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 > 2021 Cummins 1075 lbft peak torque at 1356 rpm

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Grit dog

Black Diamond, WA

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Posted: 01/02/21 11:06am Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

larry barnhart wrote:

what happened to shiner I enjoy his comments.
chevman


I would have expected him to be knee deep into this!


Thank the lord he finally gave up arguing with 4x4ord!
You know a thread is done like dinner when folks are quoting strings of posts with 6 quotes above their post.....


"Yes Sir, Oct 10 1888, Those poor school children froze to death in their tracks. They did not even find them until Spring. Especially hard hit were the ones who had to trek uphill to school both ways, with no shoes." -Bert A.

Grit dog

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Posted: 01/02/21 11:09am Link  |  Quote  |  Print  |  Notify Moderator

Oh and not that I care or that it matters one [email protected] bit, but 4x is probably right, and started this thread based on mis interpretation of an article.
Which should have been evident for someone so “savvy” and passionate about these types of things! Lol

wilber1

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Posted: 01/02/21 01:27pm Link  |  Quote  |  Print  |  Notify Moderator

Seven year old article but among other things it explains why diesels are using lower compression ratios..

Economist


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RoyJ

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Posted: 01/02/21 05:43pm Link  |  Quote  |  Print  |  Notify Moderator

4x4ord wrote:

Here is a quote from the article that mentions 1356 rpm as where peak torque is developed:


Ram and Cummins increased boost from the variable geometry turbocharger and upped the fuel delivery system’s flow rate. The changes for 2021 account for an additional 75 lb-ft. of torque versus a 2020 model. It’s worth noting the torque figure of 1,075 lb-ft. applies to the High Output version of the 6.7-liter Cummins Turbo Diesel, which is only available for the Ram 3500 HD. If you opt for a Ram 2500, the truck will come with the standard output Cummins engine with 850 lb-ft. of torque.

Another key difference is where the peak torque hits in the rpm band. The standard output Cummins provides peak torque at 1,700 rpm, while the High Output version will do so at 1,356 rpm.


The journalist was talking to a Ram engineer to get his information and after thinking about this I have a theory of a misunderstanding taking place. I’m thinking the engineer may have been comparing the standard vs HO engines. The engineer may have been talking about the rpm where torque is created and said something like “standard output engine makes peak torque of 850 lbft at 1700 rpm. The HO does that at 1356 rpm”. So maybe he was meaning the HO produces 850 lbft at 1356 rpm.

Until I know more I’m choosing to believe the new 2021 peak torque is 1075 lbft @ 1800 rpm.


I too think 1800 rpm is more realistic. The older articles that still reference 420 hp quoted 1075 lb-ft @ 1800.

1356 rpm is also too precise to be meaningful - not 1355, not 1357, but exactly at 1356 our engine makes 1075 torque... Most torque and hp ratings go down to a granularity of 50 rpm, not single digit precision.

I also doubt the torque makes a sharp downturn @ 1801 rpm, and make a linear drop to 2800, that's just not how engines naturally behave. If this engine can sustain 1000 lb-ft to around 2200 rpm, it'll make a very fat torque curve.

The closest curve I can find is the B6.7 marine tuned to 419 hp:

https://mart.cummins.com/imagelibrary/data/assetfiles/0055798.pdf

This engine holds near constant 420hp from 2200 to 3000 rpm. I bet the truck engine is close, because there're only so many ways to make 1075 lb-ft @ 1800, and also make 430 hp @ 2800.

blofgren

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Posted: 01/02/21 05:47pm Link  |  Quote  |  Print  |  Notify Moderator

Cummins12V98 wrote:

larry barnhart wrote:

what happened to shiner I enjoy his comments.
chevman


I would have expected him to be knee deep into this!


Hopefully he hasn't abandoned this site like many other great posters throughout the years have...


