I had a thread going in the 1st GEN PS section to try and get a handle on understanding how torque output relates to real pulling and is HP HP.


The guy's over there helped me alot but their was confusion on the real world results. One crew was saying the HP and math does not lie and another was saying it does.


I have been communicating with a man who operates the weighted box in tractor pulls. He told me there is no compare, he said you can have a class with less HP and more torque and it will out pull another class with more HP and less torque. He say's the higher HP class will get out of the box with more MPH but then the weighted box will choke them down much easier than the class with less HP and more torque.


Nobody has provided the explanation in physics to why so the one group saying math is math and you just need to gear has one up.


I am much closer however and understand all the math and power curve stuff and will post when I find the answer, if anybody knows please post.


I know there are some people as curious as I am, The Drags are coming to town next month and I bet the Pro Stock boy's know the answer.

 

I'm no expert but torque is an actual rotational force. Horsepower is fuzzier because it is calculated using torque values at a given rpm. I'm not sure why that is but my guess is it has to do with inertia of turning higher rpms and the crank having less time to exert the force per revolution (yet having more revolutions to exert with). An example is exerting 300ft. lbs. On a breaker bar, your providing torque but not many rpms or horsepower. As far as pulling horsepower requires rpm and as the sled box comes up and begins to overcome the engine it loses rpm and therefore horsepower. The higher torque motor will put up more of a "fight" as it gets pulled down.

 

Technically, HP = torque times RPM. Simple as that.
So, in terms of math, you can make up for torque with RPM.

That being said, in the real world, things aren't so cut and dry.

For one thing, gearing creates losses. The more gearing you have to do, the more loss(I believe).

Also, you have the whole 'area under the curve' thing - It's probably not a 'law', but I'll bet that an engine that makes a lot of torque at higher revs will tend to make good torque below that point. So even as the truck gets bogged down and the engine is making less HP, it'll still make close to the same torque.

In theory, you should be able to just use more gearing to take care of this, but I'm guessing there are problems with getting good enough gearing in the real world. I mean, 'optimally', you would have a 0-loss CVT transmission, which would be able to have the 'perfect' gear ratio for any given wheel speed and engine RPM. However, we don't have that -- we either have manual gearboxes which you probably have to keep in one gear during the entire pull, or an automatic which /might/ switch between two. CVTs have too much loss to be useful, and it's hard to design something that can handle the HP anyway.

 

horsepower is how fast you hit the wall.
torque is how far the wall moves.

In a vehicle, torque is measured at various engine speeds, or revolutions per minute (RPM). These two numbers are fed into a formula -- torque times RPM divided by 5,252 -- to arrive at horsepower.

in laymens terms. hp is nothing more than a calculation of torque and work being done

 

Thanks I do not want this going on and on, there seem to be 2 groups where one group is saying as long as all things are equal HP is HP and group two says no it is not and the engine that does the work earlier and has more torque has the ability to drag more load to that peak output and the peak HP is just your top MPH.


Group 2 has not provided a valid good scientific explanation as to why, just their experience in real world app. When the guy operating the weight sled at tractor pulls says group two is right it makes me think something is missing.


Thanks.

 

perhaps you should grab an encyclopaedia.

stop listening to people and do your own research?

this has been a question since the dawn of the automotive industry.

and has been answered about just as long.

 

That is the thing, the information is hard to find that I am looking for. On paper it is like I am wrong because the math does not lie but the real worlder's say no torque is to HP what current is to electricity.


Even on a drag race site there were 2 camps, the physics site said HP is HP, I have been reading on this to no avail.


I think because Pro Stock NHRA lives or dies by a dyno somebody there will have the information at the coming drags to show what I am missing.


It could very well just be the power under the curve is much broader in the more powerful engines that perform better even though rated at same peak HP.


If you have a peakier power band with narrower HP the easier it is under big load to knock it out of the power band so then you need more gears and it can gets to a point to where a gear set is not practical to make it work..


Thanks. I will do more reading.

 

torque times RPM divided by 5,252

 

Thanks....

 

Ok. Pick a number 200 HP for instance. Think of all the possibilities for an internal combustion engine to deliver this. Gas 4 banger drift car, gas v6 pickup, maybe a v8 turbo diesel pickup like we know. The drift car will be stripped out, lightened, the pickup will be set up for medium or light loading and towing, most things about the diesel v8 set up will be oriented toward heavier laden and towing mass. Each system has components matched or tuned to purpose. If the drift engine goes in the pickup something is out of balance. Compare f150,250,350,450, how are different capacities and work rates achieved? A calculation is made of mass, reasonable assessment of laden mass, and gearing , frame, box, and other components are designed accordingly. What is common to all? The horsepower, torque, gearing are matched to the required ability to perform as a set of considerations. If a 4banger gas had to do the work gearing would be different, and the potential may be less even though the HP and torque output may be similar. It's the old piece of string thing and sometimes it just comes down to color.