Rich1961
Spring Creek Nevada
Senior Member
Joined: 09/09/2006
View Profile
Good Sam RV Club Member
 Offline
|
4x4ord wrote:Huntindog wrote:4x4ord wrote:travelnutz wrote:Me Again,
DUH! HP is merely a theoretical calculation moniker derived from how fast the TORQUE applied to the drive wheels rotates them thus creating measurable RPM. HP is NOT a direct measurable value! Zero torque = Zero RPM and thus Zero HP could even be calculated. Even 1000 lbs feet torque with zero RPM = zero HP. There is Zero RPM if there's insufficient TORQUE to rotate the wheels. HP is merely a theoretical value calculation, not a measured value!
A "horse" does not have a given pulling or rotational strength value as there are vast differences is sizes and pulling strengths of all the various horses. A given size horse's pulling strength can be actually measured but which horse?
The more FORCE (TORQUE) one applies to wheel shaft, the more RPM's it will turn! No where is the word HP used or even involved to make the wheel turn to any RPM's!
TORQUE and RPM are measurable but NOT HP as it's only a theoretical calculation!
Read the article that meagain posted a link to. Power is the rate of doing work. Neither Rpm nor torque are needed to calculate HP. The formula: HP= torque x rpm/5252 is derived from the definition of horsepower(1 horsepower is the power required to lift 550 lbs 1ft in 1 second). If the formula involving rpm and torque were to be stated accurately it would read HP = torque x rpm x pi/16500. No matter. It is a well known fact that 4.10 gears will perform better in towing than 3.73s
So obviously, if the DA had 4.10s it would do better.
At one time, the Ram/Cummins was available with 3 different gear ratios, and 3 different tow ratings.
I will leave it up to the math gurus to debate as to why that is.
On this particular hill the Chevy might have been geared right. It started out at 55 mph and averaged about 46 mph so it likely spent a fair amount of time at around 40 mph. With 235/80r17 tires and the 3.73 gears the Duramax would be running 2854 rpm at 40 mph in second gear. If it had had a 4.10 final gear ratio at 40 mph the engine would be turning 2427 rpm in 3rd gear or 3137 in 2nd gear.....In either gear the truck would have slowed down.
Edit: The Ford should have been pretty comfortable at 40 mph with 4.10 final drives. It would have been running in 3rd gear at 2662 Which is pretty close to peak HP.
I doubt the Chevy got down to second gear as it would have to drop down to close to 2100 rpms in 3rd gear before it would shift to second. This would have caused an overall slower average speed and increased the time for the run.
Are you also taking the transmission gear ratios into consideration with your calculations? The Allison has the highest gear ratios of the three transmissions, and along with the 3.73's it is at a disadvantage to the other two with their considerably deeper gearing. A closer comparison would have been if the Ford had 3.55's and the Ram with 3.73's. With Fords and Rams deeper geared transmissions, the final drive ratios would have been much closer, and who knows, maybe the results would have been different.
It would be nice if they included in their testing which gears and rpm's the trucks used for the run, transmission temp, engine temp, and how much the suspension drops in the rear.
Rich
2016 Chevrolet/Duramax 3500HD Dually Crew Cab B&W RVK 3700 5th Wheel Hitch
2014 Arctic Fox 29-5T
|
ShinerBock
LVTX
Senior Member
Joined: 02/22/2015
View Profile
|
I agree with travelnutz. To add to it, an engine with more hp is useless if you don't have enough torque(engine or via gear multiplication) to be at the rpm to make that power. Some people think that once you take off from a stop then you don't need torque anymore and it is all HP. Well this is completely false because the force pulling you back is usually never constant and is always changing. Basically, HP cannot spin your tires at a certain speed if you do not have enough torque behind that spin to overcome the force that are keeping it from spinning. A vehicle will be limited to a gear and rpm that it has enough torque to overcome the forces holding it back and therefore limiting the amount of HP available and the speed it can go.
As far as the test, it was good but how fast a truck pull a certain amount of weight up a hill is only one factor. Being how close all three were, I don't see it being a major factor.
* This post was
edited 03/04/17 09:22am by ShinerBock *
2014 Ram 2500 6.7L CTD
2016 BMW 2.0L diesel (work and back car)
2023 Jeep Wrangler Rubicon 3.0L Ecodiesel
Highland Ridge Silverstar 378RBS
|
Cummins12V98
on the road
Senior Member
Joined: 06/03/2012
View Profile
Offline
|
SouthpawHD wrote:JustLabs wrote:Cummins12V98 wrote:FishOnOne wrote:Thanks for posting
That's all you are going to say????
Any reason for this post, other than to bait someone into an argument?
And you don't consider yourself a troll...lol
You hit the nail on the head! Even after warnings, it doesn't stop with these two.
A little late to the party! Things have been scrubbed from this thread you don't see. I was KIDDING Fish because he always has something to say. Guess I should have added a smiley face.
Have a good day!
2015 RAM LongHorn 3500 Dually CrewCab 4X4 CUMMINS/AISIN RearAir 385HP/865TQ 4:10's
37,800# GCVWR "Towing Beast"
"HeavyWeight" B&W RVK3600
2016 MobileSuites 39TKSB3 highly "Elited" In the stable
2007.5 Mobile Suites 36 SB3 29,000# Combined SOLD
|
Cummins12V98
on the road
Senior Member
Joined: 06/03/2012
View Profile
Offline
|
cummins2014 wrote:SouthpawHD wrote:JustLabs wrote:Cummins12V98 wrote:FishOnOne wrote:Thanks for posting
That's all you are going to say????
