Horsepower vs Torque
Instructor
Joined: Sep 2001
Posts: 159
Likes: 21
From: McKinney Tx
Re: Horsepower vs Torque (Red94Vette)
Red94Vette,
""At 60MPH with 3.45 gears in 2nd gear in a ZF 6spd you are at 5143 RPMs.
At 60 MPH you have 70.6 pounds of air resistance.
The car with 400 ft lbs will accelerate at .480 g's (this is 391.7 HP)
The car with 300 ft lbs will accelerate at .353 g's (this is 293.8 HP) ""
You are assuming that the car that had 300 foot pounds had to already shift out of 1rst gear. Now do your equation with the car a (300 ft pounds) still in 1rst gear while car b (400 ft pounds) has had to shift earlier. Things change don't they even though one car has only 3/4 the tq of the other.
Of course maybe they have the same rpm limits and maintain the same level of tq throughout the range. This only then says that the car with more hp is winning again.
Now take two cars with the same tq but one that can maintain that same identical tq to twice the rpm limit. This car can stay in the same gears twice as long so it will accelerate the same off the line until the lower rpm (and power) car has to shift gears. Now who's accelerating faster? But yet they both produce the same tq don't they? But again the more powerfull car wins.
Seems like hp is what determines the winner huh?
""At 60MPH with 3.45 gears in 2nd gear in a ZF 6spd you are at 5143 RPMs.
At 60 MPH you have 70.6 pounds of air resistance.
The car with 400 ft lbs will accelerate at .480 g's (this is 391.7 HP)
The car with 300 ft lbs will accelerate at .353 g's (this is 293.8 HP) ""
You are assuming that the car that had 300 foot pounds had to already shift out of 1rst gear. Now do your equation with the car a (300 ft pounds) still in 1rst gear while car b (400 ft pounds) has had to shift earlier. Things change don't they even though one car has only 3/4 the tq of the other.
Of course maybe they have the same rpm limits and maintain the same level of tq throughout the range. This only then says that the car with more hp is winning again.
Now take two cars with the same tq but one that can maintain that same identical tq to twice the rpm limit. This car can stay in the same gears twice as long so it will accelerate the same off the line until the lower rpm (and power) car has to shift gears. Now who's accelerating faster? But yet they both produce the same tq don't they? But again the more powerfull car wins.
Seems like hp is what determines the winner huh?
Instructor
Joined: Sep 2001
Posts: 159
Likes: 21
From: McKinney Tx
Re: Horsepower vs Torque (RACER7088)
Red94Vette,
I didn't mean any of my posts as flames towards you and I didn't mean to end this discussion. that's the great thing about these boards as people can really learn a thing or two sometimes when thinking this stuff through.
Everything you said mostly is true in your original arguments except, as I said, it also shows that hp is what matters most because it links tq and rpm and allows for different gearing to optimize RWTQ which IS what really accelerates the car. Engine TQ and RWTQ can be manipulated by gearing but HP is fixed by the total amount of fuel the engine can process per unit time. You can have a small engine (less tq) turning high rpm with a deeper gear or a larger one (more tq) turning less rpm and working through a taller gear but in the end it's how much power or fuel the engine can process in a set amount of time that will determine how fast the car can accelerate or top out.
I didn't mean any of my posts as flames towards you and I didn't mean to end this discussion. that's the great thing about these boards as people can really learn a thing or two sometimes when thinking this stuff through.
Everything you said mostly is true in your original arguments except, as I said, it also shows that hp is what matters most because it links tq and rpm and allows for different gearing to optimize RWTQ which IS what really accelerates the car. Engine TQ and RWTQ can be manipulated by gearing but HP is fixed by the total amount of fuel the engine can process per unit time. You can have a small engine (less tq) turning high rpm with a deeper gear or a larger one (more tq) turning less rpm and working through a taller gear but in the end it's how much power or fuel the engine can process in a set amount of time that will determine how fast the car can accelerate or top out.
Melting Slicks
Joined: Jan 2002
Posts: 3,159
Likes: 0
Re: Horsepower vs Torque (Red94Vette)
and to say that tq gives u acceleration on the bottom end and hp accelerates you top end is the dumbest thing in the world. why would tq no accelerate your top end... :mad: I hate it when people say that
" have lots of tq so i got bottom end but no hp so no top end" :rolleyes:
the ls1 has gobs of tq but no bottom end
that is the most ignorant statement
although it maybe true in many cars, hp does at 500 rpms what it does at 8500 rpms- the same is true for tq
top end hp yields top end tq
if you use the forumla you will see this :cheers: :conehead
Thread Starter
Racer
Joined: Aug 2000
Posts: 491
Likes: 0
From: Houston, Texas
Re: Horsepower vs Torque (RACER7088)
You are right, horsepower is what matters most, I agree. I wanted to try and show how torque and horsepower play in the 'physics' without throwing up a bunch on numbers.
