Damn those k20's
12-14-2006, 05:00 PM
#21
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Originally Posted by Patman17
Well heres the thing. When you get on a dyno, it measures torque, and calculates an estimated figure for horsepower. Torque is what acheives work, and work can be anything. How do you turn a stuck bolt? You sure dont apply more horsepower to it. At anypoint you are trying to move a vechicle torque is important. ever wonder why ricers take a while to move until the boost kicks in? b.c they have low torque number, and the extra boost is when they start building the horsepower....
-Patrick
-Patrick
Torque only measures where hp will end up. Horsepower is a measurement of work and torque is defined as being a rotational force. I would rather have torque in higher rpm's with a linear curve than peak hp down low. What if you had an engine that made 10,000ft/lbs of torque easily. But it ran at 1rpm. (10000ft/lbs * 1rpm) / 5252 = 1.904 hp. I would love to see you try and a tractor through the quarter mile.
(3 ft/lb of torque @ 2 RPM) / 5252 = .0011424 HP
(1 ft/lb of torque @ 8 RPM) /5252 = .0015232 hp
12-14-2006, 05:16 PM
#25
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Originally Posted by 71camaro
yeah probably, So your saying that torque really is just a useless number?
12-14-2006, 05:17 PM
#26
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Originally Posted by 25psi
Torque will win you the first 60ft, thats about it. Tell me when has torque been a deciding factor in a race.
I've been in plenty of races where a cars torque if more than 200ftlb more than mine and I was right there with em until my hp comes into play. A car with 500ftlb and 100hp will still run 16sec 1/4 times.
I've been in plenty of races where a cars torque if more than 200ftlb more than mine and I was right there with em until my hp comes into play. A car with 500ftlb and 100hp will still run 16sec 1/4 times.
Looks like we have to go over this again...
The torque CURVE is what matters(not peak numbers), that and gearing because gears manipulate TORQUE. The reasion a 500ft.lbs/100hp car wouldnt move very fast is it runs out of steam too quickly, and has to switch gears, making less TORQUE at the wheels. It has lots of low down torque, but not enough up high. Same applys for the 500hp/274ft.lbs Civic, using is super high ratio gears its making lots of TORQUE at the wheels. It may have no low down torque, but with those super high gears it doesnt really matter because they allow for the car to rev really quickly through the RPMs.
12-14-2006, 05:18 PM
#27
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Originally Posted by 25psi
Toque as a number is useless to brag about. Do you think someone would buy a viper, if it made 300hp and 500ftlb of torque?
12-14-2006, 05:22 PM
#28
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Originally Posted by 25psi
The point I'm trying to advocate is that there is no reason to look at the torque. If you want an engine that produces 1000hp a@ 8,500rpm you will need 617ft/lbs of torque. The misunderstanding is that you are thinking that I'm saying you will never need torque at all. This is not the point I was trying to make. I was trying to say that you can throw out your torque numbers, they are unimportant. Now for the car to make X amount of horsepower it will need Y amount of torque at Z rpm. So you will need torque to make horsepower. However the torque, as a number, is useless to brag about. It is useless to say "Oh yeah, well my car makes 400ft/lbs of torque. Now if that same person was to say "My car makes 400ft/lbs of torque at 8000rpm" its a different story. But thats only because that means he's making 609RWHP. Which is definitely a force to be reckoned with. So in the end I think we were arguing totally different points (atleast I hope I've caught the problem here). I'm saying Torque as a number means nothing but rather that horsepower is what you should pay attention to because that is what makes your car go down the track. You're saying that torque is necessary for an engine to make good horsepower. So in the end we're both correct. Obviously the better your torque, the better your horsepower. But high torque is nothing without a good amount of RPMs. I'm just tired of V8's throwing their torque numbers around when it doesnt prove anything.
12-14-2006, 05:29 PM
#29
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Originally Posted by JD_AMG
Like it or not, your car accelerates on your torque curve EXACTLY. So when your car is making, say, 300ft.lbs at 2000RPMs, and 300ft.lbs at 4000RPMs, in the same gear the car will NOT be pulling any harder, although, hp is doubled. What the V8 guys brag about is the torque CURVE, that from idle to redline its pretty much linear, so we dont constantly have to be in the highest RPMs to be pulling the hardest.
Take an extreme example to illustrate why the torque number is meaningless. Compare in the same car with two different engines, an engine that puts out 50 ft lbs of torque and an engine that puts out 500 ft lbs. Say we are going to race the cars for a given distance with a 1 speed transmission. Which engine will be faster?
Hmmm, can't say right?
Lets say the 50 ft lb engine puts out it's 50 ft lbs to 10000 RPM, and the 500 ft lb engine puts out it's 500 ft lbs to 1000 RPM. Now we are getting somewhere, because before, with out knowing the speeds at which the engines produce those numbers, we don't know how much power they can produce, which tells what gearing they can support in the race to distance without hitting redline.
Now, for the 50 ft lb engine we put in 20:1 rear gears and when we run it on our racetrack we just get to 10,000 RPM right at the finish line. Everything looks good; the gears maximize the potential of the car as it sits for this combination.
Now we put in our 500 ft lb engine, and leave the gears the same. Now the engine redlines about a tenth of the way down the track, the 20:1 rear is no good. We look at the first combination and we know to go the same speed with 1/10 the redline we need 1/10 the gears, right? So replace the 20:1 rear with a 2:1 rear. Now the car will run the same, because both cars have the same HP (RPM x T)/2525 in both cases. They also have the same torque at the rear wheels (50 x 20= 500 x 2). So what number told the tale, the torque numbers, which varied by a factor of 10, or the HP number, which is the same?
