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Torque... Horsepower...
#1
Torque and Horsepower - A Primer

OK. Here's the deal, in moderately plain English.

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.

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 dynamometer) 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, incidentally, 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:


HP = (Torque X RPM) / 5250


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

The Case For Torque
Now, what does all this mean in carland?

First of all, from a driver's perspective, torque, to use the vernacular, RULES :-). Any given car, in any given gear, will accelerate at a rate that *exactly* matches its torque curve (allowing for increased air and rolling resistance as speeds climb). Another way of saying this is that a car will accelerate hardest at its torque peak in any given gear, and will not accelerate as hard below that peak, or above it. 300 foot pounds of torque will accelerate you just as hard at 2000 rpm as it would if you were making that torque at 4000 rpm in the same gear, yet, per the formula, the horsepower would be *double* at 4000 rpm.

In contrast to a torque curve (and the matching pushback into your seat), horsepower rises rapidly with rpm, especially when torque values are also climbing. Horsepower will continue to climb, however, until well past the torque peak, and will continue to rise as engine speed climbs, until the torque curve really begins to plummet, faster than engine rpm is rising. However, as I said, horsepower has nothing to do with what a driver *feels*.

You don't believe all this?

Fine. Take your non turbo car (turbo lag muddles the results) to its torque peak in first gear, and punch it. Notice the belt in the back? Now take it to the power peak, and punch it. Notice that the belt in the back is a bit weaker? Fine. Can we go on, now?

The Case For Horsepower
OK. If torque is so all-fired important, why do we care about horsepower?

Because (to quote a friend), "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*.

For an extreme example of this, I'll leave carland for a moment, and describe a waterwheel I got to watch awhile ago. This was a pretty massive wheel (built a couple of hundred years ago), rotating lazily on a shaft which was connected to the works inside a flour mill. Working some things out from what the people in the mill said, I was able to determine that the wheel typically generated about 2600(!) foot pounds of torque. I had clocked its speed, and determined that it was rotating at about 12 rpm. If we hooked that wheel to, say, the drive wheels of a car, that car would go from zero to twelve rpm in a flash, and the waterwheel would hardly notice.

On the other hand, twelve rpm of the drive wheels is around one mph for the average car, and, in order to go faster, we'd need to gear it up. To get to 60 mph would require gearing the wheel up enough so that it would be effectively making a little over 43 foot pounds of torque at the output, which is not only a relatively small amount, it's less than what the average car would need in order to actually get to 60. Applying the conversion formula gives us the facts on this. Twelve times twenty six hundred, over five thousand two hundred fifty two gives us:

6 HP.

Oops. Now we see the rest of the story. While it's clearly true that the water wheel can exert a *bunch* of force, its *power* (ability to do work over time) is severely limited.

At The Dragstrip
OK. Back to carland, and some examples of how horsepower makes a major difference in how fast a car can accelerate, in spite of what torque on your backside tells you :-).

A very good example would be to compare the current LT1 Corvette with the last of the L98 Vettes, built in 1991. Figures as follows:


Engine Peak HP @ RPM Peak Torque @ RPM
------ ------------- -----------------
L98 250 @ 4000 340 @ 3200
LT1 300 @ 5000 340 @ 3600

The cars are geared identically, and car weights are within a few pounds, so it's a good comparison.

First, each car will push you back in the seat (the fun factor) with the same authority - at least at or near peak torque in each gear. One will tend to *feel* about as fast as the other to the driver, but the LT1 will actually be significantly faster than the L98, even though it won't pull any harder. If we mess about with the formula, we can begin to discover exactly *why* the LT1 is faster. Here's another slice at that formula:


Horsepower * 5252
Torque = -----------------
RPM

If we plug some numbers in, we can see that the L98 is making 328 foot pounds of torque at its power peak (250 hp @ 4000), and we can infer that it cannot be making any more than 263 pound feet of torque at 5000 rpm, or it would be making more than 250 hp at that engine speed, and would be so rated. In actuality, the L98 is probably making no more than around 210 pound feet or so at 5000 rpm, and anybody who owns one would shift it at around 46-4700 rpm, because more torque is available at the drive wheels in the next gear at that point.

