Forum Discussion
96 Replies
- And towing just got easier with the medium duty 6.7 Power Stroke and Torque Shift transmission.
4x4ord wrote:
........so isn't it likely that "torque management" refers to cutting fuel during shift points to protect the clutches in the transmission?
Torque management is also cutting fuel, boost, and timing in lower gears and rpms to keep cylinder pressure(aka torque) in check so you don't blow head gaskets. It will also defuel if your EGT's get too high. If you have ever tuned a diesel with EFILive and saw the tables then you would understand.
Maybe the video below might help explain things a little better than I. Note that it is a tuned engine so the torque management is altered and the percentages would be less in more gears in stock form. An tuned diesel with head studs and a built trans can run with torque management off or lowered.
LNF Torque Management Video- The F350 DRW has a 6000 fawr and a 9900 rawr = 15900 lbs of braking performance at a minimum.
Now hook up a 30000 lb Kaufman tri axle GN flat deck trailer with 3 10k axles = 30000 lbs of braking performance. Other brands can have two 15k axles.
Now the F350 DRW and a 30k trailer have 45900 lbs of braking performance at a minimum.
In this line of work the trucks brakes stops the truck and its rated load and the trailers brakes stops the trailer.
Its rare we see a 30000+ lb rv trailer on the road. transamz9 wrote:
My Aisin locks the TC in 2nd in TH.
So does the 68RFE, but what I am referring to the times it isn't locked like at wide open or above 70% throttle. The stock TC is very inefficient when unlocked due to its high stall speed.- So now you have a truck with the same HP and 2/3 the torque of a Big Rig over the road tractor.
Have they- Ford-Dodge-Chevy increased the braking ability? Not with an exhaust brake, but with brake rotor diameter, larger calipers, stronger pistons in the calipers, etc? So you can tow 32000 lbs, but can you stop it? According to the SAE J2807, the truck only has to stop 3500lbs. ShinerBock wrote:
LMMNOCATS_EFI wrote:
I’m making numbers that would eat this truck alive towing the same weight (I’d be over on the pin lol but I’d win lol anyway) also on a stock trans at its limits and the rest all has 377k and ticking but the TC issue is somthin that can’t be messed with with efi? Mine locks up but it seems to be if I switch to a higher tune from the next that it’ll stay locked but yeah you will notice it switch from what I have tunes 1-5 . It makes a big difference now can only imagine how it’ll be with new lift pump ??it’s nice to be able to pull pass semis that can’t be built as well while towing a large load
Yes, the TC lockup strategy on the 68RFE can be manipulated as it is with my tune. However, when I talk about TC inefficiency, I am talking about when it isn't locked.
Let me paint a scenario for you. Say you are making a slow turn to go up a hill. As you make the turn your truck remains in 3rd gear with the TC unlocked. As you start up the hill you press the throttle bot all your engine does is wail away at high rpms, but doesn't seem to be going anywhere fast. As you gain speed your rpms will start to drop as your TC starts to couple and eventually lock up giving you a rush of torque to power up the hill.
The point at which the TC isn't locked and your just spinning uncoupled at high rpms not going anywhere fast is what I am talking about when I say that the stock TC is inefficient since it has a high stall speed(which I assume is to protect the trans). This not an issue for an aftermarket TC with a lower stall speed. There is not wailing away at high rpms waiting for the torque converter to lock since it is more efficient at giving more of the engine power even when not locked.
This is one of the major reasoned why I believe the Aisin is so slow off the line(aside from torque management) as well from dead stop. The torque converter is not that efficient and is just wasting most of the engines power as it spins at high rpms.
Best way I can explain it is this video. If you watch at 1:20 of the video when he drives their shop truck, you will notice how much more power was sent to the wheels even when the TC wasn't locked. Trust me, it is night and day on how much power is sent to the wheels when unlocked versus the stocker.
How I RUINED My Diesel's Transmission... Don't Ever Try This!
My Aisin locks the TC in 2nd in TH.Cummins12V98 wrote:
They know they need to do something since the 2019 RAM will have zero engine emissions and will be coming out with big numbers because of that.
There are a few (like you) pulling 30,000 lb rv's with 385 HP who could maybe use a little more power but I think I would have more use for a cold water dispenser in my truck than more power.ShinerBock wrote:
4x4ord wrote:
I am not certain but I think you guys haven't got a clue what you're talking about as far as how torque management works. When I put my truck in 4 low with a 30,000 lb trailer hooked up and sunk in the mud the amount of torque going to the rear wheels is huge. .. The driveline has to be able to handle full engine torque in 2nd gear while the tranfer case is in high range. My limited understanding of torque management is that the computer backs off fuel delivery during shifts in order to limit high torque on the clutches before they have a chance to fully engage.
That is due to gear torque multiplication in the transfer case which is after the transmission. The amount of torque going in and being multiplied out of the transmission is still the same whether you are in 2 high or 4 low. In the case of your truck, 4 low multiplies the torque coming out of your transmission by 2.72 and then additional amount depending on your front/rear gear ratio.
Additionally the torque converter has a wide open throttle torque ratio of 1.9:1. The 2.72:1 was the transfer case ratio in the old body style; the new trucks have a transfer case with a low range ratio of 2.64:1. Regardless, it is obvious that the driveshaft and axle can take high torque and even more obvious is the fact that the input shaft of the transmission and the torque converter can handle full engine torque.........so isn't it likely that "torque management" refers to cutting fuel during shift points to protect the clutches in the transmission?LMMNOCATS_EFI wrote:
I’m making numbers that would eat this truck alive towing the same weight (I’d be over on the pin lol but I’d win lol anyway) also on a stock trans at its limits and the rest all has 377k and ticking but the TC issue is somthin that can’t be messed with with efi? Mine locks up but it seems to be if I switch to a higher tune from the next that it’ll stay locked but yeah you will notice it switch from what I have tunes 1-5 . It makes a big difference now can only imagine how it’ll be with new lift pump ??it’s nice to be able to pull pass semis that can’t be built as well while towing a large load
Yes, the TC lockup strategy on the 68RFE can be manipulated as it is with my tune. However, when I talk about TC inefficiency, I am talking about when it isn't locked.
Let me paint a scenario for you. Say you are making a slow turn to go up a hill. As you make the turn your truck remains in 3rd gear with the TC unlocked. As you start up the hill you press the throttle bot all your engine does is wail away at high rpms, but doesn't seem to be going anywhere fast. As you gain speed your rpms will start to drop as your TC starts to couple and eventually lock up giving you a rush of torque to power up the hill.
The point at which the TC isn't locked and your just spinning uncoupled at high rpms not going anywhere fast is what I am talking about when I say that the stock TC is inefficient since it has a high stall speed(which I assume is to protect the trans). This not an issue for an aftermarket TC with a lower stall speed. There is not wailing away at high rpms waiting for the torque converter to lock since it is more efficient at giving more of the engine power even when not locked.
This is one of the major reasoned why I believe the Aisin is so slow off the line(aside from torque management) as well from dead stop. The torque converter is not that efficient and is just wasting most of the engines power as it spins at high rpms.
Best way I can explain it is this video. If you watch at 1:20 of the video when he drives their shop truck, you will notice how much more power was sent to the wheels even when the TC wasn't locked. Trust me, it is night and day on how much power is sent to the wheels when unlocked versus the stocker.
How I RUINED My Diesel's Transmission... Don't Ever Try This!- They know they need to do something since the 2019 RAM will have zero engine emissions and will be coming out with big numbers because of that.