2013 Ram 3500 Megacab DRW Laramie 4x4, 6.7L Cummins, G56, 3.73, Maximum Steel, black lthr, RAM 20k sliding hitch, Retrax, Linex, and a bunch of options incl. cargo camera
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blofgren

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Posted: 01/02/21 05:48pm Link  |  Quote  |  Print  |  Notify Moderator

RoyJ wrote:

4x4ord wrote:

Here is a quote from the article that mentions 1356 rpm as where peak torque is developed:


Ram and Cummins increased boost from the variable geometry turbocharger and upped the fuel delivery system’s flow rate. The changes for 2021 account for an additional 75 lb-ft. of torque versus a 2020 model. It’s worth noting the torque figure of 1,075 lb-ft. applies to the High Output version of the 6.7-liter Cummins Turbo Diesel, which is only available for the Ram 3500 HD. If you opt for a Ram 2500, the truck will come with the standard output Cummins engine with 850 lb-ft. of torque.

Another key difference is where the peak torque hits in the rpm band. The standard output Cummins provides peak torque at 1,700 rpm, while the High Output version will do so at 1,356 rpm.


The journalist was talking to a Ram engineer to get his information and after thinking about this I have a theory of a misunderstanding taking place. I’m thinking the engineer may have been comparing the standard vs HO engines. The engineer may have been talking about the rpm where torque is created and said something like “standard output engine makes peak torque of 850 lbft at 1700 rpm. The HO does that at 1356 rpm”. So maybe he was meaning the HO produces 850 lbft at 1356 rpm.

Until I know more I’m choosing to believe the new 2021 peak torque is 1075 lbft @ 1800 rpm.


I too think 1800 rpm is more realistic. The older articles that still reference 420 hp quoted 1075 lb-ft @ 1800.

1356 rpm is also too precise to be meaningful - not 1355, not 1357, but exactly at 1356 our engine makes 1075 torque... Most torque and hp ratings go down to a granularity of 50 rpm, not single digit precision.

I also doubt the torque makes a sharp downturn @ 1801 rpm, and make a linear drop to 2800, that's just not how engines naturally behave. If this engine can sustain 1000 lb-ft to around 2200 rpm, it'll make a very fat torque curve.

The closest curve I can find is the B6.7 marine tuned to 419 hp:

https://mart.cummins.com/imagelibrary/data/assetfiles/0055798.pdf

This engine holds near constant 420hp from 2200 to 3000 rpm. I bet the truck engine is close, because there're only so many ways to make 1075 lb-ft @ 1800, and also make 430 hp @ 2800.


This makes total sense. I'm staying far away from the Ram dealerships because it could be dangerous to test drive one! [emoticon]

4x4ord

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Posted: 01/03/21 08:27am Link  |  Quote  |  Print  |  Notify Moderator

RoyJ wrote:

4x4ord wrote:

Here is a quote from the article that mentions 1356 rpm as where peak torque is developed:


Ram and Cummins increased boost from the variable geometry turbocharger and upped the fuel delivery system’s flow rate. The changes for 2021 account for an additional 75 lb-ft. of torque versus a 2020 model. It’s worth noting the torque figure of 1,075 lb-ft. applies to the High Output version of the 6.7-liter Cummins Turbo Diesel, which is only available for the Ram 3500 HD. If you opt for a Ram 2500, the truck will come with the standard output Cummins engine with 850 lb-ft. of torque.

Another key difference is where the peak torque hits in the rpm band. The standard output Cummins provides peak torque at 1,700 rpm, while the High Output version will do so at 1,356 rpm.


The journalist was talking to a Ram engineer to get his information and after thinking about this I have a theory of a misunderstanding taking place. I’m thinking the engineer may have been comparing the standard vs HO engines. The engineer may have been talking about the rpm where torque is created and said something like “standard output engine makes peak torque of 850 lbft at 1700 rpm. The HO does that at 1356 rpm”. So maybe he was meaning the HO produces 850 lbft at 1356 rpm.

Until I know more I’m choosing to believe the new 2021 peak torque is 1075 lbft @ 1800 rpm.


I too think 1800 rpm is more realistic. The older articles that still reference 420 hp quoted 1075 lb-ft @ 1800.

1356 rpm is also too precise to be meaningful - not 1355, not 1357, but exactly at 1356 our engine makes 1075 torque... Most torque and hp ratings go down to a granularity of 50 rpm, not single digit precision.

I also doubt the torque makes a sharp downturn @ 1801 rpm, and make a linear drop to 2800, that's just not how engines naturally behave. If this engine can sustain 1000 lb-ft to around 2200 rpm, it'll make a very fat torque curve.

