Cat vs Powerstroke torque curves

Wes Tausend wrote:
I couldn't get the portion of post below this paragraph, to take yesterday, but it is still a real-time situation to why HP is more important in a race. Offhand, one could theoretically get to the top of a hill first with 1 footpound, if rpms were high enough (millions!) to generate more HP than a 1000 footpound diesel limited to only 6000 rpm. The amount of torque is not important in such a race as long as there is any at all. So you are right, it takes some torque along with HP... but not a lot.

I am not talking about theoretical made up instances that have no bearing on the real world. In the real world, all truck engines have greater than 1 lb-ft. Also, if what you are towing requires more than 1 lb-ft from the engine to move it, then you will not be going anywhere.

Wes Tausend wrote:
ShinerBock, I had to look for your statement, "To say that it is only horsepower that helps you up hills is false." I found something similar, perhaps what you meant, in bold type below.


"Debunking Horsepower and Torque Myths

....Myth 1 - An engine with more torque 'pulls' better.

........... So it isn’t engine torque that decides how fast you go up the hill, it is horsepower...."

I don't agree with everything the Laine Family page says either, but taken in context I think he is correct about HP on hills. He doesn't say it's better, but just that it ultimately determines maximum speed up the hill. As an example I have the two trucks described in post #7. Wide open, the 310 hp 3/4 ton Excursion V-10 gasser should beat the 235 HP F-250 diesel up a hill with the same camper in tow. But the F-250 has 500 footpounds of torque, and the Excursion only has 450. However the reason is the Excursion will shift down, then wind out to find it's HP peak and more than make up the actual increased geared-down torque to the rear tires at a faster rate up the hill.

He stated in the title of the myth that "An engine with more torque 'pulls' better", and then he went on to compare two different engines with different gear sets. Why give them two different gear sets if the myth is about engines? If he thinks it is a myth that an engine with more torque does not pull better then he should use the same gears sets for two different engines. If he would use the same gears sets(since the myth is about engines) then he would find out that an engine with more torque does pull heavier loads better and it is not a myth.

He should rename his myth if he is going to change gears along with the different engines in his examples. After all, most of the truck in the real world use the same transmission gearing and/or rear gearing between the engines in their lineups.

Was your Excursion a 4.30 gear ratio like most V10s were or was it a 3.73 that only came with the F250 diesels. If so, then your V10 Excursion was putting down more torque to the wheels gear for gear than the 7.3L along with more hp.

Wes Tausend wrote:
By the same token, the Hemi will theoretically beat the Cummins up the hill during a race providing it can run at it's full HP peak RPM's. Since there is a good chance the Hemi gearing will not perfectly match it's powerband HP peak, I too would probably more enjoy the lower RPM purr of that fine 6 cylinder wideband diesel than the scream of the peaky Hemi, and the diesel might even beat the Hemi if:
1) either the gearing matches better,
2) or more likely, the diesel powerband is so wide that gearing match is a lesser concern.

Wes
...

The myth's title that I disagreed with was about engines, not gearing. Of course you can gear any vehicle to multiply and optimize the torque the engine, but that is not what he said in the title of the myth. If the myth was about engines, then why did he change the gearing to multiply torque in his examples especially when most pickup trucks today utilize the same gearing for each engine in their line-up.


Riddle me this! Let’s use the engines in the articl, and since we are trying to debunk the supposed myth that engines with more torque pull better, we are going to keep the gearing the same at 1:1 to keep it simple. So engine A was the higher torque engine making a peak torque 400 lb-ft at 2,000rpm, and let’s say its peak horsepower is 175 hp at 2,800 rpm. Engine B is has a peak torque of 200 lb-ft at 4,000 rpm like he states, and lest say its peak horsepower is 225 hp at 6,500. Although the peak numbers are low, the rpms each reaches them is typical for diesel versus gas engine.

Let’s take both engines and apply a load to them simulating pulling weight up a hill. Both start off on flat plains and barely need any output to keep the wheels moving. Let’s start off the hill at a low grade requiring only 175 lb-ft of force from the engine to keep them moving. Which one of these engines will be able to put out more horsepower making whatever they are powering move faster and why?

Just like an incline gets steeper and the force required to overcome it increases, let’s increase the force required to 200 lb-ft. Which one of these engines will be able to put out more horsepower making whatever they are powering move faster and why?

Finally, let’s increase the grade even more requiring 400 lb-ft . Which one of these engines will be able to put out more horsepower making whatever they are powering move faster and why?

So engine torque has no influence on how fast you can pull up a hill like the article states? An engine can't apply its peak horsepower if it does't have enough torque at that rpm to move the wheels and keep them moving so yes, it takes both torque and horsepower.