No, just trying to clear the air and make sure that although this thread was hijacked (sorry) the subject matter is clear.

 

I'm still wondering how you can measure torque without first measuring horsepower and rpm. I know you can find torque with math, but you first have to find horsepower. What I have understood and am trying to express, is that torque (in an engine) is not measurable by itself and is a numbers game that we use to rate how an engine makes its horsepower. Horsepower being the force that is measurable and predictable.

Example, an engine with 300 hp/ 300 tq will not do the same amount of work as an engine with 200 hp/ 300 tq. Whereas two engines with equal horsepower and different torque will do the same amount of work, although not always practical (F1 engine in a semi)

Does that make any sense, or am I just crazy?

The point of my discussion on this is simple. If you look at what a torque number really is, you will see that it has to do with what rpm range the engine makes horsepower, and absolutely nothing to do with whether the engine is an inline or v-8.

I am always trying to learn, I want to hear more thoughts on how torque can be measured by itself, and why it is not horsepower that does the work. Why can a 3rd gen with say 400 hp and 800 tq out pull a 1st gen with 300 hp and 1000tq? That tells me that torque is not the measure of ability to do work.

---AutoMerged DoublePost---

By the way, I am building a diesel powered space rocket and am looking for volunteers to test pilot it.

 

cummins

 

Matt,

I'm sorry to beat this dead horse with a big stick but without ever putting a truck, motor or whatever else on a dyno you know what the torque is at any given RPM. How do I know that, simple, if you know the cam lossess and the other internal losses, know the piston length etc you now the torque. Why, because you have the mass, the acceleration, the distance of the moment arm and all the friction identifiers. The RPM is based on the radi of the shaft etc. and those applicable known numbers defining the remainder of the RPM requirements.

So, as I have indicated before but will clarify again, although you can have identical HP and TQ numbers from a I6 or V8 the V8 is less efficient because if the internal losses. Take the same displacement of the V8 and make it an I6 and it would run better. Why a manufacturer chooses to do what they do have lots to do with marketing and little to do with physics.

Another way to look at it still is this, people buy HP but drive TQ and a large number don't know the difference.

Anyway, have a great day.

 

Did I enter high school physics class again? Damn time travel device.......DAMN YOU! Oh and one more thing...torque>horsepower

 

OK I give up. No one wants to discuss what torque really is, or at least won't tell me how to quantify it, which makes the discussion pointless.

I will still ask, how can an engine with more horsepower and less torque outperform an engine with more torque and less horsepower if torque is the "real" number?

 

Define "performance." Torque gets you going. Horsepower keeps you going.

 

Matt,

That's easy - RPM.

High HP and Lower TQ to outperform High TQ and Low HP

HP = TQ x RPM so say HP was 100 and TQ was 50 in this case the RPM would be equal to 100 = (50)(RPM)/5252 or (100)(5252)/50 = RPM or 10504

But if HP was 50 and TQ was 100

(50)(5252)/100 = RPM = 2626

In one case, a classic example of say a top fuel dragster and the other a 3rd gen Cummins. It isn't that simple but this is the basic concept.

 

Engine dynamometer by RevSearch - Race engine dyno testing and development.

Make sure you guys check out the Comments page at the bottom of the article.


I will say this though. If a human being has enough torque(or exerts enough force) he can pick up or move an object. Doesn't mean he can pick it up fast. Just means he can. He can not apply more torque(or force) than is required to move the object.(just like an engine at 50% load produces less torque than one at 100% load).

Horsepower means he can move the object at a certain speed. More horsepower= Moving the object faster and more work done. Which is why drag cars have high horsepower engines rather than high torque engines. WHich is a function of engine design. You can build an engine to operate at high RPM(generate more torque at a high rpm) which would make more horsepower and get more work done.(faster times at the drag strip) or build it for low rpm(More torque at a lower rpm) which would make less horsepower(as long as torque remains constant)

Now you can directly measure both but it seems most dyno's think that measureing Torque and RPM is more accurate than measuring Horsepower ad RPM.

 

That's a good article! I am left somewhat confused though, as it is 100% backwards from what I have been told how a dyno does what it does, and what I thought I understood.

I think I might be confusing myself more here, but in all actuality, since torque and horsepower are both elements of a fixed equation, doesn't that mean they represent the same thing?