VM Motori vs. Power Stroke vs. Duramax: Which Half-Ton Diesel Is Best?

• June 6, 2019
• Story By
  Mike McGlothlin

The past five years haven’t exactly appeared promising for the diesel engine’s reputation. What with the dieselgate scandal and all the buzz surrounding electric propulsion, diesel has definitely taken a backseat in headline news, even despite its extremely high take-rate in the ¾-ton and larger truck segment. However, Ford and GM have still managed to forge ahead with their plans to offer more fuel efficient half-ton series pickups, FoMoCo having released the 3.0L Power Stroke in ’18 and the General recently announcing plans to debut its inline-six version of the Duramax in 2020. In addition to 30-mpg capability, these state-of-the-art common-rail workhorses provide an effortless towing experience to the end-user, along with a quiet ride and virtually zero tailpipe emissions.

But how does GM’s 3.0L diesel stack up against the 3.0L Power Stroke? Better yet, how does the aging 3.0L EcoDiesel in the Ram 1500 fare against these newcomers? To answer those questions and more, we’ll delve beneath the valve covers of each power plant to compare hard-parts, fuel system components and power ratings.

Battle of the 3 Liters

Whether or not the Big Three intend to keep diesel relevant or eventually succumb to the electric takeover remains to be seen, but for now these are the most efficient internal combustion engines you can find in a domestic half-ton truck: the 3.0L EcoDiesel V6 found in the Ram 1500 and Jeep Grand Cherokee (left), the 3.0L Power Stroke V6 available in Ford’s F-150 (center) and the 3.0L Duramax I6 slated for ’20 Chevrolet Silverados and GMC 1500s.

3.0L EcoDiesel Hard Facts

The Old Man

Things were definitely hunky dory when Ram occupied the half-ton diesel segment all by its lonesome from ’14-’17, but the arrival of Ford’s 3.0L Power Stroke stripped the EcoDiesel of virtually any accolades it laid claim to. After all, the V6 Power Stroke boasts better fuel economy, higher towing and payload ratings, more horsepower and a superior torque curve. Though the EcoDiesel will receive a slight power uprate in the coming ’20 Jeep Gladiator pickup (reportedly checking in at 260hp and 442 lb-ft of torque), it remains to be seen how FCA, in conjunction with engine builder VM Motori, will keep this aging power plant competitive in the years ahead.

Rock-Solid Bottom End, Proven Injectors

The 3.0L EcoDiesel might be the most dated diesel in the half-ton segment, but its architecture has proven durable in its now seven-year production run. The combination of a compacted graphite iron block with a one-piece bedplate ensures it will have no problem coping with added cylinder pressure and that main bearing cap distortion is never an issue. At the same time, its rigid construction offers VM Motori plenty of room for growth as far as horsepower and torque figures are concerned. In the aftermarket, it’s believed that most of the factory hard parts can handle more than 600hp. Another high mark for the EcoDiesel revolves around its use of solenoid-style injectors as opposed to piezoelectric units, which gives them a slight edge in the reliability department. It may technically be considered the old man on the block now, but the EcoDiesel platform still has a lot of potential.

3.0L Power Stroke Hard Facts

More Torque Than the EcoDiesel

Often thought of as a new and improved version of the Lion V6 engine produced in Europe for use in the Land Rover Discovery and Range Rover, Ford’s 3.0L Power Stroke V6 packs a bigger punch than the EcoDiesel—and it does so earlier in the rpm range. Not only do 10 more ponies check in sooner than with the VM Motori 3.0L, but the Power Stroke’s peak torque output arrives at 1,750 rpm and that same 440 lb-ft sticks around until 2,250 rpm.

Broad Power Band

As proof that the 3.0L Power Stroke is more than ready to work, take a look at the engine dyno graph from Ford. Even more impressive than the aforementioned 440 lb-ft number being sustained for 500 rpm, if you follow the torque curve you can see that at least 400 lb-ft of twist is available from 1,400 rpm to 3,400 rpm. In terms of trying to justify just how potent the 3.0L Power Stroke is, when you break out the calculator you’ll discover that the engine produces 1.37hp per cubic inch and 2.4 lb-ft of torque per cubic inch. Twenty years ago, those numbers would’ve been half that.

MPG King

Although a diesel-powered F-150 can out-tow and out-haul an EcoDiesel-equipped Ram 1500, Ford’s key objective with the 3.0L Power Stroke was to field the most fuel efficient full-size pickup in North America. According to an EPA-estimated 30-mpg highway figure in 4x2 SuperCab form, Ford achieved its mission in surpassing EcoDiesel Rams for the mileage crown (an HFE trim 4x2 Ram is good for 29-mpg highway). Of course, the 10-speed SelectShift automatic transmission behind the 3.0L Power Stroke played a necessary supporting role in Ford’s accomplishing the mpg feat.

3.0L Duramax Hard Facts

Six in a Row…

Breaking away from the V6 mold, GM decided on an I6 diesel for the Chevrolet Silverado and GMC Sierra 1500s—and its torque figures don’t disappoint. With 460 lb-ft of torque available from 1,500 rpm through 3,000 rpm—and 95 percent of that torque already online at 1,250 rpm—we have zero doubt that GM’s new mini-Duramax will be the Cummins of the half-ton world. Similar to the EcoDiesel and Power Stroke, GM reduced the overall weight of its engine by using a lighter material to construct the block—only GM didn’t go with compacted graphite iron. Instead, the I6 Duramax features a cast-aluminum, deep-skirt crankcase, complete with seven main bearing caps securing the forged-steel crank. Other key parts of the rotating assembly are the forged-steel connecting rods and hypereutectic aluminum pistons. A DOHC aluminum cylinder head provides easy breathing and a unique, electronically-variable intake manifold offers dual air inlet pathways for each cylinder.

DEF and 5,000 RPM?!

Notice the DEF gauge in the gauge cluster. This means, just like the EcoDiesel and Power Stroke, GM’s 3.0L Duramax will utilize “diesel exhaust fluid” as part of the selective catalytic reduction (SCR) system tied into the engine’s emissions equipment. Since 2011, DEF has afforded GM the ability to meet stringent NOx emission regulations while making more power with its 6.6L Duramax diesel mills. Also take note of the tach and the engine’s 5,100 rpm red line. Not bad for an I-6 diesel!

High Expectations

It remains to be seen how heavily Chevy and GMC will impact Ford’s grasp on the half-ton market when the 3.0L Duramax debuts in 2020, but we’re eager to see a toe-to-toe shootout between the two. GM certainly seems to have the engine side of things figured out, thanks to the inherently torquey I6 configuration, injection pressure that exceeds 36,000 psi and a variable geometry turbo that’s rumored to produce 43 pounds of boost right out of the gate. We can’t wait until these things begin to populate dealership lots.