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Mil-Spec Automotive set out to do for Hummer H1s what Singer does for Porsche 911s, rebuilding them to a Swiss-watch standard, modernizing them with myriad upgrades, and then pricing them like Fabergé eggs. We pointed out some chips in the enamel of MSA’s original egg when we drove a Mil-Spec Hummer H1 in 2018, but the company has spent the pandemic developing the second generation of its H1 build, which it dubs the M1 or M1-R, depending on its state of tune. The upgrades make it even more worthy of consideration, with factory-original used examples of the low-production 2006 Hummer H1 Alpha fetching $200,000 or more at auction.
Mil-Spec Hummer H1 Engine Specifications
As before, the most crucial MSA upgrade is to the Hummer’s wheezing stock diesel or small block gasoline powertrain. Those pitiful V-8s are replaced by a 2006-2007.5 model-year 6.6-liter Duramax diesel. The Mil-Spec team regards this LBZ engine as “the last of the hot-rod diesels.” As before, HSP Diesel Performance & Accessories of Romeo, Michigan does an extensive balance and blueprint rebuild, strengthening various components to withstand power and torque that gets elevated from the stock 350-hp/650-lb-ft rating to 500 hp and 1,000 lb-ft in M1 spec (that’s about what the first-gen MSA H1s produced). This engine runs EGR to preserve the emissions compliance required of the 1992-2004 model-year VINs appearing on these civilian Hummers’ titles (this one’s a 1998). Spending $60,000 on the Intrepid Performance Package turns the wick up to 800 hp and 1,300 lb-ft.
Achieving either output requires a much larger turbo and intercooler, an upgraded Bosch fuel-injection system, and a new engine controller, and managing that enhanced output requires an equally robust transmission. In this case, that’s an Allison 1000 T6 six-speed automatic, also reinforced by HSP to either Stage 3 or Stage 5 standards, depending on engine output. A new electronic gear selector and transmission controller provides access to all six gears via optional steering-wheel paddles or console buttons (the stock mechanical shifter only featured D-2-1 positions).
To keep everything cool there’s a greatly enhanced thermal management system that starts with a more robust engine-mounted clutch and fan with shrouding that better seals it to the angled radiator/intercooler/AC condenser stack under the hood. Two electric pusher fans augment this as necessary. A small power-steering cooler also rides up front, but transmission cooling happens at the rear via a separate cooling circuit positioned where the auxiliary fuel tank used to be. (A 30-gallon fuel cell replaces the standard fuel tank.)
As with the first-generation Mil-Spec Hummer H1, the M1s all start as well-worn civilian Hummers that get fully disassembled and have their girder frames blasted and powder-coated. They are then reassembled using lots of new/old-stock and aftermarket parts for a better-than-new driving experience. The inboard brakes are upgraded to 12.5-inch vented and slotted rotors all around clamped by single-piston calipers with the option of six-piston Wilwood calipers ($14,000, including heavy-duty differentials).
The four half-shafts are reinforced, and on base M1s the offset gear-reduction (1.92:1) drive units get rebuilt with quieter helical gears, but Intrepid Performance trucks get rebuilt with the noisier but more robust straight-cut gears. Unless a customer strenuously insists on retaining the Hummer’s central tire-inflation system, CTIS gets deleted in favor of an onboard ARB compressor and a hose that’s long enough to reach all the tires (those rotating CTIS air bearings always end up leaking and airing down the tires).
An $11,500 Baja Suspension Package adds a Rod Hall suspension that increases the stock 6.5-inch suspension travel to as much as 13.0 inches and boosts the gross-vehicle weight rating to 12,000 pounds. It also adds 3.0-inch remote-reservoir shocks, billet ball joints, and beefier anti-roll bars. The yellow truck has had its suspension travel limited to 11.0 inches, because those extra two inches apparently wreak havoc on the steering geometry. The Baja suspension itself doesn’t alter the stock ride height much, though the 38 x 13.5-inch Nitto Ridge Grappler tires certainly do. Selecting all three performance options (Intrepid Performance, Wilwoods, and Baja suspension) earns the M1-R moniker.
This M1-R features MSA’s Bold Body and Tire package ($5,500) and the Baja Exterior Package ($3,500 for a tubular spare tire rack and side storage racks), plus a 12,000-pound winch ($2,500), brush guard ($1,750), light bar ($600), and rear step bumper ($1,850). It was commissioned by a sports car enthusiast who wanted it to match his fly-yellow fleet. So, the Scorpion coating (a bed-liner-like material that offers more color and sheen options) was custom tinted to match, adding $11,000. It also features a welcome power running board ($1,950) that greatly eases the climb aboard.
Hummer H1 Alpha-Besting Interior Upgrades
Early examples of the Mil-Spec Hummer H1 hewed a little too faithfully to the utilitarian vibe of the donor trucks, featuring too much plastic, vinyl, and recognizable mass-market hardware. Key gauges were obscured by the steering wheel, and the air conditioning offered a single (too windy) fan speed. Capitalizing on some expertise gained by designing and producing interiors for marine and private jet interiors during the pandemic, Mil-Spec gives the second-gen Mil-Spec Hummer H1 a much more “designed” interior filled with custom switchgear and instrumentation. This truck’s bespoke color-coordinated interior features diamond-stitched leather, which added $22,000.
The billet steering wheel is a masterpiece. Its face is leather-wrapped, but the back side is machined aluminum with indentations for your fingers. The turn signal engages with a rifle bolt’s precision and a satisfying click, as does the high-beam switch protruding from its end. (Sadly, with the Hummer’s slower steering ratio, this steering column tailored to the hotrod market frequently fails to cancel when executing less than a right-angle turn.)
The combination speedometer/tach/odometer gauge is repositioned far to the right of the steering wheel where it can be clearly seen, though the combination fuel level/voltage/water and oil temp gauge to its left can be obscured by the steering wheel. The three smaller gauges viewed through the wheel rim display exhaust-gas temperature (a novelty), turbo boost, and transmission temperature. A new electric parking brake is actuated by a button located just ahead of the electronic transmission shift buttons.
The main climate control system gets three unmarked billet dials that adjust fan speed, temperature, and mode (blending between vents and floor, as the electric windshield needs no vents). The rear gets its own evaporator and separate control that feeds two high-flow vents, and all the vents are cool billet eyeball-style units.
The 700-watt, nine-speaker JL Audio system control panel mounts within easy reach of the driver below the speedometer and features redundant rear controls. Billet wiper and washer switches are located just below the radio and above the ignition switch (which still requires a key, though it’s milled from billet). Centered on the broad console is a bank of billet switches controlling the standard and auxiliary lighting, defroster, transmission cooler fans, ARB air compressor, and rear diff lock. The only remaining factory switches control the transfer case and the mirror adjustment. They’re not pretty, so they’re located down in a shallow bin high on the center console, within easy reach but mostly out of view of the driver.
So How Does the M1-R Drive?
Speaking as the person who performed the first instrumented test of a Hummer H1 and has driven all the original powertrains, save the auction-insane Hummer H1 Alpha, trust me when I say this one is the nicest—especially in terms of acceleration.
M1-Rs like this one get a magical little black dial-a-power knob beneath the ignition switch. With the pointer straight up, it’s set for 500 hp and 1,000 lb-ft, and it pulls like an old Audi Q5 or BMW X5 turbodiesel weighing about half as much, with the six-speed automatic banging off crisp shifts. That knob offers five clockwise clicks, each good for about 60 more horsepower, and when it’s fully cranked right, you’re aiming a four-ton WMD capable of achieving 60 mph in about 5 seconds. Hopefully, those fancy Wilwoods are able to erase 60 mph worth of momentum in a shorter distance than the 164 feet required by our factory-spec Hummer H1 Alpha …
Brake feel can best be described as “decent for a 7,500-pound-plus vehicle.” There is not a ton of feedback, and their action is dulled somewhat by the half-shafts, the gear reduction hubs, and those giant tires—all of which accounts for that charming back-and-forth rocking you get following a hard stop. Also note that Mil-Spec doesn’t typically include antilock brakes or traction control, as the option was only briefly offered on factory H1s, and the hardware is difficult to come by.
That Baja suspension imparts a somewhat brittle ride quality that seems destined to provoke squeaks and rattles, but I’m sure it’s worth it for buyers who envision desert racing their M1-R against a Ram 1500 TRX or Ford F-150 Raptor. The steering effort is surprisingly light, and not quite as linear as expected, perhaps because of the altered steering geometry necessitated by that long-travel suspension.
Of course, no amount of diamond-stitch yellow leather and billet aluminum switchgear can alter the fact that this is a military vehicle. Around town, you hear quite a bit of whine from those gear reduction hubs. The giant tires are reasonably quiet, or at least easily drowned out by the racket coming from the soft top at highway speeds. Note that this vehicle’s soft-top was a special order—standard Mil-Spec builds are all hardtops.
Is This Mil-Spec Hummer M1-R Worth $440,250?
It is to someone! Just know that if your goal is to win the Baja 1000 or participate in elaborate military cosplay, even the base $300,000 is probably better spent elsewhere. But if you already have a Thor diesel-pusher motor coach, a Nord Star 31+ yacht, and a Singer 911, and the next toy you envision dropping similar cash on is an off-roader, then a fully decked one of these makes perfect sense! The attention to detail and even some of the switchgear will seem familiar from these other luxury items, as will your ability to tailor every aspect of the M1’s design. The assembly quality is high and following each four-to-eight-month build, Mil-Spec Automotive puts at least 500 miles of shakedown driving on every M1 to ensure quality control. And if exclusivity is your bag, know that MSA’s target is just four M1/M1-Rs per year.
|1998 Mil-Spec Automotive M1-R Specifications|
|LAYOUT||Mid-engine, 4WD, 2-4-pass, 2-4-door SUV or truck|
|ENGINE||6.6L/500-800-hp/1,000-1,300-lb-ft turbodiesel OHV 32-valve V-8|
|CURB WEIGHT||6,900-7,600 lb (mfr)|
|L x W x H||195.5 x 86.5 x 85.0 in|
|0-60 MPH||5.0-6.6 sec (mfr est)|
|EPA FUEL ECON||Not rated|