Should I build my motor to have more horsepower or torque? I understand the more torque you have, the more the Camaro pins you to the seat at the drag strip. The more horsepower you have, the higher the top speed. Since I will be doing daily driving before going drag racing, torque is more important right? On the other hand, horsepower numbers got the Camaro the respect it has today. What does the rest of this forum think?

horsepower is just a measurement of torque i believe.

i think jack rousch said it best 'horsepower sells cars, but torque wins races'

Jack Rousch - inst he a ford guy, no wonder our chevy's been beatin up on the mustang guys!

The rest of this forum thinks that torque is IT, but I think Joe Sherman said it
best - horsepower will give you the mph, and a quicker et. (if the car is set up right)
HORSEPOWER RULES!!! :D


by the way
(stick with torque for a daily driver) graemlins/thumbsup.gif

Are you playing with a big block or small block? What size engine? Torque gets the car moving HP keeps it moving. There are two schools of thought here and even the pro's can't agree on it. I have always said you can't have one without the other. You have to design your build around what you have or plan to have. Fit your parts to that RPM range, this will depend on rear gears, tire size, convertor if auto, etc... Try to build as much torque AND horsepower as you can and try to spread it out over a wide RPM band. Just build it in a range that the sar will see it.

Originally posted by 67RS502:
Jack Rousch - inst he a ford guy, no wonder our chevy's been beatin up on the mustang guys!

The rest of this forum thinks that torque is IT, but I think Joe Sherman said it
best - horsepower will give you the mph, and a quicker et. (if the car is set up right)
HORSEPOWER RULES!!! :D


by the way
(stick with torque for a daily driver) graemlins/thumbsup.gif Exactly - your chassis and your engine have to be on the same page. Horsepower is worthless if you can't get to it in the distance you race. There is no free power, so giving up torque you can use for horsepower you can't get to is not going to make your car faster.

Torque and horsepower aren't independent of each other. If two cars have exactly the same torque curve, they will have exactly the same horsepower curve. There is no way around it.

So, another way to put it:
If you want to make more torque at a particular RPM, make more horsepower. If you want to make more horsepower at a particular RPM, make more torque.

I think this whole concept of torque and horsepower being not related stems from the fact that at low RPM, torque is a more impressive quantity to look at that Horsepower...and at high RPM (where torque is small) it is more impressive to see a big number (HP) than a small number (TQ).

So this whole "Torque vs HP" battle is just a battle of where people think the ideal operating RPM range is for a car to move. Basically, just build the car for the RPM range you want to work in.


***BUT I WILL SAY THIS***
Those people who "build for torque" but then rev their car up to redline or beyond during a run are contradicting themselves. If they truly believed that "torque is it", theyd shift the car at 3000RPM throughout the run. graemlins/sad.gif Something to think about.

Cruiser67,

Since my car will be a weekend cruiser/car show car, I am going to build my 327 with an emphasis on torque from idle to 5,500rpm and let the hp numbers fall where they may.

So far in DD2k, my mild 327 combo has come up with 339HP and 379 ft. lbs. of torque peaking at 4K rpm. This is with a .030 327,Dart Iron Eagle 180 heads, a Crane 266/272 "Powermax" aka "fireball" cam, Performer intake and 625cfm carb & 1 & 5/8" headers.

My combo is not "set in concrete" yet,but for street use, I am trying to build for the best and widest overall torque curve in my rpm range.

Good luck,
-Mark P.

Torque is simply a rotating force. With a long enough lever arm, I can put 600 ftlbs of torque on a wheel with a breaker bar, but I bet I won't be accelerating the car very fast, but I would definitely move it. Horsepower is a unit of power. I think that one horsepower is equal to around 750 watts. Power is defined as the ability to do work over time. Given a set amount of work, i.e. accelerating a car to a given speed, a more powerful engine will accelerate the car faster than the less powerful engine. It is also true that you can't have horsepower without torque. Horsepower is actually a function of torque and RPM. Most water braked dynos simply measure torque at various engine RPM's then use a formula to calculate horsepower. When you look at horsepower and torque curves, notice that they always cross at 5250 RPM, no matter what the engine, this is because 5250 is a constant in the horsepower equation. The thing that complicates all of this the most is the fact that engines make different amounts of horsepower and torque at different RPM's so you can't always say that a 425hp engine will always outrun at 400hp engine.

