Special Coverage

2011 Chicago Auto Show

CHICAGO – It’s no stretch to say loyalists would bet the ranch, literally, on the reliability of the Cummins turbodiesel engine in their Ram heavy-duty pickup trucks.

Even while rivals Ford and Chevrolet developed new engines with significantly higher torque ratings, these Ram lovers couldn’t imagine using another truck to haul horse trailers or other massive loads up and down steep grades in the rocky wilderness out West.

But here in the Windy City, Chrysler and its Ram brand are making news sure to spark a hoedown among Ram devotees: The Cummins 6.7L turbodiesel inline-6 has been improved and recalibrated to produce 800 lb.-ft. (1,084 Nm) of torque, tying it with the Ford Super Duty in the battle for spec-sheet supremacy.

For years, Detroit’s three auto makers were pretty evenly matched with turbodiesel engines producing between 650-660 lb.-ft. (881-895 Nm) of torque for heavy-duty buyers.

The battle grew intense – then turned silly – in 2010 when Ford launched its all-new home-grown 6.7L Power Stroke V-8 last spring in the new Super Duty, rated at 735 lb.-ft. (997 Nm) of torque.

GM followed with an upgraded 6.6L Duramax V-8 in its new HD pickups last summer, weighing in at 765 lb.-ft. (1,037 Nm). Within weeks, Ford one-upped its rival with a new torque rating for the Power Stroke: 800 lb.-ft.

The earlier version of the Power Stroke, rated at 735 lb.-ft., won the first-ever Ward’s Best Engines Diesel Shootout last summer, which pitted the three trucks against each other in a day of testing at the Robert Bosch proving grounds in Flat Rock, MI.

Which brings us to Chicago and the prodigious new numbers touted at the Ram pavilion. In a few short months, GM’s Duramax engine has gone from first to last and Chrysler’s Cummins engine has gone from last to first, or at least tied for first.

Couldn’t Chrysler and Cummins wait a little longer until their engineers could push the engine a little further, say, to 801 lb.-ft. (1,086 Nm), for undisputed heavyweight champion status?

“We probably could, but I don’t want to play that game,” Fred Diaz, CEO and brand president of Ram Truck, says after the press conference.

“I want to preserve the integrity of our truck with our truck buyers, because we’re real,” he says. “That’s the way we’ve positioned our brand, having nobility and having credibility. If one of our Ram buyers saw us go to 801 or 802, I think they’d think, ‘We’re being Mickey Moused.’ They wouldn’t believe it. I will not do that with our brand.”

Going on sale in the second quarter, the improved High Output Cummins turbodiesel gets a new engine controller with revised performance calibration that allows peak torque to be achieved by 1,600 rpm. The old Cummins engine reached 650 lb.-ft. by 1,500 rpm.

A new higher-rated torque converter improves engine/transmission integration for better towing capability on grades and optimizes engine performance. Also integrated is a new crankshaft damper that reduces engine noise and vibration.

Maximum horsepower (350 at 3,500 rpm) remains unchanged.

The rear axle, supplied by American Axle, has been beefed up to manage the additional torque, and a new aluminum differential cover is finned for improved cooling.

Like the previous Cummins engine, the improved one uses an oxides-of- nitrogen catalyst to comply with exhaust emissions rules, completely eliminating the need for the selective catalytic reduction technology used by Ford and GM, which requires replenishing ammonia-based diesel exhaust fluid.

The new Ram engine will be available in all 50 states with the 2500 and 3500 pickups, mated with a 6-speed automatic transmission. The detuned Cummins turbodiesel will continue to be available, but only with a 6-speed manual gearbox.

With 800 lb.-ft. of torque, the Ram receives a gross combined weight rating of 30,000 lbs. (13,608 kg) and is capable of a maximum trailer tow weight of 22,700 lbs. (10,297 kg), which Chrysler says leads the segment.

Do customers really need this much brute force?

“Yes, they’re looking for it, for hauling stuff up and down grades out West,” says Michael Cairns, chief engineer-Ram programs. “It’s the capability they’re looking for. And GM and Ford upped the ante, so we had to do something about it.”

Also at the auto show here, Chrysler unveils the Ram Tradesman, a value-priced option package designed to meet the hard-working needs of small businessmen and commercial fleets.

The Tradesman, available with short or long bed, starts with the Ram 1500 ST trim package and adds a standard 5.7L Hemi V-8 with 5-speed automatic transmission, as well as a standard Class IV trailer hitch and stylish steel wheels.

tmurphy@wardsauto.com