Forum Discussion
ktmrfs wrote:
todays trucks are all so capable (even over capable) of hauling big loads and high enough reliability such that these differences for me are so minor that my buying decisions have been based on other things like creature comfort, how quite the truck is, and other features long before I get to the "which truck is faster" criteria.
That's exactly right. My 08 Duramax 2500 towed my 14k (weight at a scale) fifth wheel up every mountain pass I drive over in the Northwest/Montana at the speed limit. When it was stock and after I tuned it. And I only tow a few times a year, so daily driving is my main focus when I bought miy 2020 Denali. I really wanted the RAM, but the Aisin drives like a big rig even unloaded. If I used it mostly to pull, I probably would have bought the RAM.RoyJ wrote:
4x4ord wrote:
If it can average 42 mph it would reach the top of the hill in 10 minutes 50 seconds.
According to the drag formula it would require 89 HP tp overcome drag and rolling resistance at 42 mph.
320 minus 89 leaves 231 HP which is the required HP to raise the 39000 lbs 2120 feet in 6 minutes and 50 seconds.
Edit: I guess I should have quoted the definition of HP:
1 horsepower is the power required to raise 550 lbs 1 ft in 1 second
So 39000 lbs x 2120 ft / (620 seconds x 550) is 242.46 HP
I think I spot the error now - when I crunch the following:
39000x2120/550/231hp
I get 650 seconds, not 6:50s. 650 seconds translates to 10:50s, which is a more reasonable time for the Ram.
If the Ram did do it in 6:50s, then its average speed would be significantly higher, and we'd have to start the iterative process all over again...
It takes a whole sack of flour to make a big biscuit.- todays trucks are all so capable (even over capable) of hauling big loads and high enough reliability such that these differences for me are so minor that my buying decisions have been based on other things like creature comfort, how quite the truck is, and other features long before I get to the "which truck is faster" criteria.
FishOnOne wrote:
blofgren wrote:
Now the real test will be to see the long term reliability of the new Powerstroke. I’m of an age now that I don’t give a **** about being the first to the top of the hill but I want to do it many times reliably which is why I went away from Ford to my current truck.
LOL... the new Power Stroke added Steel Pistons and the Cummins added a CP4.2!
If I were looking to buy a new diesel truck today, it would most likely be a GM.Cummins12V98 wrote:
4X you make my head hurt!
I do appreciate your knowledge.
X2. Your office must look like Einstein’s full of boards on the wall and sheets of paper spread around with many complex equations! :B- 4X you make my head hurt!
I do appreciate your knowledge. 4x4ord wrote:
If it can average 42 mph it would reach the top of the hill in 10 minutes 50 seconds.
According to the drag formula it would require 89 HP tp overcome drag and rolling resistance at 42 mph.
320 minus 89 leaves 231 HP which is the required HP to raise the 39000 lbs 2120 feet in 6 minutes and 50 seconds.
Edit: I guess I should have quoted the definition of HP:
1 horsepower is the power required to raise 550 lbs 1 ft in 1 second
So 39000 lbs x 2120 ft / (620 seconds x 550) is 242.46 HP
I think I spot the error now - when I crunch the following:
39000x2120/550/231hp
I get 650 seconds, not 6:50s. 650 seconds translates to 10:50s, which is a more reasonable time for the Ram.
If the Ram did do it in 6:50s, then its average speed would be significantly higher, and we'd have to start the iterative process all over again...FishOnOne wrote:
blofgren wrote:
Now the real test will be to see the long term reliability of the new Powerstroke. I’m of an age now that I don’t give a **** about being the first to the top of the hill but I want to do it many times reliably which is why I went away from Ford to my current truck.
LOL... the new Power Stroke added Steel Pistons and the Cummins added a CP4.2!
Cummins never had an issue with cracked pistons like the Powerstroke has had and the current pistons can easily handle over 600 RWHP for a long time so there is no need to change it. The CP4.2 was required in order to make more horsepower and meet emissions. If it weren't for emissions, they would no doubt still use the CP3.blofgren wrote:
Now the real test will be to see the long term reliability of the new Powerstroke. I’m of an age now that I don’t give a **** about being the first to the top of the hill but I want to do it many times reliably which is why I went away from Ford to my current truck.
LOL... the new Power Stroke added Steel Pistons and the Cummins added a CP4.2!RoyJ wrote:
4x4ord wrote:
I've been screwing around with the numbers and I think the Duramax time was not really that far off what should have been expected based on a 39000 lb truck and trailer and 2220 ft of elevation gain climbing the hill. Based on those same numbers the Ram should climb the hill in about 12 minutes. The thing that doesn't add up is that the Ford should not have been able to climb the hill in 6 minutes and 20 seconds running at the rpm it ran at unless it is putting out more power than Ford claims.
4x4ord, I'm curious what your calculation shows, if we pretend the L5P has a bigger turbo that does not lose hp at elevation. According to GM's graph, the engine is suppose to climb from 380 to 445hp from 2300 to 2800 rpm:
We know the high elevation dyno flattens out at 320 rwhp from 2300 - 2800 rpm. Assuming it climbs 55hp (account for drivetrain loss), so that it dynos 375 rwhp @ 2600 - 2800 rpm. What time would that turn out?
I'll let you play with the numbers:
Here's the way I come up with numbers to make the Ford run reasonable and predict a run time of 10 minutes 50 seconds for the Ram:
The distance from the freeway entrance at Dillon to just before the Eisenhower tunnel is 7.6 miles according to Google maps.
The elevation change from the ramp at Silverthorne/Dillon (9038 ft) to the Eisenhower tunnel (11158 ft) is 2120 ft.
The power required to raise 39000 lbs 2120 ft in 620 seconds is exactly 242.4 HP
Additionally there is drag and rolling resistance which can be approximated as follows:
For the Ford to travel 7.6 miles in 10 minutes 20 seconds it averaged 44 mph.
Weight of truck and trailer is 39000 lbs
HP based on frontal area and drag calculator at bottom of page
If I plug in a frontal area of 90, a coefficient of drag of .7, a speed of 44 mph and a weight of 39000 lbs the calculator spits out a HP requirement of 97 hp
242 plus 97 equals a rear wheel HP requirement of 339 HP. If the driveline is 85% efficient the Ford would have to be making 399 HP at the crankshaft to accomplish what it did.
the Ford is rated at 475 HP at 2800 rpm and 340 HP at 1700 .... looking at power curves of the Powerstroke it seems reasonable to assume it looses about 12.5 HP per 100 rpm. This would mean the Ford could make 400 HP at 2200 rpm.
Using the same logic and calculations for the Ram:
The Cummins makes 400 HP @ 2800 rpm and 343 HP at 1800 rpm
It seems reasonable to assume it will run up the hill in 3rd gear between 2100 and 2900 rpm. It should be able to average about 376 HP while running in that rpm range. Using the same 85% efficiency number 376 crank HP is 320 rear wheel HP.
If it can average 42 mph it would reach the top of the hill in 10 minutes 50 seconds.
According to the drag formula it would require 89 HP tp overcome drag and rolling resistance at 42 mph.
320 minus 89 leaves 231 HP which is the required HP to raise the 39000 lbs 2120 feet in 10 minutes and 50 seconds.
Edit: I guess I should have quoted the definition of HP:
1 horsepower is the power required to raise 550 lbs 1 ft in 1 second
So 39000 lbs x 2120 ft / (620 seconds x 550) is 242.46 HP
Edit: Fixed the error of calling 650 seconds 6 minutes 50 seconds changed it to to read 10 min 50 sec.
