Are high horse power cars really necessary for racing?

Philippine Mango

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Oct 29, 2004
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Is it really necessary to have a car be high horsepower for racing? Couldn't you just have a high torque low HP car with a tuned transmission be used in racing instead? Having more torque is what allows you to accelerate faster and reach those top speeds, right? Because if you don't have enough torque to overcome the forces of nature, having all that HP won't really do any good...
 

dighn

Lifer
Aug 12, 2001
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well to bring a car quickly to speed you need higher power output because of the change in kinetic energy. about the only thing you can do to reduce power required is to lower the car's mass. in essence, speed is energy, higher speed in shorter amount of time means more energy per unit of time = higher power. this can be worked out with high school physics.
 

jpeyton

Moderator in SFF, Notebooks, Pre-Built/Barebones
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Aug 23, 2003
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F1 cars have a high HP to torque ratio.
 

Pacfanweb

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Jan 2, 2000
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You can't have horsepower without torque.

So you can't build a 600 lb/ft of torque gas engine with only 250 hp. Not possible. You also can't have an engine that puts our gobs of torque at low RPM, then also gobs of HP at high RPM.

The lower an RPM you can get HP at, you will have more torque. This is what big cube engines are good at. A small engine simply won't make that much horsepower at a low RPM, so you have to rev it to get power....and if your HP peak is at a higher RPM, so will your torque peak be.
 

Pacfanweb

Lifer
Jan 2, 2000
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Originally posted by: jpeyton
F1 cars have a high HP to torque ratio.
That's because they are small engines that have to rev very high to make horsepower.

Edit: an engine is basically an air pump. The way to make power is to burn more fuel. The way to burn more fuel is to get more air pumped through it so you can add more fuel and not be too rich.
If you have a small engine, the way to make more power is to rev it higher, thus moving more air/fuel mixture through the engine.

Or you can build a larger engine, which will naturally move more air/fuel mixture through at lower rpm, resulting in a lower HP peak and more torque.

Then you complicate matters by adding forced induction...super charger, turbo, nitrous.
All these items essentially do is force more air into the engine than it could suck in on its own. Basically, forced induction is a way of fooling the engine into acting like it's a larger cubic inch than it really is.
 

thedarkwolf

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Oct 13, 1999
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No you don't need high horsepower for racing. Plenty of the lower racing series use pretty low powered engines, miata spec series for instance.
 

Philippine Mango

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Oct 29, 2004
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Originally posted by: trmiv
You know that horsepower is a function of torque, right?

thats my point, because you need torque to have horsepower, it'd would seem to make sense that HP is less important than torque. More HP allows the wheels to spin faster but if you were to just covert the extra torque from the engine into more movement via the transmission, more HP isn't really necessary then.

 

Vic

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Jun 12, 2001
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Yeah, 'cause diesels rule the racing circuits. :roll:

Horsepower is torque over time. More horsepower means the ability to output torque more rapidly.
 

Vic

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Jun 12, 2001
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Originally posted by: Pacfanweb
You can't have horsepower without torque.

So you can't build a 600 lb/ft of torque gas engine with only 250 hp. Not possible. You also can't have an engine that puts our gobs of torque at low RPM, then also gobs of HP at high RPM.

The lower an RPM you can get HP at, you will have more torque. This is what big cube engines are good at. A small engine simply won't make that much horsepower at a low RPM, so you have to rev it to get power....and if your HP peak is at a higher RPM, so will your torque peak be.

Sure you could build a 600 lb-ft. gas engine with only 250 hp. Just make its peak torque max out at 2200 rpm with either the torque curve falling off rapidly or redline shorty after. Go back 100 years in automotive technology and such a thing would not have been unusual. The Model T made a whopping 20 hp with a 2.9L engine with a redline in the 2k rpm range.

Your last paragraph is backwards. The lower an RPM you can get torque at, the more HP you will make at that rpm. hp = (torque*rpm)/5252
Torque and power are functions of displacement (or more properly, the amount of air the engine can "pump"). Given engines identical in every way but displacement, the larger engine will always make more torque and more power all the way across the rpm range.
 

Vic

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Originally posted by: Colt45
Originally posted by: Vic
Yeah, 'cause diesels rule the racing circuits. :roll:

Horsepower is torque over time. More horsepower means the ability to output torque more rapidly.

One diesel does.

Note the specs on the engine. Audi is getting over 5k rpm out of that diesel, which means that they're finally getting hp output close to torque output, thus making it usable for racing.
 

Colt45

Lifer
Apr 18, 2001
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Originally posted by: Vic
Originally posted by: Colt45
Originally posted by: Vic
Yeah, 'cause diesels rule the racing circuits. :roll:

Horsepower is torque over time. More horsepower means the ability to output torque more rapidly.

