A Duramax-Powered Luxury Tank Built for Any Terrain

Thousands of off-road enthusiasts hit the desert, the trail or head up the mountain every day, but how many do it in a tank? The answer is very few. Better yet, how many do it in the fastest tank in existence? Only one that we can think of. It’s called the Ripsaw by its manufacturer, the Twister by its owner, and it’s practically unstoppable. Developed by Howe and Howe Tech (now under the Textron umbrella), the Ripsaw EV series platform was originally designed for military use, but has been available in consumer-based form the past several years. As for this civilian version’s off-road performance, it doesn’t stray very far from those initial battle-ready roots or in its off-road capability. With nearly two feet of ground clearance, 16 inches worth of suspension travel, 112-inches of track on the ground, a diesel-fired Webasto heating system, and an 800hp Duramax capable of propelling the 6-ton mini-behemoth to 65 mph, it’s the ultimate play toy.

Fresh out of PPE’s booth at SEMA 2019 and in many ways still untested as a brand-new machine, the Ripsaw, its owner and crew, and the team from Howe and Howe Tech set out for the red rock and sand of southwest Utah. Initial testing was conducted at Sand Hollow State Park before taking the Ripsaw on a 200-mile torture test to the Grand Canyon. The Ripsaw never skipped a beat.

The Ripsaw’s 800hp Heart

How exactly does this near-12,000-pound tank feel so light on its feet? It starts with the 800hp 6.6L Duramax situated behind the cabin. Built by Pacific Performance Engineering, a company that’s long familiarized itself with high-horsepower versions of GM’s common-rail V-8, the Duramax is overbuilt in virtually every way. Carrillo rods, valve-relieved, 15.5:1 compression Mahle pistons, and one of its Stage 1 camshafts reside in the short-block. Above the head gaskets sit a set of PPE’s Stage 1 heads, complete with CNC porting, a 5-angle performance valve job, and beehive valve springs.

The Ripsaw’s cockpit sits fully isolated from the rest of the tubular chassis. It’s air-suspended via 10 separate Goodyear pucks. An onboard air compressor maintains air pressure to the air pucks, with air pressure being fully adjustable for utmost passenger comfort or according to the terrain you’re traversing.

Single Turbo & Dual Fuelers

A single Garrett turbo is tasked with building boost for the engine, and a ball bearing center section aids its responsiveness. Compressed air routes through an application-specific intercooler, fabricated by Ron Davis Racing, before entering the heads. A duo of CP3’s ensure rail pressure is maintained at all times thanks to PPE’s Dual Fueler system, with ported fuel rail fittings and one of the company’s race valves also being part of the equation. Oversized injectors built to PPE’s specifications conduct in-cylinder fuel delivery. A stand-alone engine harness handles communication duties, while an Xcelerator Hot +2 ET Race tuner holds the key to overall power output, with seven custom-tailored ECM calibrations to choose from.

For superb visibility at night, a state-of-the-art FLIR M625cs thermal camera graces the Ripsaw. The pan and tilt camera system is joystick-controlled for precise movements and both day and night time navigation. This camera’s visibility capabilities make driving the Ripsaw at speed in the dead of night a non-issue.

Battle-Ready Transmission

When you’ve perfected the Allison 1000 the way PPE has, there is no need to reinvent the wheel—not even for a tank. Not only can the company’s proven Stage 5 six-speed automatic handle the 1,500 lb-ft of torque the Duramax sends its way, but it’s been fortified to withstand both the heft of the vehicle and the strain that comes with jumping it. Billet shafts are a big part of its fortifications, along with a billet C2 clutch hub and P1 sun gear. Other pieces in the Allison’s build recipe include a triple disc torque converter, additional clutches in the C1, C2, C3 and C4 clutch packs, and a recalibrated valve body.

A pair of Recaro Sport Topline seats accommodate the driver and front passenger, and they were leather-wrapped to match the rest of the Ripsaw’s interior. The seat mounts were sourced from a C5 Corvette, which allows full adjustability forward and back, as well as up and down. The seats are also heated and cooled for maximized comfort. And even though this is technically an EV3-F4 model (the 4 designating the fact that it’s a four-seater), a third shoulder retractable harness was added in the back, bringing total occupant capacity up to five.

