Ok real numbers. Lets use 1000rpm launch, both trucks standing still, then WOT. What happens?

Dodge
450lbs X 5.69 x 4.10 = 10498

Ford
400lbs x 1.85 x 3.09 x 4.10 = 9375

As I suspected LH is correct. You can't beat the granny for pure torque. This also explains the Dodge's higher GCVW. But this came at a price, the Dodge is only doing 4mph while the Ford is at 7mph.

For the fun of it lets do a 2nd gear take off in the Dodge.

Dodge
450lbs X 3.38 x 4.10 = 6236

With the Dodge in this gear both trucks are doing 7mph but the Dodge looses 40% of its torque to the wheels. This shows why most automatics are rated to tow more than manuals. Most manuals don't come with grannys but all auto's have torque converters and multiply torque.

In addition gear for gear other than 1st the it is possible for the PSD to put more torque to the ground than the Dodge until the converter reaches lockup. At that point the Dodge has more torque again. As little as 1.08 multiplication puts 600lbs of torque to the gear.

P.S. LH, I only have your 2003 pdf to go by for the Dodge so I don't have an exact torque figure at 1000rpm for the newr engine. It makes no difference anyway. I do question it though I have only seen graphs like that after major mods. Its from Cummins so I'll accept it but I suspect some funny business going on here. It would sure be nice have an independent graph.

 

Inluding low revving diesels? Or ford 300s.

Most of this discussion has been somewhat repetitive. You actually taught me something new. I appreciate that. I would like to learn more about flash stall. In many years of reading. I have never heard anybody mention it. Is there any figures for how much power actually gets to the ground during flash stall? This is intriguing to me. Even my friend who rebuilds trannies has never mentioned it. I will have to get his take on it.

 

Tmyers. I try to be objective. As I have no investment either way. I like inlines because of my experiences with 200s 240s and 300s. All good engines. Never much been a hp guy. I tend to be more practical. My wife calls me a pragmatist. Not sure if that applies.
Dodge has prior to this year had higher gcvwr for the manual. Now ford has a very excellent auto so it is different. NV vs ZF. The NV is a very durable tranny. Obviously moreso than the ZF in this particular application. Have heard great things about ZF in other apps. Two speed axles and stuff.

The manual will have to shift much sooner than the auto. The second gear in the auto is also a blow to torque at the wheels. The dodge manual has too big of a leap to second. Too much torque is lost. Giving the TS a big advantage. Once you are up in the rpms and gears though. Very little torque multiplication is taking place. It is closer to a 1 to 1 multiplier. No gain for the auto. Only in first is there an advantage but the manuals gear is so short its tough to beat. I may be mistaken but this is how I was taught. Then again why wasnt I told about the flash.

I do not fully understand but it appears that during the flash there will be an advantage but that dissappears once all the workings catch up. I dont suspect it takes long for the tc to catch up to the engine. Then your multiplier is long gone. In a very high torque race engine with many rpms. I would maybe see the 40mph you are talking about. I was told that at 1500 it is better than half gone already. Of course without the flash. Once again I reiterate how important it is FROM AN ENGINEERING PERSPECTIVE to calculate their respective driveline losses into the fray. At their extremes a 12% loss to a 25% loss can be a huge difference in torque to the ground. It is known that dodges auto tranny is a major handicap to the cummins engine.

Edge products has some independent graphs. http://www.edgeproductsinc.com/

 

L.H., the major point you just made is that the 6-speed will have to shift much sooner. Once the PSD makes it up into the powerband it has a major advantage. Shifts with the auto are also much faster than with a manual.

 

I never said the auto wasnt faster. The manual will give up its 5.63 multiplier for a 3.38. Which is still more than the first gear that the TS has which is a 3.09. Once the truck and TC are up to speed though. There is little or no multiplication present. It only flashes cause the truck is at a dead stop. Once its moving. Its different. 600x3.38 is more than 560x3.09. Torque multiplication is gone once both ends of the converter catch up to each other. This cannot take too long if you want the rpms to translate to forward movement QUICKLY. Torque multiplication means less rpms are getting to the tires. Less movement.
I made an error. I posted numbers for the 5 speed. These are the corrected numbers. 5.63 first. 3.38 second. These figures ignore multiplication and rear axle ratios. If they have identical rear axles, which they do, it does not matter.
second
600x3.38=2028
560x2.20=1232
third
600x2.04=1224
560x1.54=862
fourth
600x1.39=834
560x1.00=560
fifth + sixth
600x1.00=600
560x0.71=397.6
600x0.73=527
More numbers to think about
588x0.73=429
517x0.71=367
429 vs 367. What both engines deliver to the rear axle in od. Which do you believe would hold its speed better going up a steep incline? Remember there is little or no multiplication to help you at higher rpms. And zero multiplication in lockup.

