Forum Discussion
192 Replies
4x4ord wrote:
The drive line can handle tremendous torque and could very likely handle the 3000 or so lbft that comes out the back of the transmission under full fueling. I pull heavy trailers in very soft ground at times and have needed to shift the transfer case into 4 low where the torque is multiplied by 2.72. If the driveline can't handle full fuel in high range just think how severely the fuel must be limited in low range.
Yes they can handle an immense amount, but not full engine torque with resistance and survive in terms of longevity.
Get an OBDII scanner and watch load, you would be shocked at how little load it takes in lower gears to get the job done especially once you are in 4lo.
I'm not the one who put torque management into these trucks, I just know it exists and the reasons for it.4x4ord wrote:
AH64ID wrote:
The second comment is also about a chassis dyno and how they are effected by engine loading. To make 50 more ft/lbs of torque at 2500 rpms takes 35 more hp, you know the equation since you posted it. So you should have no problems understanding that at 2500 rpms 800 ft/lbs is 380 hp, and 850 ft/lbs is 405 hp... A difference of 35, weird right!. There you go , gears made hp... Um no, not really the point if that was to show the issues of a loading the engine on a chassis dyno, not real world power production. On a chassis dyno taller gearing allows the engine to make more hp, and more torque.. Not because of the gearing but because the load required to spin the tires is higher.
If a vehicle on the dyno is ran in 5th and makes 415/800 and then ran in 6th and makes 425/850 the hp curves are not identical. Which one do you think is more accurate? What do you think made the extra hp in the middle of the rpm band? I can tell you the gearing didn't do it, it just facilitated it.
Think about it from the engine's perspective. An engine is placed on a bench and is running at full throttle and loaded down to 2500 rpm. The power output is measured at the crank and determined to be 500 HP. Now hook it up to a driveline and load it down to 2500 rpm. The engine has no knowledge of what happens down stream of the crank. The power measured at the rear wheels will be less than 500 HP due to inefficiencies in the driveline. If in 5th gear you happen to measure less power than 6th gear it is because more power is being turned into heat while running through 5th or because your dyno is not capable of taking accurate measurements at different wheel speeds or a combination of the two. So you could say gears make heat ... therefore consume power.
Very true real world, but not true on an chassis dyno unless it's a pull down dyno which are rare. If you could find a pull down dyno and run from redline down to 1500 you might see that, and that would be cool info to see.
However, on a standard chassis dyno the engine isn't fully loaded in a shorter gear, the rpms revved too fast for full power to be developed. A chassis dyno measures acceleration of the dyno wheel, if you have a short run with a small mph gain, i.e. short gears, then the power is lower than a run that takes the same time but has more mph gain on the wheel, i.e. taller gear.
This is very common putting a turbo diesel on a chassis dyno, run in the highest gear possible. Increases smoke and low boost are both indicators of the engine not having enough load.
Anyways, this has gone too fat OT. The data here, and elsewhere, gearing increases rearranged wheel torque. The gearing can come from the trans or axle, but in the end the more hp and the more wheel torque means the most work at the highest rate. Taller rear axle gears do fine at speed, 1 gear lower, and lower gears get going quicker.4x4ord wrote:
AH64ID wrote:
4x4ord wrote:
Cummins12V98 wrote:
AH64ID wrote:
Cummins12V98 wrote:
4x4ord wrote:
Cummins12V98 wrote:
Would have been interesting to see what would have happened if they could have turned off the torque management.
What do you mean by "torque maagement"?
RAM does not allow full power in the low gears until you are moving along.
None of the engines are allowed to make full power in lower gears.
There isn't a drive-train that would fit and hold full torque off the line, and not cost what a full drag trans costs.
I know the RAM reduces it a lot. I can really feel when it comes on.
Interesting to know how much on each brand. Anyone know?
Where does this idea come from that "none of the engines are allowed to make full power in the lower gears"? does the computer limit fuel until it shifts into 3rd? I have heard people throw this "torque management" term around but have doubts that it refers to limiting torque in lower gears. I think the computer backs off fuel during shifting to avoid slipping the transmission clutches and wonder if this might be what "torque management" refers to?
