Back in Time, Part 10: The Big Three Move Beyond 900 LB-FT
Just three summers ago, while the diesel world was still buzzing about the 900 lb-ft ’16 Ram, Ford announced its plan to debut a more powerful 6.7L Power Stroke in its redesigned ’17 Super Duty. Ford’s revamped V8 would reclaim the torque title with 925 lb-ft, along with 440 hp. But just as Ford and Ram were inching their way beyond the 900 lb-ft threshold, GM blasted back onto the scene with a brand-new Duramax slated for its ’17 truck lineup. In September of 2016, the General announced that its fresh L5P code Duramax would join the big-twist party with 910 lb-ft of its own, along with 445 ponies—best-in-class horsepower at the time.
Less than a year later, Ram would top Ford’s segment-leading torque figure by squeezing 930 lb-ft out of the 6.7L Cummins. By December of 2017, Ford found another 10 lb-ft and 10 horsepower to play with and retook the torque crown with 935 lb-ft. Then, on January 14, 2019 it happened. Just as it was the first manufacturer to offer a 900 lb-ft truck, Ram became the first to reach 1,000 lb-ft. Thanks to a completely redesigned 6.7L I6 from Cummins, the ’19 Ram 3500’s available on dealer lots right now are the current kings in the never-ending torque war.
Don’t settle in yet! In the months ahead Ford will release its 2020 Super Duty, complete with a third-generation 6.7L Power Stroke under the hood. Will it have enough twist to force Ram and Cummins back to the drawing board? Keep your eyes and ears peeled for industry news from us. We’ll have a full report when Ford goes public with its highly-anticipated counter-attack.
|Specs||'17-'19 6.7L Power Stroke||'17-'19 L5P Duramax||'17-'19 6.7L Cummins|
|Displacement||406 ci||403 ci||408 ci|
|Bore||3.90 inches||4.06 inches||4.21 inches|
|Stroke||4.25 inches||3.90 inches||4.88 inches|
|Compression Ratio||16.2:1||16.0:1||17.3:1 (’17-’18), 16.2:1 (’19 H.O.)|
|Block||Deep-skirt, compacted graphite iron (CGI)||Deep-skirt, cast-iron||Cast-iron (’17-’18), compacted graphite iron (’19 H.O.)|
|Rods||Powdered-metal||Powdered-metal, cracked cap||Powdered-metal (’17-’18), forged-steel (’19 H.O.)|
|Head(s)||Cast-aluminum, reverse-flow with six head bolts per cylinder||Cast-aluminum with six head bolts per cylinder||Cast-iron with six head bolts per cylinder|
|Valvetrain||OHV, four valves, four rockers and four pushrods per cylinder, single cam||OHV, four valves per cylinder, single cam||OHV, four valves per cylinder, single cam (solid lifters ’17-’18, hydraulic lifters ’19)|
|Injection System||Bosch high-pressure common-rail, direct injection||Denso high-pressure common-rail, direct injection||Bosch high-pressure common-rail, direct injection (CP4.2 added for ‘19)|
|Turbocharger||Garrett GT37||BorgWarner VGT||Holset VGT|
|Emissions||Exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), diesel particulate filter (DPF), selective catalytic reduction (SCR)||Exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), diesel particulate filter (DPF), selective catalytic reduction (SCR)||Exhaust gas recirculation (EGR), diesel oxidation catalyst (DOC), diesel|
|Horsepower||440 hp at 2,800 rpm (‘17), 450 hp at 2,800 rpm (’18-‘19)||445 hp at 2,800 rpm||385 hp at 2,800 rpm (’17-’18), 400 hp at 2,800 rpm (’19 H.O.)|
|Torque||925 lb-ft at 1,800 rpm (‘17), 935 lb-ft at 1,800 rpm (’18-‘19)||910 lb-ft at 1,600 rpm||900 lb-ft at 1,700 rpm (‘17), 930 lb-ft at 1,700 rpm (‘18), 1,000 lb-ft at 1,800 rpm (’19 H.O.)|
925 LB-FT 6.7L Power Stroke
For ’17, Ford released the aluminum bodied Super Duty—a first for the heavy-duty pickup segment. In addition to the redesign, Ford made sure to press forward in the torque game, pushing its 6.7L Power Stroke to a segment-best 925 lb-ft and a class-leading (at the time) 440 hp rating. The higher torque rating came by way of PCM calibration changes which upped the engine’s maximum torque output from 1,600 rpm to 1,800 rpm. With peak torque being moved to a higher rpm, some took it as a sign that Ford was trying to avoid excessive cylinder pressure (bottom end stress)—and more importantly that it was potentially nearing the edge of what the short-block could handle, long-term.
