Torque vs. HP

[PaNsyBoy8]

Could someone please explain to me the difference between torque and hp and how they effect cars.

 

[yakko]

Yes.

 

[Thegonagle]

Sure.

 

[PaNsyBoy8]

thanks guy =), I'm glad you guys are always here to help

 

[Thegonagle]

OK, the most important thing to realize is that you can't have one without the other, and without motion (RPM), there's no HP, even with 1,000,000 ft/lbs of torque.

I think this formula explains it best:

[*] Horsepower = (Torque x RPM) / 5,252

If you think about it, it's really quite simple.

EDIT: There's a lot more information available at How Stuff Works here, here, and here.

 

[LivinLaVivaPollo]

Hehe one of my rice rocket buddies told me that "Torque is what makes your car go up hills, and horsepower is what makes your car go straight." I don't really know the answer, but his sure does make sense

 

[Thegonagle]

Your rice buddy's answer is profoundly unintelligible because he has no clue.

 

[CYLINDERMAN]

To keep it simple, torque is the twisting force of the crankshaft and HP is the product of torque and RPM.

which is to say if you increase torque at a given RPM you increase HP or if you increase RPM and maintain torque you also increase HP.

now the effect, high torque low RPM engine such as deisel can take a high load but work slow. Low torque high RPM engines such as grand prix engine cannot handle as high a load but work fast. torque engines tend to have smooth power through a wide RPM range where as high RPM engine have very explosive power through a narrow range.

hope this helps

 

[Thegonagle]

Without picking nits about the engines in a 5.7L Camaro vs. a 2L Honda S2000, you're right, but you simply can't tell the entire story without a torque curve on a graph.

 

[CYLINDERMAN]

Yes Garfang, you are absolutely correct the torque curve is the most important in determining an engines state of tune.

 

[Jerboy]

<< Could someone please explain to me the difference between torque and hp and how they effect cars. >>




Torque=twisting force

RPM=revolutions per minute

Torque x RPM= hp (although you can't multiply ft-lbs, RPM dirctly to get hp. This is just the concept).


Think of multispeed bicycle. low gear=more climbing less speed, high gear=not much climbing and fast, and you'll soon discover that you can't go faster than certain speed regardless of whatever gear you use and this is because its limited by your power.

 

[Thegonagle]

<< Torque x RPM= hp (although you can't multiply ft-lbs, RPM dirctly to get hp. This is just the concept). >>



Not to be rude, as I still have some respect for you, but do you ever read the thread? I already posted the correct formula which you can indeed use to calculate HP from torque and RPM. If you rearrange the formula (algebra, they still teach that in high school right?), you can figure out any one (torque, HP, or RPM) if you know the other two.

 

[Baffler]

nope, dont have a clue..........

 

[Jerboy]

<<

<< Torque x RPM= hp (although you can't multiply ft-lbs, RPM dirctly to get hp. This is just the concept). >>



Not to be rude, as I still have some respect for you, but do you ever read the thread? I already posted the correct formula which you can indeed use to calculate HP from torque and RPM. If you rearrange the formula (algebra, they still teach that in high school right?), you can figure out any one (torque, HP, or RPM) if you know the other two. >>



Yup I know. I didn't feel like digging it out. I was just pointing out that you can't do a dead simple multiplication 100ft-lbs x 3500RPM = 350,000horsepower.




<< but do you ever read the thread? >>



No I don't always read the whole thread every time I post. Can you say you're not guilty of posting without thoroughly reading the entire thread?

 

[Thegonagle]

<< Yup I know. I didn't feel like digging it out. I was just pointing out that you can't do a dead simple multiplication 100ft-lbs x 3500RPM = 350,000horsepower. >>


That's right. There's one more step: 350,000 / 5252 = 66.6 HP @ 3500 RPM



<< No I don't always read the whole thread every time I post. Can you say you're not guilty of posting without thoroughly reading the entire thread? >>


Well, no, I can't say that. There have been some whoppers here that would take an hour or more to read, but I try to fully read those threads of under 10 posts before I contribute just to avoid looking like a dumbass.

 

[yakko]

<< which is to say if you increase torque at a given RPM you increase HP >>

That is incoorect. When VW had Porsche tune their VR6 for the Eurovan camper torque was increased but HP dropped.

 

[cipher00]

I think of it like this:

Torque gets you there, horsepower keeps you there.

'Nuff said.

 

[geekender]

Usage wise you will look more at torque for pulling power and horsepower for higher speeds. Torque will allow you to pull heavy loads or accellerate quickly; horsepower will allow that accelleration to continue.

 

[Turbopit]

rpm/5252 *torque=hp

 

[azazyel]

Torque just sounds cool....Torque

 

[isasir]

<< I think of it like this:

Torque gets you there, horsepower keeps you there.

'Nuff said. >>



Can someone confirm that this is reasonably accurate? (Obviously an oversimplification). Cuz I still have trouble following the more complex explanations.

 

[Bulk Beef]

<<

<< which is to say if you increase torque at a given RPM you increase HP >>

That is incoorect. When VW had Porsche tune their VR6 for the Eurovan camper torque was increased but HP dropped. >>

The key here was "at a given RPM". Cylinderman is correct. In your example, you are talking about peak torque and peak HP figures. Different deal.

 

[NonTechGuy]

the guy who said HP is torque * RPM / something was right

Torque is force on the axle, it determines how fast you can accelerate basically (if you have a good tranny that is)
Horsepower is the old school way of measuring power (kilowatts is new school) and power is W/t which turns into Fd/t force * distance / time and as you know force is the torque and distance / time is speed which is the RPM

*wink* *wink* *wink* *wink* *wink* *wink* *wink* *wink* *wink* *wink* *wink* *wink* *wink*

i had to put that hehe

 

[SCSIfreek]

Torque <---- If you step on the gas and see your passengers wave their head back thats torque. it always makes me laugh when I see everyone in the car wave their heads back once i step on the gas.


HP<----- While you're going up a hill and you step on the gas it keeps on accelerating now thats when HP plays a large part. You won't see Civics nor Corrolas accelerate much going up the Hill do you? and I aint talking about small hills but more like 35 degree to 45 degree hills.


--Scsi

 

[NonTechGuy]

to sum up basically:
when you are buying a car and the guy says "its 300HP!!!" tell him you want to see it's true torque specs THEN you can judge how much power it really has.

you can give a 500CC engine 200HP if you make it run at 10,000RPM easily but what good is that if it won't have the torque to get it up to that RPM in the first place!
technically i could say my dirtbike has 10 trillion horsepower and in fine print put "at 99 heptillion RPM"