I made a point torque is what accelerates us. When you are at your torque peak you are pulling the hardest, not your horsepower peak. I think that is the point I wanted to make.
I like to throw ideas back and forth as well. It's good for the brain.
:boxing :seeya
I made a point torque is what accelerates us. When you are at your torque peak you are pulling the hardest, not your horsepower peak. I think that is the point I wanted to make.
I like to throw ideas back and forth as well. It's good for the brain.
:boxing :seeya
Pro
Joined: Feb 2002
Posts: 744
Likes: 1
From: Houston Tx
Re: Horsepower vs Torque (Red94Vette)
Its a good thread and as has been mentioned , SO many people have all kinds of misconceptions about power in their cars, hopefully these help clear some up......... :seeya
Burning Brakes
Joined: Nov 2001
Posts: 1,241
Likes: 9
From: Houston TX
Re: Horsepower vs Torque (Shriker)
more fuel to the fire... ever feel like you're pissing into the wind? ;)
http://forums.corvetteforum.com/zerothread?id=265118
bottom line: don't ever think a topic hasn't already been argued to death. on every forum i've frequented, the same topics flare up over and over. this hp vs torque thing, erik and i have been arguing this for decades!
shriker, sorry i haven't called about dyno time, been really busy. maybe this saturday?
http://forums.corvetteforum.com/zerothread?id=265118
bottom line: don't ever think a topic hasn't already been argued to death. on every forum i've frequented, the same topics flare up over and over. this hp vs torque thing, erik and i have been arguing this for decades!
shriker, sorry i haven't called about dyno time, been really busy. maybe this saturday?
Le Mans Master
Joined: Dec 1999
Posts: 8,540
Likes: 1
From: And on the fifth day, subpoenas were served to Obama senior staff
Re: Horsepower vs Torque
More comparisons:
The water analogy:
Think of water in your garden hose.
Water pressure = Torque (psi) (potential energy)
Water flow = RPM (g/s) (rate of energy flow) (hose diameter)
Combination of the two can do work (HP).
So very small hose (low RPM) will need very high pressure (torque) to do the same work as a very big hose (high rpm).
The Electrical Analogy
Voltage = Torque (potential energy)
Current = RPM (wire size)
Watts = Horsepower (work)
Small wire will need a lot of voltage to drive the same wattage (work). Large wire can provide same wattage with much less voltage.
Both over simplified, but good comparisons.
The water analogy:
Think of water in your garden hose.
Water pressure = Torque (psi) (potential energy)
Water flow = RPM (g/s) (rate of energy flow) (hose diameter)
Combination of the two can do work (HP).
So very small hose (low RPM) will need very high pressure (torque) to do the same work as a very big hose (high rpm).
The Electrical Analogy
Voltage = Torque (potential energy)
Current = RPM (wire size)
Watts = Horsepower (work)
Small wire will need a lot of voltage to drive the same wattage (work). Large wire can provide same wattage with much less voltage.
Both over simplified, but good comparisons.
Instructor
Joined: Sep 2001
Posts: 159
Likes: 21
From: McKinney Tx
Re: Horsepower vs Torque (Red94Vette)
""I made a point torque is what accelerates us. When you are at your torque peak you are pulling the hardest, not your horsepower peak. I think that is the point I wanted to make.
I like to throw ideas back and forth as well. It's good for the brain.""
Absolutely true. When stuck in any one gear you have the best acceleration in that gear at the Tq peak for the most part neglecting any weird aero drag or other non linear frictional force. The great thing about power is that it enable to to use a different gear and keep pulling way further with the additional mechanical advantage of the lower gear.
I like to throw ideas back and forth as well. It's good for the brain.""
Absolutely true. When stuck in any one gear you have the best acceleration in that gear at the Tq peak for the most part neglecting any weird aero drag or other non linear frictional force. The great thing about power is that it enable to to use a different gear and keep pulling way further with the additional mechanical advantage of the lower gear.
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Drifting
Joined: May 2001
Posts: 1,295
Likes: 2
From: Surprise Arizona
Re: Horsepower vs Torque (RACER7088)
I cant speak for anyone else but I have learned a great deal in this thread. It took a while to read and I needed an extra cup of coffee to stay awake through the middle but it was worth it. :seeya
Melting Slicks
Joined: Jan 2002
Posts: 3,159
Likes: 0
Re: Horsepower vs Torque (Red94Vette)
"hp is what puts you into the wall
tq is what puts you through the wall"
pretty freakin inaccurate but i just had to say it because of who said it :D
he also said
"if everything is under controll,
your not going fast enough " :smash:
tq is what puts you through the wall"
pretty freakin inaccurate but i just had to say it because of who said it :D
he also said
"if everything is under controll,
your not going fast enough " :smash:
