Diesel Power Curve Comparison! 2011 Power Stroke V-8 vs 2011 Duramax V-8

Diesel Power Curve Comparison! 2011 Power Stroke V-8 vs 2011 Duramax V-8
We already know that Ford’s all-new 6.7-liter Power Stroke V-8 diesel is rated at 390 horsepower (at 2,800 rpm) and 735 pounds-feet of torque (at 1,600 rpm) and GM’s updated 6.6 Duramax V-8 diesel is rated at 397 hp (at 3,000 rpm) and 765 pounds-feet, but those numbers don’t tell the whole story.

The true measure of diesel performance is how well its muscle is managed over the engine’s power band. How soon is peak torque available and for how long? The broader the torque curve is and the sooner peak torque hits, the better.

For the first time, we’re presenting the horsepower and torque curves for both the 2011 Power Stroke and 2011 Duramax engines. The data is courtesy of Ford and General Motors with the disclaimer that both power curves were delivered as rendered image files and not as tabular data, which would have allowed us to recreate the graphics independently.

The individual curves are presented first but we’ve taken both graphs and combined them into a single chart, so you can see where the differences are across engine speeds.

6.7-liter Power Stroke V-8 Power Curves

2011 6.7-liter Power Stroke V-8 Power Curves (courtesy of Ford)

6.6-liter Duramax LML vs LMM V-8 Power Curves

2011 6.6-liter LML Duramax V-8 vs. 2010 6.6-liter LMM Duramax V-8 Power Curves (courtesy of GM)

Power Stroke vs Duramax Power Curves
The Comparison: 2011 6.7-liter Power Stroke V-8 vs. 2011 6.6-liter Duramax V-8

Here’s what we think is interesting:

  • Torque: The Power Stroke puts out more torque than the Duramax until about 1,350 rpm, at which point the Duramax rapidly spikes towards its best-in-class peak torque at 1,600 rpm. After that point, the two motors appear to even up again around 2,450 rpm before the PSD drops below 700 lbs-ft around 2,700 rpm. The Duramax maintains a wider torque band that remains north of the PSD until 3,000 rpm, at which point rapidly tails off and both engines overlap again around 3,300 rpm. In general, the Duramax has a taller, broader torque band than the PSD.
  • Horsepower: The Power Stroke appears to maintain higher horsepower than the Duramax throughout most of the rpm range but the Duramax is able to keep the power coming a bit longer and outguns the PSD at about 2,900 rpm before it rapidly tails off and again falls below the PSD around 3,300 rpm.

    Part of Ford's apparent horsepower advantage may be the rendering of Ford's power curve. When we calculate horsepower using the formula HP = (rpm x torque)/5252 we come up with a rating of 223 hp for the Power Stroke and 233 hp for the Duramax at 1,600 rpm -- the claimed peak torque point for both motors. The graph overlay should show the Duramax slightly higher than the PSD at this point but it doesn't.

    It will be interesting to see how horsepower differences impact acceleration times when the trucks are empty and pulling heavy trailers during our upcoming HD Shootout.

One thing the comparison chart can’t tell us -- until we put the trucks head-to-head -- is how well their power is managed by their six-speed automatic transmissions. With ratings as close as these, transmission logic is going to be critical for differentiating which rig performs better. The chart also doesn’t account for weight differences. The Ford Super has traditionally been the heaviest pickup in the segment. We also wonder how much of a role controlling emissions is playing in changing some of the inflection points of the curves. 

We’re looking forward to testing both new engines on a chassis dyno ourselves, so we can see the power and torque curves calculated outside of Ford’s and GM’s powertrain labs.

Comments

Something doesn't make sense... Horsepower is torque x RPM / 5252. That means where the D Max maintains a higher torque compare to the PS, its horsepower should also be higher... but according to those graphs its not.

Good article, it should get some interesting debates.

I'll take the d-max.

@454

That formula is a rough guess. It is not the gospel.

Another thing to look at it the dynos these engines were tested on. the same engine will give very different numbers on different dynos. They should be tested on the same dyno to get a real comparison.

Mike,

Great job on this article, so far one of your best. You put together some real good data and presented perfectly. Thank you for the comparison and I look forward to your "real world" tests.

