Mother of Metal

Thor 24: The most epic big-rig truck ever built

At first glance, Mike Harrah might be mistaken for someone in a ZZ Top tribute band, what with the sunshades, ball cap and of course that full, oh-so-fine beard that ends wherever it damn well pleases.

And just as the Hall of Fame rock band’s most iconic visual, a customized, fire-engine red 1933 Ford coupe, helped catapult it to superstardom via MTV music vids in the 1980s, Harrah’s jaw-dropping creation, Thor 24, a $7 million, 3,974-hp. mother of metal super rig, might be the defining achievement of his life.

Might. Because as founder and president of Caribou Industries, Harrah has designed and built, owned and operated restaurants, shopping malls, luxury condominium towers, golf courses, industrial parks, air-charter services, hotels and marinas, and subdivisions in Arizona, Hawaii, Nevada, and California. So he’s had an incredible life already. He also has been a member of the Screen Actors Guild as a helicopter stunt pilot since 1998.

His real passion, though, has always been riding motorcycles, racing Grand National boats, off-road racing, water ski racing, snow skiing, and designing and building exotic cars and big-rig trucks.

Harrah believes he is blessed with an “extraordinary ability to look beyond the ordinary and transport the impossible into a reality.”

Perhaps only such a visionary (and multi-millionaire) could actually deliver Thor 24. It’s named Thor because of its enormous amount of raw power. The ‘24’ is from the V24-71 Detroit Diesel engine.

Currently living in Hawaii and running his multiple businesses from there, Harrah provided American Trucker with email responses to our questions.

I’ve professionally raced cars, motorcycles and boats, and water, snow and jet skied my entire life. And I always had this vision of taking a huge diesel engine and putting it into a custom-built semi-truck. One day, this guy from San Pedro, California, called me and said he had these two 24-71 Detroit Diesel engines off a 300-foot boat he wanted to sell.

That’s 24 cylinders with 71 cubic inches per cylinder. If someone ever wanted a monster truck engine, this would be it! Wow!

I drove to San Pedro and looked at these two gigantic engines. They were incredible! I was so blown-away I bought them both right then. I brought them to Lake Havasu, Arizona, and they sat in a hangar.

After about a year, I started to envision Thor. I asked myself, “What could I design and build that was unlike anything else in the semi-truck world?”

My first thought was to put both engines into one truck, but I didn’t because it was too heavy, with too much torque.

Then I decided the engine needed more power, and so I personally built a blower manifold that houses eight 871 blowers that force pressurized air through a pressure chamber and into four other blowers underneath, for a total of twelve 871 blowers.

Then I fed nitrogen into the engine for even more power from top-mounted big and ugly injectors.

I spent about a year designing the manifold and all the systems, and machining the parts necessary out of wood to make wood templates. I then took the templates and turned them into aluminum fabrication that formed the final manifold.

I built the entire engine around that manifold.

Almost everyone told me it would never work. That’s when I ran it on a dyno and realized its maximum power, with explosive potential.

I knew then I had to do something with the now-completed massive monster engine, 8-feet tall and 8-feet long overall dimensions.

What inspired you?
As a child, [drag racing legend] Tommy Ivo had a four-engine dragster, which I now own, and I always thought it was the most incredible race-car vehicle to have a multi-engine setup.

I built a little model of that and thought it would be incredible to put a 24-71, which literally is four 671s or two V-12 Detroits, nose-to-nose.

What really kept me going was to not fail the great Tommy Ivo legacy, and I was determined to see this project through to the end.

A lot of people wanted me to put the engine in the back, but I was against that because I believed the engine should be in the front, especially with its massive size. And that’s when I designed the 1933 custom-built Ford Grille Tribute.

Every week I would go to our fabrication shop with a lot of different ideas that I thought should go here or there in the truck. I did some of the fabrication myself, and we continued building and adding and meticulously completing every component. There’s nothing in the truck that wasn’t designed or built by our team.

The whole project started as a string hanging from a ceiling, from which we tied the engine to and built everything around it.

Did you have the blueprint for it from the start or did it evolve?
I sketched and designed a blueprint to build the engine, but designed and built the rig as we went along—a process of trial and error.

How do people react when they see Thor 24 coming down the street or at an event?

It’s amazing to watch their faces. Depending on their age, which can be from 8 to 80, everyone sees something different. But what they all have is the wow factor. The massive size, powerful image, chrome, smoke, and bad to the bone. It’s overwhelming and compelling; it’s different from anything they’ve ever seen in the form of any type of vehicle.

How much have you driven it?

I’ve driven down Interstate 40 outside Havasu for about 50 miles and for the Thor sizzle reel on our website ( It’s a lot to handle, but it runs and handles like a 2018 “Pete.”

The biggest issue in driving Thor isn’t the power; it’s stopping, because of its enormous power and weight. And looking forward from the driver’s seat, there’s a blind spot from the blowers, but we have forward-facing cameras. As you look up in the overhead, you can see perfectly clearly what’s in front of you. It takes a while to get used to, though.

Because of the complexities of driving Thor, and because it has such a tremendous amount of torque and power, you need one foot on the brake and one foot on the gas when you’re in tight quarters, because it wants to move forcefully all the time.

What are some of the unique things about Thor?
I would think that the engine and the original, one-of-a-kind 1979 Peter­bilt 359 crew cab that has been custom-stretched are unique. Oh, and there’s the jet engine that works as the ground power-auxiliary generator.

There’s such an enormous amount of incredible detail in every aspect of this rig. Most people don’t believe until they actually see it in person.

What about the stereo?
It’s a 1,500-watt-per-channel, 110-volt world-class sound system that runs off a 110-volt jet generator (APU). It has an array of speakers that come out of power door panels from each side of the truck.

Have you gotten interest for having Thor in movies?
We want to share it in the trucking industry with people from all walks of life, and we feel as though that would be best served by having it in a full-length movie, putting it into car and truck shows, and taking it to the drags for special exhibit events.

And if you just have to own the only world-class, ultimate, badass monster semi-truck, it’s also for sale.

What are you working on now?
We’re about two-thirds complete with another project. I’m calling her Medusa. She has a 24-71 super-charged and turbo-charged mid-engine drivetrain, versus Thor, which has a front engine drivetrain. She will probably be finished in two years.

Medusa is a little more streamlined, closer to the ground, and lighter in weight.

Do you keep track of what’s happening in the trucking industry?
I actually started driving a set of doubles when I was 19 years old, from the pineapple fields to the canneries in Maui. I fell in love with driving the big rigs. When I was 25, I bought three trucks and ran produce from the West to the East Coast. I ended up selling those trucks and pursuing my career in the construction industry.

I’ve held a Class A license for a long time. To relax, I’ll smoke a cigar, turn on some great tunes, head east on I-40, and just enjoy the drive. I have “big rig” in my blood.

This article was originally posted by American Trucker.