Off-Roading On Another Level: Jeff Friesen’s Hydrodynamic Buggy

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Great things can happen when men take two or more passions and merge them together. Leonardo Da Vinci created rudimentary tanks and aircraft, Thomas Edison invented motion pictures, Kirk Christiansen devised Legos. It’s all the more fascinating when something as brilliant and innovative comes along in the off-road world, as we discovered in Johnson Valley earlier this year.

Well, “found” may seem a little misplaced here in the context of builders and innovators … but we digress. While  out covering the King of the Hammers in February, the sprawling mass of 20,000 off-roaders congregating around Hammertown was a smorgasbord of rigs. Any one of them could have served as great subject matter for Off Road Xtreme, but none of them could hold a candle to the Hydrodynamic Buggy, a beast of a machine with more practical science and creativity than a 3D printer.

It was pure chance that we happened to spot the vehicle as we were traipsing around the outskirts of Hammertown, but we’re glad we did. Once we located the owner, Jeff Friesen, we were eager to begin our interview and learn just what made this monster move. As it turned out, we were about to get schooled in the art of engineering.

With a 123-inch wheelbase, Jeff Friesen's Hydrodynamic Buggy has the dimensions of a full-size pickup truck, but the off-road capability factor is in a whole different league.

With a 123-inch wheelbase, Jeff Friesen’s Hydrodynamic Buggy has the dimensions of a full-size pickup truck, but the off-road capability factor is in a whole different league.

The Guts Of A Giant

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Learning about the inception of the Hydrodynamic Buggy was nothing short of enthralling. It all began in the early 2000s, when Jeff was an engineering student at Cal Poly San Luis Obispo (the only true Cal Poly, if you ask him; sorry, Pomona). A born and bred off-roader, Jeff had owned his fair share of souped-up trucks, including a Dodge Ram 1500 and a Ford F-150. “The F-150 was built for going fast, but I was always more attracted to the slow stuff,” he said. “Crawling in the mountains and being up in the trees is where I’m most happy.”

Jeff Friesen (pictured driving the buggy) got the urge to create his monster after graduating from Cal Poly Pomona.

Jeff Friesen (pictured driving the buggy) got the urge to create his monster after graduating from Cal Poly San Luis Obispo.

He became involved in a school competition called the Quarter Scale Tractor. “It centered around a four-wheel-drive competition tractor, which was basically like a Polaris RZR before RZRs ever existed,” Jeff said. “We were the first ones to put a full roll cage onto the tractor, when everyone else’s entry looked like a lawnmower. Ours had all six pillars, a roll cage, seats with four-point harnesses, locking hubs, miniature tires, and independent suspension on the front. I spent way too much time on that thing … I failed the class because of it and had to retake it.”

“Anyway, all of the other schools had money to do hydraulics, and we went mechanical – driveshafts, reduction boxes, CV axles, U-joints, all that stuff,” continued Jeff. “The hydraulic-based tractors had planetary gears and pumps, and there were pros and cons to it. It turned out that we did the best thanks to the heavyweight pull, even though another school cheated and had a hitch with their mechanical-based tractor. Basically, we beat out all of the hydraulic teams in that competition.”

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Yet despite winning the competition with a mechanically-based tractor, Jeff was deeply interested in the inner workings of hydraulically-based vehicles, and sought to make his own. “I thought it would be awesome for a rockcrawler so once I graduated in 2004, I planned on building a full-scale vehicle,” he said.

It only goes 30 mph, but you can go 30 mph wherever you want to go. -Jeff Friesen, owner/builder

“I started sourcing all of the parts and figuring out what I was going to do, if I wanted a cab or no cab, laying out suspension, and so on. It took shape in AutoCAD using a two-dimensional model, and it was 2006 when I started construction,”. he explained. “It took me four years to build the vehicle, and I was still designing as I was building, but the main layout with the frame stayed the same throughout. So now, 10 years later, I’m still tweaking it, but the core of the buggy is still true to that 2006 design.”

For all of the blood, sweat, and tears that the Hydrodynamic Buggy had demanded of Jeff, it was surprising to learn that the vehicle was purely built as a passion project, and not commissioned by patrons or demanded by professors for school credit. “It’s a work of art and a hobby,” commented Jeff. “It’s a crawler that I use personally, and not for competition. That’s why it only goes 30 mph, but you can go 30 mph wherever you want to go.”

