You've seen how the 2010 Dodge Ram 3500, 2011 Ford F-350 Super Duty and 2011 GMC Sierra 3500 HD stack up to one another in our Heavy-Duty Truck Comparison Test. Now here's a look at how well each engine puts its stuff to the pavement -- rather, the drum -- as we recently spent some time on the dyno rollers with these trucks.
What did we learn? Hit the jump.
Diesel newbies will probably be puzzled by the low redlines found in these dyno charts. Yes, diesels rev low, owing in part to the fact that the diesel combustion process involves an elaborate courtship of the fuel and air in the combustion chambers. That, and diesels' high cylinder pressures require massive components, which in turn impose mechanical limitations on maximum speed.
Modern diesels employ ever-higher fuel delivery pressures and multiple injections per combustion event in order to improve fuel atomization, promote mixing and manage the resulting combustion process. These factors help to improve not only emissions and fuel consumption, but output benefits as well, something that is apparent by the impressive numbers generated by these trucks.
As usual, we strapped each truck to a Dynojet 248 inertial chassis dyno and performed as many runs as necessary to achieve a stabilized and repeatable result.
The GMC Sierra HD's 6.6-liter Duramax V8 threw down the biggest power number of the three diesels, turning the rollers to the tune of 360 horsepower. Torque, which peaked at 665 lb-ft, wasn't exactly thin, either. You'll notice this peak torque value occurs at some kind of tumor from the prevaling torque characteristic.
The GMC produced somewhat inconsistent results on the dyno, as its transmission insisted on downshifting when in manual mode. It took a bit of coercion and a lot of runs on the dyno to get the big white pickup to turn the rollers in an agreeable way.
This kind of grunt is impressive in a box-stock truck. Sure, you can buy aftermarket controllers to extract silly numbers that would eclipse those of the trucks in this test. The tradeoff with those black boxes is that you run the risk of extremely high exhaust gas temperatures which translate into long-term durability that can only be described as a giant question mark.
Of all three trucks here, the Ford's 6.7-liter Powerstroke V8 powertrain was by far the most cooperative on the dyno. Its transmission stays on task, resolutely staying in the gear of your choosing when in manual mode. After all, sometimes you just want that extra bit of control over the powertrain, and what would be the point of manual mode if the transmission grows neurons and decides it knows better than you?
The Ford's friendly transmission allowed its dyno pulls to begin from very low in the rev range, unlike the other trucks that would downshift of their own accord. We saw dead-consistent results from the Ford, too, which ground out 333 horsepower and a test-topping 690 lb-ft of torque to the rollers.
Although the GMC ekes out the most power in this comparison, it does so only briefy -- the Ford has the edge for the brunt of the rev range (see overlay of dyno data from each truck below). Torque is quite flat from 1850 to 2650 rpm, which is a substantial fraction of the engine's total rev capability.
In a way, it's remarkable that the Dodge's 280 horsepower and 559 lb-ft of torque as measured by the Dynojet chassis dyno were the meekest results in the test. Just a few years ago this kind of sauce would have been unheard of in a production diesel pickup.
The Dodge has neither the peak output nor the broad shoulders of the other two. Similar to the GMC, the Dodge's transmission takes matters into into its own hands when it decides there are too few revs on the tach.
Powered by a substantially overhauled 6.7-liter Cummins inline-six, the Dodge sports the eldest engine in the bunch. Ford's Powerstroke is all-new this year, and GMC's Duramax was new in 2010 and, unlike the Dodge, both employ urea as their exhaust aftertreatment strategy.
Without urea, the Dodge's engine requires more exhaust gas recirculation to tamp down NOx emissions, which is one explanation as to why its output lags the others.
--Jason Kavanagh, Engineering Editor
v8vader says:
09:36 PM, 02/ 1/11
despite how heavy the engines themselves are (and the heavy duty substructures needed to support them), i would be interested to see them in a lighter-weight application a la R8 TDI. i don't even think i would want something like that, but i really want to see it done...
v8vader says:
09:37 PM, 02/ 1/11
despite how heavy the engines themselves are (and the heavy duty substructures needed to support them), i would be interested to see them in a lighter-weight application a la R8 TDI. i don't even think i would want something like that, but i really want to see it done...
wjtinatl says:
10:07 PM, 02/ 1/11
Seems like either the Duramax is way underrated or the Ford driveline produces way more friction than the GM twins.
campi3ell says:
11:03 PM, 02/ 1/11
Maybe it's me, but I kind-of don't like the blocky exterior of the F350. It's... something that throws me off, as if it's trying *too* hard to be a truck's truck. However, the Denali treatment on the Sierra is quite nice. Smoothed over a bit better...
dirtycarl says:
01:37 AM, 02/ 2/11
Thank you Ford for programming your transmission to stay in the selected gear when in manual mode. When I select "5" I don't mean that I want any gear up to fifth, I mean I want fifth! Please make note of this GM and Chrysler.
cz_75 says:
02:11 AM, 02/ 2/11
GM, Ford, and I believe Chrysler too, all had smaller diesels ready for use in light duty (1/2 ton) trucks just before the financial crisis hit. With EPA mileage requirements increasing for trucks and fuel prices taking off, they will likely have to offer diesels, as I can't see a gas hybrid being up to the job on a truck that actually works for a living and the increased cost of operation will otherwise drive many owners away who don't really need a truck often when they pay $5/gal. for fuel and get relatively poor mileage.
lostboyz says:
04:52 AM, 02/ 2/11
@cz_75, unless you are willing to pay $3-4k over the cost of the v8 you won't see any light duty diesels. The current regulations we have make them uncompetitive.
bankerdanny says:
09:59 AM, 02/ 2/11
Interesting article. Too bad it is hidden behind the latest stupid GM ad taking up the limited space in the feature scroll.
cz_75 says:
10:01 AM, 02/ 2/11
They were billed as only adding $2000 or so to the price and the longevity, versatility and economy of a diesel would make that worth it.
viss1 says:
10:36 AM, 02/ 2/11
Nice. I like this new emphasis on dyno testing your test vehicles.
stoppre75 says:
10:41 AM, 02/ 2/11
Yeah, If i were ever in the market for a light duty, full sized pickup - for a $2500 premium I would definitely go for a small (i believe they were 4 - 4.4L) diesel engine. Much more useful for towing and driving with a full bed. Plus when its empty you'll be rewarded with mileage in the mid-upper teens vs the 12-14 of the gas v8.
