F=ma bitches!
09-27-2005, 12:44 PM
#1
Senior Member
Thread Starter
Join Date: Feb 2003
Location: pittsburgh.
Posts: 1,863
Likes: 0
Received 0 Likes
on
0 Posts
F=ma bitches!
I am always hearing people talk about torque and hp as if they are entirely separate entities and argue about which one is better and so on. I think most of us have got a handle on it but I think this could still useful to a lot of pepole out there. This is a brief explanation of how torque and horsepower are related and how they affect the performance of your car. I will try to avoid using lots of numbers because that just gets retarded.
In the most basic sense, torque is the force you feel pushing you back in your seat. Well actually Torque at the wheels is directly proportionate to force between the tires and the ground, and that is what determines the acceleration of the car. Even though a if you look at a dyno and the power increases with RPMs, if the torque is the same through out the RPM range the car will accelerate at exactly the same rate at 3000RPM as at 6000RPM. This is where a lot of people are misinformed. So why does everybody look at hp? Because cars have gears. Let me explain: With the exception of 1st to 2nd every time I shift up I go to a gear that is geared about 30% higher. That means that due to gearing I am now making 30% less torque at the wheels, which means that the force between my tires and the ground is 30% less which means you reduce the acceleration of the car by 30%. So the advantage of making the same torque at a higher RPM is simply that it you don’t have to shift to a higher gear as soon, meaning that you don’t have to reduce your acceleration as soon. Having max horsepower at a high RPM doesn’t necessarily mean you will accelerate faster at higher RPMs. Believe it or not in a stock GSR you will be accelerating slower at 8000RPM than at 7000RPM, because the torque starts to drop at 7000. So does that mean you should shift before 8000? No because if you shift you will be making 30% less tourqe at the wheels, which far more than the torque drops off.
Hp is simply tq x rpm (if you get the units right. There is also a fairly widely used factor to convert from tq/min to hp but I don’t have it on me.) Think of hp as a convenient way to rate the ability of a motor to make torque at high RPMs.
if someone wants to post this as a sticky somewhere let me know and i can clean it up a little.
In the most basic sense, torque is the force you feel pushing you back in your seat. Well actually Torque at the wheels is directly proportionate to force between the tires and the ground, and that is what determines the acceleration of the car. Even though a if you look at a dyno and the power increases with RPMs, if the torque is the same through out the RPM range the car will accelerate at exactly the same rate at 3000RPM as at 6000RPM. This is where a lot of people are misinformed. So why does everybody look at hp? Because cars have gears. Let me explain: With the exception of 1st to 2nd every time I shift up I go to a gear that is geared about 30% higher. That means that due to gearing I am now making 30% less torque at the wheels, which means that the force between my tires and the ground is 30% less which means you reduce the acceleration of the car by 30%. So the advantage of making the same torque at a higher RPM is simply that it you don’t have to shift to a higher gear as soon, meaning that you don’t have to reduce your acceleration as soon. Having max horsepower at a high RPM doesn’t necessarily mean you will accelerate faster at higher RPMs. Believe it or not in a stock GSR you will be accelerating slower at 8000RPM than at 7000RPM, because the torque starts to drop at 7000. So does that mean you should shift before 8000? No because if you shift you will be making 30% less tourqe at the wheels, which far more than the torque drops off.
Hp is simply tq x rpm (if you get the units right. There is also a fairly widely used factor to convert from tq/min to hp but I don’t have it on me.) Think of hp as a convenient way to rate the ability of a motor to make torque at high RPMs.
if someone wants to post this as a sticky somewhere let me know and i can clean it up a little.
h:
09-27-2005, 01:06 PM
#4
lots and lots of fail
Join Date: Dec 1999
Location: Deeeeeeeeeeeeeeetroit
Posts: 23,004
Likes: 0
Received 1 Like
on
1 Post
Originally Posted by bnuk
Hp is simply tq x rpm (if you get the units right. There is also a fairly widely used factor to convert from tq/min to hp but I don’t have it on me.)
