HP vrs Torque

[Blue89rs]

Sounds like an easy one right? Well, it is. WHAT IS THE FRICKEN DIFFERENCE!!?!?!?!

Seems like HP = Torque*RPM/5252 but what does that mean to performance and the "seat of the pants" driver? Do you notice a difference when you can wind up the motor versus not? I never have been in a car that can wind past 6000rpm so I have no idea.

Also, according to the equation above, HP = Torque at 5,252RPM...but that's not always true. Does it change as per what kind of Dyno you use (water vrs whatever)?

I'm sure I'll get plenty of comments ;D

[formula mark]

http://vettenet.org/torquehp.html

[Blue89rs]

THAT............was awesome. Someone should sticky this as a constant reminder. I have never seen such a good explaination relating the two. Thanks for sharing!

[Dan92Z]

if i was a mdoerator for this forum i would do so.. *cough* so one of the other mods must do it, i agree it was a well written document

[79 Z28]

done and done ;D

[89vert]

that article was to long for me to read but what i was told was torque is how much work it can do horsepower how fast it is done
rx 7 lots of horse no toque fast car till it goes up a hill
427 camaro lots of torque lots of horse always fast

[manchesterbeast]

those rotary engines can wind out to 8000 rpm

[formula mark]

those rotary engines can wind out to 8000 rpm

Maybe, but they are torque-less and suck gas like a 60's big block.

[89vert]

those rotary engines can wind out to 8000 rpm

Maybe, but they are torque-less and suck gas like a 60's big block.

They don't even feel fast whats the point
gota have torque

[manchesterbeast]

Well my V8 definetly has better bottom end power than any rotary. but those rx7's do go pretty fast.

[Dan92Z]

ever seen the video of the rotary being redlined to shit for like over a minute?

[manchesterbeast]

no, i aint seen it. how bout a link? do you know where i could see it? did it catch fire? those cars are known to catch fire. my buddys rx7 burnt down. heh

[Wagonized]

a friend of mine has a 2nd gen rx7 turbo, best track time was 12.99. Its a pretty impressive car IMO. Of course with the money he has into his car an f-body could be running more than a second quicker.

im not sure about the 1st and 3rd gen rx7s but the 2nd gens handle very well due to 50/50 weight distribution. They're very common in autocross



big low end torque has to be the funnest thing...theres nothing like a car that will break em loose in any gear.

[IROC-Z]

a friend of mine has a 2nd gen rx7 turbo, best track time was 12.99. Its a pretty impressive car IMO. Of course with the money he has into his car an f-body could be running more than a second quicker.

im not sure about the 1st and 3rd gen rx7s but the 2nd gens handle very well due to 50/50 weight distribution. They're very common in autocross



big low end torque has to be the funnest thing...theres nothing like a car that will break em loose in any gear.


my buddy has a first gen RX7 that currently runs low 11's and will be running low 10s this years.

I also have another buddy who has a Mazda R100 with a 13B, 95 RX7 engine making 450hp plus 150hp NOS and weighing in at just over 2000 lbs. hasn't ran it yet but should be fun.
http://www.cc-racing.com/db_IM0001441.jpg

[Bristol]

Yup. Seen it at Shanes shop.....very impressive and pics definetly dont show it well at all. This is one car that HAS to be seen in person to appreciate. ;D

[Wagonized]

Yup. Seen it at Shanes shop.....very impressive and pics definetly dont show it well at all. This is one car that HAS to be seen in person to appreciate. ;D


thats basically the same as a datsun 510 isnt it?

[IROC-Z]

Yup. Seen it at Shanes shop.....very impressive and pics definetly dont show it well at all. This is one car that HAS to be seen in person to appreciate. ;D


thats basically the same as a datsun 510 isnt it?


same idea only Mazda

[manchesterbeast]

hey i was looking thru old threads and i found that video of the rx7 being redlined till it blows up.

all i can say is: HOLY FUCK!!!!!