On the other hand, the LT1 is fairly happy making 315 pound feet at 5000 rpm, and is happy right up to its mid 5s redline.

So, in a drag race, the cars would launch more or less together. The L98 might have a slight advantage due to its peak torque occurring a little earlier in the rev range, but that is debatable, since the LT1 has a wider, flatter curve (again pretty much by definition, looking at the figures). From somewhere in the mid range and up, however, the LT1 would begin to pull away. Where the L98 has to shift to second (and throw away torque multiplication for speed), the LT1 still has around another 1000 rpm to go in first, and thus begins to widen its lead, more and more as the speeds climb. As long as the revs are high, the LT1, by definition, has an advantage.

Another example would be the LT1 against the ZR-1. Same deal, only in reverse. The ZR-1 actually pulls a little harder than the LT1, although its torque advantage is softened somewhat by its extra weight. The real advantage, however, is that the ZR-1 has another 1500 rpm in hand at the point where the LT1 has to shift.

There are numerous examples of this phenomenon. The Integra GS-R, for instance, is faster than the garden variety Integra, not because it pulls particularly harder (it doesn't), but because it pulls *longer*. It doesn't feel particularly faster, but it is.

A final example of this requires your imagination. Figure that we can tweak an LT1 engine so that it still makes peak torque of 340 foot pounds at 3600 rpm, but, instead of the curve dropping off to 315 pound feet at 5000, we extend the torque curve so much that it doesn't fall off to 315 pound feet until 15000 rpm. OK, so we'd need to have virtually all the moving parts made out of unobtanium :-), and some sort of turbocharging on demand that would make enough high-rpm boost to keep the curve from falling, but hey, bear with me.

If you raced a stock LT1 with this car, they would launch together, but, somewhere around the 60 foot point, the stocker would begin to fade, and would have to grab second gear shortly thereafter. Not long after that, you'd see in your mirror that the stocker has grabbed third, and not too long after that, it would get fourth, but you'd wouldn't be able to see that due to the distance between you as you crossed the line, *still in first gear*, and pulling like crazy.

I've got a computer simulation that models an LT1 Vette in a quarter mile pass, and it predicts a 13.38 second ET, at 104.5 mph. That's pretty close (actually a tiny bit conservative) to what a stock LT1 can do at 100% air density at a high traction drag strip, being powershifted. However, our modified car, while belting the driver in the back no harder than the stocker (at peak torque) does an 11.96, at 135.1 mph, all in first gear, of course. It doesn't pull any harder, but it sure as hell pulls longer. It's also making *900* hp, at 15,000 rpm.

Of course, folks who are knowledgeable about drag racing are now openly snickering, because they've read the preceding paragraph, and it occurs to them that any self respecting car that can get to 135 mph in a quarter mile will just naturally be doing this in less than ten seconds. Of course that's true, but I remind these same folks that any self-respecting engine that propels a Vette into the nines is also making a whole bunch more than 340 foot pounds of torque.

That does bring up another point, though. Essentially, a more "real" Corvette running 135 mph in a quarter mile (maybe a mega big block) might be making 700-800 foot pounds of torque, and thus it would pull a whole bunch harder than my paper tiger would. It would need slicks and other modifications in order to turn that torque into forward motion, but it would also get from here to way over there a bunch quicker.

On the other hand, as long as we're making quarter mile passes with fantasy engines, if we put a 10.35:1 final-drive gear (3.45 is stock) in our fantasy LT1, with slicks and other chassis mods, we'd be in the nines just as easily as the big block would, and thus save face. The mechanical advantage of such a nonsensical rear gear would allow our combination to pull just as hard as the big block, plus we'd get to do all that gear banging and such that real racers do, and finish in fourth gear, as God intends.

