I really think this arguement is childish and silly. What is there to argue about? If you want a PSD then get one, if you want a Cummins then get one. Its just the same people going round and round. There both great engines that are better for diffferent purposeses.

 

Yep but the only differnce between men a boys is the size of the toys and the size of the words we use when saying what is best. I'm having fun though, sorry your not.

 

It really doseant matter I guess just seems like with all the stuff going on in the world people could realize that arguing about 2 different engines for months is a bit silly.

 

Y'know Ford352V8, I remember thinking exactly the same thing as you, but now I look forward to reading this, It has actually gotten educational I guess? Or just funny. Either way it has grown on me and I do look forward to it. Keep up the good work there guys.

 

Taken in that context you are correct. But we can't live in the world 24/7 nor is it healthy too. This is just an escape and IMO a good one.

 

Tmyers. I was under the impression that 6 speed vs 6 speed the cummins is faster. I pointed out that at 1730 feet the 305hp cummins was a little more than a second behind on a 7% grade in that pickuptruck . com test. 325 vs 325. The cummins will pull ahead. Better low end torque equals better launch and initial acceleration. You dont have to rev so much to get into the meat of the hp.

Gears are why the PSD is faster. If they had a cvt they would accelerate at exactly the same speed. Because torque at a higher rpm allows you to hold a gear longer. This makes it faster. 2500vs5000 identical peak hp. The 5000 does it faster but CANNOT do any more work. The 2500 can pull twice as much half as fast. The 5000 can pull half as much twice as fast. You can gear the 5000 down to pull the same as the 2500 or gear the 2500 to pull the same as a 5000. The 2500 will most likely outlast the 5000.

The lower the rpm the more likely it will last longer. The lower rpm the torque. The less rpms you are likely to use. The longer it should last. Very broad and general but it will generally apply.

The low rpm torque of the cummins is why it will perform better on the highway. The PSD will have a higher top speed but the cummins will be more likely to hold its gear and keep its rpms down.

 

Sometimes ludacris comparisons make things easier to grasp. Notice that all three diesels have nearly identical performance. PSD faster across the board with the auto.

The case for higher rpm torque. An engine that made 325hp at 10000 rpm could do exactly the same amount of work as either the cummins or the PSD. Unfortunately it only makes about 225 lb ft of torque peak at 6000 rpm. Launching a 15k lb trailer or daily driving would be a chore if it was in a 6 or 7 thousand pound truck. It would be very very fast and deliver excellent e.t.s at the track. It does much less. Much faster.
The case for low rpm torque. An engine that makes 325hp at 2500 rpm could do exactly the same amount of work as the cummins or the PSD. It makes 700 lb ft of torque at 1300 rpm. It can pull a house but not fast. Engines like this are usually specd in applications of 30 to 50k pound loads.

I have yet to see a 10000 rpm engine specd for towing this heavy. Could you tow 30 to 50k with it. Heck yeah. It would need rediculous gears but it would happily do it. It might last a year with that kind of load. If you were lucky.

I would rather race with the 10000 rpm engine. I would rather tow with the 2500 rpm engine. Though they both can do almost 1.1 million lb ft of work per minute. One is superior to the other for the prospective applications. One will last longer and tow better the other is a force to be reckoned with at the track. The 2500 rpm would most likely be more driveable in all situations though. Not to mention much more fuel efficient.

Lower rpm hp. Means it takes less rpms to launch. Less rpms to drive down the interstate. Less rpms to tow heavy. Often it will deliver better economy. Have better all around drivebility. Guess the engine manufacturers really pulled the wool over my eyes.

I have to disagree. Everybody and there cousin wants as much hp and rpm as they can get. And a v8 would be minimum. A v10 or v12 would be much better. Much more manly. Its the few that want less and want it low with fewer cylinders to boot. So if anything. The high rpm v8 guys are the ones that have been fooled. I will say nothing beats a big block for racing. If you dont like diesels they are the only choice for towing your 5ver. Everything has its uses. Its all in the eyes of the beholder.

 

I had an interesting thought after Ironman said everyone who bought a Cummins was dooped. Maybe its the other way around. Maybe Ford only gears their truck specifically for the magazine test... and through the power of press, and years of bias passed on through the generations everyone is like well hmmmm... isn't that a real humdinger. If it makes it to the top of the hill first it must be more: More exceptional, more appropriate, more suitable, more fitting, more select, more useful in every possible situation, more valuable, not to mention preferable, prominent, superior, higher quality, surpassing and worthier.

Then you see Cummins guys still buying their slower, inferior, unremarkable in any way trucks. Some might say... is it the power of denial?? Is someone actually that dumb to go and buy a truck that is so far below the greatness of the 6.0 Ford PSD. Is it the self-induced poppycock legend of the almighty reliable I-6 vision of grandeur taking over their brain?