As for which is better to have more of, it depends on what you want to the car to do well. If you want a car that performs good on the dragstrip with high (low numerically) gears, you would want an engine with good low end horsepower and torque and a nice wide powerband. When you do this, you trade off some power in the higher RPM ranges and you get a lower peak horsepower number. If you wanted a purpose built drag car, you would want a purpose built drag engine that had a narrow power band and you would gear the car so that the engine stays in that power band as long as possible during the run. That car wouldn't be very good for every day driving though.

So, really, you need to decide what you want to the car to do the best then plan out an engine that meets those goals. I think that you'll find that everyone here is very willing to help and also that there are some very, very knowledgeable people that would be more than happy to help plan that engine out. You can also use the search function. There have been hundreds of engine build and planning posts in the past.

i gotta say man....WRONG motor to build for torque, if you want torque throw a long stroke in there and make it a 383. Longer stroke= more low speed torque, Shorter stroke= higher RPM hp. Your 327 has a 3.25" stroke and will wind until the cows come home but it wont ever be a torque monster but if you want torque ditch the 327 idea and go 383. your 4" bore block will work {its the same bore as a 350 and a 3.75 stroke crank. The only stipulation i see is if you have the small journals cause i dont know if the 327 came with large journals. Hmmmm somone will chime in

the last couple of years of 327 were large journal, 68 and 69

I think torque makes for quick ets as well, hp doesn't move you off the line ya know?

I didn't read all the posts so forgive me if I duped something someone else said. It's important to recognize that a street vehichle sees a wider range of RPM than a 1/4 mile car. Torque is import from low RPM to mid. A 1/4 mile car on the other hand comes up to speed quickly and maintains a relatively narrow RPM band. This accounts for some of the difference between the two schools of thought.

"I think torque makes for quick ets as well, hp doesn't move you off the line ya know?"

It does if the engine is in it's power band and you have the correct gearing.

if you're a high rpm drag car sure
not very fun to drive

I still don't know why people make this so complicated. Cameron and sik68 explained very well in techincal terms. I have yet to see an u=internal comustion engine that make lots of torque and zero HP. I don't think it can be done. If you build more low end torque you will also have more low end HP. Don't get to caught up with the whole Torque Vs. HP thing. True the 327 is not a torque monster and they like to rev but, you can adjust the power band (or torque band) to fit your needs. It all comes down to what you want to do with the car. There is no answer to the question, as it is stated. If you throw in a few more details then there can be a better or best answer. Details like expected use, gears, tranny, goals. 327's are awesome engines and can run real hard, just have to figure out what you want.

Guys,

I agree that the 327 isn't known for it's torque,but rather for it's high rev capability.
And if your after big torque, go with a 350,383 or 406. And some might say that if your not building a 327 to run high rpms, then your doing it all wrong.

Also, in my previous post, I just used my own 327 as an example. The original poster may not be running a 327.

But for those of us who want to run or are stuck with 327's for street cars, one can try to make the best of it and maximize the torque for more fun on the street. But I realize that's just my opinion...... smile.gif

In the end, like Royce said, there isn't an "always correct" answer to the torque vs. horsepower debate.... It all depends on what you want to do with the car.

- Mark P.