The only modification to the preceding paragraph would be the polar moments of inertia (flywheel effect) argument brought about by such a stiff rear gear, and that argument is outside of the scope of this already massive document. Another time, maybe, if you can stand it.

At The Bonneville Salt Flats
Looking at top speed, horsepower wins again, in the sense that making more torque at high rpm means you can use a stiffer gear for any given car speed, and thus have more effective torque *at the drive wheels*.

Finally, operating at the power peak means you are doing the absolute best you can at any given car speed, measuring torque at the drive wheels. I know I said that acceleration follows the torque curve in any given gear, but if you factor in gearing vs car speed, the power peak is *it*. An example, yet again, of the LT1 Vette will illustrate this. If you take it up to its torque peak (3600 rpm) in a gear, it will generate some level of torque (340 foot pounds times whatever overall gearing) at the drive wheels, which is the best it will do in that gear (meaning, that's where it is pulling hardest in that gear).

However, if you re-gear the car so it is operating at the power peak (5000 rpm) *at the same car speed*, it will deliver more torque to the drive wheels, because you'll need to gear it up by nearly 39% (5000/3600), while engine torque has only dropped by a little over 7% (315/340). You'll net a 29% gain in drive wheel torque at the power peak vs the torque peak, at a given car speed.

Any other rpm (other than the power peak) at a given car speed will net you a lower torque value at the drive wheels. This would be true of any car on the planet, so, theoretical "best" top speed will always occur when a given vehicle is operating at its power peak.

"Modernizing" The 18th Century
OK. For the final-final point (Really. I Promise.), what if we ditched that water wheel, and bolted an LT1 in its place? Now, no LT1 is going to be making over 2600 foot pounds of torque (except possibly for a single, glorious instant, running on nitromethane), but, assuming we needed 12 rpm for an input to the mill, we could run the LT1 at 5000 rpm (where it's making 315 foot pounds of torque), and gear it down to a 12 rpm output. Result? We'd have over *131,000* foot pounds of torque to play with. We could probably twist the whole flour mill around the input shaft, if we needed .
#2
Quote:Originally posted by SiN-6
Torque and Horsepower - A Primer
The Only Thing You Really Need to Know
Repeat after me. "It is better to make torque at high rpm than at low rpm, because you can take advantage of *gearing*."

Torque at high RPM is simply horsepower. Given lots of horsepower, you can gear to get the desired acceleration. If you ignore wind resistance, the problem boils down to freshman physics:

(1) kinetic energy = 1/2 mass * velocity^2.

The rate of change in kinetic energy equals power, which has the units of horsepower. Torque doesn't have the correct units when talking about acceleration - it simply doesn't parse. With proper gearing, you can make a car with a high horsepower engine accelerate fast. You can't say the same thing about torque. Technically ICY HOT is right on this one.

I will now address RS/377's question. Horsepower is the product of torque (ft lbs or Newton meters) times angular velocity (RPMs, radians/sec,...). If you have an engine that produces very high horsepower but low torque, you can use lower gears, in the rear end for example, to get increased "effective torque." Let's say engine 2 has a 1/2 the torque of engine 1 at three times the rpms. You could simply increase the gears in the ass end by a factor of three and produce 1.5 times as much torque as engine 1, the engine with "higher torque."
#3
The definition of horsepower is

Quote:2 : a unit of power equal in the U.S. to 746 watts and nearly equivalent to the English gravitational unit of the same name that equals 550 foot-pounds of work per second


Torque does not define horsepower.

