Been a while since you drove a clutch. The 1000 rpm assumption would lead to a stall on a lot of vehicles, specially the 6.0 . As for being able to hold 2900 rpm without pulling it down. I can do that. Without much effort in my little car. Not that I would want to but it is possible.
As for the 4.1 making higher rpms. At highway speeds this is beneficial but its true gain is the fact that it multiplies the torque by 4.1 instead of 3.73. 4.1 makes a bigger number.
The cummins has 2200 more lb ft. Get it right.
The nv can engage the clutch at an even lower rpm than 1000 but thats not the way you usually get the truck moving. My truck I rev to at least 1400 before letting off the clutch and thats not loaded. The bigger the load the more I rev. The higher you go the more hp you have available. If you want to get moving fast. Then its necessary to grab more rpms i.e. pulling out in traffic. I would never start my truck moving at 1000 rpm.
You can get better than 13000 with the stick at the rubber. You can control the rate of rpm drop by the rate you let up on the clutch or the amount of go juice you give it. The fact of the matter is. The auto will do it faster but the stick will get more torque to the wheels.
It doesnt have to be at engagement. This is only a brief period during the acceleration. I will admit. It may be possible for a split second for an auto to get more torque to the wheels. Then it is gone. Cause once that clutch and the rpm is up its all going to the wheels. Unlike an auto which is wasting a portion of the torque. An auto equipped vehicle can have driveline losses as high as 25%. Especially those with 5 or 6 speeds. A manual will generally have 12-15% parasitic driveline losses. I would expect the TS to lose about 20-22%. The allison is more of a torque gobbler so be thankful. So once you do the math factoring in the losses. The manuals lead in power to the wheels widens.
That font is hard on my eyes too.

 

Heretic ... you're right. Lady was the wrong term. Flipper is better. Which is it going to be ... does the Cummns/manual have more torque at clutch engagement or the PSD/auto?

Tell ya what ... let's make this simple. Give me a clutch-engagement RPM (a real one, not this 2900 stuff). In fact, you said 1400. What's the Cummins torque at 1400? I'll do the math for you.

MARINE IRONMAN

 

Interesting. I can let my clutch off at idle (700 RPM) in first and second gear without stalling.

 

John,
Heretic doesn't know it yet, but I have him pinned down in a Fork maneuver (chess term). He is either forced to argue that Cummins "low-end torque" is something good, and then deal with the fact that you actually have lower torque at low RPM (max is up the RPM chain). Since the auto can get the revs it needs ... the auto wins.

On the other hand, as you can see, he is weaseling back up the RPM chain to get that torque he needs, as my math is showing the Cummins needs no less than 553 ft-lbs of flywheel torque to match an auto (with conservative 1.8 torque converter estimate for PSD ... it's actually probably worse). So now he will come up w/ some argument to be clutching real high in RPM just to match the number. Then ... he only proves my original point, which is that horsepower at higher RPMS is ALWAYS a better set up.

Either way ... he either loses the tow-king argument .. OR ... he must concede that high RPM is necessary and ends up being what it takes.

The actual outcome is that I am well-aware of clutch-engagement RPMS and engine lug-responses ... I'm just letting him twist in the wind a bit, to see which RPM direction he goes .... lower for all that "great" cummins torque performance ... or higher for all that horsepower.

Stay tuned ... we await the heretic .....

C600 rollin down the strip ... airborne daddy gonna take a little trip
Jump up buckle up, shuffle to the door ... make bad assumptions and we show you the door

(just hummin some cadences while I mark time ...)

MARINE IRONMAN

 

Do you have a 6.0? And is this with a load?

 

No I don't, I have a 7.3. The 6.0 produces an almost identical amount of low end torque though, it just peaks at a higher RPM. My whole point was that your statement about stalling out is bogus. Unless you don't know how to drive a manual transmission you aren't going to stall it out at 1000 RPM, gas or diesel.

 

You are operating under a false assumption ironman. There is no torque multiplication at 2000 rpm or above, rough est. unless you can find the stall,. In fact its down to a multiplier of about 1.4 or 1.5 by the time its at 1500. It only doubles the torque at like 1000-1200 rpm. Then it makes less and less and less. Do me a favor. Go out to your 6.0 and powerbrake it. Tell me where the rpms stop and the wheels bust loose. Give us an est of the stall.