The closest curve I can find is the B6.7 marine tuned to 419 hp:

https://mart.cummins.com/imagelibrary/data/assetfiles/0055798.pdf

This engine holds near constant 420hp from 2200 to 3000 rpm. I bet the truck engine is close, because there're only so many ways to make 1075 lb-ft @ 1800, and also make 430 hp @ 2800.


I think this is going to be very close to what the torque curves of the Powerstroke vs 2021 HO Cummins will look like;

[image]

* This post was last edited 01/04/21 12:37pm by 4x4ord *   View edit history


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FishOnOne

The Great State of Texas

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Posted: 01/03/21 04:23pm Link  |  Quote  |  Print  |  Notify Moderator

4x4ord wrote:

RoyJ wrote:

4x4ord wrote:

Here is a quote from the article that mentions 1356 rpm as where peak torque is developed:


Ram and Cummins increased boost from the variable geometry turbocharger and upped the fuel delivery system’s flow rate. The changes for 2021 account for an additional 75 lb-ft. of torque versus a 2020 model. It’s worth noting the torque figure of 1,075 lb-ft. applies to the High Output version of the 6.7-liter Cummins Turbo Diesel, which is only available for the Ram 3500 HD. If you opt for a Ram 2500, the truck will come with the standard output Cummins engine with 850 lb-ft. of torque.

Another key difference is where the peak torque hits in the rpm band. The standard output Cummins provides peak torque at 1,700 rpm, while the High Output version will do so at 1,356 rpm.


The journalist was talking to a Ram engineer to get his information and after thinking about this I have a theory of a misunderstanding taking place. I’m thinking the engineer may have been comparing the standard vs HO engines. The engineer may have been talking about the rpm where torque is created and said something like “standard output engine makes peak torque of 850 lbft at 1700 rpm. The HO does that at 1356 rpm”. So maybe he was meaning the HO produces 850 lbft at 1356 rpm.

Until I know more I’m choosing to believe the new 2021 peak torque is 1075 lbft @ 1800 rpm.


I too think 1800 rpm is more realistic. The older articles that still reference 420 hp quoted 1075 lb-ft @ 1800.

1356 rpm is also too precise to be meaningful - not 1355, not 1357, but exactly at 1356 our engine makes 1075 torque... Most torque and hp ratings go down to a granularity of 50 rpm, not single digit precision.

I also doubt the torque makes a sharp downturn @ 1801 rpm, and make a linear drop to 2800, that's just not how engines naturally behave. If this engine can sustain 1000 lb-ft to around 2200 rpm, it'll make a very fat torque curve.

The closest curve I can find is the B6.7 marine tuned to 419 hp:

https://mart.cummins.com/imagelibrary/data/assetfiles/0055798.pdf

This engine holds near constant 420hp from 2200 to 3000 rpm. I bet the truck engine is close, because there're only so many ways to make 1075 lb-ft @ 1800, and also make 430 hp @ 2800.


I think this is going to be very close to what the torque curves of the Powerstroke vs 2021 HO Cummins will look like;[image]


That torque curve on the Power Stroke looks very flat.


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4x4ord

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Posted: 01/03/21 04:39pm Link  |  Quote  |  Print  |  Notify Moderator

^^^It is. We know two points on the Powerstroke's torque curve. 1050 lbft @ 1600 rpm and 960 lbft @ 2600 rpm. So it only has a torque rise of 90 lbft over 1000 rpm.

If the Powerstroke doesn't make enough torque to pull a hill in a particular gear the engine will slow down without putting a whole lot more torque to the rear wheels until the rpm drops enough to allow for a shift in the transmission. The Cummins on the other hand has a little more torque rise so as the engine slows more and more torque is put to the rear wheels to meet the demands of the hill. The Cummins is really quite happy with a 6 speed.

* This post was edited 01/03/21 04:49pm by 4x4ord *

Me Again

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Posted: 01/04/21 05:08am Link  |  Quote  |  Print  |  Notify Moderator

Hum, I have known that for 5+ years now!


Ford Edge ST Twin Turbo 2.7L V6 335HP and 380 Lb Ft - Summer Home 2017 Bighorn 3575el. Can Am Spyder RT-L Chrome. Retired and enjoying it!


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