Jeff928S4

I'm on another forum trying to explain to some Honda guys that a car with 200 horses vs another car with 200 horses isn't always the same.

What I'm trying to explain to them is that a 944 has more power in the higher revs in comparison to the power a Civic would have in the higher revs. They all keep saying you have to wind out a Civic to gets it's full horsepower and they can't understand what I'm saying about a car having more power in higher revs.

What do I say? I need numbers from a typical Civic vs a 944 (or any other rev-happy car) to explain how it works.

Thanks

Jeff (944S Boyeee)

hoffman912

easy, kindly explain to him the definition of torque, and that your lug nuts require more torque, than his car can make .

hoffman912

**** double post

Jeff928S4

That is my problem Harry - I cannot explain torque. I personally don't even really get it.

Is torque what makes car "rev-happy"? I know higher torque is better, but some muscle cars have super torque, but die in the higher revs.

Jeff (944S Boyeee)

hoffman912

maybe this will help http://science.howstuffworks.com/fpte3.htm

some great diagrams there comparing a 430 hp catapillar tractor, and a 437 hp mustang

what we need is a physics guru.. i suck at physics

ian

Horse Power = Torque x RPM / 5252

If you have ever noticed torque and hp curves always cross at 5252 rpms, this is due to the fact that horse power is derived from torque, torque can actually me measured, where hp is a calculation based on those numbers. This is why cars with nice broad flat torque curves have forever rising hp numbers, or with a honda how they have such low torque figures, yet still have good hp numbers.

SidViscous

Torque is a twisting forse, horsepower, a pulling force. Torque gives you acceleration, HP gives you top speed.

Best way to explain it to them. Torque in the lower range gives better acceleration. Electric motors (as in electric cars) have maximum TQ at 0 rom. And because of that they have sick acceleration, even though a low top speed.

We have a high top speed because of gearing.

Does that help? No I didn't think so.

SoCal Driver

I've yet to find a Honda Ricer that has enough gray cells to understand these calculations.

Sami951

The guy who makes more torque at similar rpms also makes more HP. Are they revving higher..? Otherwise you can't have same HP output.

This article managed to make sense to me: http://vettenet.org/torquehp.html

In short, torque is what moves the car, hp is just a number that's calculated from torque and rpms. It will give a clue on what the engine is capable of though, as engines producing similar hp numbers should produce also similar torque at the driving wheels, as long as the gear ratios are suitable.... or something, I think I have it but I can't quite describe it ... just read the website above

streckfu's

Another thought is: Think of torque as a measurement of how much work your engine can perform. HP is how fast that work gets done. So HP is just torque applied over time.

Horsepower is a by-product of torque. There are a lot of factors that go into determining torque (bore, stroke, compression ratio, etc) which brings you to the formula ian posted:

HP=TQ x RPM/5252.

SO if you make 300 lb/ft at 2800rpms you end up with 159hp. If you sstill make 300 lb/ft at 6000 rpms, you are up to 342 hp.

One thing to consider that so many people forget about is that when you add performance mods, you are increasing torque. The increase in HP from those mods is a result of the torque increase at the measured rpm. The only way to increase HP exclusively is to increase your rpms.

Does this help?

Darth Coupe

Torque is the force that will push the car forward, tangentially at the wheels. HP is the rate at which you get that force or rate that you lose it. As simple as that.

See, some Honda guys know it..... Its funny to run into those P-snobs that dont... Shouldnt just stereotype, although there are a lot of kids that own Civics and such and are asses and I too call em ricers, but then there are plenty that know their stuff too. And the same goes for P-car owners, muscle car owners, etc, they are all ricers or they are car enthusiests that know what they are talking about.

Dave951M

The really amusing part is that many consider themselves to be experts because they own the DVD of Fast and Furious, or as my son calls it- Slow and Disgruntled.

The main goal in hp is to have good torque over the broadest possible rpm range, not absolute high hp numbers. If your hp and torque are only available in a band of say 200 rpm, then you have to stay in that band to make max power. That's what we mean when we mean an engine is flexible.

Jeff928S4

All this has helped so much, but I still get responses like this one.....

"Using Honda's as an example of a car that doesn't need to be revved is probably the worst example of every car manufacturer on earth."

How can I explain that they don't need to rev their lil' Honda's so high? Or am I wrong in assuming that most Civics don't have much in the top part of the RPM's?

Jeff (944S Boyeee)

Jeff928S4

I made the mistake of saying that I thought most Civics would be useless over 4000 RPM (I know, that was too low). Now they all hate me!!!

But what RPM SHOULD a Civic driver be shifting at for optimal performance?

What do these things redline at?

Jeff (944S Boyeee)

Porsh-uh

Thanks for the article Sami. It hasn't clicked completely yet, but it certainly is making more sense for me.