I always liked those cars, and now i have even more respect for them after seeing that. It blew the rad cap off, blew off the muffler, caught on fire, and still it kept turning over! that was sweet!

[Blue89rs]

First off, post the links to that thread! I wanna see!

Second, so HP is the ability to use the gear ratio multiplier at the back end. So 100ft/lbs through a 2:1 rear end = 200ft/lbs right? Or just put a taller rear end in your car and see what happens. Well that would make sense then, because the rear end ultimately determines how many gears you need to get to the other end of the track. So if you don't have to shift out of 1st gear ever, you get to keep your 4:1 multiplier in your transmission. I think I got it..... ::)

[manchesterbeast]

okay here. i dug thru the old forum posts and found it for you....
http://www.vancouverfbody.com/yabbse/index.php?board=6;action=display;threadid=692

and check this one out too, i found this interesting. looks like an acura camaro.
http://www.vancouverfbody.com/yabbse/index.php?board=6;action=display;threadid=655
they all hated it, but i think it looks cool. that style of headlights is the only thing i like about acuras.

[BPS]

The short answer

Horsepower is how hard you hit the wall.
Torque is how far you take the wall with you

A bit more detail

Horsepower

The definition of 1 horsepower is the ability to do 33,000 pounds-feet of work in one minute. So horsepower is a measurement of torque over time. The measurement of horsepower was invented by James Watt when he replaced horses turning a water pump with a steam engine and wanted to know how many horses the engine could replace in order to rate the engines power. He figured that a horse could pull with 180 lbs. of force. The horse traveled in a circle with a 12 ft. radius, and could make 144 complete revolutions in 1 hour. This means that the horse traveled 181 feet per minute. 180 lbs. of force times 181 feet equals 32,580 pounds-feet of work in 1 minute. Watt rounded that up to 33,000 pounds-feet of work in 1 minute.

Figuring Engine Horsepower

Watt's definition of horsepower is a horse pulling on lever, so the power was applied to the lever. An engine does not work like this, the power is made at the crankshaft. So to know the horsepower of an engine you will need to imagine a 1 ft. lever at the crankshaft and figure the circumference of that one ft. lever and how many rotations per minute it is traveling. A 1 ft lever will have a circumference of 6.2831853 ft., so the formula for hp would look like this:

HP = (6.2831853 × RPM × Torque) ÷ 33,000

And can be simplified to:

HP = (rpm × Torque) ÷ 5252

By using this formula you can see that HP and Torque curves will always cross at 5252 rpm. To help put horsepower into perspective, imagine two engine that both make 300 ft. lbs. of torque One engine makes it at 3000 rpm and the other makes it at 6000 rpm. Which one makes more power? The one revving at 6000, because the same amount of torque is being used twice as fast. Gearing the engine down to the the same 3000 rpm will double the torque at the final drive making it 600 ft. lbs. If both engines had the same final drive, they would be able to do the exact same amount of work (300 ft. lbs. worth), but the 6000 rpm engine will do it in 1/2 the time.

Torque

Torque is simple, imagine a 1 ft. lever with 1 lb. of force pushing on it. That is 1 pound ft. of torque. The formula to figure torque from a known HP is:

Torque = (5252 × HP) ÷ rpm

Brake Horsepower and Torque

Dynamometers measure torque by use of a brake. Brake torque is simply a measurement of how much resistance is needed to hold the engine at a steady rate of speed. This is commonly referred to as a step test, usually taken in 250 rpm increments. Brake Horsepower (BHP) is then figured using the above formula. The problem with brake torque is that it is not effected a measurable amount by the inertia of the engines rotating and reciprocating parts. For an acceleration engine, there is a better way.

