Low-end Torque
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From: Laurel
Here's the forest (for the trees): While all of this is an interesting discussion it doesn't get to the point of the original request. Since I don't think our esteemed thread starter quite knew what he wanted, let me put his question another way:
"How can I go quicker off idle?"
The answer, of course, is "you can't get there from here" in an S2000 or other small displacement car that depends on "torque multiplication" (those revs and gearing that you guys are arguing about) to develop power. Most street cars have a powerband that's about 3-4k wide. But for a car that depends on multiplying torque, there will always be a greater rpm distance from idle to the powerband than a car that uses displacement to develop power.
Torque is the real measurement. Horsepower is a made up construct used (originally) to sell steam engines. How engines develop power is determined by many factors but it's pretty well true (as a general rule) that big displacement motors make power at closer to idle than small motors. Likewise small motors can make power by torque multiplication since they can rotate at higher speeds.
Each has it's advantages. Off idle power just isn't an advantage of the F20C.
"How can I go quicker off idle?"
The answer, of course, is "you can't get there from here" in an S2000 or other small displacement car that depends on "torque multiplication" (those revs and gearing that you guys are arguing about) to develop power. Most street cars have a powerband that's about 3-4k wide. But for a car that depends on multiplying torque, there will always be a greater rpm distance from idle to the powerband than a car that uses displacement to develop power.
Torque is the real measurement. Horsepower is a made up construct used (originally) to sell steam engines. How engines develop power is determined by many factors but it's pretty well true (as a general rule) that big displacement motors make power at closer to idle than small motors. Likewise small motors can make power by torque multiplication since they can rotate at higher speeds.
Each has it's advantages. Off idle power just isn't an advantage of the F20C.
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From: Milwaukee
[QUOTE]Originally posted by Sunder
[B]How about a lysholm twin screw super charger?
Unlike Vortech (centrifugal) and turbos which have a latency, the lysholm screw is designed to boost from the word "Engine Start".
[B]How about a lysholm twin screw super charger?
Unlike Vortech (centrifugal) and turbos which have a latency, the lysholm screw is designed to boost from the word "Engine Start".
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From: You wish
(thanks to Jim for a little bit of on topic discussion, and Luis, I'm going to try and open John's eyes because he's a good guy :-)
Bam! There is your answer John. If wheel power is not affected by gearing, then why do we accelerate faster in 1st gear than we do in 3rd?
The discussions of power, energy, etc. are all fine and dandy, but what we're really concerned about when accelerating is thrust to weight. That's it, how much thrust can I apply vs. how much mass (in earth's gravity well) I have to move. Do you think rocket engineers and jet aircraft designers worry about how much torque their engines produce (as it relates to acceleration)? Outside of thrust and mass (weight) the only other concern is aero drag. If you can compute thrust by looking at the hp number, great. But for me its simplest to do it using torque.
When you accelerate through the rpm range, your acceleration at 3000 rpm with 90% of peak torque vs. at 7000 rpm will be approximately 90% as strong. Put a G-meter on your car (I'll let you borrow my Vericom with continuous G-mode) and you'll see. The only reason it feels stronger is because of the step function change in acceleration at VTEC. The human body is much better at detecting changes in acceleration (known as "jerk" believe it or not :-) than it is at accurately assessing a constant acceleration rate. That's why the S2K can be so deceptively quick. It accelerates at a near constant rate from 6000-8500 rpm.
As for my example, note that I said at least 2/3rd the torque. At exactly 2/3rd the torque you could gear the car to accelerate anywhere in that range. At more than 2/3rds, you'd want to be at the power peak.
UL
[QUOTE]Originally posted by twohoos
[B]
Anyway, my point all along has been that "gearing" is a red herring.
Bam! There is your answer John. If wheel power is not affected by gearing, then why do we accelerate faster in 1st gear than we do in 3rd?
The discussions of power, energy, etc. are all fine and dandy, but what we're really concerned about when accelerating is thrust to weight. That's it, how much thrust can I apply vs. how much mass (in earth's gravity well) I have to move. Do you think rocket engineers and jet aircraft designers worry about how much torque their engines produce (as it relates to acceleration)? Outside of thrust and mass (weight) the only other concern is aero drag. If you can compute thrust by looking at the hp number, great. But for me its simplest to do it using torque.
When you accelerate through the rpm range, your acceleration at 3000 rpm with 90% of peak torque vs. at 7000 rpm will be approximately 90% as strong. Put a G-meter on your car (I'll let you borrow my Vericom with continuous G-mode) and you'll see. The only reason it feels stronger is because of the step function change in acceleration at VTEC. The human body is much better at detecting changes in acceleration (known as "jerk" believe it or not :-) than it is at accurately assessing a constant acceleration rate. That's why the S2K can be so deceptively quick. It accelerates at a near constant rate from 6000-8500 rpm.
As for my example, note that I said at least 2/3rd the torque. At exactly 2/3rd the torque you could gear the car to accelerate anywhere in that range. At more than 2/3rds, you'd want to be at the power peak.
UL
[QUOTE]Originally posted by twohoos
[B]
Anyway, my point all along has been that "gearing" is a red herring.
Joined: Feb 2001
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From: Redondo Beach
Originally posted by ultimate lurker
I'm going to try and open John's eyes because he's a good guy :-)
I'm going to try and open John's eyes because he's a good guy :-)
[QUOTE][B]When you accelerate through the rpm range, your acceleration at 3000 rpm with 90% of peak torque vs. at 7000 rpm will be approximately 90% as strong.
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From: Orange Park
Mussoline,
Sorry everyone has seemed to go off on their own tangent and ignore your initial post but as I mentioned earlier... the turbo is the way to go if you have the money. If not... nitrous is about the only other alternative that will offer low end power. I find it very difficult to believe that the Vortech cars are spinning the tires at 3-4000 RPMS after seeing a couple of their dynos... however I can promise you that at 4000 RPMs on a turbo S2 that wheelspin will be a concern. Those who say that the turbo doesn't offer low end power don't know what they're talking about and definitely have not been in a turbo S2. As far as I know ChrisD still has the fastest posted time slip and is putting down about the same power as cars with a supercharger and nitrous.
Sorry everyone has seemed to go off on their own tangent and ignore your initial post but as I mentioned earlier... the turbo is the way to go if you have the money. If not... nitrous is about the only other alternative that will offer low end power. I find it very difficult to believe that the Vortech cars are spinning the tires at 3-4000 RPMS after seeing a couple of their dynos... however I can promise you that at 4000 RPMs on a turbo S2 that wheelspin will be a concern. Those who say that the turbo doesn't offer low end power don't know what they're talking about and definitely have not been in a turbo S2. As far as I know ChrisD still has the fastest posted time slip and is putting down about the same power as cars with a supercharger and nitrous.
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From: Glendale/Burbank/LA
Originally posted by TimTheFoolMan
It could be worse. You could've posted something like:
F = M x a
Then (speaking from experience) you'd REALLY look dorky.
Tim
It could be worse. You could've posted something like:
F = M x a
Then (speaking from experience) you'd REALLY look dorky.
Tim
