Very interesting article. I seem to recall gear reduction to make torque...
Now if you insist torque is what moves you, simply remove your engine, have your buddy sit in the engine bay with a 5ft long torque wrench and crank the tranny input at the tune of 600ft/lbs with a ratcheting motion kinda like the power strokes of the motor. He'll be able to move the truck with great ease. Now do 70mph.
You see, your buddy can make torque with leverage but he doesn't have enough horsepower to apply that torque fast enough to be useful for speed. Horsepower is how fast you can apply any amount of torque.
You'll understand some day when you realize horsepower IS torque in motion.

 

Guys, you're splitting hairs here. One factor that makes a good towing rig is the torque rise characteristic of the engine - specifically, the ability of the engine to ride up the torque curve as speed degrades. This is one of the rating factors for the large diesels used in Class 8 rigs. This can also be thought of as horsepower produced at a specific RPM - a good towing engine will produce more BHP in the normal working RPM range than will a comparable engine tuned for higher BHP at the top of the RPM band, even though the latter might be faster at a drag strip.

Torque and BHP are interrelated by the infamous BHP= (QxN)/5252 formula, so it's not an "either/or" proposition. Both factor into the discussion.

Rusty

 

Katoom and Hannibal:

You are both right - I think you guys are just wording your explanations differently.

Torque is the measured amount of force or the amount of force required to move a given load. HP is the measure of how fast the torque can be applied.

So the analogy of the guy turning the input shaft of the tranny with a torque wrench is correct. Torque can be multiplied - HP cannot. You can use a tool to multiply the torque to move the truck easily but since a human can generate very little HP you will not move it very fast. Torque IS what moves the vehicle - HP is how fast you can move it.

I know there is alot more to it than this and that HP and torque are much more interelated as Rusty touched on, but I think we can realize the difference between the two.

just a little more .02 to the fire

 

I think all you guys are missing the issue

Here it is in a nut shell.

If you want to go someplace, you push the little skinny pedal a little bit.

If you want to go someplace faster, you push the little skinny pedal a little bit more.

 

This really helps! But now I need to figger out what to do with this long, whippy lever stickin' up out of the floorboards.

Rusty

 

If you want to get there even faster than that you:
Add TST box
Stack a BD programmer
Pusher pump
Dual turbo's
Tranny mods.
Tight seatbelt and good cup holders.

Torque this.

Nice job on those trailers. I'm a real light weight now. I'm down around 13k with my tow hauler.

 

Good for you!

Rusty

 

Rusty,

Can't help you with the long, whippy lever thingy... my truck doesn't have one

 

Now your getting it. But take away that 5ft wrench, give him a 1/4" ratchet and your now driving a high HP low torque engine. If he can spin the tranny input fast enough you might get somewhere. Oh Yea, stop using what I've been telling you to make yourself look like you know what your talking about.

 

Not to be beligerent but horsepower is a mathamatical equasion of torque and rpm. Torque is what is measured. Gasser engine makes 300 horse at like 5000 rpm, big truck makes 300 horse at less than 2000. the high rpm's is giving the gasser the high horsepower ratings but won't pull crap.

Detroit figured out long ago that raising the rated rpm makes it possible to advertise high horsepower ratings. New trucks make 325 horse at 3000 or so, mine makes 275 at 2500, I blow their doors off pulling a hill with freight. But mine starts with 660 torque theirs much less. My stock engine was 460 torque.

Horsepower is a poor way to rate a truck engine, torque is the real measurement. I forget exactly but it seems that Horsepower equals Torque times rpm devided by 5600 or something like that. Dodge pulls good with a Cumins because the torque curve is basically flat up to near rated rpm.

 

"Oh Yea, stop using what I've been telling you to make yourself look like you know what your talking about."

You don't need to worry about me using your misinformation. I know what I'm talking about. I think now YOU'RE getting it. High horsepower engines can MAKE torque through gear reduction. You cannot calculate how much torque it takes to move a vehicle 70mph without first calculating the horsepower required. Torque is not a speed measurement. It's a static twisting force measurement. It has nothing to do with speed.
The Hemi makes as much torque at the output shaft of the tranny in direct drive as my standard output Cummins makes in O/D at the output shaft of the tranny. Consequently my Cummins makes equal horsepower at 1900rpm in O/D as the Hemi makes at 3,000rpm in direct drive at the same speed. Do the math. Torque in motion is horsepower. High torque engines make more horsepower.
Cummins rates thier OTR engines in terms of horsepower. You're not going to convince me Cummins doesn't know what they're talking about and you do.

 

The way I look at horse power and torque is if you have a water wheel and you take a 1/8" pipe (torque) and squriting water at a 100psi (horse power) , it will start moving slowly and evently pickup speed. Now if you take that same water wheel and use a 2" pipe (torque) at a 100psi (horse power) then the wheel will pickup speed much faster.

