http://www.physicsforums.com/showthread.php?t=153996

 

I can`t give stone facts, but I can give examples. Go back and look at the bob glidden race days when he was at his prime. Listen to the exhaust note, he`s not revving no where near as high as the pack is because he was using the torque of the engine to win races and it was obviously working, as he won I don`t know how many championships.
Next up was what I seen at the 1/8th mile drag strip we used to go to that only raced street style. There was a guy who showed up with a tubbed out fully caged falcon. Under the hood sat a 302 with dual quads and the whole 9 yards. It had a 5 speed tranny. What he would do is get on the line, tach it to 9000 RPM and side step the clutch. He was using horsepower in attempts to win. However, he got his doors blown off by 350`s that peaked at 6000 RPM. My instructor build a high revver in the late 60`s and he always said, if it don`t break, you go fast. Sure you`ll go fast with 5.13 gears and revving it up to 9000 RPM, but why put the drive train through all that stress and risk breaking something every pass? Not to mention you`ll spend twice as much beefing everything to get it to rev that high and hold together. Many of the old sayings aren`t something that can be ignored like "You can`t beat cubic inches" and "Win on sunday, sell on monday" and lastly, "Torque wins races, horsepower sells it"
As you would often see on many engines the given horsepower on the air cleaner but you never seen the torque rating, that`s because everybody knows what horsepower is, but everybody don`t know what torque is.
I`d rather build a engine to make torque than revs, torque is far more fun on the street than revs will ever be. But since you tend to question so much then I`d say you build a high revver yourself, hit the track and find out first hand. My instructor showed me the carnage from his high revver days, broke axles, grenaded GM 3 speed stick tranny`s, twisted in half drive shafts, exploded clutches and busted bell housings. I asked him what engine he ran, he said it was a 283 bored to 4 inches, stock 3 inch stroke crank, Forged pistons, fully ported camel back heads, the largest solid lifter cam he could find, after market rods, open headers and a tunnel ram with twin holleys. The rear was running a spool and 5.13 gears. All this in a tubbed 55 chevy.

 

http://www.physicsforums.com/showthread.php?t=153996

I agree with super beetle

 

Nonsense?

WOW... Why so quick to say people are full of nonsense? You may want to look in the mirror...

 

I agree with super beetle

Did you read the thread? There wasn't really an answer, just more of "will some one once told me that..." No real theory or proof was given.

Even all of what DV gave was hearsay- which supports the blind leading the blind theory.

And I didn't say people are full of nonsense, just that believing hp wins races is. Sure there are engines that do well that have high tq, but they also have high hp... And the ones that have high hp but low tq do just as well, thus even the empirical evidence shows tq is relatively meaningless.

BTW, "Torque wins races, horsepower sells it." is a GREAT marketing slogan- doesn't mean its anything more than that.

 

I agree with super beetle

I could spend all day soaking up that info and still be confused as to which is best.

 

Food for thought:

A modern top fuel dragster uses a slipper clutch with no transmission. What this means is that if the engine turns 9000rpm's which is pretty much it's limit and their 1/4 mile time is 4.5 seconds then the engine itself only makes 675 rotations to get to the finish line. All else being equal (engine rpms/distance) for the car to run quicker than 4.5 seconds and not exceed 9000rpm's means the engine will need to make less than 675 rotations for the quarter mile to go quicker.

So in this case what needs to increase to make the vehicle go quicker with less rotations of the engine?

 

Food for thought:

A modern top fuel dragster uses a slipper clutch with no transmission. What this means is that if the engine turns 9000rpm's which is pretty much it's limit and their 1/4 mile time is 4.5 seconds then the engine itself only makes 675 rotations to get to the finish line. All else being equal (engine rpms/distance) for the car to run quicker than 4.5 seconds and not exceed 9000rpm's means the engine will need to make less than 675 rotations for the quarter mile to go quicker.

So in this case what needs to increase to make the vehicle go quicker with less rotations of the engine?

Anytime you restrict yourself to a particular engine speed you have to increase torque IN ORDER TO INCREASE THE AVERAGE POWER.

Now you're running in a "restricted class" though; nonetheless the increase in torque was made to increase the power while complying to a restriction, there are other ways to make power though if you don't place restrictions. In the end the only thing consistent is the needed increase in power to go faster.

 

From your posts you seem to be a pretty sharp young man so your question somewhat surprises me. It's not a "theory", "urban legend" or "old wive's tale" because without torque there is no horsepower. HP is calculated from torque applied over time or distance. Given the exact same peak TQ but at different RPM an engine will produce very different HP readings but TQ and HP are ALWAYS , ALWAYS equal at 5252 RPM. High HP engines just make their TQ higher in the RPM range. The lower the peak Tq, the lower the peak HP regardless of RPM.