Tubular Chassis & Floating Cockpit

To keep the Ripsaw’s handcrafted cockpit fully isolated from the terrain it’s covering, the cab is suspended via air springs (air pucks). Their inflation pressure can be fine-tuned courtesy of the tank’s onboard air compressor for a more comfortable ride or to stiffen things up should the terrain call for it. The chassis itself is made from fully welded, high-strength tubular steel. To make sure the tubular exoskeleton would hold up to long-term exposure to the elements and abuse, it was treated to both powder coating and then Rhino Lining.

From the driver’s perspective, things are busy but well-placed. A MoTec dash display and gauge cluster keeps an eye on vitals, namely EGT, coolant temp, and oil pressure, while up-fitter switches control steering wheel heat, auxiliary battery, hazards (yes, it also has turn signals), and windshield wiper controls, among other things. A telescoping steering column brings the heated steering wheel to you, and adjustable foot pedals can be fine-tuned to suit the needs of virtually any pilot. The steering system is hydraulic, but everything is drive-by-wire, including the accelerator and brake pedals.

Custom-Tailored Interior

Inside the cockpit is where things vary tremendously from a standard Ripsaw. In what is akin to approaching Ferrari with plans to alter its supercar’s interior at the OEM level, the owner asked the folks at Howe and Howe Tech if they’d be willing to allow him to add his personal touches while the Ripsaw was being built. More than receptive to the idea, the guys at Howe and Howe were both open to suggestions and willing to help put them into action. As a result, this particular version is just about as avant-garde as it gets. A redesigned dash with hand-sewn leather and integrated dual iPads, digital climate control, heated and cooled Recaro Sport Topline seats, a MoTec gauge cluster, Bose intercom system, Rockford Fosgate sound system, and interior RGB lighting all made the list. Then, to bring a fifth passenger along for the ride, a third retractable shoulder harness was added in the back of the cockpit.

Within the cockpit, the interior was a joint effort between Howe and Howe Tech and the owner, whereby various personal touches were added during the build. The dash was designed by an outside contractor, a digital climate control system was added, as were dual integrated iPads, a digital gear selector, a MoTec gauge cluster, and a whole host of other subtle changes.

“We haven’t gotten it stuck yet, but we’re working on it.”

Optimized Visibility

Visibility is never an issue in the Ripsaw thanks to a plethora of lighting and camera options. A remote pop-up FLIR M625cs thermal camera provides unbelievable clarity at night, a backup camera and sensor system keeps things safe when maneuvering in reverse, and a 360-degree camera offers an unmatched, overhead view of all surroundings. As for illumination, countless ADAPT LED’s from Rigid Industries and the combination of five light bars turn night time into day. To zero-in on something specific, a pop-up Golight remote spot light is called upon. For a personal touch, an RGB lighting system is also onboard, with a million different hue variations on the table. Though it is in no way street-legal, the Ripsaw even has fully functional turn signals.

On the passenger side of the cockpit, you’ll find an iPad incorporated into the dash. It’s smaller than the unit embedded in the center of the dash, but perfect for the passenger (i.e. navigator) to pull up the map, prepare a route, or pinpoint your exact location.

Off-Road Prowess

Suspension travel checks in at an impressive 16 inches controlled by the Ripsaw’s King Off Road racing shocks. There are three custom-valved, race-inspired shocks per side, which wear custom red anodizing. For bottoming control, two King bump stops, custom-anodized in black, are employed per side as well. With the drive line fully enclosed, the Ripsaw’s under belly resembles a giant, smooth skid plate, and the closest point to the ground measures 22 inches. As for drivability, it’s as advanced as it gets thanks to a state-of-the-art drive by wire system.

Downwind of the Duramax (and handling everything the 6.6L dishes out) sits a Stage 5 Allison 1000, also sourced from PPE. Once through the six-speed automatic, power transfers to a Currie Enterprises differential and an extreme duty final drive system. Gear selection and control over the Allison takes place on this Freightliner-derived electronic push button shift selector.

