There has been alot of controversy on the topic of Torque and Horsepower and how it relates to automobile performance. I'm curious as to what is more important for a 1/4 mile drag race? Here's a scenario: 2 identical cars are about to drag. They have the same weight, tires, gears...everything is the same except for their engine specs. One car has a high torque engine with low horsepower and the other has a high horsepower engine with low torque. Now I know in actuality these cars need different gear ratios but in the given scenario, what cars wins the 1/4 mile drag and why??

Thanks
Pete

If the cars were set up identically it depends on which type of engine they were set up for. If they were set up for a high revving low tork engine then the high HP engine would win but if they were set up for high torque engines then the high torque engine would win. I personally think that high torque is more important because I like the kick in the pants that you get off the line, whether it's at a strip or a set of lights. High horsepower is nice too but it only makes a difference at higher speeds.

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Chris Dagenais
Saskatchewan
'71 Malibu with a home built 454!
member.xoom.com/Gandalf80/ (http://member.xoom.com/Gandalf80/)

Torque=horsepower

Torque is what it takes to twist a driveshaft. HP = Tq x RPM/5250.

think of high hp as hi torque at hi rpm rather than lower....
because thats really what the difference is...ie where the torque is made... where the "power band" is...
my 454 is hi torque therefore daily driving is very nice butit runs outa steam above 3500 so when you punch it at the top end it isnt impressive...
depends on what you want i suppose

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Rich
Cocoa Beach, Fla
Team Chevelle #380
46 but feeling like 20 when i'm in my 70 SS 454
wa3men@aol.com
www.chevelles.com/showroom/70_SS_454.jpg (http://www.chevelles.com/showroom/70_SS_454.jpg)

Is this a rhetorical question?? LMAO!!
Seriously, torque is what gets you out of the hole and HP keeps you going, correct me if I am wrong.
Also, BOTH are 2 important factors in our lives!

I'll take a stab at it. HP is an indication of the rate at which you "could" make torque. I say "could" because for most motors, at peak HP, the torque curve is usually falling off. I think this has to do with the efficiency of the engine as an air pump. Basic air flow restrictions kick in at the higher engine speeds and all the HP just does not get converted into useable energy at the flywheel.The torque peak has already passed.

Looking at the Pace Parts catalog, the ZZ430 SB and the 454HO are side by side. The SB makes more HP so it is better, right? Maybe not for the street. At 3000RPM, the SB is making 250HP and just under 400lb-ft of torque while the BB is making 300HP and 450lb-ft of torque. From 2000 to 5000 RPM, the BB stays well above 400lb-ft while the SB jumps above 400lb-ft briefly before falling off again.

As to which car would win? I agree with the previous post. If set up for a quick winding 4spd high HP car, the SB may win. A street geared TH400, look out for the BB.

jmw

I read somewhere that Smokey Yunick once said, "Horsepower sells cars, torque wins races." People are too awed by horsepower numbers.

Grandalf80 has it right ! The entire drivetrain needs to be set up differently, thus whatever the car was set up for (HP or torque)would win.
I view torque as the "grunt" at low RPM to get off the line and horsepower as the high RPM power to keep you accelerating.
Think of a torque wrench; pulling on it without it moving you have torque but no horsepower. Horsepower requires motion where torque doesn't.

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Gotta have a Chevy !In Durham N.C.
Make it look the way you like it, forget what the other guys say! :D

Or another way, to end up even at the end of your theoretical race, the torque car would be running 3.70's and shifting at 5500 and the horsepower car would be running 4.56's and shifting at 7500. Hypothetically speaking. So for engine longevity and ease of driving, I would have to give torque the nod as the key engine spec for street especially. Yet I like many others keep dwelling on how to eek out another 50 horses from my mill. I guess I should be thinking about how to get another 50 lbs.ft. or ideally both.

To add some real life example, I don;t think my BBC is the torquiest rat out there. Not close. But I launch her at 4000 rpm shift at 6500 rpm and for that power band it seems to move. Unlike some BBC's this mill has less torque than HP ( 520HP/490 lbs ft).

[This message has been edited by Gene Chas (edited 02-03-2000).]