Also engines do put out measureable horsepower, it is possible to measure horsepower from an engine. It is just extremely diffictult since engines spin.


from here
#4
cars in the end always use torque to accelerate
thats the only way the translational acceleration can be derived from the ROTATIONAL acceleration of the wheels

and about the gear changes to get greater torque, good luck finding a gearbox complex enuff to do that, small enough to fit in a car, and efficient enough so that half the power wont be lost through the numerous gears the power has to be transferred through

and in order to derive the maximum power out of a car just from horsepower, the engine has to be spinning at its fastest

meaning that every car has to launch starting at its redline, and always stay at the redline, giving out the same amount of horsepower, but using infinitely variable gearing (as mentioned above) to convert it into usable acceleration

THAT's why cars need torque, every car starts at low rpm's and go up to high ones, cuz cars have either 4, 5, or 6 fixed gear ratios, and cuz spinning at redline all the time would kill ur engine and waste all ur gas
#5
Quote:I will now address RS/377's question. Horsepower is the product of torque (ft lbs or Newton meters) times angular velocity (RPMs, radians/sec,...). If you have an engine that produces very high horsepower but low torque, you can use lower gears, in the rear end for example, to get increased "effective torque." Let's say engine 2 has a 1/2 the torque of engine 1 at three times the rpms. You could simply increase the gears in the ass end by a factor of three and produce 1.5 times as much torque as engine 1, the engine with "higher torque."


So, in the ed, you are still building your car to have an acceptable level of torque (acceleration) at the wheels, intsead of the engine
#6
Quote:Originally posted by XiaoMing
alrite u monkeynut
its time to bust out deanza's physics 4a on ur sorry ass

torque is the rotational analogy of force
force is mass times acceleration
torque is the angular acceleartion of an object about a fixed axis
the angular acceleration is the wheels, the axis is the axle
thus, torque is mass times angular acceleration (how fast it accelerates rotationally)

thus, with a large mass riding on ur wheels, the ability of the wheels to accelerate is all dependent on the torque being supplied to the wheels from the powerplant divided by the mass of the car

and uhm... yea take some physics before u start mouthing off
that or drive a corvette
fuck, if u wanna feel torque, go on a highway doing 35 with a vette and a civic si, both in 5th gear, and lets say both having the same gear ratio
if u floor it in both cars, before the civic si's upper end horsepower kicks in (and even after), the vette will spank the civic silly with its torque
Who are you talking smack about?

You forgot the effect of the transmission. If you're making less torque and more horsepower, you need to be geared lower obviously.
You should consider the torque of the composite of the engine and transmission to be applied to the wheels. The torque at the rear wheels is an interesting number, the torque at the engine isn't.

Let's modify your example a little. You're running at 40 MPH in 6th gear in the vette at around 1200 RPMs and about 5500 RPMs in second gear in your V6 Camry. The vette is putting out 320 ft lbs of torque, the Camry is only putting out maybe 200. The vette is putting out maybe 100 HP, the Camry close to 200. Which one is going to initially accelerate quicker, the Camry.

Take two cars equal in all ways save engines. Assume some fixed fraction of the power makes it to the rear wheels (say 0.85 or 1.0). If the engine in car 1 consistently makes more horsepower than the engine in car 2, car one will accelerate faster than car 2. Period. You cannot make the same simple statement about torque.
#7
Quote:So, in the ed, you are still building your car to have an acceptable level of torque (acceleration) at the wheels, intsead of the engine


Torque is not acceleration, Xiaming was making every bit of that up


Torque = weight * lever arm

PROOF

Torque is not angular acceleration around a fixed axis, that is complete bullshit.

Quote:You should consider the torque of the composite of the engine and transmission to be applied to the wheels. The torque at the rear wheels is an interesting number, the torque at the engine isn't.


Neither of them are interesting. Even if you know rear wheel torque you still don't know if that engine can sustain it.

An illustration of this would be a 10 foot beam attached to the rear axle of a car, if you put 500 pounds on that beam you would be making 5,000ft/lbs of torque at the wheels, you would move that car about a foot.



Quote:THAT's why cars need torque, every car starts at low rpm's and go up to high ones, cuz cars have either 4, 5, or 6 fixed gear ratios, and cuz spinning at redline all the time would kill ur engine and waste all ur gas


Engines don't make max power at the redline, they fall off way before that.