Torque Management does refer to low gear fueling, there is less total power available in lower gears. Most people never notice it because the gearing reduction makes up for the lower power output, and the trucks still accelerate quickly with a load.
What you are thinking of is called shift defuel and a different ECM control than torque management.
Torque management has been around since the late 90's and occurs in all 3 makes and both manual and automatic transmissions.
EFI live actually has tables you can see that show the max torque available at a certain rpm.
Vehicle engineers have also verified this.
The driveline simply cannot handle full torque with the gear reduction of low gears.
The drive line can handle tremendous torque and could very likely handle the 3000 or so lbft that comes out the back of the transmission under full fueling. I pull heavy trailers in very soft ground at times and have needed to shift the transfer case into 4 low where the torque is multiplied by 2.72. If the driveline can't handle full fuel in high range just think how severely the fuel must be limited in low range.
I think it need to quoted a few more times.AH64ID wrote:
The second comment is also about a chassis dyno and how they are effected by engine loading. To make 50 more ft/lbs of torque at 2500 rpms takes 35 more hp, you know the equation since you posted it. So you should have no problems understanding that at 2500 rpms 800 ft/lbs is 380 hp, and 850 ft/lbs is 405 hp... A difference of 35, weird right!. There you go , gears made hp... Um no, not really the point if that was to show the issues of a loading the engine on a chassis dyno, not real world power production. On a chassis dyno taller gearing allows the engine to make more hp, and more torque.. Not because of the gearing but because the load required to spin the tires is higher.
If a vehicle on the dyno is ran in 5th and makes 415/800 and then ran in 6th and makes 425/850 the hp curves are not identical. Which one do you think is more accurate? What do you think made the extra hp in the middle of the rpm band? I can tell you the gearing didn't do it, it just facilitated it.
Think about it from the engine's perspective. An engine is placed on a bench and is running at full throttle and loaded down to 2500 rpm. The power output is measured at the crank and determined to be 500 HP. Now hook it up to a driveline and load it down to 2500 rpm. The engine has no knowledge of what happens down stream of the crank. The power measured at the rear wheels will be less than 500 HP due to inefficiencies in the driveline. If in 5th gear you happen to measure less power than 6th gear it is because more power is being turned into heat while running through 5th or because your dyno is not capable of taking accurate measurements at different wheel speeds or a combination of the two. So you could say gears make heat ... therefore consume power.AH64ID wrote:
4x4ord wrote:
Cummins12V98 wrote:
AH64ID wrote:
Cummins12V98 wrote:
4x4ord wrote:
Cummins12V98 wrote:
Would have been interesting to see what would have happened if they could have turned off the torque management.
What do you mean by "torque maagement"?
RAM does not allow full power in the low gears until you are moving along.
None of the engines are allowed to make full power in lower gears.
There isn't a drive-train that would fit and hold full torque off the line, and not cost what a full drag trans costs.
I know the RAM reduces it a lot. I can really feel when it comes on.
Interesting to know how much on each brand. Anyone know?
Where does this idea come from that "none of the engines are allowed to make full power in the lower gears"? does the computer limit fuel until it shifts into 3rd? I have heard people throw this "torque management" term around but have doubts that it refers to limiting torque in lower gears. I think the computer backs off fuel during shifting to avoid slipping the transmission clutches and wonder if this might be what "torque management" refers to?
Torque Management does refer to low gear fueling, there is less total power available in lower gears. Most people never notice it because the gearing reduction makes up for the lower power output, and the trucks still accelerate quickly with a load.
What you are thinking of is called shift defuel and a different ECM control than torque management.
Torque management has been around since the late 90's and occurs in all 3 makes and both manual and automatic transmissions.
EFI live actually has tables you can see that show the max torque available at a certain rpm.
Vehicle engineers have also verified this.
The driveline simply cannot handle full torque with the gear reduction of low gears.
