 PM (UTC+4)
by Ben Thompson
Last updated on Feb 19, 2026 at 9:49 PM (UTC+4)
Edited by
Emma Matthews
For one YouTuber, modding his monster truck with a huge diesel engine just couldn’t wait any longer.
HeavyDSparks has a lot of projects on the go in his workshop.
But one project that had dominated a lot of his focus was his California Grizzly, which he wanted to place a CAT C13 diesel into.
Would this bear roar to life, or would it be heading into hibernation?
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This Utah man is giving his monster truck a huge upgrade with a diesel engine
Dave Sparks, the man behind the HeavyDSparks channel, has taken on a lot of ambitious car projects in his time on the internet.
After all, this is the guy who worked on a 104-year-old car he found in a barn.
He also transformed an old SUV into a homemade helicopter, which is just as impressive as it sounds.
Now, it was time for his monster truck, California Grizzly, to get some attention.
The CAT C13 engine in question had been sitting for five years, and Sparks first performed a ‘blowby’ test with the oil cap to confirm it was in good health.
Fortunately, it passed with flying colors.
Spark’s plan was to turn the truck into a replica of the Brodozer Monster Jam truck – a prominent monster truck created by the Diesel Brothers in collaboration with FELD Motorsports.
In order to make this possible, the Grizzly’s fiberglass would have to be carefully removed while preparing the chassis for the new CAT engine.
With a forklift handy, Sparks and his team test-fitted the engine into the frame.
Despite its intimidating size, the engine seemed to fit surprisingly well.
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What’s left to do with this project?
The team still needed custom-machined adapter plates and spacers from Venom Wheels to come in for them to bolt the CAT engine to the heavy-duty loader transmission.
But for now, that would have to wait until the next video.
It’s going to be exciting to see this project come to fruition.
They say everything’s bigger in Texas, but they need to check the garage of a certain YouTuber in Utah to see that’s not always the case.
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Following stints at LadBible, The Sun, The New York Post, and the Daily Mail, Ben joined the team full-time in February 2025. In his role as Senior Content Writer, his sparkling copy, the ability to sniff out a good story at 100 paces, and a GSOH quickly led to him becoming an integral and invaluable member of the writing staff.