 

The article goes on to say that multiplication is only available when first accelerating.
So by this I was able to get one more multiplication problem With a multiplier of 3.09 by 1.86. You get 5.74. This is higher than first gear for the nv5600. Lets take peak torque and see which one is higher. 3214 vs 3378. Cummins in favor. The only problem is. Torque multiplication doesn get anywhere near peak torque except for a brief FLASH in first gear.

All this debate has made me lose track of whats important. More low rpm hp will make for a more driveable truck. Especially when towing. Will not win you a race but getting around the rv park will be a pleasure.

 

Quote:

Originally Posted by Logical Heritic[FONT=Arial

]More low rpm hp will make for a more driveable truck. Especially when towing. Will not win you a race but getting around the rv park will be a pleasure.

Heretic, it's still not clicking w/ you. Let's review some facts:

(a) Yesterday, I drove my Excursion PSD and did some acceleration testing from stop. I did not have the tow/haul button on (I don't think it kicks in logic for idle start, but then again it might force 1st gear to hold a bit longer). I also did not have a load/trailer. But I wanted to watch what it does, so I could have something to go with. It revs right up to the max torque area for the PSD (~2000 rpms). Because I get forward motion almost instantly, it can rev even higher, if I keep pushing it, and fairly soon it's followed by an upshift. DO NOT POST TO THIS THREAD THAT THE PSD CAN ONLY LAUNCH A TOW AT 1000 RPM. That is completely misleading! So, I think I'm very safe in assuming that the PSD with a load, will rev into it's max torque band of ~560 ft-lbs. (FACT #1)

(b) What is the gearing comparison for this starting point? We dont have torque converter data for the TS, but it is a beefy trany and should be respectable. LH gave us 1.86, which I think is low, but we'll favor Dodge on this assumption: NV5600: 5.63 and TS: 3.09 x 1.86= 5.75 (FACT #2) I.e. no matter how you slice this pie, this automatic is geared better for tow-start (haven't I been saying this?)

(c) The final remaining piece to this puzzle is what torque can the Cummins/5600 put to the rear for a heavy load, when letting off the clutch and engaging the drive shaft. The engine is going at some RPM, usually not much above idle, and the pressure plate is slowly applied. As the plate is applied, a % of engagement occurs, part of which applies torque, and part of which turns into friction heat. The bigger the load, the more friction heat. I KNOW for a fact that you CANNOT get the whole torque engaged, it is an impossibility. The pressure plate is usually slowly applied over a period of about 1 to 2 seconds. As forward motion sets in, the idle remains low. If motion does NOT occur, the drive instinctively applies more throttle, more rpm, lets out the clutch slightly. More friction-heat occurs, but more torque is also being applied. The question is: WHAT RPM and WHAT TORQUE does the cummins/5600 give in all that. IT AIN'T NEAR 100% I can tell you that. AT MOST, from testing I've seen, I think you're looking at 75% being a very good day, with a good tow-experienced driver. Now ... ONCE you get forward motion going ... it's all down hill, as you can let the clutch fully engage, and then you have whatever you have. Oh .. by the way, once you get forward motion again you MUST BE BACK DOWN NEAR IDLE RPMS!!!!!!!!!!!!! Your first 25 feet of movement is so slow, and the clutch is now fully engaged, you MUST BE LOW IN RPM. What is the Torque of the Cummins at 800 to 900 RPM? Well, what is 75% of 600? It equals 450 ft-lbs. But, once again, like we always do, we will make only super-conservative assumptions for the PSD (worst-case) and generous assumptions for the Cummins (best-case) and ROUND UP to 500 ft-lbs. The Cummins will put 500 ft-lbs to flywheel at clutch-engagement. (QUASI-FACT #3).

New Calculations:

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.