I used to outrun a lot of big block, high torque F o r d s with my low (no) torque 283 with Duntov cam, high comp. pistons etc, with 4;11 gear and close ratio four speed. For serious racing, go with horsepower. Lots of high torque diesels out there, not so fast.

[This message has been edited by tom3 (edited 02-03-2000).]

I think one of the most important factors is the range of usable torque, especially on the street. With a broad torque band, an engine will usually be a strong runner. A peaky high HP, high rpm engine will need to be kept in it's high rpm powerband to be strong. The new Honda S2000 is a good example. 240 hp at 7000+ rpm. But catch one with its revs down and a 4 cyl Cavalier will walk away-briefly. I remember a test of a '69 Z28. The article said at idle, open the door and the dome light's drag on the alternator almost kills the engine, but at 4000 rpm at WOT, hang on cause it really comes to life. An exaggeration buts makes the point. I think a heavy automatic car needs a broad torque range, even on the track. The light stick cars can live with mediocre torque and good hp, especially at the track and will work on the street with the right gearing and lots of revs.

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von '69 300 Dlx SS Murphy's Law is always in effect

Everyone else has waxed eloquently.

Torque is why our Elky is getting a 406 SB, with roughly Performer RPM specs. to replace the 355, set up as a Performer. The 355 torques ok, but a 406 rocks! Over 400lbs of torque at like 2300-2500 rpm.

The darn 355 runs out of steam too soon too, hence a bit more cam and intake on the 406.

Drooling in anticipation!

Dave H.
Houston

For torque, nothin' beats a Rat http://www.chevelles.com/forum/biggrin.gif
That's why I've chosen to go that route.

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70 Malibu
350/300hp
Soon to be 396/325hp

Okay as "The Chevelle Engineer" explained it to me:

Torque is the repersentation of the force of the rotating body, the horsepower is the rate at which the torque is generated, thus the higher the horsepower(in a perfect world) the more torque can be generated.

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Francis Taracido Gold# 201 :)
sniper0666@aol.com
History shows again and again how nature points out the folly of man.
Oh No! You Know She's Got To Go!
Go Go Quadzilla! <oo=+=oo>
http://members.aol.com/sniper0666/page/intro.html

hmm.. something I thought I would add (although its a bit off-topic, then again not really) is this:

when you put an engine or a car on a dyno you are measuring torque.. from the torque curve, you can figure horsepower with the formula

HP = (torque * rpm) / 5252

something interesting is that the torque & horsepower curves will always cross at 5252 rpm... I have literally had people argue with me for HOURS but I assure you its true http://www.chevelles.com/forum/smile.gif

If you want to read a really good article on torque & horsepower check out this link: http://vettenet.org/torquehp.html

good day

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Mike Reeh
Gold #34
San Diego, CA

Mike,
People who argue with you on that topic need to ge back to math class. If RPM = 5252, and HP = (torque*rpm)/5252, plugging in 5252 for rpm will cancel the bottom 5252, leaving you with HP = torque. You, of course know this. But now that I know it's true as well, I wanna tell that to people and see them argue. That'll be cool http://www.chevelles.com/forum/smile.gif

For racing, I think HP is better. If you are gonna fart around in a street car and like to peel out, make lots of torque. I know torque gets you moving in a race, but toque also loses races (due to traction loss). I have lost quite a few races to smallblocks simply because my motor generates excessive torque. I think if you build a motor to make good HP, torque can be had by changing your gear ratio, tranny etc...but more times than not, torque is an obstacle in a 10-inch DOT tire racer like myself.

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66 SS Chevelle Houston, TX ACES#3321 "There is no Replacement for Displacement"

Ah, Rat Power

See "gearhead" topic. After the 406 goes in. and since we will NOT tub the Elky....

I will be able to measure rear tire life in weeks, and will never win a standing start race.

But oh the kick in the pants in a rolling stab!!!!

Dave H.
Houston

The torque and hp curves will cross at 5252 rpm if the following conditions are met: the torque and horsepower will be plotted against the same numeric scale and the measurements of torque must be in lb-ft. Some manufacturers of small engines and industrial engines will use 2 different scales for power and torque , so the curves may cross elswhere.

