I caught that too, right after I posted. It was a rounding error, because I did the 5.4 in multiple steps, since it had a reduction in the tranny. I calculated the 7.3 in one step, since the tranny was 1:1.

Thanks for the double-check.

Excellent point. And I concur with your numbers.

 

Phillips, I think I figured out what the problem is.

Nearly every post you make is completely ignoring speed. For example, this one:

The truck with 2.73s at the same RPM would be going one and a half times FASTER than the one with 4.30s at the same RPM! Takes more HP to move the same mass a faster speed! Take that 4.30 geared truck and accelerate to the same speed the 2.73 one is. Now try it! The 4.30 truck would have to shift to O/D, and for whichever given speed we're talking about, the 4.30 truck would now have a disadvantage in gearing, as you'd have a reduction gear in there.

Can't ignore speed!

Now, let's try this again...

3500 RPMs/2.72 = 1287 RPMs at the rear wheels.

3500 RPMs/4.30 = 814 RPMs at the rear wheels. MUCH slower!

So, using that, let's see which theoretical ratio would get the 4.30 truck to turn the same speed...

814/x = 1287
814 = 1287x
x = 0.63

So you'd need a super tall O/D with a 0.63 ratio to get the same speed...right?

So let's get back into torque, but this time at the same road speed. We'll assume 425 ft-lbs here...

425 ft-lbs x 2.72 = 1156 ft-lbs at the rear wheel

OR

425 ft-lbs x 0.63 x 4.30 = 1151 ft-lbs.

The 5 ft-lb variation is due to rounding when I calculated the theoretical O/D gear necessary to get the 4.30 truck to go as fast as the 2.72 truck at 3500 RPMs.

See? Horsepower is the same, speed is the same, therefore Torque HAS TO BE THE SAME!

 

Crazy, I see your formula and I believe it on paper. It must be true, but it is giving me a headache thinking about it.LOL

 

I give up. The V-10 has more power and wins the competition. The diesel is at a disadvantage because it cannot turn 5000 rpm. I think I get it.

 

im just taking my hp and tq numbers from what ford says they make. both of them are 100% stock, so the hp and tq ratings should be what they were from the factory. the gear ratios, tire size and the rpms are a fact. there's no getting those wrong. your formula comes up with one result but my driving comes up with a totally different one.

ive tested my trucks every way imagineable and the 5.4 isnt even close to my 7.3. no way, no how. with my camper (26' and ~6k lbs) i can toy with it on hills in 5th gear that my 5.4 has to be in 3rd and 4th gear wide open just to maintain speed. theres one red light i get stopped at a lot thats at the bottom of a decent hill. with my 5.4 i have to start out in granny gear, run it pretty dang hard and top the hill in 3rd gear. if i hit 4th gear, its immediately back down to 3rd. just falls on its face. in 3rd it can accelerate, but i dont have to run it wide open. with my 7.3 on that same hill, i can top it in 5th gear without ever having to go over 2500 rpm. im not arguing that your formulas arent correct. i dont think youve made a mistake on them or anything like that. im just saying that formulas dont always translate to the real world.

 

OK lets try Rock, Paper, Sizzorrs

 

Actually, someone should edit out all the BS & mis-information, and get us back to 10 pages........

 

It must be down hill both ways to work.

 

Ah, that depends on the competition!

Realize for a minute that KelVarnson and I both own diesels. When I went up to Millersburg and met up with Monster-4 and i eat hybrids, we got to try them out. Wasn't a fair comparison to Monster-4's V10, as he had the older model with less power than the 3V V10 of the same generation as the '07 F150 and my '08 PSD we lined it up against. Still, it did a great job with that kind of load, and I really have lots of respect for the engine. I would have been really interested to see how a stock 7.3 would have done.

From what I've seen out of my 6.4, as well as the stats on paper, there's no doubt that the 7.3 will seem to have an easier time with a load. After all, it has the definite torque advantage, which translates to a horsepower advantage all through it's rev range. At the same revs, the V10 can not match the horsepower output of the turbodiesel. Therefore, the only time you'd realize a benefit to the V10 is when you crank it up over 3,500 RPMs and let it sing. Perfectly capable of doing it, and I think it'd do it all day long for many years without a problem. The fact still remains that the 7.3 will likely be a more pleasant engine to tow with.

Which doesn't mean the V10 can't do it, though!

 

any time you want to ride with me just let me know. ill be more than happy to let you ride to and from work with me for as long as you want. im willing to back up my claim. you willing to come prove me wrong?

 

Let's just say that there's LESS of an advantage to the diesel than you think

 

Sure it can - but not for long

 

If someone did that there would be nothing left of the thread but the title!


Are you guys actually taking this seriously??

Seems to me the only thing that guys are arguing about is hypothetical situations.

For me the PSD is the best available choice of motors in a Superduty.

 

Holy cow!! 139 pages!!

 

For YOU.

The real crux of the matter is that it's not the best choice for everyone.

With Ford losing the V10 in 2011 in the F250/350, and going backwards to an 8-cylinder 6.2L, they are making the choice for those who prefer the gasser.

Looks like I'm keeping my 2001 for the rest of my life