A Swiss Army Knife

At nearly 12,000 pounds fully loaded, the Ripsaw is a mini-behemoth, but thanks to the 800hp Duramax and 112 inches of track applied to the terrain it’s covering, it can dig its way out of virtually any predicament. But even though the Ripsaw is yet to encounter an obstacle it couldn’t overcome, there is plenty of extraction equipment onboard to keep things that way. A 17,500-pound Smittybilt winch is present out back, while a 9,500-pound unit is concealed up front. D-ring shackles, front and rear, are tied in with the chassis for added points of recovery.

Boost for the 800hp Duramax is produced by a single, ball-bearing Garrett turbocharger, and a custom-built intercooler from Ron Davis Racing drops intake and exhaust temps significantly. The turbine side of the Garrett is efficiently driven thanks to PPE’s high-flow exhaust manifolds and 304 stainless steel up-pipes. On the fuel side, a set of PPE-spec’d injectors are supported by one of its Dual Fueler systems, complete with factory displacement Bosch CP3’s, ported fuel rail fittings, and one of PPE’s race valves.

Perfecting A Proven Platform

When the Twister project kicked off in the spring of 2018, no one knew exactly where the endeavor was going to go. But thanks to Howe and Howe Tech’s openness to suggestions, its ability to redesign things on the fly, and its willingness to allow a third party to personalize the vehicle during the manufacturing process, the customer’s needs were met and then exceeded. In the cockpit, it’s the Mercedes-Benz of tanks. Outside, it’s all business, with every single component serving a purpose. We’re told the goal for the Ripsaw was not only to build the ultimate off-road vehicle, but one that could travel hundreds of miles at a time, and last forever. Thanks to the Duramax/Allison combo, tubular exoskeleton chassis, and all the military-grade ingredients that’d already been proven in the field, that shouldn’t be a problem.

King Off Road racing shocks specifically valved to accommodate the Ripsaw’s 11,500-pound curb weight (and treated to custom red anodizing), provide 16-inches worth of suspension travel. Six bump stops (also from King Off Road and custom anodized black after the sale) protect the suspension should the shocks ever near their compression limit. Both the shocks and bump stops are anodized for maximum resistance to corrosion and abrasion.
For a bit of audible fun, a five-bell train horn system is sure to get your attention. The system sits in the driver side of the engine compartment, and is more than enough noise to stop any living thing within earshot in its tracks.
Aside from the inboard 64-gallon fuel tank, 58-gallons worth of extra fuel capacity are available thanks to the in-bed auxiliary tank shown here next to the backup Honda generator. Additional fuel capacity comes in the form of half a dozen jerry cans.
If worse comes to worst, the Ripsaw can be winched out of any predicament from the front or the rear. Nestled within the rear bumper, the biggest and baddest winch Smittybilt offers, its 17,500-pound X2O, is ready for any job. Up front, a 9,500-pound unit (also from Smittybilt) is charged with recovery duties. Also notice the bed-mounted backup camera in this photo, above the rear winch.
The Ripsaw’s fully-removable bed may only measure 61-inches by 34-inches deep, but in this instance it provides plenty of space for the auxiliary fuel tank and this Honda generator, which sit under a one-off tonneau cover. Also notice the roof and side racks, which were made for hauling luggage, tools, and any other storable item that needs to come along for the adventure.
A personalized RBG lighting system helps light up the night, illuminating all sides of the Ripsaw. Even the dual whips (employed to maximize vehicle visibility and safety while blasting through the dunes) are adorned with RGB LED’s. After all, in its intended environment the Ripsaw may provide the only man-made light source for miles.

You May Also Like

Diesel History Retrospective: AM General and the Humvee

AM General is without qualification an American survivor. Its heritage has roots which run deep into the 1800s when Standard Wheel Company—located in…


MAY ALREADY BE SITTING IN YOUR DRIVEWAY In the pursuit of piecing together the perfect daily driver, many of us allow the end goal to control the course of…

Out with the Old

I can’t seem to buy vehicles without a diesel anymore. Before I ramble on here since I’m going to be talking about a couple “unconventional diesels”, know that I have had my 7.3L