Who starts a tow w/ more torque: PSD or Cummins?
 

Given that at tow-start we have the following conditions:

1. TORQUE of the PSD at start of tow: 560 ft-lbs x 1st gear (3.09) x 1.86 torque converter x 4.1 rear end = 13,196 ft-lbs.
2. TORQUE of the CUMMINS at start of tow: 500 ft-lbs (clutch engagement) x 1st gear (5.63) times 4.10 tow-rear = 11,541 ft-lbs

Please respond to the poll.

Mr Ironman, how exactly do you figure a 1.86 multiplication factor in the torque converter?

does it matter. who owns cummins.
u can get a cummins in a ford. i was at a dealership and saw one with a 5.9. some guy ordered it and then backed out. i dont blame him a 7.3 or 6.0 is better

1.86 is a torque conversion number given to us by a Dodge-Cummins guy, trying to insist the Cummins has more torque at tow-start.

The number, in reality, is at least 2.0. However, in the figures above, we used conservative estimates for the PSD (worst case), and liberal estimates for the Cummins (best case), just to show that it is impossible for a Cummins/Manual to lay more torque-to-wheels than a PSD/TS.

Attn Dodge Lovers: If you want a Cummins like mine, get the Auto w/ 4.10 rear end for towing. You have better towing performance that way.

MARINE IRONMAN

It seems to me that everyone in this subforum could use a lesson in maturity and respect.

With that said, my contention is that torque multiplication from a TC is not gear-like, it is only a function of the fact that they allow an engine to spin closer to the torque peak for a given slow road speed. It is impossible for the TC to give any more torque to the transmission than what it takes from the engine, as the rest is wasted. In other words, the effective torque availible at the input shaft of the transmission is the torque at engine speed minus whatever is being eaten up by the TC. It is not nearly as much of a low end advantage in a low-revving diesel as it is in a higher revving gasoline engine.

Also, I'm not voting in your poll, because since I don't believe your math, apparently I'm an idiot, according to the way it's worded.

Hey Ironman:

As benwantland and tmyers are the only people I've seen so far that know what they're talking about and use unbiased logic I think you should take notes from them.

It's a free country. It's a free forum. Anyone can post a poll. Anyone can suggest a new equation. Anyone can post to this thread and give their own calculations.

I, for one, will go on record and state that a torque converter does, indeed, multiply torque when the rpm of the engine is higher than the rpm of the transmission. This is due to a centrifugal force from fluid being accelerated out through vanes in the TC. The fluid comes in at a small diameter. It goes out at a larger diameter. This is practically the same as a the principle involved in a regular gear (change in diameter = multiplication or division of the torque input). There is an RPM difference too, just as in a regular gear. The "effect" of the TC ONLY lasts as long as that RPM is different ... JUST LIKE a regular gear.

Anyone is free to announce they don't think a torque converter multiplies torque during acceleration. But, respectfully, it is because of ignorant statements like this, that I have taken the time to discuss some math & physics in several threads in this forum, in the hopes of educating some people.

I'm an engineer, so I know when/where to draw the line on cold hard facts and principles of physics. I make my assumptions and postulates known. I give estimations and calculations. If anyone can give better assumptions, explain their logic, and show their calculations or point out my errors ... hey ... I'm completely open to that. Fire away.

The Marine Ironman

For some info on how a torque convertor sends more torque to the transmission than the engine actually produces take a look at http://www.tciauto.com/tech_info/tor..._explained.htm
and http://www.carcarecouncil.org/Auto_T...onverter.shtml

Thanks, SpeedRacer. I swear ... If I posted a poll on "is 2+2=4?" .... I'd get arguments from the Dodge-Cummins crowd.

For Benwantland, here is the link to the PSD/TS brochure, and Logical Heretic has pointed out that on page three, under the gear ratio table, it lists the TS stall torque ratio to be 1.86. Racerman has provided some educational links which explain in laymen terms how a TC multiplies torque. Go educate yourself, and report back for duty.

Marine Ironman

oops, forgot the link:

http://www.fordvehicles.com/images/t...el_Brochur.pdf

Just like this poll is going to prove nothing and be a waste of space. Anyone that knows nothing but Ford rules can come on here and vote in favor of the Ford, and this is a Ford enthusiast forum so I can bet that is exactly whats going to happen. So guess what, your poll is in favor of the PSD... now what?

DieselDoner, you're just sour grapes. I've seen no math or calculations from you. In post-87, you agreed, and I quote "the PSD/auto beats the Cummins manual even worse than the Cummins auto". I.e. you agree.

I just finally called everyone's hand, that's all. No more raises. Lay your cards on the table. Calculate ... or zip the beer hole. If you think the numbers are different ... show me your numbers. Otherwise, my three Kings win the hand.

Sorry Marine Ironman, that was ignorant on my part. My thinking was based on the fact that with a torque converter, if an engine produces more torque, it stalls higher. Just seemed like common sense to me. Ironically, I have even glanced over the TCI page posted, but never really read the whole thing. If TCI says it, I believe it; they build good transmissions and compononents.


But, even with that said, I do not see it possible that, even negating frictional losses, a torque converter could ever produce more torque than a gear reduction that allowed the same rpm differential. And, with that said, the multiplication factor (shouldn't there be a constant variable letter that we can attribute to that?), would be dynamic, based on the load behind the vehicle, because the engine is going to be able to rev harder without movement the greater the load it encounters... also, if the same trans/TC were installed behind another engine with more or less max torque, the stall speed would be different, and thus the multiplication factor.

But.... the numbers seem legit, so I'll give you a vote for the Ford. Also, the Cummins 600 produces 440 lb-ft at 1000 rpm, so there's another advantage for ford.

DieselDoner, you're just sour grapes.

On of the BEST things he has been called...

Benwantland ... so it's 440 ft-lbs at 1000 rpm, eh? I got lured into a much higher (500) estimate because the dodge-ladies kept crying when I guessed it at 450. If you calculate backwards from the the PSD is doing, you'd need 553 out of the Cummins at just off idle (1000 rpm) to match the PSD anyway. Of course .... it'd be a cold day in Heck before you get that. (ssshhhh. The dodge ladies think their torque curve is so flat that it's just under 600 ft-lbs at idle. Let's don't tell them, cause they get all agitated and stirred up).

IRONMAN