The drive line can handle tremendous torque and could very likely handle the 3000 or so lbft that comes out the back of the transmission under full fueling. I pull heavy trailers in very soft ground at times and have needed to shift the transfer case into 4 low where the torque is multiplied by 2.72. If the driveline can't handle full fuel in high range just think how severely the fuel must be limited in low range.- OK, I did this work a long time ago to illustrate the difference in power delivery between the Ford 6.7 (at its old 390/735 tune or whatever it first came out as vs. the ecoboost motor. In these charts, you can see that horsepower only changes with the RPM, it neither increases nor decreases as you go through the gears. However, torque applied to the pavement certainly changes as you slam through the gears of a transmission.
Some things need to be straightened out. Work is a measure in productivity. In all physics, work is only accomplished when a force being applied moves an object over a certain distance or in an engine's case, number of revolutions. Torque is only a force, period. If you apply 1,000 lbft of force onto a leverage bar, but it doesn't move at all, you have accomplished nothing. No work was completed. If you apply 2 lbft of torque and move the leverage bar, you've accomplished work and horsepower can be rated. it's that simple. Any old school physics professor would whack your knuckles with a yard stick if you called torque "work".
Turtle n Peeps wrote:
Why am I hung up on power?
Because you keep on saying things like:This is why higher gears make more power, especially on turbo motors.
It's the second time you said gears make power. No they do not.
And you said before that:At 2500 rpms that is like an additional 35hp... So yes it does make a difference.
So there you flat out said gears made 35 HP. :S
This is real simple. If gears made 35 HP like you said above link me up. Show me a chassis dyno run that shows more power being generated to the ground with shorter gears just like you said above. Should be easy to show............if you are correct.
I'm done if you can't show me a dyno run or even link me up to a thread showing your point.
Turtle, normally we see things the same in the HP/torque discussion and I know you know the technical difference. I think you two guys are simply miscommunicating.
I think AH64ID's comment about 35HP more was referring to the HP available at a given road speed. While gearing does not make HP, it does directly affect the engine RPM (for a specific road speed) which in turn directly affects the HP the engine produces. This doesn't mean the gearing makes the HP, but it enables the engine to do it.
So...for a specific load on and specific hill, lower rear end gears may very well help. Let's pick two identical engines pulling the same load on the same hill but with different gearing. Let's say to pull at 50mph one runs at 2500rpm and the other at 2750rpm. With a flat torque curve, the 2750rpm engine will be outputting 10% more HP than the 2500rpm one. The extra power can be applied to accelerate the truck.
However, ease up the hill a little and you may end up with a different result. If the lower-geared truck rev's out and needs to shift, the higher-geared one will outperform it.Turtle n Peeps wrote:
Why am I hung up on power?
Because you keep on saying things like:This is why higher gears make more power, especially on turbo motors.
It's the second time you said gears make power. No they do not.
And you said before that:At 2500 rpms that is like an additional 35hp... So yes it does make a difference.
So there you flat out said gears made 35 HP. :S
This is real simple. If gears made 35 HP like you said above link me up. Show me a chassis dyno run that shows more power being generated to the ground with shorter gears just like you said above. Should be easy to show............if you are correct.
I'm done if you can't show me a dyno run or even link me up to a thread showing your point.
You are mixing points, and cannot follow the conversation. Power is the correct term in both of those quotes, but thats not what this discussion is really about.
The comment about higher gears and more power was speaking directly to a dyno. Go dyno in 1st and 6th, which one makes more hp? The 6th gear run does, which goes directly inline with my comment on loading the motor on the dyno and NOT real world. Torque management aside the hp is the same and the torque to the wheels would be higher in 1st than 6th on the street.
The second comment is also about a chassis dyno and how they are effected by engine loading. To make 50 more ft/lbs of torque at 2500 rpms takes 35 more hp, you know the equation since you posted it. So you should have no problems understanding that at 2500 rpms 800 ft/lbs is 380 hp, and 850 ft/lbs is 405 hp... A difference of 35, weird right!. There you go , gears made hp... Um no, not really the point if that was to show the issues of a loading the engine on a chassis dyno, not real world power production. On a chassis dyno taller gearing allows the engine to make more hp, and more torque.. Not because of the gearing but because the load required to spin the tires is higher.
