Forum Discussion
192 Replies
chevor wrote:
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.
wut- Actually nice we can razz one another and not have it closed.
BTW you forgot to show the CHEBY guy looking for his keys in your clips. dshelley wrote:
It seems the Chevy received a few extra points for making it completely through the test without a single recall.
I must admit, that was funny!larry barnhart wrote:
I didn't think the whining was going to be this bad.....
chevman
Really? I was looking forward to it...
Upon seeing the results:
Ford Dude
Ram Dude
- I agree Roy, I have looked for one around here and haven't found one.
4x4ord wrote:
You are thinking about it in too much depth, it's much simpler. The longer the engine has to load the more power it will make.
There is also a big difference in torque, and sometime hp, based on how the run is started. 1400 rpms with no boost will make a lot less torque and possibly hp than 1400 rpm with 10 psi at the start of the run.
A 5th gear run from 1400-3200 has 46 mph to complete the run in, but 6th has 64. That extra speed of the roller means the engine gets closer to full load.
Correct, conditions on a hill are very difficult to duplicate on a chassis dyno. I make 30-32psi on no grade, and only 28ish on the dyno. That's load.
And it's for this reason that IMHO, all turbo diesel trucks should be done on a pull-down dyno, like big rigs.
A big diesel's inertia is too high for inertial dynos to measure accurately, and modern transmissions do not always allow full loading in a high gear.
Every heavy truck, school bus, tour coach, that I've seen is measure on a reverse pull-down dyno, which you start at max rpm and load it till below peak torque. But few light diesel shops are equipped with such expensive hardware.AH64ID wrote:
4x4ord wrote:
I have thought a bit about why a chassis dyno might read higher horsepower numbers in higher gears and have come up with what I think is a logical explanation: When power is transfered from the vehical tires to the chasis dyno's rollers, the torque exerted on the tiny contact patch distorts the tire. This distortion of the tire sidewall cosumes power. Running the truck in a higher gear would reduce the torque and therefore the distortion and power loss at the tire/roller contact point. The inertia type chasis dyno numbers are probably more valuable to dragsters interested in a 15 second run down the track. The conditions associated with a truck pulling a loaded trailer up a hill might be hard to duplicate on an inertia based chasis dyno.
You are thinking about it in too much depth, it's much simpler. The longer the engine has to load the more power it will make.
There is also a big difference in torque, and sometime hp, based on how the run is started. 1400 rpms with no boost will make a lot less torque and possibly hp than 1400 rpm with 10 psi at the start of the run.
A 5th gear run from 1400-3200 has 46 mph to complete the run in, but 6th has 64. That extra speed of the roller means the engine gets closer to full load.
Correct, conditions on a hill are very difficult to duplicate on a chassis dyno. I make 30-32psi on no grade, and only 28ish on the dyno. That's load.
OK, I think we can return to regular programming:)4x4ord wrote:
I have thought a bit about why a chassis dyno might read higher horsepower numbers in higher gears and have come up with what I think is a logical explanation: When power is transfered from the vehical tires to the chasis dyno's rollers, the torque exerted on the tiny contact patch distorts the tire. This distortion of the tire sidewall cosumes power. Running the truck in a higher gear would reduce the torque and therefore the distortion and power loss at the tire/roller contact point. The inertia type chasis dyno numbers are probably more valuable to dragsters interested in a 15 second run down the track. The conditions associated with a truck pulling a loaded trailer up a hill might be hard to duplicate on an inertia based chasis dyno.
You are thinking about it in too much depth, it's much simpler. The longer the engine has to load the more power it will make.
There is also a big difference in torque, and sometime hp, based on how the run is started. 1400 rpms with no boost will make a lot less torque and possibly hp than 1400 rpm with 10 psi at the start of the run.
A 5th gear run from 1400-3200 has 46 mph to complete the run in, but 6th has 64. That extra speed of the roller means the engine gets closer to full load.
Correct, conditions on a hill are very difficult to duplicate on a chassis dyno. I make 30-32psi on no grade, and only 28ish on the dyno. That's load.- I have thought a bit about why a chassis dyno might read higher horsepower numbers in higher gears and have come up with what I think is a logical explanation: When power is transfered from the vehical tires to the chasis dyno's rollers, the torque exerted on the tiny contact patch distorts the tire. This distortion of the tire sidewall cosumes power. Running the truck in a higher gear would reduce the torque and therefore the distortion and power loss at the tire/roller contact point. The inertia type chasis dyno numbers are probably more valuable to dragsters interested in a 15 second run down the track. The conditions associated with a truck pulling a loaded trailer up a hill might be hard to duplicate on an inertia based chasis dyno.
chevor wrote:
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 be quoted a few more times.
X2 :Z