One diesel does.

Note the specs on the engine. Audi is getting over 5k rpm out of that diesel, which means that they're finally getting hp output close to torque output, thus making it usable for racing.

Even the little 4cyl 1.9L TDI's have a pretty high redline. 5500 i think, ranging from 90 - 150hp, depending on the model.

It's not grandpa's Oldsmobile with a 350 diesel anymore :)

Although this isn't really related to the OP's question. haha.
 

eldorado99

Lifer
Feb 16, 2004
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Originally posted by: Pacfanweb
You can't have horsepower without torque.

So you can't build a 600 lb/ft of torque gas engine with only 250 hp. Not possible. You also can't have an engine that puts our gobs of torque at low RPM, then also gobs of HP at high RPM.

The lower an RPM you can get HP at, you will have more torque. This is what big cube engines are good at. A small engine simply won't make that much horsepower at a low RPM, so you have to rev it to get power....and if your HP peak is at a higher RPM, so will your torque peak be.

My car has roughly 200 HP and 550 Ft. pounds of torque...
 

FallenHero

Diamond Member
Jan 2, 2006
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Originally posted by: eldorado99
Originally posted by: Pacfanweb
You can't have horsepower without torque.

So you can't build a 600 lb/ft of torque gas engine with only 250 hp. Not possible. You also can't have an engine that puts our gobs of torque at low RPM, then also gobs of HP at high RPM.

The lower an RPM you can get HP at, you will have more torque. This is what big cube engines are good at. A small engine simply won't make that much horsepower at a low RPM, so you have to rev it to get power....and if your HP peak is at a higher RPM, so will your torque peak be.

My car has roughly 200 HP and 550 Ft. pounds of torque...

jesus. What car do you drive?
 

eldorado99

Lifer
Feb 16, 2004
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Originally posted by: FallenHero
Originally posted by: eldorado99
Originally posted by: Pacfanweb
You can't have horsepower without torque.

So you can't build a 600 lb/ft of torque gas engine with only 250 hp. Not possible. You also can't have an engine that puts our gobs of torque at low RPM, then also gobs of HP at high RPM.

The lower an RPM you can get HP at, you will have more torque. This is what big cube engines are good at. A small engine simply won't make that much horsepower at a low RPM, so you have to rev it to get power....and if your HP peak is at a higher RPM, so will your torque peak be.

My car has roughly 200 HP and 550 Ft. pounds of torque...

jesus. What car do you drive?

1970 Cadillac Deville... 7.7 Litres makes for a lot of torque, but it redlines at about 4500-5000.
 

angminas

Diamond Member
Dec 17, 2006
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I don't know a lot about racing, but I'm reminded of a quote attributed to Carroll Shelby, who knows more about racing than all of ATOT combined...

"Horsepower sells cars, torque wins races."
 

mercanucaribe

Banned
Oct 20, 2004
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I don't think you know what horsepower is. Horsepower is basically torque * rpm. 800 lb-ft of torque at 2000rpm is the exact same horsepower as 400 lb-ft at 4000 rpm. Both will accelerate the car the exact same amount when geared down to the same wheel speed.

Horsepower is the actual power that moves the car.
 

mercanucaribe

Banned
Oct 20, 2004
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That 1970 Cadillac with 550 ft-lbs and 200hp still only has 200 peak horsepower, the same as an Acura RSX. If the engines were both put in cars of the same weight, and hooked up to CVT transmissions that kept them at peak horsepower, they would accelerate the cars identically.
 

funboy6942

Lifer
Nov 13, 2001
15,311
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Originally posted by: Colt45
Originally posted by: Vic
Yeah, 'cause diesels rule the racing circuits. :roll:

Horsepower is torque over time. More horsepower means the ability to output torque more rapidly.

One diesel does.

The main novelty of the R10 is its engine: a TDI turbodiesel engine, running on Shell V-Power Diesel. It is a 5.5 L (335.6 ci) all-aluminium bi-turbo 90° V12, with common rail direct injection of more than 1600 bar (23,206 psi). Its output should be 650 hp (485 kW) (regulated) and 1100 N·m (811 ft·lbf) of torque, and its usable power band is between 3000 and 5000 rpm. Its benefits are a broad range of usable power, high torque and economy.

Damn at that PSI the injector is doing it can squirt through several inches of steel! Freaking awesome engine there, love to hear it run. 3000-5000 rpm vs what, around 17,000-20,000 rpm from a 4 stroke F1 engine? Thats would be like hearing the difference between a run of a dirt bike race with a 2 stroke and a 4 stroke bike, just at 300x rpm diff :p I can bet they save a ****** load on fuel costs not having to feed as much through that motor at high rpms, and it being diesel fuel.