[ 12-09-2003, 07:12 PM: Message edited by: Granny's 69 ]

Simply put if it is small displacement you have to be able to buzz it to get any air through it if you want to be able to compete.
Dyno's measure torque and then apply a formula to get the HP figures. If you max your torque at low rpm you won't see big hp #'s. If you move your tq to max at higher rpm your hp will be that much higher. If I'm not mistaking the famous 302 had incredible hp/cid but had to be rev'd to the moon (actually at any rpm below 5000 it was a dog - thats why it wasn't available with automatic tranny) Compared to say a 440 that rev'd to 5000, it had 500 lb of tq not far off idle. But at the track in stock form in simular weight vehicles not much different 1/4 results. Go figure eh! Of course this is just my opinion. - Barry

I know this is another animal but why do diesels make little horsepower but a lot of torque? Does anyone know why diesel exhaust is so big in diameter?

Here is a F350 that did 11.24@120mph with 680hp 1200lbs
http://www.olypen.com/bulldog/movies.html/F350Run.wmv

http://www.diesel-central.com/forums/thread.asp?ForumID=33&TopicID=1839

Over the road diesels are usually governed at around 2400 or so RPM, and since HP is a function of torque and RPM, they just don't rev high enough to get the big HP figures. Torque is what they need to get the large mass moving. That is also why they have so many forward gears - it keeps them in the power band where they need to operate.

That is a great example of all torque and little HP. They (diesels) are a different beast. THey can tow anything (talking personal trucks, SUVs) but they can't go fast enough to get out of their own way. That's why there has to be a happy point with the torque vs. HP thing. If you focus too much on either you will not have a fun vehicle.

Just thought i would add my .02 here.
HP is a caluculated force based on RPM. It is measure of how much work is being done in a given time. Hp= torque X RPM / 5252.
Above 5252rpm torque can be decreasing and hp rising.
Torque is generally a function of displacement. Larger displacement engines will make more torque. The amount of HP is a function of what RPM the torque is made.
For example, look at 3 different 400 hp engines
1. 4 cylinder honda 233 ft/lbs@ 9000
2. 302 SBC 280 ft/lbs @7500
3. 383 SBC 418 ft/lbs @5500

ALL these engines make 400hp which one would you want in your street car.
Make the best possible torque in the RPM range the engine is intented to be used in and HP will take care of itself.

MO67
The diesel exhaust is larger because diesels engine speed is fuel regulated. That is there is no restriction in the intake tract. Diesels inhale and exhaust very Large amounts of air. The amount of fuel that is injected determines speed /power.
In contrast to a gas engine speed which is air regulated. You dont step on the gas you step on the air and mix gas with it.

All this means to me is that a torque motor has the max. torque point in the lower rpm ranges whereas a horsepower motor has the max. torque point moved over moreso in the higher rpm ranges!!

One thing I do try to do is build my motors to have max. torque under the curve in the rpm range that I want to run it in due to my gearing and tire size!! That way I get max. GRUNT for my use.....

pdq67

Dave Mizell summed it up nicely. I really don't care about the horse power readings. 500 HP doesn't mean much to me if I have to turn 7000RPM to get it. But never the less, people use them for comparison between different engines. Vehicle manufacturers use the public's ignorance as to what their HP ratings really mean to their advantage.

500HP doesnt mean much?? 7000RPM? Whats that? You must be a big block guy. Christ many 383's are maxing power around 6600, therefore they would shift at 7000.

And for RPM's not being fun,
You guys really need to drive an old 302 and say its not fun.....

Torque in street driven cars will be faster at the track with proper tarction.

HP will be faster in pure drag cars.

I believe a horse power engine is much funner to drive. Blowing the tires off is fun and all, but so is shifting at 7500RPMS. I think HP wins on the street because traction is always at a minimum. Sure, 502 will beat 383 and 383 will beat 302 at the track, but when it comes to a little illegal action its hard to argue against the 302. All that torque does nothing unless you have traction...


Lets put a 502 with a 4 speed with 4.11 gears and polyglass vs a 302 with a 4 speed and 4.11 and see you wins, my money is on the 302. I think you could put a 632 vs a 302 and the 302 would still win because the 632 would just spin.