Last word: to answer the question about 1/4 mile performance in a high torque vs. high HP cars, consider the following real-life common-sense scenario:
You're driving down a curvy country road, stuck behind ol' Grandpa Jones and his oil-burning '55 Buick barge, when you hit a straight-away. As you pull out to go around Mr. Jones, you see a logging truck barrelling down the road straight at you. You could fall back in behind the Buick, but NO WAY, you're in your 5-speed musclecar and you've got other things to do today rather than inhale Mr. Jones' exhaust fumes. So you floor it....but you don't gain speed fast enough. If you're already in fourth gear at 3000 rpm but not accelerating fast enough to avoid being flattened by the logging truck, do you 1) shift up into overdrive (lowering rpm and improving torque) or 2) shift down into 3rd (raising rpm and reaching for more HP)? The choice is yours....
I think this scenario would hold true for drag racing also, eh? http://www.chevelles.com/forum/wink.gif

We built a 454 with torque in mind. On the Desktop Dyno programme it shows a 440 foot flat torque curve from the bottom to 4500 rpm. Within this rpm range the car feels as good as our 427-425 HP car did. Above this the power drops off. It is a very nice street combination. I've driven 302 Z/28s and they were terrible around town but great at high rpm. It all depends on what you want the car to do as to how you build the engine.

Doc, I don't think this question applies. When you floor a Chevelle, it goes fast enough. No need for fancy gear work http://www.chevelles.com/forum/smile.gif

If both cars reach the finish line at 4000rpm the torque motor will win. If they reach the line at 6000rpm the HP motor will win. http://www.chevelles.com/forum/biggrin.gif http://www.chevelles.com/forum/biggrin.gif

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Lowered '67 Elcamino
ZZ430HP / 4L60
"Canyon Carver"

Torque X RPM / 5252 = Horsepower.

Torque is the force we apply through a rotating shaft. Horsepower is a computaion of the amount of work we can do with the torque over time. We can compute horsepower given the amount of work already done through weight/accereration/time or probably an endless number of possibilities, but it is always a calculation because it is over time.

Torque can be measured directly. It can be multiplied through levers/gears, horsepower can not. Put a 2-1 gear behind an engine making 400 lbs ft of torque at 4000rpm, and we end up with 800 lbs ft of torque @ 2000 rpm out put. The horsepower will remain the same, wheither computed at the flywheel [400x4000/5252=305] or at the gearbox output [800X2000/5252=305].

A 283 making 325 lbs ft of torque at 8000 rpm is making more horsepower than a 502 making 600 lbs ft at 4000rpm. Put twice the gear in the 283 and it'll move a car down the drag strip quicker, presuming of course that they are both limited to those rpm.

James Watt gave us the formula for how much work a horse could do in an hour [horsepower] so he could compare the amount of work a steam engine could do. We use it to compute how much work our engines can do. It is a useful calculation, but always a calculation.

If we can maintain a certain amount of torque while raising the rpm, we make more horsepower, and the potential performance goes up. A 2quart Honda doesn't make any more torque than any other 2 ltr, but because they've moved the curve up above 8000 rpm, they've made'm pretty fast. Formula 1 engines only make around 250 lbs ft of torque, but at 17,000 rpm it's a ton of horsepower.

The highest average amount of torque delivered to the rear wheels decides the winner. It'll compute to the highest rear wheel horsepower. Confused?

Here's my 2-cents. I've been doing the dyno thing for over 20 years and hopefully I've learned something(maybe not).

Any engine that produces 300 lbs-ft of torque at 3000 rpm has 171 hp at that engine speed. Any engine, long stroke, short stroke, blown, FI, etc.

This "any" engine will also produce 286 hp if it makes 300 lbs-ft of torque at 5000 rpm, and 457 hp if it makes 300 lbs-ft at 8000 rpm. Which engine would you rather have?

Competition engines are built to maximize torque at high engine speeds, becasue as Greybeard said, this yields the most potential horsepower. If you made two engines from the examples above, the engine making 300 lbs-ft of torque from 3000 through 5000 would definitely get a good head start on the 'High-rpm performance" engine. Plus the low rpm engine would have stonger performance on the street while the 8000-rpm engine would be soggy and boggy until it got up to speed.

Even more confused?!