Any reason for this post, other than to bait someone into an argument?
And you don't consider yourself a troll...lol
You hit the nail on the head! Even after warnings, it doesn't stop with these two.
I'll second that
I thought we were friends? ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/wink.gif "wink")
|
4x4ord
Alberta
Senior Member
Joined: 12/23/2010
View Profile
|
ShinerBock wrote:I agree with travelnutz. To add to it, an engine with more hp is useless if you don't have enough torque(engine or via gear multiplication) to be at the rpm to make that power. Some people think that once you take off from a stop then you don't need torque anymore and it is all HP. Well this is completely false because the force pulling you back is usually never constant and is always changing. Basically, HP cannot spin your tires at a certain speed if you do not have enough torque behind that spin to overcome the force that are keeping it from spinning. A vehicle will be limited to a gear and rpm that it has enough torque to overcome the forces holding it back and therefore limiting the amount of HP available and the speed it can go.
As far as the test, it was good but how fast a truck pull a certain amount of weight up a hill is only one factor. Being how close all three were, I don't see it being a major factor.
The truck with the flattest power curve and most torque did the poorest..... this really doesn't make sense. The gear ratios of the TorqShift along with the flat power curve of the Powerstroke should have been able to keep the engine rpm at a level where it produces more HP than the peak horsepower of the Cummins at any point on the hill. No matter how you look at it things don't add up. Even at 2200 rpm the Powerstroke should be producing 380 HP. If the manufactures' HP and torque ratings are honest the Cummins could be coupled to an infinite speed transmission and still wouldn't keep up.
2023 F350 SRW Platinum short box 4x4.
B&W Companion
2008 Citation Platinum XL 34.5
|
|
|
Cummins12V98
on the road
Senior Member
Joined: 06/03/2012
View Profile
Offline
|
4x4ord wrote:I wonder if the trucks performance is based on the manufacturers advertising budget? Why would the Ford pull a 30,000 lb trailer up the hill a minute faster than the Ram and now with a lighter trailer it can't keep up? Why can't the new Duramax blow the doors off the old one?
All good points! I was very surprised the RAM was not way behind.
|
Cummins12V98
on the road
Senior Member
Joined: 06/03/2012
View Profile
Offline
|
"What most people dont understand is that the two V8's in this test have higher hp ratings that the mighty I6 but they get those numbers through RPM. If you don't have enough torque on the ground to get you to those higher RPM the hp numbers make no difference. I would love to see them do that same test with a Ram with 3.42 gearing. Other than taking a little longer to get up to speed i would bet it would be extremely close on average speed climbing the hill."
Since they start the timer at a rollin specified speed based on my experience owning 3.42's performing very well and in 5th the RPM's are very close to my current AISIN/4.10 combo in 6th. I think the results would be virtually identical for the RAM or very close. Some grades my old 3.42 truck out performed and some underperformed towing 29K compared to 4.10's towing 33K. No expert here but different gears with different ration at different speeds gave me mixed results.
|
4x4ord
Alberta
Senior Member
Joined: 12/23/2010
View Profile
|
I wonder if all three trucks were meeting emission requirements while the tests were being conducted. I suppose the more sophisticated engines might back the fuel off slightly if the turbo is not maintaining a high enough level of boost at the high elevation? Just a thought....
|
FishOnOne
The Great State of Texas
Senior Member
Joined: 02/12/2011
View Profile
Offline
|
Cummins12V98 wrote:SouthpawHD wrote:JustLabs wrote:Cummins12V98 wrote:FishOnOne wrote:Thanks for posting
That's all you are going to say????
Any reason for this post, other than to bait someone into an argument?
And you don't consider yourself a troll...lol
You hit the nail on the head! Even after warnings, it doesn't stop with these two.
A little late to the party! Things have been scrubbed from this thread you don't see. I was KIDDING Fish because he always has something to say. Guess I should have added a smiley face.
Have a good day!
I actually like cummins9812V comments and he generally has a good attitude. ![[emoticon]](http://www.coastresorts.com/sharedcontent/cfb/images/biggrin.gif "biggrin")
'12 Ford Super Duty FX4 ELD CC 6.7 PSD 400HP 800ft/lbs "270k Miles"
'16 Sprinter 319MKS "Wide Body"
|
ShinerBock
LVTX
Senior Member
Joined: 02/22/2015
View Profile
|
4x4ord wrote:
The truck with the flattest power curve and most torque did the poorest..... this really doesn't make sense. The gear ratios of the TorqShift along with the flat power curve of the Powerstroke should have been able to keep the engine rpm at a level where it produces more HP than the peak horsepower of the Cummins at any point on the hill. No matter how you look at it things don't add up. Even at 2200 rpm the Powerstroke should be producing 380 HP. If the manufactures' HP and torque ratings are honest the Cummins could be coupled to an infinite speed transmission and still wouldn't keep up.
My statement agreeing with travelnutz was more of a general statement regarding HP and Torque, and not about the Ike Test.
In regards to the Ike test, I agree that it is a bit of a head scratcher that the Ford had the slowest time with it's power rating. I know that Ford and Cummins use different SAE methods in determining their power ratings so their numbers really should not be seen as apples to apples.
The DPF on the Ford could have been clogged up or creating more back-pressure than the Ram. Another thing I could think that happened would be if the Ford defueled due to high exhaust temps which in turn would lower its power output. To my knowledge, only Ram with its Active Air and GM with its hood scoop have a way of pulling air from the front of the truck which would have an impact on exhaust gas temps.
|
|
|
