Say goodbye to the old 205hp, 6.5L turbodiesel V-8 in the H1. We say it's about time. Hummer has stepped up to the plate for the '06 model year and reengineered the H1 series to accept a potent 6.6L Duramax turbodiesel V-8 engine and Allison 1000 five-speed automatic 1-2 combination and labeled it with an Alpha badge to distinguish it from lesser Hummers. Alpha will be the top-of-the-line trim and will only account for about 10 percent of each line's production. To a potential Hummer buyer, Alpha means higher performance, more horsepower, better suspension, and a level of exclusivity that might annoy drivers of other premium brands. In H1 trim, the engine makes 300 hp and 520 lb-ft of torque-a lead foot-inspiring 46 and 18 percent gain.
 |  Here is the new Alpha badge...  Here is the new Alpha badge that distinguishes the men from the boys. |  Introduced last year, the...  Introduced last year, the upscale interior does a good job of softening the H1's roots. |
The Alpha will look just like the same old Hummer, save for the much-upgraded interior and switch gear that appeared in last year's version and the unobtrusive 2-inch filler panel, used to bridge the gap created by the body lift necessary to fit the new drivetrain. But, the changes didn't stop there: Fitting the Duramax was not a simple engine swap; it required a host of other alterations to the H1's chassis. Because of the longer length of the Duramax/Allison combo, the fuel tanks had to be shortened, but the body lift allowed them to be made taller, which resulted in an increased fuel capacity to 28.5 gallons for the main tank and 24 gallons for the auxiliary tank, giving the H1 Alpha a nearly 600-mile, bladder-busting cruising range. The bottom of the Duramax engine also had to be redesigned, because the original oil pan hung 2 inches below the framerails, which is unacceptable for a vehicle designed to have all of its vitals tucked out of harm's way. So, the engineers not only reshaped the oil pan, but also changed the oil pick-up and baffled it to prevent oil starvation at the extreme angles that an H1 was designed to experience. With 520 lb-ft of torque on tap, the old CV axles were set aside for beefier pieces, which now attach to the newly enlarged inboard 12-inch brake rotors.
Getting the Duramax to fit...
Getting the Duramax to fit in the H1 left precious little room under the hood.
The next challenge engineers faced was with the cooling system. A whole new cooling stack also had to be developed, this time incorporating an intercooler and fuel cooler. Because of the thicker stack, the mechanical fan has to be run off the crank pulley (while an electrical fan would have been easier to package, Hummer engineers have yet to find an electrical fan that can stand up to the H1's demanding design requirement) and angled up to the radiators through a small gearbox. This setup routes the air cleanly through the radiator and out through the bottom of the engine bay, which reduces pressure buildup under the hood and adds the unintended benefit of drawing cool air over the inboard brake rotors, which reduces brake fade and heat buildup.
While the engineers were evaluating the H1 chassis for areas of improvements, they decided to take some liberties in refinement. One of these areas was the geared hub assemblies, which now feature helical-cut gears instead of the straight-cut gears of the previous H1s. This not only reduces noise, but also reduces the rocking sensation upon stopping-a characteristic common to older H1s. Another convenience feature are new grab handles to help passengers hoist themselves in to the cabin.
The addition of the Duramax and all of its improvements to the H1 chassis make the H1 Alpha a better real-world machine. With everything said and done, the Hummer H1 Alpha's crawl ratio improved to 41.5:1-a 25 percent enhancement. Acceleration from 0-60 dropped by 18 percent to around 13.5 seconds, but the towing capacity improved 13 percent to as much as 9,303 pounds on an open-top model. Hopping up into the Hummer reminds you instantly of its functional roots as a purpose-built machine. Each seating position only has a small cockpit space, since the driver and occupants are draped around the engine and transmission. Sightlines are generally good, but there are unavoidable blind spots to the rear. Still, the driving experience is unlike any other on the planet.
On the highway, the H1's full-time four-wheel-drive system and four-channel ABS do a great job of making the Hummer easy to drive-as long as you remember how wide you are. The Duramax accelerates with authority, and the limited sound proofing of the engine bay lets you hear every scream of the turbo spooling up and down.
All H1s come standard with...
All H1s come standard with belly armor, which helps the H1 to easily slide over driveline-snagging obstacles.
Even though the Hummer is more refined on the highway, the H1 Alpha's main objective is to tackle the toughest terrain and bring its occupants home safely. Despite the newfound sophistication, the H1 Alpha is as capable as ever and can still climb a 22-inch vertical wall, cross a 60 percent grade, traverse a 40 percent side slope with 2,500 pounds of payload, and ford 30 inches of water. With the Central Tire Inflation System (CTIS), you can air up or down on the fly, and if you happen to get a flat, the run-flat bead-lock system will get you safely off of the trail. Front and Rear Eaton E-Lockers are even offered as a factory option.
Until you have experienced it first hand, it is hard to explain just how much character an H1 exudes. Finally equipped with the Duramax, it is now fun to drive on pavement - a compliment formerly reserved only for dirt driving. If you have that spirit of adventure calling, a cool $140K-plus stretching the linings of your pockets, and you are one of the lucky 500 or so a year to buy one, it won't take you long to realize what makes the H1 Alpha such an awesome ride. And thanks to the Duramax, it is a ride you will want to take more often.