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Old 02-13-2006, 03:44 PM
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Torque

What engine modifications are torque enhancing? Not horsepower.

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Old 02-13-2006, 03:50 PM
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Install small diameter, long tube headers, increase the compression ratio, and install a short dual plane intake manifold. A better camshaft works wonders too, if you don't scroll down the page too far.

Oh yeah, Anytime the torque goes up the horsepower does too. It's a function of mathematics.


Larry
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Old 02-13-2006, 03:57 PM
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Quote:
Originally Posted by coldknock
Oh yeah, Anytime the torque goes up the horsepower does too. It's a function of mathematics.


Larry
While hp is simpley the speed at which torque is delivered increasing torque will not ALWAYS increase horsepower, you also have to have that torque increase follow thhrough the entire power band, usually this does not ahppen, and increasing torque on the low end can reduce hp if the torque at the high end falls (think short duration camshafts) it can also mean a quicker et with lower hp numbers.
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Old 02-13-2006, 04:02 PM
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True but we need to keep it apples to apples here. Most folks aren't quite as studied about the particulars as we are.

I should have stated that more torque at the same rpm will equal more horsepower.


Larry
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Old 02-13-2006, 04:15 PM
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Quote:
Originally Posted by ap72
While hp is simpley the speed at which torque is delivered increasing torque will not ALWAYS increase horsepower, you also have to have that torque increase follow thhrough the entire power band, usually this does not ahppen, and increasing torque on the low end can reduce hp if the torque at the high end falls (think short duration camshafts) it can also mean a quicker et with lower hp numbers.
How can you not increase horsepower with an increase in torque? What's the formula for horsepower? Something like:
hp = #ft(rpm/5252)
If I keep the rpm constant and increase the torque, the hp will always increase.
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Old 02-13-2006, 04:41 PM
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Just a lil tidbit of info since that forumla was brought up . . . if you look at a dyno chart for any engine, the Horsepower and Torque will be the same at 5252RPM.
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Old 02-13-2006, 04:59 PM
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^ Why is that Siggy? is it just the computer programming they use? or are all engines like that??
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Old 02-13-2006, 05:07 PM
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Force, Work and Time
If you have a one pound weight bolted to the floor, and try to lift it with one pound of force (or 10, or 50 pounds), you will have applied force and exerted energy, but no work will have been done. If you unbolt the weight, and apply a force sufficient to lift the weight one foot, then one foot pound of work will have been done. If that event takes a minute to accomplish, then you will be doing work at the rate of one foot pound per minute. If it takes one second to accomplish the task, then work will be done at the rate of 60 foot pounds per minute, and so on.

In order to apply these measurements to automobiles and their performance (whether you're speaking of torque, horsepower, newton meters, watts, or any other terms), you need to address the three variables of force, work and time.

Awhile back, a gentleman by the name of Watt (the same gent who did all that neat stuff with steam engines) made some observations, and concluded that the average horse of the time could lift a 550 pound weight one foot in one second, thereby performing work at the rate of 550 foot pounds per second, or 33,000 foot pounds per minute, for an eight hour shift, more or less. He then published those observations, and stated that 33,000 foot pounds per minute of work was equivalent to the power of one horse, or, one horsepower.

Everybody else said OK. :-)

For purposes of this discussion, we need to measure units of force from rotating objects such as crankshafts, so we'll use terms which define a *twisting* force, such as foot pounds of torque. A foot pound of torque is the twisting force necessary to support a one pound weight on a weightless horizontal bar, one foot from the fulcrum.

Now, it's important to understand that nobody on the planet ever actually measures horsepower from a running engine. What we actually measure (on a dynomometer) is torque, expressed in foot pounds (in the U.S.), and then we *calculate* actual horsepower by converting the twisting force of torque into the work units of horsepower.

Visualize that one pound weight we mentioned, one foot from the fulcrum on its weightless bar. If we rotate that weight for one full revolution against a one pound resistance, we have moved it a total of 6.2832 feet (Pi * a two foot circle), and, incidently, we have done 6.2832 foot pounds of work.