Acceleration Horsepower

For an acceleration engine, you want to measure power as the engine is accelerating. You don't only care how much HP the engine has, you also want to know how fast it can rev up. This will take into account all of the inertia of the rotating and reciprocating parts. So instead of a brake holding the engine at a steady speed, the brake holds the engine at a steady acceleration rate, 300 rpm per second and 600 rpm per second are commonly used. Hp and Torque readings will be lower, due to less braking force required, but the mass of all the moving parts will be better measured. You could have two engines put out the exact same brake power readings, but if one has much lighter pistons crank and rods, it have more acceleration power and be quicker at the track. To put this into perspective, it is easy to lose 6 lbs. from a stock small-block Chevy crankshaft and actually make it stronger in the process. My Camaro has a 3.27:1 1st gear ratio and a 3.50:1 rear gear ratio making a total ratio of 11.445:1. Losing 6 lbs. rotating weight is like losing over 68 lbs. off the car in 1st gear. That's just the crank, using lighter pistons, rods, pins, and aluminum flywheel can get the rotating and reciprocating mass over 20 lbs. lighter. Now 229 lbs. lighter in 1st gear is a big difference. You see why people get crazy to loose a few lbs.

Building Power

Many engine builders will say that torque is what wins races and too much emphasis is put on horsepower. It is true that torque is what actually pushes the car, but torque and horsepower are directly related, you can't have one without the other. The chart below shows how you can increase the rpm range of an engine to get more horsepower, at the cost of torque, but still make more rear wheel torque.

Engine Horsepower @ RPM Flywheel ft. lbs. @ Peak Horsepower Final Drive Ratio Rear Wheel ft. lbs. @ 1000 RPM
First 500 @ 6000 437.6 6:1 2625.6
Second 550 @ 8000 361.1 8:1 2888.8


In this example, both engine have the same rear wheel speed, but the higher rpm engine, which makes less flywheel torque, makes more rear wheel torque. Torque does win races, but you need horsepower to put it to use, so saying torque is more important than horsepower is really a contradiction. For a street car, an 8000 rpm engine and steep gears are not practical, but for all out drag racing, build as much horsepower as you can and just gear it to suit. If you build the horsepower, the torque will be there through gearing. The engine with the most average hp for the rpm range used will have more average power, period.

[Muskys SS]

Sounds like an easy one right? Well, it is. WHAT IS THE FRICKEN DIFFERENCE!!?!?!?!

Seems like HP = Torque*RPM/5252 but what does that mean to performance and the "seat of the pants" driver? Do you notice a difference when you can wind up the motor versus not? I never have been in a car that can wind past 6000rpm so I have no idea.

Also, according to the equation above, HP = Torque at 5,252RPM...but that's not always true. Does it change as per what kind of Dyno you use (water vrs whatever)?

I'm sure I'll get plenty of comments ;D

HP will always = torque at 5252rpm. Hp is derived from torque.

[Fattony]

Fav quote

"The mechanical advantage of such a nonsensical rear gear would allow our combination to pull just as hard as the big block, plus we'd get to do all that gear banging and such that real racers do, and finish in fourth gear, as God intends. :-)
"

lol
verry good article thou, even thou i knew that stuff....lol

[upgradedsupra]

that article was to long for me to read but what i was told was torque is how much work it can do horsepower how fast it is done
rx 7 lots of horse no toque fast car till it goes up a hill
427 camaro lots of torque lots of horse always fast


651 RWTQ is fast also ;)

Torque is something you will feel more so than HP> I love torque!

To bad I can't have torque off the line like the domestics but I do have alot when I get going!

Duane

[CanadianTBone]

Torque gets you going , HP keeps you going . :cool: I have lots of torque :sanchez:

[zapper1986]

i was noticing how you all thought 8000 rpm in a mazda was high. the VTEC engines in the honda s2000 have a stock rev limiter of 9200 rpm

[79 Z28]

old post, and yes mazda and honda are hurting. if im gonna go 9000rpm it better be making 1000+hp :D

[Jinks]

for 30,000$ you can make any car go fast.. :p

[trans-am]

old post, and yes mazda and honda are hurting. if im gonna go 9000rpm it better be making 1000+hp :D
Good call buddy

[79 Z28]

thanks ;D and even a year later i stick to my statement

[Love4Firme_Chevrolez]

:up: good article to have on top. i never payed attention in physics.. so this is great.