The answer is no. I believe the Cummins is a more useful everyday real-world application towing diesel that will ultimately last longer with less engine repair because it is a lower revving engine with less moving parts. It also has phenomenal performance for being such an unmanly inferior engine design. For the magazine testing yeah its PSD all the way. Do I believe Ironmans simulated weight equations or that they apply to the real world in any way? No. Well maybe 1/10th of 1% of the real world for those times that you have to tow 25,000 lbs. up a 3-mile 20% grade with a light duty diesel. Is the Ram Cummins going to be stuck in 1st going 10 mph while the PSD nonchalantly flys past it going 50 mph in 3rd. Seems unlikely but what do I know... I'm not a physics major.

 

If it had a cvt it could. But that is no more realistic than having 20 gears.

You are correct. Higher rpms will make a truck faster. The PSD will always win in a race. Auto vs auto.

Was it coincidence that the PSD could just barely reach 52mph and the cummins could not. I think not. I think you manipulate the data until you can find a spot where it would win. If you were to use realistic loads and realistic rpms, like at 65mph, you would find the cummins has the advantage.

A more realistic rpm would be 2000 or more at 60-65 mph. There is not enough hp available in any of these trucks to tow well below 2000. The last time I towed. I can assure you I wasnt doing 52mph.
It is true. The cummins will be more likely to hold 65mph than the PSD. Just the way its geared. The PSD is geared too high to run this speed and maintain it well. On flat land. PSD. Big hill. Cummins. Ill lay money on that. The cummins will have all 325hp on tap and the PSD will have 275. I can translate that to ft lbs per minute if you like. The PSD would have to be doing 75mph to be at peak hp. 75mph will require quite a bit more hp to maintain due to wind resistance. It has less torque at the wheels and a much higher hp demand just to maintain its speed against resistance. I personally think this is a bad place for the gear to land but it will tow light loads faster. So as long as your not towing heavy no worries.

Cummins has a substantial advantage at this everday speed and rpm you will likely use while towing heavy up a steep grade on the interstate. I can tell you with 99% certainty that it will not grab second so it will not lose this constant speed test. Even at gross up a 6%. The PSD with an increasing load will lose its speed eventually and have to gear down. The psd can get up there faster. The cummins can hold it better. One engine is better at racing the other at towing.

My 10000 rpm example was extreme. But I can tell you. If its true for a little its true for a lot. Just the way hp works. The absurd comparison shows what forces are at work just a lot more extreme. Faster equals less. Slower equals more. If they have identical hp.

 

IRONMAN: I think I could do that analysis. Let's assume an ideal CVT allows the engine to simply stay at just one RPM +/- a little bit. You pick and RPM for the Dodge .... I'll pick an RPM for the Ford. Give me your RPM and I'll make a stab at the analysis.

IRONMAN: Heretic. With both this and vs.-Duramax analysis, I started w/ 1600 rpm for each one ... the max torque points for CUmmins and Duramax. The ever-worshipped heart-n-soul of thoses engines claims. Ford had to downshift first, because we started there. But yet you think I "manipulate the data until you find a spot where it would win". ....... Horsepucky. Tell ya what. You give me a start speed ... or rpm. I'll redo the analysis ... against either the Dodge/48RE .... or the Dodge/5600. Fair?

 

Good point.

 

MI. I already did. The cummins is more likely to hold 65mph when the going gets tough. That was it. Dont need to do the math. It has more torque and more hp at this speed.

CVTs will generally take you to peak hp. Peak hp for both.

For a real world cvt. This perplexed me. Yamaha introduces a 4 stroke inline 4 that makes 140hp. The run it through a reducer to before it hits the primary clutch. 12000 rpm was too much they wanted to reduce it to 8000 to match the performance of maintstream snowmobiles.

 

"The cummins is more likely to hold 65mph"
More likely to hold that speed or more likely to hold without having to downshift???

If the Ford has enough RPM potential to be able to shift down into 3rd and still go 65 mph, then it would win over the Cummins staying in fourth gear, even if the PSD is putting out less at the flywheel. The multiplication of the PSD's torque by using a lower gear will win.

 

Right, any truck can be manipulated into how well it holds a certain speed through the gearing.

 

I still believe everyone is looking at this issue with brand blinders on, Both Ford and dodge Guys. The Two engines Cummins and PSD both have their strong points and both have their weaknesses. In my opinion, The PSD is a better "short haul" engine. Its better suited for stop and go than the Cummins. The Cummins is more suited for "long haul." The Cummins in the Dodge performs much like the larger Cummins in the OTR tractors. It gets the load moving, eventually, then it keeps it moving WITHOUT DOWNSHIFTING. The Cummins fills the traditional role of a Diesel engine. The PSD, on the otherhand, as far as its torque and h.p. curves performs similarly to Big Block Gasoline engine. Thats not a bad thing. I have always preferred big block Gas to diesel for "short haul." I would think that probably 75% of the Diesel p.u. owners use their trucks for short haul; so Ford is on track with the PSD meeting the market demand. I still think it is a far stretch to say the PSD is as good as the Cummins for "long haul," because the PSD can not maintain the speed without downshifting much more often than the Cummins.