If you dont have traction both HP and torque are worthless.

When your spinning the tires your not going ahead.....

Ya but, narrow the rearend and put some bad ass meats in there and watch that 502 spank the 302!

I have a restored 69 Z with a 302 built to exact original specs, solid cam, 11:1 and all. And I have a 68 SS with a mild 400 sbc and it has 9.7:1 and a mild hydraulic cam and GM 76cc "smog" heads. Using the same ET street slicks on both cars, the 302 runs mid 14s, the 400 car runs 12.70s.
If you are blowing the tires away with a big inch engine on the street, your not "driving" your car. Your tires have the same amount of traction no matter how much torque you are making. Wait untill your car has launched far enough to avoid spin before you pour on the power and that big inch high torque motor will hurl you down the track.

Before you go putting down diesels, you should know that the aftermarket is going crazy with mods for them.

Check out this video of an F-350 on the track. It weighs, with driver, 7,168 lbs and went 11.42 @ 118 mph.

F-350 track video (http://www.olypen.com/bulldog/movies.html/F350Run.wmv)

Diesel power has came a long way from the ole logging trucks. Propane injection is the same as NOS injection.
Dave Mizell sums it up good. I would build for torque, HP will follow.

Originally posted by MoeSS396:
Lets put a 502 with a 4 speed with 4.11 gears and polyglass vs a 302 with a 4 speed and 4.11 and see you wins, my money is on the 302. I think you could put a 632 vs a 302 and the 302 would still win because the 632 would just spin.Pretty desperate to come up with an example where the 302 could win aren't you? :rolleyes:

My car has had the extremes - as a Super Stock car it ran a 289 small block up past 11,000 RPM with 6.50 gears (mid/low 10's), in it's last incantation I ran a 427 big block to 8,000 RPM with 5.43's (high 9's) and as a "fast" street car as it is now with the HP500 EFI running only 6,500 with 3.90's (low 9's).

My personal experience has been that the low RPM "torque engine" is cheaper to run and easier on parts than the higher RPM "HP engines", escpecially when you are striving for 9's and 10's.

Ultimately it will depend on what you want to to and how you want to do it.

[ 12-11-2003, 07:14 AM: Message edited by: James67RS ]

This guy describes RPM's as 'Ruins Peoples Motors'...

http://www.theoldone.com/archive/world-according1whatishp.htm

LOL, I like that and it is very true "Ruins Peoples Motors". I think this topic got off track and into the extremes. Good discussion though. Diesels smoke, stink and sound funny, it doesn't matter how fast they go, LOL.

Diesels smoke, stink and sound funny, it doesn't matter how fast they go, LOL. That's true, except when they line up next to you at the dragstrip and run a 13.1 with a big giant four wheel drive goofy looking pickup truck and you can only manage a 13.9 and your driving a 69 ragtop!!!

Man that would be horrible! I'm sure glad it didn't happen to me! :rolleyes:

Okay....since we are talking torque and hp...I just had to play oneupsmanship on a few here...all in good fun. Hp is just a paper figure derived from the actual measurement of torque as many have explained.

But this site is interesting after you read the print and admire the piece!

http://scarbsf1.com/P83_700pixel.jpg

Ø 1,950 CAD drawings were made for this engine
Ø Output of the BMW P83 is over 900 bhp. The actual figures for torque and hp are secret.
Ø Maximum engine speed is 19,200 rpm.
Ø In a race, engine speed is limited to 19,000 rpm.
Ø Idle speed is 4,000 rpm...what?
Ø The engine weighs less than 90 kilograms.
Ø The air intake volume is 1,995 cubic metres per hour.
Ø Maximum piston acceleration is 10,000g.
Ø Piston speed peaks at 40 metres per second and averages 25 metres per second.
Ø Exhaust temperatures of up to 950 degrees are reached.
Ø Maximum air temperature in the pneumatic system is 250 degrees.
Ø The engine block and cylinder head are made of cast aluminium and are manufactured at the BMW Formula One foundry in Landshut using a special thin-wall casting method.

