Torque Limiting

[RVTRKN]

Yeah, I don't like torque limiting much either but didn't even know my engine was doing it other than during shifts until I read Steve St. Laurent's report.



How do you feel about Joe Donnelly's report in TDR Issue #71 about the weakness and failures of the G-56?

Actually, I liked the article, read my thread/question to Joe in 6. 7 forum. If your going to haul/tow over OEM recommendations, then you need to take precautions as well as understand your equipment. That is why I pay for my subscription, and as the article pointed out, it gives specifics on the normal wear as well as hotshoting at 30K GCVW. The NV5600 is a better trans and we all know that, but it too has it limitations. I'm a fan of both and owned both and except for the 6. 7 ECM detuning, its not the transmission limiting the torque, at an even more loss of power and torque. I knew full well what the DMF was, and again it was my choice to replace it when it or if it fails. As of now, I only plan on 22K GCVW with my 5ver fully loaded and will heed the warnings that Joe wrote about.

 

[RVTRKN]

That's about where I am shooting for as well. 400/800 is about as high as I want to go at the rear wheels.

If I ever spend another 60K on a truck again, it will have the highest HP/TQ available in the CTD no matter what that is.

 

[NIsaacs]

How does power translate into hitch or trailer damage? I can see where speed, weight, bad roads or wild driving in general could, but just brute power?



Nick

 

[HBarlow]

Actually, I liked the article, read my thread/question to Joe in 6. 7 forum. If your going to haul/tow over OEM recommendations, then you need to take precautions as well as understand your equipment. That is why I pay for my subscription, and as the article pointed out, it gives specifics on the normal wear as well as hotshoting at 30K GCVW. The NV5600 is a better trans and we all know that, but it too has it limitations. I'm a fan of both and owned both and except for the 6. 7 ECM detuning, its not the transmission limiting the torque, at an even more loss of power and torque. I knew full well what the DMF was, and again it was my choice to replace it when it or if it fails. As of now, I only plan on 22K GCVW with my 5ver fully loaded and will heed the warnings that Joe wrote about.

You wrote in your earlier post that you don't like automatic transmissions because of torque limiting.

Automatic transmissions have no capability to limit torque. Torque limiting is done by the ECM to reduce fueling, timing, boost, or some combination of all three to reduce engine torque output TO the transmission.

Engine torque output is reduced in manual transmission trucks just like it is in the automatics. Why do you think maximum torque rating is 610 ft. lbs. in pickups or C&Cs when the G-56 is specified? The G-56 is probably the weakest link in the driveline and the weakest of the three transmissions offered.

 

[CUMMINZ]

I have never given my truck at a stand still full throttle. I have always rolled off and got moving and then to the floor. When my truck at full throttle reachs 4th gear and the TC locks in it will put you back in your seat. I have always said my truck's 4th gear was its strongest gear. Maybe there is a bit of TQ management working there.

 

[RVTRKN]

The Aison and the 68rfe have a transmission module that communicates with the ECM to manage torque when the G56 does not, the Module is there to protect the auto trans under high torque conditions. The TM as you call it, to detune the C&C and the G56 version of the reg pickup is a set program, and the only way the ECM knows what the transmission is doing is by speed and RPM, TM is not communicated from the transmission.



I don't consider the detune torque management, but just simply a program that has less power. I want the maximum power transferred to my drive axles when I want it, not some module making that decision for me and in the process losing power and torque. If automatics are someones preference then its OK with me, I just don't like them.

 

[CUMMINZ]

Now don't take this wrong and it is a bit of a joke.



Real men drive CumminZ diesel trucks with automatics. That frees up their right hand to hold mamma>Oo.

 

[RVTRKN]

LOL :-laf :-laf :-laf

 

[Mikey-KE7LBB]

I guess that it does exist :-laf



Got grilled in the past when I stated that my Smarty reduced or removed TQ management on the 6. 7's... I guess that Bob & Marco weren't wearing "tinfoil hats" afterall

 

[AH64ID]

The Aison and the 68rfe have a transmission module that communicates with the ECM to manage torque when the G56 does not, the Module is there to protect the auto trans under high torque conditions. The TM as you call it, to detune the C&C and the G56 version of the reg pickup is a set program, and the only way the ECM knows what the transmission is doing is by speed and RPM, TM is not communicated from the transmission.



I don't consider the detune torque management, but just simply a program that has less power. I want the maximum power transferred to my drive axles when I want it, not some module making that decision for me and in the process losing power and torque. If automatics are someones preference then its OK with me, I just don't like them.

Do you have anything that shows that?



TQ Management is a function of the ECM from what I gather. It does it on manual trucks and on automatic trucks. Auto's do tell the ECM what gear they are in and in 4th the limiting goes away (1:1, so 3rd on a 48RE), where the ECM uses speed on a manual trans truck. I still don't know what that speed is for sure, but AAM thought it was around 35 mph.



The manual trans tq management is above and beyond the full rating of 610 ft/lbs.