It's not a matter of TQ vs. HP winning races and, as I can tell you well know from your posts on here, it's a matter of having the right overall combination.

 

From your posts you seem to be a pretty sharp young man so your question somewhat surprises me. It's not a "theory", "urban legend" or "old wive's tale" because without torque there is no horsepower. HP is calculated from torque applied over time or distance. Given the exact same peak TQ but at different RPM an engine will produce very different HP readings but TQ and HP are ALWAYS , ALWAYS equal at 5252 RPM. High HP engines just make their TQ higher in the RPM range. The lower the peak Tq, the lower the peak HP regardless of RPM.

It's not a matter of TQ vs. HP winning races and, as I can tell you well know from your posts on here, it's a matter of having the right overall combination.

true, you need some tq to make power, but having an infinite amount of torque with no power can't move a flea... And without the "time" that hp is applied in you can't run any sort of et.

Also, you can have a high peak hp with a lower peak torque, it actually happens fairly often. Its done by shifting the engines peak VE to a point with higher RPM, even if the VE itself is lowered if it is lowered by a factor less than what it was shifted up then your power still increases. If your car is set up to handle it properly then your ET is reduced witha lower peak torque value.

Lastly, the 5252 number is nothing of real significance, just a conversion factor, if we use the metric system the 5252 number is meaningless.

 

What is this, the: "hey I took a physics class and I want to prove some people wrong!" thread?

Probably what people mean when they want torque over horsepower (even though that's impossible) is that a motor that makes torque more broadly makes more horsepower at lower RPM, and in the end you have more horsepower area under the curve. Its just a different way of saying the same thing. I don't see why there's any reason to start a preachy thread obviously trying to start an argument, and telling people they're "the blind leading the blind."

K

 

more torque at a lower RPM, is essentailly saying you want more power at a lower RPM, which is good for the street, primarily for durability reasons.

But on a race car where you can spin the RPM's loosing toque to make more power will make you quicker.

And I learned all the physics needed for this discussion in 5th grade, the concept isn't advanced at all so I would think everyone should have been taught this some point along the way to their highschool diploma, which I presume most of this forum's members have.

Sometimes having a book doesn't mean you understand what is in it though. I know I didn't really understand diff eg until I almost graduated.

 

Can someone please explain to me why they think tq is what wins in the 1/4 mile?

Anytime you restrict yourself to a particular engine speed you have to increase torque IN ORDER TO INCREASE THE AVERAGE POWER.

Last time I checked TF dragsters will beat pretty much anything else in a 1/4 mile drag race. So with all else being equal rules-wise: rear gear, tires, car weight, engine displacement, and the fact that due to the current engine design they can't rev any higher then I would say that more torque and the ability to get it to the track is what wins drag races. At least in Top Fuel.

To me this question has more than just a black or white answer as most of what I build are engines in restricted classes such as stock eliminator.

 

Last time I checked TF dragsters will beat pretty much anything else in a 1/4 mile drag race. So with all else being equal rules-wise: rear gear, tires, car weight, engine displacement, and the fact that due to the current engine design they can't rev any higher then I would say that more torque and the ability to get it to the track is what wins drag races. At least in Top Fuel.

To me this question has more than just a black or white answer as most of what I build are engines in restricted classes such as stock eliminator.

Even in your example they create more average power. You like to think of it as more torque, but they could make more peak torque at a lower RPM but they don't. They strive to make the most peak torque at that RPM level, but NOT the most peak torque. The most peak torque at the peak RPM level is a long way of writing the most peak power.

 

What I'm saying is that it doesn't matter what your operating range is, you can take a look at your horsepower curve, determine how much time you can spend effectively at each point and you can describe your run that way. All other things equal a 400 horse V8 will get to the end of a 1/4 before a 400 horse 4 banger because there is more area under curve for the motor's horsepower at more time points throughout the curve. You can certainly describe that phenomenon by talking about torque, which is work, and a multiplier for power.

I don't think the folks on this forum necessarily need an educational thread about this. If they have a question, they're grown-ups and they can ask.

K

 

What I'm saying is that it doesn't matter what your operating range is, you can take a look at your horsepower curve, determine how much time you can spend effectively at each point and you can describe your run that way. All other things equal a 400 horse V8 will get to the end of a 1/4 before a 400 horse 4 banger because there is more area under curve for the motor's horsepower at more time points throughout the curve. You can certainly describe that phenomenon by talking about torque, which is work, and a multiplier for power.

I don't think the folks on this forum necessarily need an educational thread about this. If they have a question, they're grown-ups and they can ask.

K

That 4 banger could VERY easily have more power under the curve. But at least I know that you realize the average power is important. Torque is NOT a multiplier of power... I don't know where you got that one from so I'll just leave it at that. Also, torque is not work. Torque, work, and power are 3 very different things.