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Propane was used as the fuel for the first two motors, a 2.8-liter straight six and a 4.8-liter GM V8. Jeff was disappointed in the output and fuel range on these motors, however, so he jumped up to a 6.0-liter LS3 with gasoline, which is installed on the buggy now and takes care of most demands. It certainly has no trouble handling power to the wheels, we can tell you that.

Hydraulics Versus Mechanical

Jeff had entered into a contest in college to build a Quarter-Ton Tractor, which was akin to the UTVs we see today.

Jeff entered into a contest in college to build a quarter-ton tractor, which was akin to the UTVs we see today. It would become the spark for his desire to build the Hydrodynamic Buggy.

With all of this conversation steering toward the topics of hydraulic-based vehicles, we had to ask Jeff: what was so good about hydraulics, anyway? Instantly, we were treated to the virtuous guts of construction equipment.

Steering in the Hydrodynamic Buggy works by having the oil go from the central pump into a divider. The oil then diverts to the left or right side, based on driver input through the steering wheel.

Steering in the Hydrodynamic Buggy works by having the oil go from the central pump into a divider. The oil then diverts to the left or right side, based on driver input through the steering wheel.

“Excavators and skidloaders have the same drivetrains that I’ve got, from the wheel loaders to the planetaries to the oil pumps. It’s all industrial-grade,” said Jeff. “These machines are run hard by crews, day in and day out, moving earth, breaking concrete, and so on. They’re built to handle very heavy-duty tasks, so to take that and apply it to off-roading, it doesn’t even compare. I’m using these parts – pumps, motors, pistons – at a fraction of what they’re normally intended for, so I can potentially go for years without having to look at a lot of these parts.”

The buggy’s LS3, which is connected to a driveline, is hooked into a central oil pump. From there, oil is pumped through high-pressure lines to motors at each of the four wheels, where pistons are arranged in a circle and rotate up to 4,000 rpm. The pistons are very small – one-inch stroke, three-quarter-inch piston diameter – but they’re remarkably reliable, as are the lines which channel the oil. In all, Jeff estimated there was between two to three gallons of oil circulating through the buggy to make it work.

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Oil churns through the buggy at up to 4,000 psi, handling all aspects from forward and backward motion to steering and braking.

One of four hydraulically driven motors, using oil pressure instead of axle torque to move the vehicle.

One of four hydraulically driven motors using oil pressure instead of axle torque to move the vehicle.

All of the lines I have are rated for 6,000 psi,” said Jeff. “My reliefs are set at 5,000 psi, but these lines can handle four times these amounts, so if I’m running a quarter of the peak rating, it’s really not a concern.”

Simply put, the hydraulic basis of the Hydrodynamic Buggy was unique and difficult to build, but it more than made up for these shortcomings with terrific longevity and simplicity that Jeff never needed to worry about. “I built it to have a vehicle that I could take out anywhere and never have to worry about a breakdown,” he explained. “No broken driveshafts or axles or differentials, because using hydraulics safeguards everything. It also keeps everything lubricated all the time, so as long as the oil’s clean and I’m not working it all too hard, the motors and pumps will keep going all day long.”

Having a hydraulic drivetrain has allowed Jeff Friesen's buggy to go off-road in some of the worst terrain without the fear of breaking something.

Jeff has taken his Hydrodynamic Buggy to every one of the King of the Hammers events since 2010. Each year has seen another revision to the vehicle, so no visitors to any two events have ever seen the same buggy crawling around the area. “It’s been either hydraulics, engines, or suspension setups,” he said.

IMG_9722You can imagine how excited we were to ride along in the buggy after the interview, as we drove to a more sparsely populated spot. The LS3, perched just behind the passengers’ heads, is loud and rumbling, but the way it makes this vehicle move is something you have to see to believe. It was mind-blowing to watch Jeff take on almost any obstacle and make his way over it.

With the built-in air compressor and air bags strategically installed, the buggy can flex left to right to offer better weight distribution if needed. The massive, 54-inch Mickey Thompson tires are right at home clambering over busted rocks or gravel.

For a four-wheeler that started out of a friendly college competition, Jeff has definitely shown us what it means to blend smarts and passion. We can’t wait to see it next year, and who knows – with how capable the Hydrodynamic Buggy is, it’s bound to find its way to some forbidding location that we wouldn’t dare try to in anything else.

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About the author

David Chick

David Chick comes to us ready for adventure. With passions that span clean and fast Corvettes all the way to down and dirty off-road vehicles (just ask him about his dream Jurassic Park Explorer), David's eclectic tastes lend well to his multiple automotive writing passions.
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