I have not driven my PI 2V enough to say yet.
My early 2V pull hardest from about 3500 to 4500.

 

which is in it's peak TORQUE range, 4700rpm where it's peak HP is was outside of where it pulled best. Same thing with my 7.3, pulled real hard in it's peak torque range but at peak hp rpm it didn't take much of a hill for it to lose rpm and drop back into the peak torque range, but it couldn't hold the peak hp rpm.

And you will find it is more efficient in it's torque range too. will it get better fuel economy at 3500rpm or 4700rpm? and yes it's a rhetorical question.

 

You still don't get it. HP is what matter when it comes to pulling power. If you gear that 500HP rotary, and that 500HP semi diesel engine so that each one has the same top speed (engine at the limiter on both), they will be able to pull the exact same load, at the exact same speed. It is just fact.

"Horsepower (HP) is the name of several units of measurement of power."

"In physics, power is the rate at which work is performed or energy is converted"

"In physics, mechanical work is the amount of energy transferred by a force acting through a distance"

Physically moving the trailer is work, how fast you can accelerate and how high your top speed is power. Ergo, the engine with more horsepower can pull more weight, faster.

 

Lead head, since we just moved from math to the dictionary, answer the real world questions I posted here...

 

The 7.3 was running correctly unless you can prove otherwise (the owners words that it was running correctly not mine). The EGT was high do to installation of the probe in the manifold. The 7.3 had a very recent tranny rebuild. The first two videos of the V10 were at stock. The 6.0 has 5 speeds the V10 has 4 and factory tuning that locks the TC early (the 6.0 had no such handy cap). Net result the 6.0 was 9 MPH faster. Call it DESTROYED if you wish.

 

Oh brother.

You are wrong. HP is NOT measurable it IS calculated based on other measurable quantities. Even the original definitoon of HP was NOT measured. it was a made up figure used by James Watt to sell his steam engines. It was based on a number that no one knows were he came up with (that a horse could pull with a force of 180lbs) and how many times that horse could pull a corn mill setup with a 24ft diameter (or 75.4ft circumference ) in a circle to turn that mill in 1 hour.

But even beyond that you STILL don't get the point. ON PAPER you can do those calculations but until you can show me an ACTUAL vehicle with ACTUAL gear ratios that is ACTUALLY being used that makes that rotary engine equal to that 500hp semi engine you are just using theoretical stuff trying to justify your choice you made for an engine.

This fact makes me think that you don't believe you made the right choice and are trying to convince yourself of that.

now fact is in REAL life just because an engine is rated at higher hp does NOT mean it will be more suited to use as a tow vehicle. Cadillac CTS has 556hp but I darn sure don't think it would be much good for pulling my boat to the lake or my car trailer. Do you?

So using HP numbers as I originally stated does NOT make a good comparison here.


BTW since I brought it up.

Are you in this thread to convince yourself you made the right choice? If the answer is yes then you did NOT.

Are you happy with the engine you have? If the answer is yes then you have the best engine for YOU. The 7.3 I have is the best engine FOR ME. But I would never try to convince Art (Krewat) that my 7.3 is the best engine for him.... because it wouldn't be and isn't.

 

Not at all.
The 05+ 3V makes 362 at 4750.
I do not know the 97-99 Non PI specs off the top of my head but theres only 275 HP and peak RPM is much lower. The auto tranny upshifts at 4650 or so.

 

You guys keep omitting or ignoring that the 6.0L is equipped with the torqshift-a FAR superior trans with FAR superior gear spacing. The E350's had the Torqshift with the 2V 6.8L starting in '05 or so...that would be an interesting comparison to a 6.0L.
JL

 

Wrong.... How fast you can accelerate is directly related to how hard you can twist the axle against a load. ( torque ) Your top speed is measured by how long you can keep that axle twisted while speed increases. ( horsepower )....

You have to restate your last one. Here, I'll fix it for you.

'Ergo, the engine with more horsepower has the potential for a higher top speed.'

You could say that it can pull more weight, but not that it goes faster, or vice versa. just not both at the same time. The 'pull more weight' part depends on many other factors.


Another thing: If engines were made to have the same hp and torque peaks, they would either run out of steam way early, or never pull anything because there is no usable torque just off idle.

 

The v10 makes PEAK hp of 310 hp but it never turned past 3,000 rpm where it is only making about 240 hp. The 7.3 makes a PEAK hp of around 235 and it pulled right even with the v10. That make sense? If the v10 had better gearing where it could reach it's peak power then it would have pulled a lot better than it did. So again, v10 makes 310 PEAK hp but never reached peak hp, so it never put out more than 240 hp.... That is why my 5.4 reached a higher speed than the v10. Less peak hp, but my gearing allowed me to reach peak hp(which was more hp than the v10 was putting out).

They will pull better at peak hp rather than peak tq. At least every truck I have ever towed with is that way(including my 7.3). Of course you will get better fuel economy when towing at peak tq rather than peak hp, but that isn't what we are debating.

 

At a given speed, I agree, peak hp is going to pull better. But if your trying to get things moving, staying around the torque peak will get you up to speed quicker ( more twist ).

Say for instance your towing 6k lb's. It might take 200 ft/lbs to keep it at a steady speed on flat land. Horsepower has little to do here, but inertia helps a lot. To apply more torque (to accelerate on flat, or maintain speed up a hill), Horsepower steps in to keep the increase of twist constant. If your at HP peak, you might maintain torque of 400 ft/lbs while climbing a hill. If the 400 ft/lbs is greater than the demand to maintain speed, your now accelerating. If your at torque peak, with your foot on the floor, (lugging the engine) that 525 ft lbs is available to twist the axle. If your lugging, the load is taking all the torque to maintain speed. As speed increases, available torque decreases. As the available torque decreases, that 'seat of your pants' feel decreases, as does acceleration. Your still go faster, but at a slower rate. At the intersection (equal each other) of load (demand) and torque (input), you find top speed. (horsepower).

Don't raz me on numbers, I know they are not right, its a example, so go with it.

 

You say that, but have no problems using the pickup truck.com article where they used 4.3 gears and 3/4 ton truck v10 losing by 5 seconds to a psd wit 3.73 gears and drw 1ton as evidence the v10 pulls harder.

So why is gearing different than transmission?

 

The difference between torque and horspower is confusing and I never could fully grasp it even with my mechanical background. Basically torque is twisting force at a given instant but HP has a time and rpm factor built into it. Very confusing and I can see why there is a lot of controversy here. It seems to me that an engine with a tranny that could maintain the proper gear ratio at the peak torque rating (Maybe a 10 speed) would have an advantage over an engine with higher HP and less torque. Chevy had an infinite ratio auto tranny (can't remember what it was called) years ago that never really changed gears but I think the design itself devoured much of the power. Snowmobiles have a gearing system with the same principle also.
................just food for thought

 

Thank you for the video link Art....it was quite informative....It doesn't really prove which engine/trans/rearend combo is the best...but it seems all of the trucks did well pulling that winding hill.

Congrats to all who participated!!!!!!

 

Maybe this has been stated already, i have not read everything in this thread:
Horsepower gets you there, Torque keeps you there.