Well everyone it looks like tmyers is convinced. Is anyone else convinced? Lets see a show of hands now, who's convinced? Heretic? 351M? dspencer? any takers? I for one have seen the err of my ways. I am a changed man overnight. Wait it didn't even take a whole night just 1 post. I have changed sides... not a traitor I just seen the superior side(not to mention bigger army) and hoped they would forgive my ignorance. All you Cummins people need to rally up and show any minute, trivial discrepancies that might be in play with this Truck Trend diesel comparison. Because you can't mess with the King of the Hill. Especially when you're sitting at the bottom.

Thread closed we've come to a decision-- PSD by a huge margin... wait I guess I don't have that kind of authority... the thread goes on! Ford PSD baby!!! Problems?????

 

You can't mess with the king of the hill. Especially when you're sitting at the bottom. Copyright 2004. Somebody call Ford I want royalties. Lets get this on a poster or something.

 

I think stuck at the bottom would sound better.

BTW. Im pretty sure an auto cummins will beat a Ford with a standard. Its just the way turbocharged diesels work. A ford with a standard would tow better though. By better. I dont mean faster. LOL. Faster is not always better. More hp is not always better. Im from the school of thought that you can never have enough torque tho. Where can I get a truck with 250 hp and 1000lb ft of torque. Guess it wouldnt have to ge a 1000. Maybe 850. With that much torque it would only need one gear. LOL. OK two. Make it interesting and put in a split rear end. Dont the fastest cars in the world only have 2 speeds. Im pretty sure that 8 sec. cummins rail only has a two speed too.

Different people want that torque in different places. But as an avid offroader and weekend warrior. I like my torque down so low that it hurts. Peak hp is pretty meaningless to me as I hardly ever use it.

I got something to play with. MI. What if they had a cvt? For simplicity lets assume you could get the PSD with the cummins powerband or the one it has presently. PSD option number 1 and option number 2. That way we can throw out any of the differences in the trucks and their transmissions.

 

This thread started out about trucks it is not about truck power anymore it has become the personal stage for a few and their influence.

 

I was thinking of a way to describe towing ability when I remember the truck test at pickup truck . com. First lets get it out of the way the PSD won. Ok.

Now we have two other trucks with which to compare. A 300hp v8 and a 305 hp inline 6. These tests were done with the 6 speeds. The chevy is lighter than the dodge so it has an acceleration advantage. 1000 lbs should equal out to a full second difference in e.t.'s. A race car driver once told me that it is about one tenth per hundred pounds. This was for cars but maybe it applies. Movin on.

The two trucks raced empty and the duramax handily won the race. More hp. No it has less. It also has less area under the curve. So it is likely a factor of gearing and weight. Movin on.

We have these two vehicles and we now throw on a load that puts em near their gross. Does the duramax pull a repeat. No. The dodge won. One is faster empty the other is faster with a load. Could be the area under the curve but why didnt it work when it was empty. Movin on.

They repeat the test but in a way that requires much more output from the engines. A 7% grade. Does the duramax, being a higher rpm v8 win. No, it loses by a much larger margin. Why?
http://www.pickuptruck.com/html/stories/2003shootout/part2page3.html[/url]

 

In the end there is only one winning and that is us. Regardless of which truck you like or which truck won, we are all winners by having the big 3 compete for our dollars. We are all getting better and more capable trucks. Anyone of the 3 trucks will do what we ask of them and do it all day long.

Comparisions are just that comparisions, who was the best today. Its just now instead of kids comparing bicycles its men comparing trucks. Looking back at it I think we should go back to bicycles, it was cheaper.

 

Heretic,
You've convinced me, mainly due to my own curiosity, to run my constant-speed, increasing-load scenario for:

• PSD/Auto vs. Cummins/Auto
• PSD/Manual vs. Cummins/Auto

Can someone send me the Ford manual gearing? It may be tonight before I am able to post the anaysis results, which I'll pretty up a bit more than the original post. I'll also show the MPH that they are going. If you want different constant-speed levels for the same run-off, I can do that too. But to give Cummins every advantage, we'll run this at Cummins engine rpm=1600rpm, whatever speed that comes to in 48RE top gear.

Oh, Heretic, I've been trying to watch my TS overdrive lockup. For normal acceleration, most gearshifts are all occuring around 2000 to 2100 rpm. Final gear settles around 2000 rpm ... and then drops and locks down about 200 rpm to 1800 rpm. I'll keep watching to make sure that this is really what's happening.

the Ironman

 

Here at the college the buses use the Cummins B and several of them have been in the shop for dead turbos and fuel leaks over the past week, all with about 75,000 miles, they're less than a year old too. Wonder what's going on with the Cummins guys???

