TQ vs HP in its own thread! - Hot Rod Forum : Hotrodders Bulletin Board
Hotrodders.com -- Hot Rod Forum



Register FAQ Search Today's Posts Unanswered Posts Auto Escrow Insurance Auto Loans
Hot Rod Forum : Hotrodders Bulletin Board > Tech Help> Engine
User Name
Password
lost password?   |   register now

Closed Thread
 
LinkBack Thread Tools
  #1 (permalink)  
Old 05-11-2010, 12:41 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,661
Wiki Edits: 0

Thanks: 16
Thanked 277 Times in 259 Posts
TQ vs HP in its own thread!

Can someone please explain to me why they think tq is what wins in the 1/4 mile? I know there are a LOT of misguided people out there that think it matters and I want to know why they think that. I know a large part of it is because no one has explained to them how things work and some old guy told them that so it MUST be true. In reality the only thing that matters is the average power applied to the track (assuming equal weight, aerodynamics, etc), but many people for some reason are not aware of this.

So please tell me, why are those that believe in this "torque theory" so blind? I really want to know so I know how to quickly and easily correct the next guy who believes in such nonsense.

So "torque theory" followers, why do you believe such?

My next question will be in regards to why some people shift from hp peak to tq peak? Besides being easier on parts and slowing down your car I can't understand why people would do so.

    Advertisement
Quick reply to this message
Sponsored Links
Advertisement
 
  #2 (permalink)  
Old 05-11-2010, 12:58 PM
V8 Super Beetle's Avatar
VW makes it, Chevy shakes it..
 
Last photo:
Join Date: Jan 2008
Location: Houston, TX
Age: 33
Posts: 1,245
Wiki Edits: 0

Thanks: 5
Thanked 0 Times in 0 Posts
http://www.physicsforums.com/showthread.php?t=153996
Quick reply to this message
  #3 (permalink)  
Old 05-11-2010, 01:09 PM
DoubleVision's Avatar
Not Considered a Senior Member
 
Last photo:
Join Date: Oct 2002
Location: Heart Of Dixie
Age: 40
Posts: 10,654
Wiki Edits: 0

Thanks: 15
Thanked 58 Times in 55 Posts
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.
Quick reply to this message
  #4 (permalink)  
Old 05-11-2010, 01:21 PM
Registered User
 
Last photo:
Join Date: Dec 2009
Location: illinois
Posts: 189
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by V8 Super Beetle
I agree with super beetle
Quick reply to this message
  #5 (permalink)  
Old 05-11-2010, 01:33 PM
BigLeoRocks's Avatar
Registered User
 
Join Date: Apr 2010
Location: arizona
Age: 38
Posts: 66
Wiki Edits: 0

Thanks: 0
Thanked 0 Times in 0 Posts
Nonsense?

WOW... Why so quick to say people are full of nonsense? You may want to look in the mirror...
Quick reply to this message
  #6 (permalink)  
Old 05-11-2010, 01:48 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,661
Wiki Edits: 0

Thanks: 16
Thanked 277 Times in 259 Posts
Quote:
Originally Posted by crystalbluevib
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.
Quick reply to this message
  #7 (permalink)  
Old 05-11-2010, 01:48 PM
V8 Super Beetle's Avatar
VW makes it, Chevy shakes it..
 
Last photo:
Join Date: Jan 2008
Location: Houston, TX
Age: 33
Posts: 1,245
Wiki Edits: 0

Thanks: 5
Thanked 0 Times in 0 Posts
Quote:
Originally Posted by crystalbluevib
I agree with super beetle
I could spend all day soaking up that info and still be confused as to which is best.

Quick reply to this message
  #8 (permalink)  
Old 05-11-2010, 01:56 PM
engineczar's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2002
Location: In Flowbench nirvana
Age: 52
Posts: 1,630
Wiki Edits: 0

Thanks: 5
Thanked 43 Times in 40 Posts
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?
__________________
BSE Racing Engines
Quick reply to this message
  #9 (permalink)  
Old 05-11-2010, 02:03 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,661
Wiki Edits: 0

Thanks: 16
Thanked 277 Times in 259 Posts
Quote:
Originally Posted by engineczar
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.
Quick reply to this message
  #10 (permalink)  
Old 05-11-2010, 02:04 PM
Hippie's Avatar
Analog man in a digital world.
 

Last journal entry: HEI comparison.
Last photo:
Join Date: May 2003
Posts: 2,255
Wiki Edits: 0

Thanks: 3
Thanked 5 Times in 5 Posts
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.
Quick reply to this message
  #11 (permalink)  
Old 05-11-2010, 02:10 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,661
Wiki Edits: 0

Thanks: 16
Thanked 277 Times in 259 Posts
Quote:
Originally Posted by Hippie
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.
Quick reply to this message
  #12 (permalink)  
Old 05-11-2010, 02:14 PM
killerformula's Avatar
Hotrodders.com Moderator
 
Last wiki edit: Carburetor
Last journal entry: Clean up
Last photo:
Join Date: Oct 2003
Location: Northeast
Age: 34
Posts: 3,485
Wiki Edits: 3

Thanks: 13
Thanked 27 Times in 18 Posts
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
Quick reply to this message
  #13 (permalink)  
Old 05-11-2010, 02:30 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,661
Wiki Edits: 0

Thanks: 16
Thanked 277 Times in 259 Posts
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.
Quick reply to this message
  #14 (permalink)  
Old 05-11-2010, 02:33 PM
engineczar's Avatar
Hotrodders.com Moderator
 
Last photo:
Join Date: Sep 2002
Location: In Flowbench nirvana
Age: 52
Posts: 1,630
Wiki Edits: 0

Thanks: 5
Thanked 43 Times in 40 Posts
Quote:
Originally Posted by ap72
Can someone please explain to me why they think tq is what wins in the 1/4 mile?
Quote:
Originally Posted by ap72
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.
__________________
BSE Racing Engines
Quick reply to this message
  #15 (permalink)  
Old 05-11-2010, 02:37 PM
How fast is fast enough?
 
Last photo:
Join Date: Jun 2005
Location: St. Louis, MO
Age: 28
Posts: 8,661
Wiki Edits: 0

Thanks: 16
Thanked 277 Times in 259 Posts
Quote:
Originally Posted by engineczar
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.
Quick reply to this message
Closed Thread

Recent Engine posts with photos

Quick Reply
Message:
Options

Register Now

In order to be able to post messages on the Hot Rod Forum : Hotrodders Bulletin Board forums, you must first register.
Please enter your desired user name (usually not your first and last name), your email address and other required details in the form below.
User Name:
If you do not want to register, fill this field only and the name will be used as user name for your post.
Password
Please enter a password for your user account. Note that passwords are case-sensitive.
Password:
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:

Log-in

Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.




Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools

Posting Rules
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On


Similar Threads
Thread Thread Starter Forum Replies Last Post
New toy for mikey powerrodsmike Garage - Tools 47 12-09-2008 01:28 PM
HP and TQ Guesses of my 357 build ORANGEGASM Engine 2 08-13-2008 07:08 PM
Would you rather low end TQ or HP ChevyThunder Hotrodders' Lounge 23 12-26-2005 10:29 AM


All times are GMT -6. The time now is 01:11 PM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2014, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0 PL2
Copyright Hotrodders.com 1999 - 2012. All Rights Reserved.