The more it slips the more torque it makes. I use slips for lack of a better term. The more you truck is moving forward under power. The less multiplication is present. You can feel at what rpms most of the forward momentum is not being applied and at what rpms it is. Its like a clutch in this aspect. Torque is not doubled at 1500 rpm. So its not anywhere close to peak torque when the multiplication is all but gone.

The manual has the same multiplication across the rpm band so it has a torque advantage. Without multiplication the 6.0 is making 7100 compared to the over 13000 a manual will make in first. Less parasitic losses.

Now it requires so many hp to get the load moving. An empty truck might only require 60-100hp to get moving and maintain speed. At gross it requires a bit more hp to get the load moving. You will get this with the auto or the manual. A hp is a hp a load is a load. The only difference is one converts rpms to heat. The other puts it to the ground.

John. Go hook your 5th wheel to your truck and do a zero throttle launch in second. Tell me how it turns out. Just for giggles I started my idi from a dead stop in 5th. It is possible. Requires some rpms because of the lack of mechanical advantage.

I too. Love the game of chess. I quit playing. Couldnt find someone to beat me.

 

Actually, I backed up my truck at idle up my driveway at a former house that was pretty steep with 2400 lbs in the bed. Again, you don't need to rev an engine to engage the clutch. If you do I imagine your clutch won't last too long and it doesn't speak to well for one's driving skills.

I think the chess game is over and someone beat you.

 

I guess Im in a bigger hurry than you. I dont use first unless Im towing so it is a bad example. You dont need that much torque at the wheels empty. It will start in second with zero throttle but I give it more. This actually lends to how much torque is present.

The 6.0 on the other hand has difficulty launching in second. I mean the actual second as first is marked granny low. And second is marked first. Needs many rpms because of a lack of low end power. You can research this on the dieselstop if you wish. I will refrain from linking.

Do you remember the 6.0 launch being postponed? Perhaps you have not read of the lack of low end power with a 6.0 and a manual. Many owners say it has nothing below 1800 rpms. A 7.3 has a better launch regardless of what the dynos say. There is more at work here than I understand.

 

I always start in second gear unless I'm towing.

 

LOL. And I can idle up a hill steeper than 10% in first gear without throttle. Its the torque at the wheels, and the centrifugal force of the large flywheel. If you could lock the converter in an auto it would most likely do the same. This does not prove one way or the other which has more torque at the wheels. The fact the truck needs less rpms to do the work is a benifit.

Try it with 15k. This doesnt really show anything. Just that it has enough hp and centrifugal force at idle to idle up a hill. You can do it with an auto if you put it in 4 lo.

You also have more torque than I. Mine is an idi. Maybe 390lb ft.

 

Again, my point was that your stalling statement is false. You're really grasping at straws here.

 

For you or me yes. Not for the 6.0. Before you go any further on that. I would recommend a little research on the dieselstop about getting a 6.0 with a manual to do what you want. It is a bad combo.

I can assure you if my wife tried a zero throttle launch in second. She would stall my truck. It requires a bit of finess. I have around 2000lbs in my truck at all times. Maybe this is a factor.

All this shows is a diesel with a manual unloaded doesnt really need much to get going. My references to stalling were mainly aimed towards towing and actually needing and using the torque present in first gear. I will agree with you. I can get my truck moving with zero throttle in second. This is worse than an auto because? An auto requires more rpms and more torque to get going. Is this what your trying to say? You can do more with less hp with a manual? I guess your right. I only admit this begrudgingly.

 

This is what I said. I must admit to thinking about gas engines when I typed it. I have a little 60 hp car and was thinking how many rpms I could hold when I let the clutch out. Trying to rationalise what he was getting towards. A diesel has a lot of very low rpm hp. It has enough to move the weight of the truck without throttle in second. If you are coming off of a stop sign into high speed traffic. You might want to use the throttle. I can get my 60 hp car moving without throttle too. But I will likely get hit because I have to slip it quite a bit.
Im not grasping. Just trying to explain rationally what Im getting at.

 

LH, you are forgeting flash stall. Flash stall is most of the times much higher than advertised stall. AN example of this is my 77 when I had the 429 in it. 1800-2000 was about the point where the the engine overcame the brakes. From a standing start and just mashing the pedal though the engine would rev to almost 3500 before the rear wheels would start turning. This happens in a fraction of a sec on a gas motor. Of course they are turning but I'm not moving. Makes alot of smoke though. Flash can happen at all speeds provided the converter is not locked up.