Ford is touting their Ecoboost V6 as getting "best mileage" but they only top their own V8 by 1mpg city and highway. And thats on the not-real-world EPA test track. In reality I'd guess its equivalent. But either way, the diesel will last longer so long term - it will cost less anyway.
bodyblue says:
10:43 AM, 02/ 2/11
GM and Dodge are quite competitive with their diesel engine offerings but are a mile behind Ford in the volume base engines power.....they need to catch up fast.
bauerjw says:
11:04 AM, 02/ 2/11
I totally want AUDIO for these tests!!
csubowtie says:
11:31 AM, 02/ 2/11
bodyblue: I usually try to ignore most of your crap, but come on, a statement like that is easily proven with facts. GM 4.8 liter, 302 hp, 305 lb-ft, Dodge 4.7, 310 hp, 330 lb-ft, Ford 4.6, 248 hp, 294 lb-ft. Ford is about 50 hp down and down on torque too. Next step up, GM 5.3, 315 hp, 338 ft-lbs. Dodge 5.7, 390 hp, 407 lb-ft (although I think this is Dodges biggest gas engine, where as GM still has the 6.2), Ford 5.4l, 310 hp, 365 lb-ft. So even at this level, The GM has more hp, but less torque, and the hemi whoops ass. Looks to me like Ford is the one who needs to catch up.
cubbybear1 says:
12:15 PM, 02/ 2/11
@csu
Ford introduced 4 new gas engines. A 302hp V6, 400hp ttV6, 350hp 5.0l, and the 412hp 6.2l.
bodyblue says:
12:34 PM, 02/ 2/11
"bodyblue: I usually try to ignore most of your crap, but come on, a statement like that is easily proven with facts. GM 4.8 liter, 302 hp, 305 lb-ft, Dodge 4.7, 310 hp, 330 lb-ft, Ford 4.6, 248 hp, 294 lb-ft. Ford is about 50 hp down and down on torque too"
Maybe you should...you look like an idiot when you dont. Do you really want to get slapped down again or do you want to brush up on your facts before talking like the GM shill you are? :)
topheezy says:
12:48 PM, 02/ 2/11
Csubowtie I'm sorry to say the 4.6 and 5.4 are no longer available and have been replaced by the highly competitive 5.0 and 6.2. That along with the addition of the ecoboost, Ford has quite the solid lineup of engines in their stable for the first time since I can remember. I love GM but Ford is coming on strong.
bodyblue says:
12:55 PM, 02/ 2/11
I doubt he will show up on this thread again. It is embarrassing when you are THAT wrong. :)
csubowtie says:
03:28 PM, 02/ 2/11
Wow, that is embarrassing. I pulled the 2010 F-150 numbers, although I will admit when I'm wrong. I suppose in the last few months, Ford's newly realeased engines have finally managed to beat GM's engines that have been around for years. I suppose for ~now~ I'll have to eat my smack talking words, or save the numbers game for the diesel engines, or the Camaro vs. Mustang horsepower battles.
bodyblue says:
07:55 AM, 02/ 3/11
And I will admit when I am wrong....you did show back up. We all jump when we see a chance and sometimes we dont see the cliff.
lsobboh says:
11:53 AM, 02/ 4/11
I'd still take the Dodge. Love that straight 6...
jdhog424 says:
08:06 PM, 02/ 7/11
Ford has the highest horsepower and torque numbers of all three trucks, this was after they did a software upgrade on their engine management system so they could brag about having more power than the updated GM Duramax. I hope the Ford software upgrade doesn't affect the durability and lifetime of the engine like the aftermarket powerchips do. The new Ford diesel is still an unproven engine that only time will tell how well it is, I hope it's better than when Ford came out with the 6.0L diesel a few years back because it was a real lemon for the first two years of production.
I didn't know the GM Duramax was an all new engine for 2010, I thought by the 6.6L size, it was just an improved version of the existing Isuzu/ GM diesel. It would be nice if GM offered a new gasoline V8 instead of the 5.3L in it's light duty trucks.
The RAM has the oldest engine, having been totally redone for 2007 meeting 2010 emission standards without requiring any urea, which to most owners is a big benefit. The Cummins also achieve's maximum torque a lot sooner at a lower RPM than the Ford and GM which a lot of truck owners really appreciate when taking off from a fully stopped position.
Truck owners already have enough things to worry about keeping an eye on, I like that you don't have to worry about a urea tank fluid level getting low.
I've read that the only reason the RAM has the lowest power levels is because the engineers have ensured that the power is not too high so that it damages the transmission. Apparently when the new 8 speed automatic becomes available in the RAM diesel in one year, the power levels will be much higher and put the RAM on top with the highest ratings, I'm waiting to see if this is true.
paulvincent1 says:
04:14 PM, 02/ 8/11
The 2011 GMC Sierra 3500 HD says, "orthodontics." Why can't GM do better than this?
mikeebear says:
11:20 PM, 02/10/11
Am I the only one to see the S1 Lotus Exige in the last pic? Nice... What place was this?