In order to not have to calculate rear wheel torque every time you want to compare two cars, or even the same car, you can just look at the calculated HP number. The HP number tells the whole story.
12-14-2006, 05:35 PM
#30
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Originally Posted by JD_AMG
Oh god, who let you back in?
Looks like we have to go over this again...
The torque CURVE is what matters(not peak numbers), that and gearing because gears manipulate TORQUE. The reasion a 500ft.lbs/100hp car wouldnt move very fast is it runs out of steam too quickly, and has to switch gears, making less TORQUE at the wheels. It has lots of low down torque, but not enough up high. Same applys for the 500hp/274ft.lbs Civic, using is super high ratio gears its making lots of TORQUE at the wheels. It may have no low down torque, but with those super high gears it doesnt really matter because they allow for the car to rev really quickly through the RPMs.
Looks like we have to go over this again...
The torque CURVE is what matters(not peak numbers), that and gearing because gears manipulate TORQUE. The reasion a 500ft.lbs/100hp car wouldnt move very fast is it runs out of steam too quickly, and has to switch gears, making less TORQUE at the wheels. It has lots of low down torque, but not enough up high. Same applys for the 500hp/274ft.lbs Civic, using is super high ratio gears its making lots of TORQUE at the wheels. It may have no low down torque, but with those super high gears it doesnt really matter because they allow for the car to rev really quickly through the RPMs.
So once again, torque is useless to brag about!
12-14-2006, 07:41 PM
#35
TECH Senior Member
Originally Posted by 25psi
Take an extreme example to illustrate why the torque number is meaningless. Compare in the same car with two different engines, an engine that puts out 50 ft lbs of torque and an engine that puts out 500 ft lbs. Say we are going to race the cars for a given distance with a 1 speed transmission. Which engine will be faster?
Hmmm, can't say right?
Lets say the 50 ft lb engine puts out it's 50 ft lbs to 10000 RPM, and the 500 ft lb engine puts out it's 500 ft lbs to 1000 RPM. Now we are getting somewhere, because before, with out knowing the speeds at which the engines produce those numbers, we don't know how much power they can produce, which tells what gearing they can support in the race to distance without hitting redline.
Hmmm, can't say right?
Lets say the 50 ft lb engine puts out it's 50 ft lbs to 10000 RPM, and the 500 ft lb engine puts out it's 500 ft lbs to 1000 RPM. Now we are getting somewhere, because before, with out knowing the speeds at which the engines produce those numbers, we don't know how much power they can produce, which tells what gearing they can support in the race to distance without hitting redline.
Now, for the 50 ft lb engine we put in 20:1 rear gears and when we run it on our racetrack we just get to 10,000 RPM right at the finish line. Everything looks good; the gears maximize the potential of the car as it sits for this combination.
Now we put in our 500 ft lb engine, and leave the gears the same. Now the engine redlines about a tenth of the way down the track, the 20:1 rear is no good. We look at the first combination and we know to go the same speed with 1/10 the redline we need 1/10 the gears, right? So replace the 20:1 rear with a 2:1 rear. Now the car will run the same, because both cars have the same HP (RPM x T)/2525 (you mean 5252)in both cases. They also have the same torque at the rear wheels (50 x 20= 500 x 2). So what number told the tale, the torque numbers, which varied by a factor of 10, or the HP number, which is the same?
Now we put in our 500 ft lb engine, and leave the gears the same. Now the engine redlines about a tenth of the way down the track, the 20:1 rear is no good. We look at the first combination and we know to go the same speed with 1/10 the redline we need 1/10 the gears, right? So replace the 20:1 rear with a 2:1 rear. Now the car will run the same, because both cars have the same HP (RPM x T)/2525 (you mean 5252)in both cases. They also have the same torque at the rear wheels (50 x 20= 500 x 2). So what number told the tale, the torque numbers, which varied by a factor of 10, or the HP number, which is the same?
Say you have the two cars, both the same. One your shifting, say, 1000RPMs sooner than the other, how would you explain its slower acceleration?
The car shifting higher is making X torque in that particular gear for longer than the car shifting too soon. You can throw out your hp numbers and just look at the torque curve alone and be fine.
In order to not have to calculate rear wheel torque every time you want to compare two cars, or even the same car, you can just look at the calculated HP number. The HP number tells the whole story.
Those cars for example, are making that high peak number only for a few RPMs, if you would look at the TORQUE CURVE you would see they are 12 second cars...
Carrol Shelby himself said "horsepower sells car, torque [curve] wins races."
12-14-2006, 07:48 PM
#37
TECH Senior Member
Originally Posted by 25psi
Torque will win you the first 60ft, thats about it. Tell me when has torque been a deciding factor in a race.
The car that has more torque at the wheels (thought the WHOLE powerband, dont bother coming back with peak numbers) will be quicker (given all else equal).
Out of this chart, which car, A or B, will be quicker? Both have the same peak hp, what you seem to live by, but very different torque curves. They are both the same cars, same gears, weight etc etc.
Last edited by JD_AMG; 12-14-2006 at 08:08 PM.
12-14-2006, 09:01 PM
#40
Originally Posted by slick1851
Dur its All motor........Keeping up with up with a Bolton LS1, Thats some 
thing to think about....
thing to think about....