2017 3/4-Ton Premium Truck Challenge: Diesels on the Dyno

Ram 2500 CC Dyno A17_0930[5] II

By Mark Williams

For those who tow (or intend to), haul heavy loads (or intend to) or need to do both while carrying family members on vacation (or intend to), the three-quarter-ton pickup truck can be a perfect choice. And in the world of full-size fully loaded 4x4 diesels, the single most important feature in this kind of vehicle is what's under the hood.

In fact, many customers in this segment choose their engine before choosing their pickup. That's how important an engine can be. To shine some light on the differing characteristics of each of the turbo-diesel engines in our 2017 3/4-Ton Premium Truck Challenge, we put them on a chassis dynamometer to see how they perform.

What does a dyno test tell us? It provides the opportunity to see — in an apples-to-apples comparison — how these different power plants create and distribute their strength.

How They Compare

Dyno rear wheels straps

Given the diversity of engines in this Challenge, it's no surprise our dyno results varied widely. The burly straight-six Cummins in the 2017 Ram 2500 made more than 95 percent of its torque around 2,000 rpm. The 2017 Nissan Titan XD, with the newest and smallest turbo-diesel of these heavy-duty trucks, uses a dual overhead cam V-8 Cummins and made its peak torque around 3,250 rpm. But it was the Duramax in the 2017 Chevrolet Silverado 2500 and Power Stroke in the 2017 Ford Super Duty F-250 that were the most alike and the most powerful. They have relatively similar architectures, and that's where the main battle for three-quarter-ton supremacy takes place. We saw that at the track and during our fuel-economy test when towing gooseneck trailers, but in the dyno testing we saw, the numerical representation.

The Chevrolet and Ford 32-valve V-8 engines were newly reconstructed for model-year 2017 to squeeze out as much power and torque as possible. They use high-pressure common-rail direct fuel injection, have similar compression ratios and have huge improvements in cooling power. Using the factory numbers, the Chevy Duramax has a 5-horsepower advantage over the Ford Power Stroke, while the Power Stroke has a torque advantage of 15 pounds-feet.

Here's what we found when we put each of our competitors on the dyno at Arizona Dyno Chip in Tempe, Ariz.

PUTCChallenge_ThreeQuart_Prem_dyno

Power to the Rear Wheels

Ram 2500 CC Dyno A17_0930[5] II

The Chevy's all-new turbo-diesel 6.6-liter V-8 Duramax made the most horsepower and torque of our four players, recording 385 peak hp and 775 pounds-feet of torque on the chassis dyno. This was just slightly ahead of the Ford's 6.7-liter V-8 Power Stroke, which made 369 hp and 721 pounds-feet of torque. Ram's 6.7-liter inline-six-cylinder Cummins came in third with 332 hp at 2,700 rpm, and 663 pounds-feet of torque at 2,200 rpm. The Nissan's 5.0-liter V-8 - the smallest engine of the group — came in last, making 267 hp and 437 pounds-feet of torque.

How We Conducted the Testing

Anyone who has experience with a chassis dynamometer knows it can be a little tricky capturing peak performance, mainly because of how smart (and dumb) many new transmissions (and the software that controls them) can be. Thankfully, we are familiar with Arizona Dyno Chip, so we made a date to test all our trucks on the same day, with the same technician, following the same procedures. Doing so allowed us to feel confident about the results of our dyno testing.

Cars.com photos by Angela Conners

Overview | Track Testing | Towing | Daily Driving | Dynamometer Testing | Results

 

Comments

can't go wrong with any of the big 3. Wonder who says who stole their engine design?Ford or Chevy

How is it that the 3/4 ton Silverado put down better numbers than the 1 ton tested by tfltruck?

Hard to beat a Chevy motor

The "Cummins made more than 95 percent of its torque around 2000 rpm."

800 x .95 = 760

Your "maximum" number of 663 is only 83% of 800.

So which is it? Either the CTD had 83% of its torque or it came in second. Can't have both. So much confusion in your articles.

Adam.... you are confusing crank power with wheel power.