OK. Remember Watt? He said that 33,000 foot pounds of work per minute was equivalent to one horsepower. If we divide the 6.2832 foot pounds of work we've done per revolution of that weight into 33,000 foot pounds, we come up with the fact that one foot pound of torque at 5252 rpm is equal to 33,000 foot pounds per minute of work, and is the equivalent of one horsepower. If we only move that weight at the rate of 2626 rpm, it's the equivalent of 1/2 horsepower (16,500 foot pounds per minute), and so on. Therefore, the following formula applies for calculating horsepower from a torque measurement:


Horsepower = Torque * RPM/5252




This is not a debatable item. It's the way it's done. Period.


From: http://vettenet.org/torquehp.html

Suppose Watt had used pigs and we rated everything in pigpower? How many piggies have you got under your hood?

Last edited by onovakind67; 02-13-2006 at 09:48 PM.
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Old 02-13-2006, 08:14 PM
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Quote:
Originally Posted by onovakind67

Suppose Watt had used pigs and we rated everything in pigpower? How many piggies have you got under your hood?
I'm thinking donkeys would have been a more viable alternative of the day. We could have been measuring everything in "asspower"

Sorry, that was not called for...
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Old 02-13-2006, 08:25 PM
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^^^ LMAO!!!!! that was good.
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Old 02-13-2006, 10:23 PM
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Quote:
Originally Posted by onovakind67
How can you not increase horsepower with an increase in torque? What's the formula for horsepower? Something like:
hp = #ft(rpm/5252)
If I keep the rpm constant and increase the torque, the hp will always increase.
IF you keep the RPM constant at which the torque peaks. If you put in a smaller cam, you can make more peak torque at a lower RPM which will make a LOWER peak HP.

For instance, my Caddy 500 makes 525 lb-ft of torque at 3200 rpm and 500 hp at about 6000. If I swapped back to my last cam, I would be making 575 lb-ft of torque at 1900 rpm and only about 390 hp at 3900 rpm. There is a good example of how more torque can equal less HP.
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Old 02-14-2006, 09:04 AM
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Quote:
Originally Posted by curtis73
IF you keep the RPM constant at which the torque peaks. If you put in a smaller cam, you can make more peak torque at a lower RPM which will make a LOWER peak HP.

For instance, my Caddy 500 makes 525 lb-ft of torque at 3200 rpm and 500 hp at about 6000. If I swapped back to my last cam, I would be making 575 lb-ft of torque at 1900 rpm and only about 390 hp at 3900 rpm. There is a good example of how more torque can equal less HP.
Can you explain the math of that? If hp = t(rpm/k), how can you decrease the horsepower by increasing the torque at a specific rpm? Somehow the math doesn't fit here. If you're motor makes 400#ft at 2000 rpm and mine makes 500#ft at 2000 rpm, which makes more horsepower?
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Old 02-14-2006, 09:49 AM
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That answer depends on who makes more torque up top.
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Old 02-14-2006, 10:12 AM
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You are implying that horsepower only occurs at one point? Most of my dyno charts have a continuous curve depicting horsepower. I find that at any point in the graph, as the torque increases, so does the horsepower.
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Old 02-14-2006, 10:38 AM
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Quote:
Originally Posted by onovakind67
Can you explain the math of that? If hp = t(rpm/k), how can you decrease the horsepower by increasing the torque at a specific rpm? Somehow the math doesn't fit here. If you're motor makes 400#ft at 2000 rpm and mine makes 500#ft at 2000 rpm, which makes more horsepower?
In that formula, the RPM is not just one RPM, its all of them. That formula is to find HP anywhere in the RPM range. HP = (TQ x RPM)/5250. Let's take an example. My Caddy 500 makes 525 hp at 3200 rpm. So to find the hp there, its (525 x 3200)/5250, or 320hp. At 3200 RPM, I'm only making 320 hp. As you can see, if you kept the same torque as the engine rose to 4000 RPM, at that RPM, the engine makes 400 hp. There is a point in the torque curve where the torque production starts dropping off faster than the RPMs rise. At that point, HP starts to fall.

On most dynos, they measure torque and simply calculate hp. The HP curve on a chart is simply taking the torque values at all rpm points and plugging them into that equation. So, if your engine makes a torque peak way down low, that means it drops off before that equation would make big hp numbers. 600 lb ft won't make much hp if it happens at 500 rpm. Let me make a couple charts to show you and I'll post again later.
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