Can someone explain to me about torque? What exactly is it and how is it calculated? Why do our diesels have more torque? I was just thumbing thru my Chilton manual and I see where a 5.9 liter cummins has 160 hp at 2500 rpm and 400 ft./lbs torque at 1700 rpm while a 5.9 liter gas burner has 193 hp at 4000rpm but only 292 ft/lbs torque at 2400 rpm.

 

Basicly torque is the amount of force applied to rotate a shaft. Horse power is the ability to maintain torque with rpm. Calculated ; Torque x rpm/divided by 5252 = HP. A diesel has the torque designed to be the greatest at a low RPM and limited Max RPM. A diesel is most fuel efficient at lower RPM's. A gaser performs best and is most efficient at higher RPM's so it is designed to run at higher RPM's. All these numbers are generated mainly on a Dynomometer so they can develope the engine to perform to maximum efficiency and adequate power for a specific application, meeting all federal emmissions and fuel economy requirements.
The power numbers you refer to are typical of the differences between the two engines. Now we get into the BIG controversy of which is better, gas or diesel? My opinion is it is personal preference and should be determined by the application you want it to do. They both have advantages and disadvantages. Which is right for you?

 

Torque is the ability to do a job and HP is how fast the job can be done. HP is actually NOT measured by a DYNO but rather calculated from the torque and RPM. There was a topic on this very subject just a couple of weeks ago that was very worn out. Do a search on it and you will get quite a few pages to read, on facts and a lot of opinions. Also read HORSEPOWER VS. TORQUE. Maybe thats just what your looking for.

 

The lower the RPM's that you can get your peak HP to fall in, the higher your TQ will be.
You can have two motors that both make 350hp. But if one makes it at 1800rpm and the other at 7000rpm, the first will have significantly more TQ than the second.

 

Oh no, not this topic again .......for a very lively and in-depth discussion on torque and hp, do a search in the towing and RV forum on the thread "RPM's while towing".......interesting, enternaining and informative.........

 

Thanks for all the input guys. I missed the last threads but I will go take a look. Just something that I always wondered about. Now its as clear as mud! Thanks again and Merry Christmas to all!!!

 

Just to add to the previous comments, when you goose your truck, you feel torque which makes you grin! Torque is what it takes to accelerate to a higher speed or to pull a load up the mountain. Gasoline engines develop their maximum torque at a high RPM which means that to get the job done in a gasser, you gotta shift to a low enuf gear to really wind up the engine. Diesels are sorta like the old steam locomotives, they pull the hardest at low RPM's.

 

Give me torque over HP anyday.

 

Torque launches you.....

HP keeps you going when the foot is down to the floor...

 

Browsing the magazine rack yesterday I came across a review of the Dodge Powr Wagon, where they named it something like best 4wd truck for 2005. The main complaint was a lack of power, and one reviewer said that it was his dream truck except that it didn't have the Cummins. Funny, considering that the Hemi has more horsepower (but as we all know, lots less torque :^)

 

I just tell people around here when they drive up with the HEMI that it has '2 too many cylinders'. You only need 6 if it is working right. Then leave them in a little CLOUD of smoke.