The idea behind shift points is that you want the max mean hp, not torque, the book called AUTO MATH written by John Lawlor has a table set up to find the correct shift points of a vehicle.
#8
oh my fuckign god, i'm talking to you about torque from the standpoint of getting an A and provin my teacher wrong after my physics 4A class, and ur using QUOTES U FOUND IN A WEB SITE to tell me torque is not acceleration?
goddamnit its angular acceleration multiplied by inertia, the tendency of an object to resist movement
the shit u have is force times lever arm, the Force first off, is tangential, and the lever arm is just the distance the force is away from the axis of rotation
not only that, but force is mass times ACCELERATION

and FUCK, aite, so engines dont make max power at redline, they still sure as hell dont make it at 2k rpm
i'm just saying u hafta rev that shit a lot higher to get the horsepower
Quote:Let's modify your example a little. You're running at 40 MPH in 6th gear in the vette at around 1200 RPMs and about 5500 RPMs in second gear in your V6 Camry. The vette is putting out 320 ft lbs of torque, the Camry is only putting out maybe 200. The vette is putting out maybe 100 HP, the Camry close to 200. Which one is going to initially accelerate quicker, the Camry.

as for that
that's why cars are rated w/ torque
CUZ NOT ALL CARS START AT 5500 rpm in second gear
torque is considered low end purely because its what gives the car acceleration at the early point of its rpm band for every gear
if you had two cars in same gears in low rpm, and one had more torque, the one w/ more torque would accelerate faster, simple as THAT


oh and the fact that u said i was making the torque shit up, i am gonna flame ur retarded stupidfuck ass silly for calling me a liar, YOU FUCKING RETARDED SILLY ASSED STUPIDFUCK, learn ur physics before u tell me i'm wrong okay? ;[ torque is defined in many ways, just like ignorance, of which you are one of those definitions (no, i do not mean ur a definition for torque)
#9
Torque is useless? HA! That's the biggest load of crap I've heard in a while.
Torque is what gets the vehicle moving in the first place.

First let's look at you Camry vs. Vette example.
Torque at the wheels varies with gear ratios. In first gear a car will put more torque through the wheels than in second, more in second than in third and so on. Even a Honda is putting out over 1000 ftlb of torque in first gear. If it wasn't the car wouldn't move. Thus your camry in second gear is actually putting out much more torque at the wheels than the Vette is in sixth gear.

Still think torque is useless?

Well then why don't you try to pull a 8,000lb trailer with a 300 hp civic. Its not gonna happen. Hook that same trailer up to a 250 hp diesel pickup. Why can the truck tow the trailer and not the civic. Well it probably due to the civic's low torque and the truck's very high torque.
#10
Quote:Originally posted by XiaoMing
oh my fuckign god, i'm talking to you about torque from the standpoint of getting an A and provin my teacher wrong after my physics 4A class, and ur using QUOTES U FOUND IN A WEB SITE to tell me torque is not acceleration?
goddamnit its angular acceleration multiplied by inertia, the tendency of an object to resist movement
the shit u have is force times lever arm, the Force first off, is tangential, and the lever arm is just the distance the force is away from the axis of rotation
not only that, but force is mass times ACCELERATION

and FUCK, aite, so engines dont make max power at redline, they still sure as hell dont make it at 2k rpm
i'm just saying u hafta rev that shit a lot higher to get the horsepower
as for that
that's why cars are rated w/ torque
CUZ NOT ALL CARS START AT 5500 rpm in second gear
torque is considered low end purely because its what gives the car acceleration at the early point of its rpm band for every gear
if you had two cars in same gears in low rpm, and one had more torque, the one w/ more torque would accelerate faster, simple as THAT


oh and the fact that u said i was making the torque shit up, i am gonna flame ur retarded stupidfuck ass silly for calling me a liar, YOU FUCKING RETARDED SILLY ASSED STUPIDFUCK, learn ur physics before u tell me i'm wrong okay? ;[ torque is defined in many ways, just like ignorance, of which you are one of those definitions (no, i do not mean ur a definition for torque)