 

heretic, please post me a link to your Cummins torque curve, or give me enough numbers to constitute the curve

 

Hmm. I wonder who is going to win this Ironman induced mathematical analysis. I can hardly wait to see the results.

Is gearing down first necessarily beneficial? What if for science's sake the 48RE was in top gear @ rpm=2900. Don't you want to hold the gear as long as possible?? Ironman was stressing the importance of gearing down first but I'm not so sure. And especially with the Cummins being a 4-speed auto. A Cummins auto that has "geared down" to 3rd will not be going near as fast as a PSD/manual that has "geared down" to 5th... am I right? there is a 2 gear gap now instead of just 1.

 

You know. I was over reading on the tdr. There have been some injector issues. Not turbos yet. The buses use a variable geometry same idea as the PSD just a different direction. More complicated. Guess those piezos arent as reliable as the old popoff style. Gotta love emissions. Ford also had problems with its actuators. Do a search on c94s. The technology has not caught up with the emissions yet. They made it but at a cost of reliability, and longevity.

MI. I have been unable to locate the graph. I have found the 555 for the dodge and the 600 for the motorcoaches but no dodge 600. We know it makes 600 at 1600. 555 at 1400 and 588 at 2900. There reasonably will not be a dip. I think it gives up the 12 lb ft after 2600 but have no proof. There is no valley. Thank you for running it MI. Is there any way to run it with a cvt. Like a snowmachine. Can you imagine how fast they would be with a cvt. Peak hp and torque multiplication to the wheels at all times.

Donor. If the PSD gears down it will have a lower top speed. Seems obvious but I thought you might miss it. The cummins in second is almost as fast as the PSD in third. If the PSD drops into second and the Cummins is in second the cummins will be faster. All of these figures are at peak hp. There is a speed and weight where both will be in second and there is a speed and a weight where only the psd will. The PSD will grab second before the cummins. Lock both in second the cummins is faster. Lock both in third the cummins is faster. Only because the PSD is a 5 speed tho. It doesnt make it better just geared higher. It appears to me with dirty math that the cummins auto will win the gear down competition against the PSD auto but I may be mistaken. Another way to put it. It can be geared higher because it makes more torque at the engine so it needs less multiplication at the wheels to match the PSD performance.
If both are in second the PSD will have more torque at the wheels but the cummins will have a higher road speed. Weird how that works. Its counterintuitive. I woulda thought the opposite was true due to the higher rpms of the PSD. This actually lends to my theory that you could gear the cummins to be faster in a race but suck at towing heavy. Just make it hold each gear longer. It works in first and second I cant think of any reason it would do it in third.

I broke the numbers down and found the TS makes better multiplication in first and second. But the cummins has more hp on tap lower in the rpm band. Mathematically it appears the PSD should jump it out of the hole but it has to shift more. The cummins has less torque at the wheels in first but it holds it for longer. I would speculate a 27mph max speed in first for the cummins and 23 for the PSD. The PSD then gives up its multiplier. Again in second the cummins will travel farther with its multiplier. If the race was only to the top of second. The cummins would get there first. Because even though it has less rpm. Its geared to HOLD that gear for slightly longer. Weird. In my mind I didnt think it was possible for a lower revving engine to hold a gear longer. Not being a smart butt. Seriously.

200 rpms sounds like a pretty tight converter. That is a good thing. Can you do something? Is it possible to lock out first gear? A second gear start. Mash the pedal and see where it revs to. It helps give you an idea of where fluid coupling is. Ford really did there homework on this one. You guys should thank chevy and allison or you would still be driving an e40d. I know they werent competing with dodge. Snicker snicker. Now I hear tale that the german speaking gentlemen want to put that ever so excellent getrag back behind the cummins. Go in house. Problem is. THE GETRAG SUCKED. Thats why they got rid of it.

 

PSD/TS vs CUMMINS/48RE

A Ford PSD/Auto-TS and a Dodge Cummins/Auto-48RE are driving across the salt-flats. They each have an empty trailer into which we are going to add weights until someone must downshift to maintain speed. They both must also maintain the same speed. The first forced to slow down loses the race. We will start with the most ideal speed for the Dodge, which is 1600 engine rpm (max torque of 600 ft-lbs). Each has a 4.10 rear axle, the best for towing and 31inch diameters tires on a 16-inch wheel. Therefore the speed they are running at is: (1600 rpm x 3.14 x 31 inches) / (0.69 x 4.1 x 1056) = 52 mph, which is a nice comfortable highway speed.