Keep up the good work.

Jeremiah Soltis
Tampa, FL

2009 F-250 4x4 6.4L Power Stroke Diesel

@454 :Great point and as you were probably writing that comment, we were updating the story to reflect that. The article is updated though keep in mind the curves were delivered as finished graphical files and not tabular data that would have allowed us to recreate the graphs independently. Nice observation!

@ Mike Levine

No complaints here, it just stuck out as odd to me. I'm still impressed with all the detail you include in your articles.. keep them coming!

VERY interesting! Now throw the transmission and rear axle ratios into the equation!

I love the power curves of the new D-Max, the Allison trans will put it to good use most certainly, as far as the new ford 6 speed auto i guess we will have to wait and see. Cummins fan forever though.

So the Ford has more lower end torque and power, the Chevy has more higher revving power and torque. Isn't that the way its always been?

It looks like the Duramax has a bigger sweet spot with will translate into better drivability

just for fun they should have one that includes the cummings just to see how the power and torque curve is in relasion to the other two.I got a 7.3l powerstroke and going to keep it till it's dead

its cummins not cummings!

The D-Max HP is maintained longer and most importantly the torque band is taller and WAAAY more sustained. Mated with the proven Allison and once again the D-Max is untouchable. Nice try Ford, you may be improving, but your still inferior!

"What we’re not likely to see, though, is another giant increase in the horsepower and torque from the 6.6-liter Duramax V-8, says GM powertrain engineering manager Jim Minneker.

“We’ve stretched this rubber band pretty tight,” Minneker said. “It’s not going to happen in the short term.”

So even GM admits this engine is highly strung. They just put the aftermarket chip in it as standard. Less low end power and torque than the Ford. So it just goes to show why you always see Chevys with an empty bed, and towing no trailer. Because people buy them for street racing. But if i was buying something for driving fast it would not be any truck. I would get a sports car.
I am going to put my money on the Ford and actually use it as a truck.

Just my way of thinking here but since both motors are so close, and I mean close it's going to come down to which truck weighs more (usually the Ford in the past) and the number of the gears in the tranny and what they are using in the rear... From different sties I have been reading Ford is using a VERY tall gear for first gear which should give it the grunt to get out ahead of the DMax. Of course if the truck weighs a thousand more pounds than the GM then it will hurt it in the end so I guess we will have to wait and see until PUTC.com gets both trucks in their hands. The new Ford 6 speed is supposed to be superior to the Allison. I know a few farmers who are working on their 2nd, 3rd, and one guy his 4th Allison in their GM/Chevy HD's so I never know why GM fans always try to rub it in everyone's faces.

I love how all the Ford fans on here are changing the subject and making up flase stories to compinsate for thier trucks shortcummings, lol. Entertainment, look at the facts boys.

^^^^ I've never heard of that kind of situation and I know plenty of people with Allisons. There is a reason they got the reputatuion they did and that Ford's doesn't shine.

I never realized how close these engines really are. These trucks will be VERY close in terms of performance.

who is changing the subject? The graphs show that GM has less low end torque. GM says their old engine is highly strung. They are the facts you are ignoring Greg. By the way Shawn is right, both engines are so close in their specs, everyone is being a little trivial in their differences. In the end, either one is going to have more than enough power and torque. And Greg, learn how to spell.

Oh please please please....another HD shootout! PLEASE?!

Can't wait to read it, then argue about it on RV.net :)

Mike,
Great write up. I think for the HD shoot out you should wait for the 2011 Ram. The reason I say this is a friend of mine that works at a Dodge dealer says the 2011 Ram non cc will have urea injection just like the cab and chassis. I think that might make a difference in the comparison because Dodge may tweak the 2011 Ram HD to get closer to Ford and GM in power numbers. I know Ford and GM have higher peak horsepower and torque, but would you do a comparison including the Cummins.

Good one with the spelling joke, bad thought process though not catching the cummins shot within the comment genius.

It's a Cummins shot not a spelling error. Think about it.

This article is a joke. If the author had half a brain and a calculator he could determine that in order to make 390hp at 2800RPM's then an engine must make 731.53lb-ft of torque. This is a simple reverse calculation where you take horsepower X 5252 / engine speed in revolutions per minute.