XiaoMing: I don't mean to be pedantic here, but you're being sloppy about mixing formulas and definitions. First, torque is defined as the vector cross-product of a force vector and the vector defining the moment arm. In a free body system, torque induces an angular acceleration that's inversely proportional to the polar moment of intertia, BUT, torque isn't defined in terms of the rotational acceleration it induces. Why not: because torque is well defined in static environments whereas your definition isn't. The proper term here is equals. Similarly, force is not mass times acceleration, namely in static or damped conditions. If we want to talk physics in a rigorous way, fine. But the precision of your statements should match the formality of them.

Lets posit hat a fixed fraction of the engine's horsepower goes into the kinetic energy of the vehicle. The increase in the kinetic energy of the vehicle comes from power out of the engine. The car whose engine is putting more power into the kinetic energy of the vehicle will accelerate faster since kinetic energy is a continuous, monotonically increasing function of velocity. It's as simple as that.

Let's say you had a Deisel engine which puts out 1000 ft lbs of torque and 250 horsepower in car 1. In car 2, you had a F1 engine which puts out 250 ft lbs of torque and 700 HP. The cars are of equal weight. Now I tell you, you can choose any gear ratios you want, presumably to maximize the power transfer to the rear wheels. Which engine would you choose in a drag race, the one with more torque or the one with more power?

If you chose torque over power, you would lose, i.e., the car with the F1 engine would accelerate faster than the car with the Diesel engine. To do so, the car with the F1 engine would have to be geared much lower. And yes, the F1 car would put more torque to the rear wheels. If a fixed fraction of the engines torque or power is getting to the rear wheels, if one car's engine consistently puts out more HP than another's, it will accelerate more quickly regardless of the torques of the engines.

Of course, torque and horsepower are related. But if you are at liberty to optimize your choice of gear ratios, horsepower is what wins drag races.
#11
and as i said before, in order to get that power, you'd have to have ur engine revving very high all the time, and have a very phat gearbox
which cars don't
for every gear, your car has to start revving from low rpms to high
and when ur in the low rpms, you need torque to accelerate
don't give me any shit about gearing a high rpm high horsepower engine to get more torque, all i'm saying is at LOW RPMS, you need torque, even the f1 engine starts somewhere Tongue
#12
Quote:Originally posted by XiaoMing
and as i said before, in order to get that power, you'd have to have ur engine revving very high all the time, and have a very phat gearbox
which cars don't
for every gear, your car has to start revving from low rpms to high
and when ur in the low rpms, you need torque to accelerate
don't give me any shit about gearing a high rpm high horsepower engine to get more torque, all i'm saying is at LOW RPMS, you need torque, even the f1 engine starts somewhere Tongue

Not true either. There are some transmissions out there that have a very wide range of gear ratios, namely the T-56. The gear ratios on one version are:

T56 = [2.97 1.94 1.35 1.00 0.84 0.62];

With 4:11 gears in the rear end and a 2.97:1 1st, you leave the line with a 12.2:1 ratio, which will launch hard. The final drive ratio in top gear is 2.54:1 which is quite fuel efficient, spinning a modest 2400 RPMs at 70 MPH on a 25" tire. Hell, you could run 4.56's in the rear end and still have great cruise performance. I understand your argument to be that initially, both cars will have to go through the low RPM range and this will materially change things. It won't. You go through the low RPM range once in a drag race, in your lowest gear, and very quickly. After that, you keep the RPMs up.

The bottom line is this, given enough HP, you can gear to get the acceleration you want. Properly geared, a high HP car will accelerate quickly. Transmissions exist to take advantage of high RPM engines. And a car's engine can put out a lot of torque (down low) and still accelerate poorly.


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