Ø It completes a distance of 500 kilometres before undergoing revision.
Ø Total production of the BMW P83 is 200 units, ten of which the team takes to each race.
Ø Before being phased out the engine will have received 1,388 upgrade modifications.
Ø It comprises around 5,000 individual components, 1,000 of them different.

Ø The ultra-high-speed 130R turn at Suzuka with its lateral load of 4g poses the greatest challenge to the oil system.
Ø The BMW P83 endured the highest full-throttle proportion on the Monza circuit at 73 per cent per lap.
Ø At the Monaco Grand Prix, the transmission and engine have to withstand an average 3,100 gear changes.
Ø BMW Munich handles, among other things the manufacture of the crankshaft (steel), camshaft (case-hardened steel) and camshaft covers, as well as processing of the cylinder head and crankcase. The oil system and engine electronics also stem from BMW Munich.

Now what's my point......everything is relative! :D

Ah, now this is my kind of post!

Here you guys go: http://dspace.dial.pipex.com/ian.crocker/torque.html

Originally posted by HOTRODSRJ:
Okay....since we are talking torque and hp...I just had to play oneupsmanship on a few here...all in good fun. Hp is just a paper figure derived from the actual measurement of torque as many have explained.

Now what's my point......everything is relative! :D Actually, in general, horsepower is an actual measureable quantity. You don't need torque to have horsepower. It just so happens that with automobile engines, the way they make power is by imposing a force on a lever arm, which makes torque. Horsepower can then be derived through the equations that relate torque to horsepower for a rotating system. graemlins/beers.gif

Torque is work (Force x Distance), and Hp is work (Force x Distance)/time. You can't have Hp without any work.

Found a better description of the basics. A little cut and paste:

Force, Work and Time

If you have a one pound weight bolted to the floor, and try to lift it with one pound of force (or 10, or 50 pounds), you will have applied force and exerted energy, but no work will have been done. If you unbolt the weight, and apply a force sufficient to lift the weight one foot, then one foot pound of work will have been done. If that event takes a minute to accomplish, then you will be doing work at the rate of one foot pound per minute. If it takes one second to accomplish the task, then work will be done at the rate of 60 foot pounds per minute, and so on.
In order to apply these measurements to automobiles and their performance (whether you're speaking of torque, horsepower, newton meters, watts, or any other terms), you need to address the three variables of force, work and time.

Awhile back, a gentleman by the name of Watt (the same gent who did all that neat stuff with steam engines) made some observations, and concluded that the average horse of the time could lift a 550 pound weight one foot in one second, thereby performing work at the rate of 550 foot pounds per second, or 33,000 foot pounds per minute, for an eight hour shift, more or less. He then published those observations, and stated that 33,000 foot pounds per minute of work was equivalent to the power of one horse, or, one horsepower.

Everybody else said OK. :)

For purposes of this discussion, we need to measure units of force from rotating objects such as crankshafts, so we'll use terms which define a *twisting* force, such as foot pounds of torque. A foot pound of torque is the twisting force necessary to support a one pound weight on a weightless horizontal bar, one foot from the fulcrum.

Now, it's important to understand that nobody on the planet ever actually measures horsepower from a running engine. What we actually measure (on a dynomometer) is torque, expressed in foot pounds (in the U.S.), and then we *calculate* actual horsepower by converting the twisting force of torque into the work units of horsepower.

Visualize that one pound weight we mentioned, one foot from the fulcrum on its weightless bar. If we rotate that weight for one full revolution against a one pound resistance, we have moved it a total of 6.2832 feet (Pi * a two foot circle), and, incidently, we have done 6.2832 foot pounds of work.