And I would say that understanding why and how to go fast is something that many members on this forum would like a thread about... The nice thing about a forum is people are allowed to express their opinions, whether they are insightful or misleading.

 

torque and power are very different? One horsepower is 550 lb/ft of torque per second. You can certainly describe horsepower by torque.

Wonderful, yes there are exceptions to every rule. Hence saying all things being equal and 400 horse, which means that the V8 would win, every time. No exceptions. Obviously professor AP is out to stir the pot today...

Have fun!

K

 

KILLERFFORMULA do you shift at 10 % past peak torgue with your mopars? I know most say shift at 10 % past peak hp, but i know , from my expirence is that the mopar guys shift at 10 % past torgue peak . Here at least by me they do .

 

KILLERFFORMULA do you shift at 10 % past peak torgue with your mopars? I know most say shift at 10 % past peak hp, but i know , from my expirence is that the mopar guys shift at 10 % past torgue peak . Here at least by me they do .

Sure, same concept, I would assume most people shift after the peak because your average power per time is higher when you do that than if you shift at the peak.

K

 

What I said about Bob Glidden isn`t hear say, that`s fact.
One of the biggest misconceptions in this country is education means wisdom and that`s not true in any shape or form. They don`t teach common sense in college. Education without common sense is useless. Blind leading the blind? Lets see, Nobody follows me because I don`t let them, I`m a loner in that respect, and I don`t go preaching what I believe or try to continously get something going based on Theory. Some theories are interesting, but this isn`t very. If the goal of your posts such as this is to make others look like a fool just to show what you know isn`t a very wise idea, you`ll make alot of enemies that way. As far as myself, I dropped out in the 9th grade but it`s funny,, I build computers, I do automotive work, I build car and home audio systems, and the list goes on and on and I learned these things myself, nobody taught me. So yeah, I`m undereducated, but I`m far from stupid.
From what I see AP, you act like you got something to prove to everybody just because you feel the need to make yourself look better. If you want this whole board to yourself, then fine, I`ll leave to just make it easier on you.
When your wrong, you can`t believe your wrong, maybe because your book said so or such and such said so, you believed a solid lifter flat tappet cam was better than a hydraulic roller so which blind person lead you?

 

torque and power are very different? One horsepower is 550 lb/ft of torque per second. You can certainly describe horsepower by torque.

Wonderful, yes there are exceptions to every rule. Hence saying all things being equal and 400 horse, which means that the V8 would win, every time. No exceptions. Obviously professor AP is out to stir the pot today...

Have fun!

K

AP i have to agree with killerformula here

now for another one of those "hear-say" quotes. " torque is what gives you your 1/4 time but hp is what gives you your trap speed"

i do understand the idea of "well if it's all about tq then why aren't all racers using desiels" i would say that when it comes right down to it that you need a healthy combination of the two to really win the race, cause you can have all the horsepower you want but no tq (ie high rpm short stroke imports) and still get beat by a vehicle that turns less rpm and has less peak hp simply beacuse it makes good tq all the way across the curve, and we know that hp= tq x RPM / 5252. so with the desiels since they only trun say 3000rpm it's hard for them to make high amounts of hp beacuse it does take rpm to make hp. and for the imports all of their power is concentrated high in the rpm band and only really lasts for about 2000rpm, while in a decent street/stip SBC it's not that hard to keep atleast 400+lb ft of tq from 2500rpm through 6000+ rpm and as long as you can keep decent tq all the way throught the curve then you will obvously make decent hp all the way throught the curve.

this may have been a little all over the place but really i'm agreeing with the idea of more average hp/tq across the entire rpm band from shift to shift will win the race

 

What was that line from Jaws? The one about not having enough sense to admit your wrong? I thought I knew everything when I was 18...not 24. But hell, maybe we are all wrong and your right. Good grief.

 

true, you need some tq to make power, but having an infinite amount of torque with no power can't move a flea...

wrong, from it's stopped position a bigboy steam locomotive made around 200,000 fpt @ 0 rpm & 0 horsepower.

 

I guess "The Genius" cant argue this anymore. Signed off. What do the kids type nowadays??? LOL? LMAO? ROTFL?

 

Double Vision did your instructor drag race in the early eighties in NHRA G/MP or H/MP. Those cars had to weigh 12.00 to 14.00 lbs per CI. They were a driveshaft makers nightmare. Ring and pinions were turned into crushed ice. I remember destroked 302s about 272ci @750hp, dropping the clutch at 10,000 rpms at 3600 lbs. You would just hold your breath watching them grab second gear so the front end would not come crashing down. You brought back some old but good memories.
Lou