910 LB-FT L5P Duramax
It may not have arrived on the scene with a bigger peak torque number than Ford, but the L5P Duramax could definitely hold its own right out of the gate. It boasted a heat-treated crankcase, higher flowing heads, new powdered-metal connecting rods, de-lipped pistons with beefier wrist pins and made 910 lb-ft of torque at 1,600 rpm. Horsepower checked in at 445 hp—the highest ever offered in a diesel-powered pickup.
Techy Turbo, Denso Fuel System
The new L5P Duramax also came equipped with the segment’s first variable geometry turbocharger that was both controlled and actuated electronically. The upside to even quicker actuation meant that the L5P was extremely responsive at virtually any engine rpm. Supplied by BorgWarner, the VGT unit sported a billet, 11-blade compressor wheel with a 61mm inducer, a 62mm turbine wheel exducer and built as much as 31 psi of boost in stock form. A new common-rail fuel system sourced through Denso, complete with GM’s first factory-included lift pump, helped the engine produce its respectable horsepower and torque numbers in addition to squeaky-clean emissions.
930 LB-FT Cummins
On the eve of the launch of its ’18 models, news broke that Ram had bested Ford’s 925 lb-ft torque figure. The 6.7L Cummins’ 930 lb-ft of twist came online at the same 1,700 rpm thanks to ECM tweaks that enhanced low-end fueling strategies and facilitated more boost pressure. Ram’s torque increase coincided with the ’18 Ram 3500’s ability to tow 30,000 pounds with the automaker’s new fifth wheel hitch—the highest in the segment, momentarily.
935 LB-FT 6.7L Power Stroke
Christmas came early in 2017 for Ford fans, as another torque increase was announced for the 6.7L Power Stroke that December. Topping Ram’s 930 lb-ft with 935 lb-ft thanks to a PCM recalibration, Ford also reclaimed the best-in-class horsepower crown, pumping its 6.7L V8 up to 450 hp (vs. the L5P Duramax’s 445 hp). Of course, power production was only half the battle. To own work, Ford also bested Ram’s maximum towing and payload capacities.
2019 6.7L Cummins
By releasing the 1,000 lb-ft Cummins, all of the incremental leap-frogging that was projected to unfold between Ram, Ford and GM in pursuit of the magical, four-digit torque number came to a screeching halt. With Ram boldly positioned out front, the pressure is now on the other two truck builders to retaliate. How much further they’re willing to climb up the mountain remains to be seen, but we expect Ford will have an answer soon. Currently, GM has decided to leave the proven L5P Duramax alone, instead focusing on out-towing Ram (its 3500 HD’s are capable of moving 35,500 pounds vs. the Ram 3500’s 35,100 pounds).
1,000 LB-FT Crankcase
From an engineering standpoint, the original 6.7L Cummins may have been out of room for further torque growth after being pushed to 930 lb-ft. After all, the same platform debuted with just 650 lb-ft of torque in 2007. Planning for the future (and perpetual continuation of the torque war), Cummins developed an all-new 6.7L for ’19, complete with a compacted graphite iron (CGI) block. CGI offers significantly more hardness, fatigue and tensile strength over cast-iron—ideal for making a crankcase live while being subjected to higher cylinder pressure.
Lighter and Stronger
Along with the CGI block shaving considerable curb weight (as much as 60 pounds), lighter cast-aluminum pistons are employed in the new 6.7L Cummins. Beneath them, Cummins turned back to forged-steel connecting rods over powdered-metal units in preparation for handling the added stresses that come from producing 1,000 lb-ft of torque. The same goes for the crankshaft. Though the new crank provides the same 4.88-inch stroke, it’s made from a much stronger alloy.
Big torque, high cylinder pressure diesels need an adequate number of head fasteners that are also sufficient in diameter. The new Cummins has both. Its all-new, 24-valve cast-iron cylinder head—which features high-temp exhaust valves and stiffer valve springs, actuated by maintenance-free hydraulic lifters—anchors to the CGI block via six 14mm diameter head bolts per cylinder (vs. 12mm on the previous engine).
Higher Pressure, Cleaner Fuel
At the heart of the 6.7L Cummins’ 400 hp and 1,000 lb-ft of torque rating, as well as its ability to produce fewer in-cylinder emissions, is a Bosch CP4.2 high-pressure fuel pump. This is the same pump used on the 6.7L Power Stroke and was previously used on the ’11-’16 LML Duramax. The CP4.2 aboard the Cummins will produce as much as 29,000 psi, be supplied low-pressure fuel by way of a factory lift pump and see the cleanest fuel possible thanks to the use of Cummins Filtration’s NanoNet (filter in filter) technology.
We’re convinced Ford will release a higher torque number than Ram this fall—and here’s why.