Using the same basic math the author would find that the Duramax making 397hp at 3000RPM's is making 695.01lb-ft of torque.

Neither of those graphs are really very accurate if the factory power figures of either motor are to be taken at face value. Why not revisit this again when both trucks can be placed on an actual dyno on the same day for a true comparison that really means anything.

Oh, and learn how to do some basic math and stop relying on graphs guys:

Horsepower = Torque X Engine Speed (RPM) / 5252 RPM

What strikes me is what incredible modern diesel work horse engines we have available to us. Probably separated by the interior and seat feel and blind loyalty more than real performance and ability anymore. It will be interesting to see how the trans choices shake out in the real world. And Ford should shed some pounds. You just have to be impressed with these choices.

looks like the Duramax/alisson will rule again in Drag race high rpm running. Since i don't use a truck for high rpm towing or racing i prefer the torque curve and awesome towing power of the Cummins the best, a perfect engine for heavy duty use, and heavy trailer towing. Nice to have a duramax in a Camaro or Trans Am, would be sweet.

even if the government built duramax has more horsepower or/and torque, its going to come down to exicution and control. also lets see gm's mpg on this.; according to GM its going to get 15-17mpg, whcih isn't bad at all but when you compaire it to Ford's 22mpg with a 1,000 pounds in the back and in an empty bed at a possible 25-30+mpgs its total domination by Ford.

@BCR: You didn't read much of the story did you? Read the entire post and get back to us when you've taken a deep breath.

Are the numbers at the crank or wheels. If its not at the wheels it doesnt really matter. You can have all the horsepower and torque you want, but if its not getting to the wheels it doesnt do any good. Truck shootout with a dyno would be real interesting, if the manufactures would allow the truth machine.

its cummins not cummings!

Posted by: Zach | Mar 30, 2010 8:07:29 PM

--- Oh it's cummings when we're talking about you princess:)

Real issue is stability, best towing platform for controlling your load.

If don't care how fast I get, I just want to get there safely.

That is why there are more of the Fords doing the work. Heavier, more stable.

For any idiot here that thinks the Allison transmission isn't as good as fords tranny they have S T for brains. For the record there isn't a better diesel and transmission combination in a truck than the Duramax Diesel and the Allison Transmission period! You got that you ford lovers.

You can argue until the cows come home but the upcoming shootout will settle the arguments once and for all and when the day is done the Duramax and Allison transmission will reign supreme when the shootout is completed.

So let it be written, so let it be done!!!

I think I would respect RR's opinion WAY before I respected Bob's. That is saying a lot. Sorry Bob. Nobody cares what you think. We already know you love anything wearing a bow tie.

Bob, you're very dogmatic, just like a preacher. But I'm an engineer, not a disciple, so just show me the facts… As in a head to head shoot-out!

I agree with Alex. Bob must be like 13 years old.

Since the 7.3 left I've always preferred the duramax(I mean after the cummins of course), but I think that will change finally with ford's new diesel and tranny. I'm very impressed with what I've heard of the 6.7 so far. I think the 6.7 will be more reliable and capable of much more power than the duramax/allison with some simple mods. I'd be afraid to squeeze any more out of a new duramax after what their engineers have said. I wish I could find the link again to the video where ford engineers compare engine and transmission parts to the chevy parts. It's surprisingly unbiased and basically lets the facts and the parts speak for themselves. Anybody have that link?

Please test the Cummings engine along with the other two.

both engines seem powerful enough....i dont know why the big three want to give us any more power, just stick with those numbers and let the engines work for a couple of years to se how reliable they turn to be.

Like I said, the shootout will prove what truck has the best Diesel and transmission. If you think the sun set's on Fords new power joke, than buy that truck. I know the Duramax will win the shootout and make Ford and the cummins fight for sloppy seconds. The shootout will pick a winner but I doubt it will make someone buy one brand over another. Truck buyers are brand loyal and will buy the brand of their choice.

For the record, the Duramax reigned supreme in the last shootout ran by pickuptruck.com and it will reign supreme over the powerjoke and the cummins.

So let it be written, so let it be done!!!

