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 > 2021 Cummins 1075 lbft peak torque at 1356 rpm

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Me Again

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Posted: 01/01/21 04:31pm Link  |  Quote  |  Print  |  Notify Moderator

MikeRP wrote:


Yes I’ve watched that video. And I think they tested 30,000lbs without looking at it again.

So my point is all of them would end up at the tip at the same time with 20,000 lbs, do you agree?


All I know is my messily 385/865 RAM at 24,500 combined did just fine in the mountains along the West Coast and into the rockies. I like running up hills fast and never felt I did not have enough power to do the job. So seat of the pants RAM's do just fine. I love the full center console bucket seat Laramie, the 8.4 uconnect, nav system etc. The uconnect is head and shoulders ahead of the Ford Sync system in our 2020 Ford Edge ST.

[image]

* This post was edited 01/01/21 05:59pm by Me Again *


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4x4ord

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Posted: 01/01/21 04:42pm Link  |  Quote  |  Print  |  Notify Moderator

delete


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4x4ord

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Posted: 01/01/21 04:46pm Link  |  Quote  |  Print  |  Notify Moderator

MikeRP wrote:

Me Again wrote:

MikeRP wrote:

4x4ord wrote:

Me Again wrote:

FishOnOne wrote:

Torque charts are nice but just remember that's at full throttle and maximum boost while consuming maximum fuel. Not something you encounter when towing down the highway.

For me what's more important is the torque the engine can make while towing and making the towing the easiest while making the best fuel economy. This is very difficult to quantify except for the fuel economy performance. In my mind the Power Stroke is the leader in this category for the 2020 models and I suspect will continue to lead for the 2021 models.


Who really cares if one truck or the other tows up the Ike 12 seconds faster or slower than the other ones. All three are not your grandfather's truck anymore. Buy what turns your crank and enjoy it.



12 seconds isn’t much but I think the 2020 Ram was about a mile behind the 2020 Powerstroke. It might not matter but it kind of put the Powerstroke in a league of its own. I think it would be nice to see the 2021 close the gap a bit.


If we limit speed to the speed limit up the IKE, AND if we tow a more normal even large fifth wheel up the IKE, AND we say for example that would be 20,000 lbs for that large RV load but it’s not the 30,000+ lbs max load on TFLTrucks, I’m 95%positive all the big three diesel trucks make it up the IKE within seconds of each other.

This is a non issue for RVers now except for bragging rights like my truck is more powerful than yours.


2020's

-------------Ram 3500------GMC Sierra 3500-Ford F-350
Downhill-----0 brakes------9 brakes--------5 brakes
Uphill Time--11 min 32 sec-11 min 47 sec---10 min 20 sec
Uphill MPG---2.5 MPG-------2.4 MPG----------2.4 MPG
Subjective score-23.5 pts--22.5 pts--------23.5 pts
Ike score----72.5 pts------59 pts----------81.5 pts

https://tfltruck.com/2020/02/does-the-20........n-the-worlds-toughest-towing-test-video/


Yes I’ve watched that video. And I think they tested 30,000lbs without looking at it again.

So my point is all of them would end up at the tip at the same time with 20,000 lbs, do you agree?

The Ike is actually not a very steep grade for much of the hill. The average slope of the grade is only 5.6%. The grade starts out about 3.5% for the first 1.5 miles, then increases to about 6% and near the top there is a section that approaches 7%. To tow a 20,000 lb trailer up a 7% grade at 60 mph would take over 500 HP. To climb a 5.6% grade towing a 20,000 lb trailer at 60 mph would take very close to 430 HP. The 2021 Ram with the HO Cummins is probably rated to put out about 400 HP at 2100 rpm. Even though these trucks have turbo charged engines it is unlikely that they put out rated HP at 10,000 ft of elevation. So, they would not all be capable of keeping the speed limit up the Ike with 20k in tow.

* This post was edited 01/01/21 04:58pm by 4x4ord *

wilber1

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Posted: 01/01/21 05:53pm Link  |  Quote  |  Print  |  Notify Moderator

4x4ord wrote:

wilber1 wrote:

4x4ord wrote:


Your thinking the torque is 1075 lbft from 1356 to 1800 rpm, then drops to 807 lbft by the time the engine hits 2800 rpm .... maybe, I hope your right but I'm not convinced. I wish they would publish torque curves.


Sounds about right. When Cummins went from the 650 Lb Ft to 800 Lb Ft in 2011. Both hit peak torque at 1600 and made the same peak 350 HP at 2800. The 650 torque curve remained flat until peak HP and the 800's torque gradually declined until it made the same peak HP at 2800 RPM.


It's impossible to know exactly what the torque curve would look like when we are only given power or torque at two rpm points. If the article I read is right stating peak torque of 1075 lbft @ 1356 rpm, then we know that point. It is only possible that the torque remains at 1075 for as long as 2100 rpm. Beyond 2100 rpm the torque absolutely drops off but it could just as easily be dropping from 1400,1600,1800 ... who knows, we can only guess. If peak HP is 430 HP @ 2800 rpm then we know the torque at 2800 rpm is 807 lbft. As the engine rpm drops lower and lower form 2100 rpm the less relevant the torque value is as far as describing how the engine will pull a hill. It would be nice if Cummins would rate the engine as making peak torque of 1075 lbft from 1356 to 1600 or 1800 rpm ... or what ever it is.