Gents. It just ain't even close. I'm sorry. Please, Lord, may some other engineer discover this thread and jump in here with me. I've thrown them every bone possible. I've explained why the manufacturers give you autos and 4.1 rear ends for towing. I've explained the realities of the physics involved. I've explained the advantages of V engines and why Chevy/Ford have gone that route. We have demonstrated that there is NO WAY POSSIBLE that a Cummins/Manual is better for towing. It can't engage more torque. Once it gets going it applies less and less torque through the upshifts, and all at lower RPMS.

The only way this is up for further discussion is if someone offers a REASONABLE explanation for using a new number somewhere in the calculations above. Please don't reply with the old "the torque converter throws away so much blah blah blah". Reply with some beef. Where's the beef.

IRONMAN
[/FONT]

 

Don't even begin to tell me or anyone else what to post or not to post. It was used for comparison only and only at the instance you go to WOT. But some facts are facts, the GCVW is 23000 for the Dodge 3500 and 20000 for the Ford F350.

Does this fact mean the Dodge tows better no, it just means it can tow more. Within the Ford GCVW limitations it will out accelerate and have an easier time at speed than the Dodge. The granny is over kill and and at the end of the day is useless for all but the largest loads.

I'll get back to this later.

 

Terry,
the note on 1000 rpm was not for you. It was to prevent Heretic from picking up that ball and trying to run it for yardage. GCVW for the PSD is not limited to 20,000 either. The limitation for GCVW has much to do with other factors, such as tire-size, rear-end sturdiness, suspension, and etc. The PSD can go up to 30,000 pounds in the right Ford Truck (obviously the 550/650's).

Additionally the Manufacturers put out numbers they will WARRANTY to ... not engineering specifications and limits. So, there is absolutley NO proof that Dodge can out-tow Ford, and in fact independent tow-sled tests put the Ford/PSD in front, winning those tests. Chevy is second. Dodge is third. I've been trying to explain WHY that is to some on this forum (auto trany, V-engine). Some are insistent that an Inline engine with a manual transmission is simply THE BEST, no discussion. Au contraire. Actually the opposite is true. Despite math, analysis, and discussion, you cannot get these guys to let go of that bone. Why? beats me. I have a Cummins and a PSD. I like my cummins, am tired of the truck it's in, but got it w/ auto and a 4.10 rear for towing. I'm literally scratching my head as to why there are so many Pro-Cummins-Manual people who insist that this is somehow better for towing. Where do they get this stuff from?

There is no published information anywhere to lead them there and engineers know better. Rather, it seems it is an URBAN LEGEND that has arisen in the Cummins-Cult .... "dodge" .... "manual" ... "better for towing" .... all walking around like it's the night of the living Cummins dead. Freaky. Just freaky.

Marine Ironman

 

All I was getting at is the limitation of the F350 is 20000 and in some states if you exceed that you can get a ticket. My Ranger will pull 7000 but is only rated at 5400 or so.

Its name reconition and Cummins as a reputation of being a very good engine builder. I'm sure if you put a Cat or something like that in these trucks people would flock to them just because its a cat. Izuzu also makes great engines but I don't like money leaving the country so I won't do business with someone who uses a forign made engine regarless of how good it is.

I also wonder about the 1.87 torque conversion figure. State of the art is 2+. I looked for a good 2 hours last night and could not find it.

LH, torque multiplication is not at only the instance of first acceleration but happens up to the point where everything is working at the same speed. The way to think about it is at WOT at 1000 it might be 1.86, and 1500 its 1.43 and at 2000 its 1. This is just an example.

 

I haven't even read most of this, and I don't care to. Too much bickering over relatively meaningless differences. Nonetheless, when I see a spot where my input may be appreciated, I try and help out.

So, regarding stall speed and flash rpm, I'll give my explanation, and then try and find a better, technical one somewhere.

Stall speed is the rpm where, at full throttle, under a load that utilizes all of the availible torque, the engine will not spin any faster. It is basically a theoretical number, but does give some basis for comparison. It has to be taken with a grain of salt though, as stall speed increases with a more torquey engine. The reason is, under a heavier load, with more torque availible, the TC will allow more slippage.