OK. Remember Watt? He said that 33,000 foot pounds of work per minute was equivalent to one horsepower. If we divide the 6.2832 foot pounds of work we've done per revolution of that weight into 33,000 foot pounds, we come up with the fact that one foot pound of torque at 5252 rpm is equal to 33,000 foot pounds per minute of work, and is the equivalent of one horsepower. If we only move that weight at the rate of 2626 rpm, it's the equivalent of 1/2 horsepower (16,500 foot pounds per minute), and so on. Therefore, the following formula applies for calculating horsepower from a torque measurement:

Horsepower = (Torque * RPM)/5252

I think I added this to a similar discussion awhile back, but it seems appropriate again:

"A horse is a horse of course of course,
And no one can talk to a horse of course.
That is of course unless the horse
Is the famous Mister Ed!

Go right to the source and ask the horse.
He'll give you the answer that you'll endorse
He's always on a steady course.
Talk to Mister Ed!


People yakkity-yak a streak
And waste your time of day,
but Mister Ed will never speak
Unless he has something to say!

A horse is a horse of course of course,
And this one'll talk 'til his voice is hoarse.
You never heard of a talking horse?
Well, listen to this...

" I am Mister Ed!" "

Originally posted by 69ProTouring:
Torque is work (Force x Distance), and Hp is work (Force x Distance)/time. You can't have Hp without any work. I don't want want to seem like I am picking apart what everyone says just for the sake of technicalities, but what you said isnt correct.

Torque is not work, torque is a moment defined by the cross product of Force and Distance. They
are perpindicular to each other. This is opposed to work, work being force in the direction of distance, parallel.

Horsepower(aka power) is work over time. Horsepower is the multiplication of parallel components of force and distace.

You don't need to have torque to develop power(horsepower) and do work. A perfect example is what you copied and pasted above, when the guy was trying to pull the 1lb weight up. There is no torque in that system, but there is still being work done in the unbolted case.

However, in the particular case of an engine, parts rotate, not translate. Therefore, torque is the only way an engine can create power. That's why horsepower is in terms torque. You just cant take
Horsepower = (Torque * RPM)/5252
and apply it it any situation.

Again, I don't want to seem like I have to be right, but I just want it to be clear for people, and those who do searches in the future may gain an understanding.

I was trying to simplify it, and looks like I over simplified it. LOL

What Sik68 is saying is correct. You have to have torque to horsepower in a reciprocating engine, but you really don't have to have torque to have horsepower. I can figure out how much horsepower my body makes by timing how long it takes me to run up a flight of stairs. All that I need to know is my body weight, the time that it took, and the height of the stairs. I think that I made about 1/4hp when I did this in college.

Also, I noticed that someone else already posted this link, but I thought that it was worth posting again.

http://dspace.dial.pipex.com/ian.crocker/torque.html

Any of you wanting a really good explanation of all of this torque and horsepower stuff in layman's terms, with examples that we can all relate to, should read this. It is pretty long, but it is well worth reading.

Force applied over a distance is work but for rotational motion, torque appied through an angle of rotation is also work and is the more appropriate equation to consider here.

Man after reading all these it seems like this is all made to be more than what the real function of torque and hp is in relationship to racing, particularily drag racing.

Maybe I am stupid, but I thought torque got you off the line hard and fast, to a point, while hp picked you up and carried you thru the traps hard and fast, meaning you need both, in proper proportion, to equate to a quick e.t.

graemlins/thumbsup.gif I am with you on that ztoy.

Originally posted by ztoy:
Man after reading all these it seems like this is all made to be more than what the real function of torque and hp is in relationship to racing, particularily drag racing.

Maybe I am stupid, but I thought torque got you off the line hard and fast, to a point, while hp picked you up and carried you thru the traps hard and fast, meaning you need both, in proper proportion, to equate to a quick e.t. From a pure racing point of view, it's horsepower all the way. You gear your car to spend as much time as you can near the horsepower peak, wherever it is.