 

[RustyJC]

Although it doesn't have all of the technical information I'd like, HERE is a pretty good discussion of the 68RFE back in 07. 5 by a factory engineer.



Rusty

 

[RVTRKN]

I don't know how it communicates with the ECM, but it does when the G56 does not. You can say that TM is controlled by the ECM, but that is what a computer is for is it not. Every modern engine has some form of it, it can change the valve timing or fueling on the Gassers. So if you put it that way, yes the CTD ECM has TM, but the G56 does not talk to the ECM so the ECM can only figure it out through RPM and speed. But the Auto can change it own gears when it "thinks" it needs too. Also it controls the torque converter as well to add another dimension to the equation. I have no experience in the Dodges auto's, but I put 35K miles on a 05 D/A 5spd, and I had to be careful if I wanted to pass someone. That trans will detune the engine until it can control the torque, and that means it will leave you hanging out to dry when trying to pass someone, it happened to me several times until I just got used to the idea that the D/A combo is a POC.

 

[HBarlow]

Although it doesn't have all of the technical information I'd like, HERE is a pretty good discussion of the 68RFE back in 07. 5 by a factory engineer.

Rusty

Rusty,

That's an excellent description of the 68RFE. I wish I could find something like that for the Aisin. Apparently the Japanese don't release any technical data on the Aisin.

 

[HBarlow]

I don't know how it communicates with the ECM, but it does when the G56 does not. You can say that TM is controlled by the ECM, but that is what a computer is for is it not. Every modern engine has some form of it, it can change the valve timing or fueling on the Gassers. So if you put it that way, yes the CTD ECM has TM, but the G56 does not talk to the ECM so the ECM can only figure it out through RPM and speed. But the Auto can change it own gears when it "thinks" it needs too. Also it controls the torque converter as well to add another dimension to the equation. I have no experience in the Dodges auto's, but I put 35K miles on a 05 D/A 5spd, and I had to be careful if I wanted to pass someone. That trans will detune the engine until it can control the torque, and that means it will leave you hanging out to dry when trying to pass someone, it happened to me several times until I just got used to the idea that the D/A combo is a POC.

An automatic transmission can't "detune" the engine. A transmission, manual or automatic is a "dumb" device. It has no capacity for making decisions or choices like an ECM, which is a mini-computer, can do.

The ECM and/or PCM gather information from the transmission and make the decisions that control the automatic transmission.

 

[RVTRKN]

So how does the ECM get the information from a G56, if your correct? And yes, the Alison does detune the Duramax, I can vouch for that, have you ever tried to pass with one? I dont know about the 68rfe or the Aison.

 

[Mikey-KE7LBB]

I'm sure that it calculates desired torque based on engine load, peddle position, RPM, and road speed.

 

[HBarlow]

So how does the ECM get the information from a G56, if your correct? And yes, the Alison does detune the Duramax, I can vouch for that, have you ever tried to pass with one? I dont know about the 68rfe or the Aison.

I think Mikey's answer above explains very well how the ECM manages engine torque applied to the manual transmission.

Would you be kind enough to enlighten us on what components in an Allison automatic transmission are capable of controlling fueling, boost, timing, and other parameters in the Duradud engine? I'll bet GM engineers would love to know. With your invention they could avoid building and installing an ECM to control engine operation. That should save GM a lot of money.

 

[RVTRKN]

I'll put it in highly technical terms, The trany says whoa, back off before I destruct. :-laf

 

[AClayton]

I think Mikey's answer above explains very well how the ECM manages engine torque applied to the manual transmission.



Would you be kind enough to enlighten us on what components in an Allison automatic transmission are capable of controlling fueling, boost, timing, and other parameters in the Duradud engine? I'll bet GM engineers would love to know. With your invention they could avoid building and installing an ECM to control engine operation. That should save GM a lot of money.

The Allison can and does send a signal through its own PCM... ... ... that in turn, detunes whatever engine it is hooked to, either the Duramax or the 8. 1 gas engine. The PCM measures slip inside the transmission and will immediately detune the engine. It will also detune when the transmission gets too hot. Why did you think that funny video about that Duramax pulling that box truck could not pass the Dodge with his 5th wheel and Jeep in tow. I know you remember that video... . it was a like a rash on TDR a couple of yrs ago! This is precisely the reason Duramax owners cannot BOMB their trucks without doing transmission mods 1st. You can add all the power you want but if the Allison senses slip, it will send the signal to detune the engine.



Alan

 

[AH64ID]

I'm sure that it calculates desired torque based on engine load, peddle position, RPM, and road speed.

That's what I feel as well.

And yes, the Alison does detune the Duramax, I can vouch for that, have you ever tried to pass with one?

I have only driven a few dmaxs, but they run like raped apes when you go to pass. . crazy acceleration.



But saying the transmission controls the tq is like saying the pilot creates lift. Now the transmission tells the ECM what it's doing and the ECM controls the enigne, the transmission control module has nothing to do with controlling the fueling.



Another thing to consider is that shift-defuel and tq management are different programming options. They have similar effects, but are still different.