The big thing is useful power. The 650 and 800 Cummins had the same peak power at the same RPM but the 800 made 30 more HP at 1600 RPM which is a normal towing RPM and very useful.


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MikeRP

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Posted: 01/01/21 06:18pm Link  |  Quote  |  Print  |  Notify Moderator

One of the advantages Cummins has on these engines is a massive database of empirical results for their products in all kinds of duty cycles. They are masters at looking at the customers application and providing correct engine for the goals of the customer.

I like all the Big 3’s products. Right now I’m just more familiar w Ram and I can’t get myself to buy a Ford.

spoon059

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Posted: 01/01/21 07:18pm Link  |  Quote  |  Print  |  Notify Moderator

Me Again wrote:

FishOnOne wrote:

Nonsensical trolling that adds nothing of value...

You are a 100-200K short there Fish!

The original troll... Why he feels the need to come to Ram threads when he will NEVER own one and can't help himself but to talk trash. I can only imagine the sad life that leads to this...

Please stop quoting him, it defeats the block feature.


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4x4ord

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Posted: 01/01/21 08:10pm Link  |  Quote  |  Print  |  Notify Moderator

wilber1 wrote:

4x4ord wrote:

wilber1 wrote:

4x4ord wrote:


Your thinking the torque is 1075 lbft from 1356 to 1800 rpm, then drops to 807 lbft by the time the engine hits 2800 rpm .... maybe, I hope your right but I'm not convinced. I wish they would publish torque curves.


Sounds about right. When Cummins went from the 650 Lb Ft to 800 Lb Ft in 2011. Both hit peak torque at 1600 and made the same peak 350 HP at 2800. The 650 torque curve remained flat until peak HP and the 800's torque gradually declined until it made the same peak HP at 2800 RPM.


It's impossible to know exactly what the torque curve would look like when we are only given power or torque at two rpm points. If the article I read is right stating peak torque of 1075 lbft @ 1356 rpm, then we know that point. It is only possible that the torque remains at 1075 for as long as 2100 rpm. Beyond 2100 rpm the torque absolutely drops off but it could just as easily be dropping from 1400,1600,1800 ... who knows, we can only guess. If peak HP is 430 HP @ 2800 rpm then we know the torque at 2800 rpm is 807 lbft. As the engine rpm drops lower and lower form 2100 rpm the less relevant the torque value is as far as describing how the engine will pull a hill. It would be nice if Cummins would rate the engine as making peak torque of 1075 lbft from 1356 to 1600 or 1800 rpm ... or what ever it is.


The big thing is useful power. The 650 and 800 Cummins had the same peak power at the same RPM but the 800 made 30 more HP at 1600 RPM which is a normal towing RPM and very useful.



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.

FishOnOne

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Posted: 01/02/21 08:15am Link  |  Quote  |  Print  |  Notify Moderator

4x4ord wrote:

wilber1 wrote:

4x4ord wrote:

wilber1 wrote:

4x4ord wrote:


Your thinking the torque is 1075 lbft from 1356 to 1800 rpm, then drops to 807 lbft by the time the engine hits 2800 rpm .... maybe, I hope your right but I'm not convinced. I wish they would publish torque curves.


Sounds about right. When Cummins went from the 650 Lb Ft to 800 Lb Ft in 2011. Both hit peak torque at 1600 and made the same peak 350 HP at 2800. The 650 torque curve remained flat until peak HP and the 800's torque gradually declined until it made the same peak HP at 2800 RPM.


It's impossible to know exactly what the torque curve would look like when we are only given power or torque at two rpm points. If the article I read is right stating peak torque of 1075 lbft @ 1356 rpm, then we know that point. It is only possible that the torque remains at 1075 for as long as 2100 rpm. Beyond 2100 rpm the torque absolutely drops off but it could just as easily be dropping from 1400,1600,1800 ... who knows, we can only guess. If peak HP is 430 HP @ 2800 rpm then we know the torque at 2800 rpm is 807 lbft. As the engine rpm drops lower and lower form 2100 rpm the less relevant the torque value is as far as describing how the engine will pull a hill. It would be nice if Cummins would rate the engine as making peak torque of 1075 lbft from 1356 to 1600 or 1800 rpm ... or what ever it is.


The big thing is useful power. The 650 and 800 Cummins had the same peak power at the same RPM but the 800 made 30 more HP at 1600 RPM which is a normal towing RPM and very useful.



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.


The other attributes to consider is the HO has lower compression and relies on the variable vane turbo more than the standard engine that has higher compression.


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larry barnhart

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Posted: 01/02/21 09:33am Link  |  Quote  |  Print  |  Notify Moderator

what happened to shiner I enjoy his comments.
chevman


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Posted: 01/02/21 10:12am Link  |  Quote  |  Print  |  Notify Moderator

larry barnhart wrote:

what happened to shiner I enjoy his comments.
chevman


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


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