The graph is very misleading, but the explanation is dead on. The torque lines look about right, but the power lines are way off. This is unfortunate, because I know many people will only look at the graph and think the PSD has a wider powerband when it isn't true. The Dmax holds onto it's torque much longer than the PSD, and thus has more power everywhere (other than below 1600RPM). Considering an engine doesn't run below 1600RPM that often (torque converter slip will put you above 1600RPM almost immidiately after a launch) the wider torque curve and higher power numbers of the Dmax should allow it to accelerate better being empty or while towing.

Good article, I have to agree with Teddy, because different dyno's will give you different readings. I don't think any manufacturer provides rear wheel torque or HP numbers. It's all at the crank. Like a few people have said - how well will the drivetrain put that power to use?
Bob - I do agree that the shootout results will not change anyone's opinions. I can't see you buying a Ford if they win.

@Alex:
"What we’re not likely to see, though, is another giant increase in the horsepower and torque from the 6.6-liter Duramax V-8, says GM powertrain engineering manager Jim Minneker.

“We’ve stretched this rubber band pretty tight,” Minneker said. “It’s not going to happen in the short term.”
If you read into that statement, it's concerning fuel mpg-to-power ratio.
All diesels when chip'd would exceed 397/765 .
Like FPL's fleet buyer said, they are looking for the truck with the best cost of ownership, which means: best mpg
In Fort Lauderdale here AT&T still use 90's 2500/3500 HD's
cuz there so good on gas and there are built like tanks.
Point here being Duramax and has more init hp(wise) but the mpg would maybe decrease as a result of the power increase.
I love Chevy and the Duramax is sweet money, but i think the Ford has a strong motor this time.
One thing to keep in mind is that both motors have Bosch injection system that could produce 30000 psi.

I really want to punch people that spell Cummins wrong. Not really, but it really bugs me.

@Bob: GM will always be last in the HD segment until they get rid of IFS. They may have a great engine and trans set up, and even a solid frame now. But when they redesigned the frame they should have put SFA in it. But, like usual, they dropped the ball. In the HD segment reliability is KING. SFA, plain and simple, is more reliable then IFS. Period!

Hay Teddy, if you think the that a straight axle is the way to go for a heavy duty truck than buy the truck of your choice. Now, opinions are just like a..holes, everyone has one and I don't share your opinion on what a heavy duty truck can or can't have to be a heavy duty truck.

I love GM's independent front suspension which offers a superior ride. GM kept the IFS but made many changes to improve strength and durability. So, if you like it buy something else. But leave people who like the IFS alone.

The duramax will win the shootout this summer and you can quote me on that. Ford and Dodge will fight for sloppy seconds.

^ you have no way of proving that teddy..

Yes it does offer a more "comfertable ride," but that is the only advantage.

Jake, a SFA has 20% less moving parts, that means a IFS has 20% higher chance of something breaking, and of those extra moving parts something will break.

This is the Same reason my the Cummins is the most reliable diesel. The I6 has 40% less moving parts then a V8.

Ask anybody who has experiece with the two. They will always have less problems with the SFA.

Doesn't SFA also stand for: Sweet F... All

at the end of the day, the cummins is still a Dodge, aka Cheap with bad frames and bad transmissions. I am glad Teddy likes his wanne be semi looking Dodge. GM makes a superior truck and Diesel, transmission, to the Dodge product.

I bet this is really going to get Teddy fired up.

Teddy, you will get beat by the Duramax and the IFS suspension. How do like those apples teddy?

Bob, I'll be sure to wave when I pass your truck when it is sitting on the should of the road.

"GM makes a superior truck and Diesel, transmission" - Bob

At the end of the day it's still a POS from Garbage Motor that took our taxes to say afloat.

Stupid Management = Stupid Products.

"But leave people who like the IFS alone". - Bob

You want some tissue CRYBABY!!!!!

@Bob - "But leave people who like the IFS alone".

if you don't like it, grab your purse and go home!

You anti-GM guys are ruining this post....Oh, wait a minute, it's also about Ford....

Bob - when GM looses the HD shoutout the sound of silence echoing from your gaping pie-hole will be deafening!

LOL@Tony



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