 

Real interesting. That means that instead of fooling with this Cummins I can just take a small block Chev and gear it right. For years I ran mid sized wreckers, mostly gas jobs. As I said in the earlier post, "horsepower is a mathamatical equasion of torque and rpm." There are tricks for torque, like seriously advanced cam timing, but horsepower will never replace low end torque. Advancing the cam will lower rpm capability and pull a load much better with lower horsepower. For an example, a 238 horse Detroit will run circles around a 380 horse 440 Dodge. I don't really care how you gear it. And they are both about the same cubic inches, The 238 is smaller 426 cubes to be exact, compared to a 440 Dodge.

I "got that" many years ago, lost a good friend and work. Put a 327 in place of a 292 six cylinder. This would not get out of its own way. It is also in evidence with our Cummins trucks. A 12 valve is governed at 2600 and the highest is what 215 horse? A 24 valve is governed at 3300 and is rated at 235, but they both do about the same stock pulling loads. The 12 valve bunch say they do better. At 2200 they are probably right.

 

Yes you could HD, you could run the small block engine and use gear reduction to make the same torque I'm making at the tailshaft with my SO Cummins. My flat torque curve allows me to run low rpm while my relatively low horsepower requires me to run at a low rpm compared to the small block. For example, if it takes 160hp to tow our 5th wheel on flat ground 70mph, I can use the small block or my Cummins. With my Cummins I run in O/D at 70. I can and I have to. No choice. 70mph X 4.10 X .69 X 336 / 30"=2218rpm. 2218rpm X 460/5252=194hp. So I've got some throttle to spare even with O/D reducing my torque output by 31%. With the small block gasser, using the Hemi for the example, I could run in O/D empty but would have to lock out O/D to tow as the Hemi doesn't make enough hp (torque X rpm) at 2218rpm. The Hemi is capable of about 350ft/lbs of torque at 3,000rpm so we should be good. 70mph X 4.10 X 336 / 30"= 3214rpm. 3214rpm X 350ft/lbs/5252=214hp. So I would have a little more hp with the Hemi mostly because I don't have to run in O/D but at the cost of high fuel consumption and shorter engine life. If you're talking about bombed Cummins or even the stock 610, It's a whole different strory. 70mph X 4.10 X .69 X 336 /30"= 2218rpm. 2218rpm X 610 / 5252= 257hp. So on paper and on the road, the HO or bombed Cummins is capable of more hp in O/D than the Hemi is even with O/D locked out. The hemi could keep up but it'll be in second gear to do it. Not exactly what we would want to do all day. Even if the motor stood up to it our nerves wouldn't.
If you have a 12v 460 Cummins rated at 235hp at 2600rpm and a 24v 460 Cummins rated at 250hp at 2900rpm, of course they'll pull the same. You still have a 460ft/lb torque band that makes the same hp at equal rpm up to 2600rpm where the 24v has a little advantage. But for towing 70mph with a 4.10 ratio and auto in O/D, they'll both be making 194hp at full throttle. You can't lock out O/D with either at 70 so the extra hp won't make any difference unless you bog down to 55mph where you could lock out O/D with the 24v and take advantage of some gear reduction. Or lack of O/D (torque reduction).
I don't know about the Chevy six verses the 327 but the Ford 300 six made more torque at a lower rpm than the 302 V8 so even though the 302 made more horsepower at peak, the 300 made more horsepower at lower rpm where it was more useful for towing and grunt work.
At any rate, torque at any rpm is horsepower. The more torque you have at any rpm, the more hp you have at that rpm. Diesels make high torque at low rpm so they can match or excede a gas engine's high rpm hp at low rpm. If you ran the Hemi at 4,200rpm it could run right along beside you towing the same load. But the fuel consumption would strangle you and it likely wouldn't see 50k miles at that rate. But it could do it even if for just a short time.
If a water wheel makes 1200 ft/lbs of torque and turns 60rpm. It's making only 9 horsepower. All that torque is great for the mill but useless for a vehicle. You'd have to use so much O/D to get any speed out of it there would be no torque left. Hense the 9hp.

 

Just for gits and shiggles, you'd have to have a .027 overdrive to reach 70mph in a Dodge truck with 1200ft/lbs of torque at 60rpm. 1200 X .027 would leave a piddly 32ft/lbs of torque. The 1200 ft/lbs of torque is more than plenty. But at only 60rpm, there's not enough horsepower to do the job. If you want to run along at a slow walking speed and be happy with your 1200ft/lbs of stump pulling torque, great but if you want to run 70mph, you have to have the horsepower (torque AND rpm) to do it.