If a vehicle on the dyno is ran in 5th and makes 415/800 and then ran in 6th and makes 425/850 the hp curves are not identical. Which one do you think is more accurate? What do you think made the extra hp in the middle of the rpm band? I can tell you the gearing didn't do it, it just facilitated it.
Out of curiosity have you ever ran a vehicle on a chassis dyno? If yes where any of them a turbo diesel?
Forget hp and forget about the chassis dyno, they output torque based on rpm and hp made and do not display the actual torque at the wheel.. We also know that based on your equation above and the simple fact of gearing reduction. Since we know hp is constant thru gearing reduction it's easy to see how a chassis dyno does not measure wheel torque, but wheel hp that we can calculate engine torque (not wheel torque) from if a engine tachometer is used.
To further show how you cannot follow the conversation the 35hp comment was with a taller gear, not a shorter one. Go ahead, scroll back up and see for yourself.
I have my latest dyno sheets at work, I will look and see if I printed the one with a 5th and 6th run; however, it's completely irrelevant to the discussion about 4.10's and their effect on towing and rear wheel torque.- Why am I hung up on power?
Because you keep on saying things like:This is why higher gears make more power, especially on turbo motors.
It's the second time you said gears make power. No they do not.
And you said before that:At 2500 rpms that is like an additional 35hp... So yes it does make a difference.
So there you flat out said gears made 35 HP. :S
This is real simple. If gears made 35 HP like you said above link me up. Show me a chassis dyno run that shows more power being generated to the ground with shorter gears just like you said above. Should be easy to show............if you are correct.
I'm done if you can't show me a dyno run or even link me up to a thread showing your point. 4x4ord wrote:
Cummins12V98 wrote:
AH64ID wrote:
Cummins12V98 wrote:
4x4ord wrote:
Cummins12V98 wrote:
Would have been interesting to see what would have happened if they could have turned off the torque management.
What do you mean by "torque maagement"?
RAM does not allow full power in the low gears until you are moving along.
None of the engines are allowed to make full power in lower gears.
There isn't a drive-train that would fit and hold full torque off the line, and not cost what a full drag trans costs.
I know the RAM reduces it a lot. I can really feel when it comes on.
Interesting to know how much on each brand. Anyone know?
Where does this idea come from that "none of the engines are allowed to make full power in the lower gears"? does the computer limit fuel until it shifts into 3rd? I have heard people throw this "torque management" term around but have doubts that it refers to limiting torque in lower gears. I think the computer backs off fuel during shifting to avoid slipping the transmission clutches and wonder if this might be what "torque management" refers to?
It absolutely reduces the power the engine can apply. You can feel when it opens up.
Someone smarter than me hopefully can explain what RAM/Cummins does.4x4ord wrote:
Cummins12V98 wrote:
It took me a while to understand why I could still pull every grade along I-5 border to border at 55 or more with the 3:42's at near 29K. It's gearing. But I found out it does not like to take off on a steep hill from a start. That is why my next RAM (not Dodge) will have 4:10's.
When I went on the TDR and told of my purchase and what I was towing you would have thought the sky was falling! I did have a price from the dealer to swap front and rear diffs to 4:10 for $1,500 but decided not to after seeing how the truck performed.
I have been thinking lately I may just go ahead and do the gear swap if RAM does not get the air ride in the 3500 dually's soon.
I tow loads close to 40,000 lbs with 3.55 gears and 20" wheels (34" tall tires) and I honestly have a hard time believing how easy the Ford makes the task of getting going seem. You put the truck in drive and touch the accelerator and it takes off as though you're not hooked to anything. Our GM on the other hand does let you know you have a huge load hooked up that you're trying to get going. The Duramax revs and you slowly start moving until the trailer wheels drop in a hole or need to climb over a mole hill causing the truck to almost stop. Part of the difference is the lower 1st gear ratio that the Ford transmission has but I believe much of it is the torque converter. The Aisin transmission has a lower 1st gear (3.74:1) than your 68RFE (3.23:1) so the Aisin mated with a 3.73 rear end would have a very similar 1st gear ratio as your 68RFE mated to 4.10 rear gears and very similar as well to my Ford's 1st gear mated to the 3.55 rear end.
Thanks good info. Something else to consider!