LOL, 16hp and 54ftlbs of torque at the wheels is not "slightly ahead" by any stretch of that word, that is a huge and noticeable difference. If you look at half ton gas trucks, most people can be quoted as noticing a "night and day" difference when a good aftermarket tuner adds only 20ft lbs (yes I know diesels see much bigger gains than that), but 50+ ft lbs is a LOT, and it definitely showed in your performance comparisons.

Excuse me, I'm not confusing anything. Run the numbers and read the article. It clearly states that Ram had 95% of its torque, which is 760. Their test graph shows 663. If they meant that the rwtq of 663 as being 95% of X, where X is the crank torque, then X is 697. Nowhere near 800 or 760 for that matter.

@ Adam,

uh huh is right.
663 is the max torque produced on the Dyno. I assume when you mention 800 you are referring to the advertised crank torque. The dyno does not measure crank torque.
What they are saying is that @ 2000 RPM the dodge is making at least 630 lbs-ft.
Wish they would show the graphs.

Okay, this is my last attempt to explain.

A) They claim to have a Ram 2500 CTD 68RFE which according to Ram, has 800 CRANK torque.
B) The article clearly states that the Ram produced 95% of its torque at 2000rpm.
C) Their graph shows 663 at the wheels.

Now, because 663 is peak torque at wheels, and it should be 95% of CRANK torque, that means crank torque is not 800. Let me show you how to verify this:

Go get a calculator, and take 663 / .95 = ?

Your answer is what should be at the crank IF we believe that the truck is doing what they claim: that 95% of the torque was produced.

So what number did you get? Hmmm? It is not 800, is it? So their review is incorrect. Or their numbers. Or this article. Now I'm done.

Why wouldn't they give rpms at peak for ford and gm? That is good to know.

267hp? Might as well go Ford 6.2 gasser F350. You will get over 300k miles with that engine tranny combo

And gm didn't upgrade yet the new engine wow ,,

The Silverado handing out yet another snack down to the King Recalll. Just shows how Fords advertising is all lies.

Very curious that the Nissan showed a torque peak at 3250rpm. Cummins specs the torque curve flat from 1700-2700, falling off above that. It sounds to me like Nissan/Cummins/Aisin have some major tuning work to do. I wonder if it doesn't come back to emissions and a cheaper ATD on the XD. The diesel option on the Nissan costs way less than the Big 3, even though the engine is the same basic configuration as Ford and GM (from a 3rd party vendor, which should cost MORE) and uses the same transmission as the most expensive RAM option. Yet somehow the package costs 3-4 grand less. If the ATD is overly restrictive, or undersize to handle NOx properly, they might have de-tuned things. At least on paper, the Cummins/Aisin combo in the XD should perform at least as well as the old Navistar 6.0 Powerstroke. Sure, that engine had design flaws that impacted its maintenance/durability, but it was generally regarded as a good runner.

@Adam, they mean 95% of measured torque at the wheels was at 2000rpms, not 95% of crank torque (800) at 2000rpms.

Edit to my last post- the Cummins/Aisin in the XD cost almost $7000 less than the Cummins/Aisin in the Ram. The transmissions are very similar and I would be amazed if Nissan paid much less for it.

Adam

Stop arguing and paying attention. You clearly do not undersatand parasitic drivetrain loss. Or what a dyno is measuring. Its not measuring from the crank like the advertised numbers. Its measuring from the wheels which incorpoates the whole drivetrain after the crank. ( known as parasitic drivetrain loss). So in this instance 800 lb-ft at the crank = 663 lb-ft at the wheels at that location, and time on that particular day. (There will be variances with altitude, barometric pressure and temperature.) So 95% of 663 is 629.85 lb-ft at 2000rpm is what is being claimed.

dynoing diesels takes skill. judging by the ford being almost 200 ft-lb less than advertised at crank. obviously they werent getting the turbo lit and/or were above peak torque

cummins claims 800 lb-ft at at 1600 rpm which is 100% of torque it produces at flywheel not 2000 rpm.
at 2000 rpm it produces 95% of 800 which is 760 lb-ft then you subtract 663 and you get 97 lb-ft of loss. ford produces its maximum torque at 1800 rpm and chevy is at 1600 rpm. so cummins and duramax are on par on there number and ford numbers are inflated even this test favors ford because it was tested closer to its peak rpm range performance



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