(1) DROP IN THE FIRST LOAD (827): Ford must downshift to 4th

Dodge work potential is 600 ft-lb x 1600rpm = 960K ft-lb(6.28rad/min), transaxle rpm = 1600 / .69 = 2319 rpm

Ford must go transaxle of 2319 rpm, so engine turns 2319 * .712 (5th gear) = 1651 rpm, Torque @ 1651 rpm = 515, work potential of the Ford = 530 ft-lb x 1560rpm = 827K ft-lbs(6.28rad/min).

The Dodge has more torque reserve (i.e. the ever-wonderful low-end torque, 960 to 827). We drop a load in each trailer, and it’s maxed to 827K ft-lbs(6.28rad/min) of load. The Ford must downshift.

Ford downshifts, must maintain transaxle rpm = 2319rpm, 4th gear is 1.0 so engine is going 2319rpm Torque @ 2319 rpm = 550 ft-lbs. Work = 2319rpm x 550 ft-lb = 1,275K ft-lbs.

(2) 2nd DROP OF MORE LOAD (960): Dodge must downshift to 3rd

Now ford has more torque reserve (1,275 to 960 ft-lbs (x6.28rad/min). We drop more load in the trailer and the load is upped to 960K ft-lbs (6.28rad/min) and Cummins must downshift.

Dodge downshifts, must maintain transaxle rpm = 2319 rpm. 3rd gear is 1.0, so engine is going 2319 rpm. Torque @ 2319 = 585 ft-lbs. Work capacity = 2319rpm x 585 ft-lb = 1,357K ft-lb (6.28rad/min)

(3) 3rd DROP OF MORE LOAD (1,217): Ford must downshift to 3rd

Now dodge has more torque reserve (1,357 to 1,217 ft-lbs (6.28rad/min)) but the margin narrows. We once again add more weight and the load is upped to 1,217K ft-lb and Ford must downshift.

Ford downshifts, must maintain transaxle rpm = 2319 rpm. 3rd gear is 1.538, so engine is going 2319 rpm x 1.538 = 3567 rpm. Torque @ 3567 = 450 ft-lbs. Work capacity = 3567rpm x 450 ft-lb = 1,605K ft-lb(6.28rad/min)

(4) 4th DROP OF MORE LOAD (1,357): Dodge must downshift to 2nd

Now Ford has more torque reserve (1,605 to 1,357 ft-lbs x 6.28rad/min). We add more weight and the load upped to 1,357K ft-lb and dodge must downshift.

Dodge downshifts, must maintain transaxle rpm = 2319 rpm. 2nd gear is 1.45, so engine is going 2319rpm x 1.45 = 3363 rpm. This is substantially beyond peak horsepower, and there is at least a 25% loss from max torque down to 450 ft-lbs (if not lower). Work capacity = 3363 rpm x 450 = 1,513K ft-lbs x 6.28rad/min.

(5) 5th DROP OF MORE LOAD (1,513): Dodge must downshift to 1st

Ford STILL retains more torque reserve (1,605 to 1,513 ft-lbs x 6.28rad/min). The dodge is now in a position of never being able to catch up. The race is soon over. Yet more weight again, and the load is upped to 1513K and dodge must downshift again.

Dodge downshifts, must maintain transaxle rpm = 2319rpm. 1st gear is 2.45, so engine is going 2319 x 2.45 = 5681 rpm. REDLINE. Cannot maintain that engine rpm… the truck is forced to slow down to a slower transaxle speed, and go slower with the new load of 1,513 ft-lbs x 6.28rad/min in the trailer. So what should the Dodge slow down too? Well, if the max RPM for the dodge is about 3500 rpm, then 1,513 ft-lbs x 6.28rad/min divided by 3500 rpm means it would need a torque of 432 ft-lbs. Can a Dodge produce that amount there? We’ll assume so. The new speed of the Dodge will now be:

Speed (mph) = (3500 RPM x 3.14 x 31 inch tires) / (2.45 x 4.1 x 1056) = 32 mph

 

Marine Ironman, one nitpick: "transaxle" is a combination of the words "transmission" and "axle". It is basically only applicable to front wheel drive cars and old VW beetles... what these trucks have are transmissions.

 

Give the man a break, he has gone to all the trouble to provide accurate calculations that you wouldn't dare attempt to do, so if he misses a word, big deal!

 

It figures, the Cummins cult can't give the man credit for his calculations without picking at everything. The game is over, the PSD wins transaxle or not.