Flash rpm is a lot more of a factor in high-horsepower, high revving application than in a diesel truck. What is it? It's the speed that the engine will "flash" to for just a moment as the vehicle starts moving when the gas pedal gets mashed. This only happens if the engine is able to rev faster than the viscosity of the trans fluid is able to transfer power through the torque converter. For example, look at a 7000 rpm big-block drag car. This car would idle at 1200 rpm, sounding like a giant popcorn popper, but at any hint of accelerator pedal, the beast inside is unleashed, and it's instantly at redline. A real hard-revving SOB. When this thing is at the starting line pushing against the TC at about 3000 rpm, and the light turns green, the engine instantaneously wants to be at redline, and it takes just a short time before the fluid starts coupling the TC together. Of course, by that point, the car is already at the 60 ft lights, and no real loss of rpm was observed as the car accelerated. The rpm that the engine gets up to is the flash point. This is entirely dependent on the engine build and weight of the car, and is not really a valid comparison between different vehicles. Also, it is hardly even observable as a different rpm than stall speed with a (comparatively) slow-revving diesel engine.

That's my opinion. Here's what TCI has to say about torque converter design and stall speed:
http://www.tciauto.com/tech_info/tor..._explained.htm

They breifly touch on flash speed too:
http://www.tciauto.com/tech_info/faq.htm#10

 

benwantland you are correct for the most part. There a 3 types of stall, true stall, brake stall and flash stall.

True Stall - the point where the engine will not make anymore rpms. This can only be obsevered with a transbrake.

Brake Stall - the point where the engines over come the brakes. In most cases this is below true stall and flash stall. How far is dependent on many factors.

Flash Stall - can be obsevered from a standing start by mashing the trottle. this is a better indication of what true stall is.

You get flash stall in all applications. You may be able to see it better in a high rpm application but regarless of application you still get it. It is a function of the way any TC works.

 

I'm sorry, I've been on vacation.
First the ford f650cat combo. The same cat configuration that Marine Ironman and most ford backers bashed most of this post. Its a low horsepower high torque low rpm engine.
Next, yes the assumptions and calculations are way off but what can be expected. 560lb/tq applied directly to a drivetrain would surely break most of our trucks or at least severely lessen its longevity. The auto loses most of its torque due to the inefficiencies of the auto. What is the power applied? I don't know but would surely take much more detailed analysis than what was offered. Also noted that this would be an extreme case of power braking which is not recomended for autos period.
I guess we could read the test of the 4.5 dodge vs 6.0 ford that said the dodge and 4sp auto started ahead of the 6.0 auto and then the 6.0 caught and passed the dodge by two trucklengths in the 2005 test we read. Or the 6sp vs 6sp test that showed the cummins besting the navistar. We could also read all the threads on each site that stated how they mashed the throttle and no power until 1500 rpms or so. I wonder what engine they are talking about.
And if thats the topic of this thread, then I would conclude as I have stated before, 325-600 and 325-560(or570).......highest number still wins.

More.. 1600rpms 600ft/lb tq=182hp and 325hp at 2900rpm=588tq. Then to consider 560(or570) at 2000rpm=213hp(217hp) and 325hp@3300rpm=518tq. Assuming normal power curves on both engines and assuming most torque at idle, the engine with 600 ft/lb should have more power at any rpms from idle to 2900rpms where its torque and horsepower always exceeds (by a slight margin) the other engine.
I'm no expert. Are my assumptions off? Calculations?

Sorry for taking so much space, but as I noted above, I've been on vacation.

 

Marine Ironman:

I think the pro Cummins-Manual people feel that way because of parasitic losses(not to mention the very well known fact that dodge autos suck bic). The engine w/Manual can use more of its own power(get more power to the wheel than the auto). I think we estimated the auto has 25% parasitic losses while the manual has 12%, therefore the manual can use more of the power produced at the flywheel! I just compared the Cummins auto to the Cummins manual; I would've compared PSD auto vs. Cummins manual but you would flip out because the Cummins isn't worthy of being mentioned in the same sentence. Also you've been complaining for ages about your own dodge Cummins with the auto. Now you seem to be advocating it. Make up your mind bud does it suck or not? or does it suck bass but the manual sucks even worse? Even if the manual isn't quite as good for some reason unbeknownst to me other than being lazy is easier the manual is going to last longer without a rebuild.

 

This argument does not work with Ironman because the Torqshift transmission is apparently using some revolutionary technology that produces no parasitic losses on the way to the wheel. Therefore, PSD-auto is able to get 325-560 to the wheel while the Cummins-manual only can get maybe 200 of the hp and 450 of the torque on a good day. and thats using very generous assumptions for the Cummins. What he doesn't realize is the "only" time the PSD has more torque to the wheels is after 3000 rpm.