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I have a 2000 dakota 4.7l and i'm looking for some more low end power from idle to about 2500 rpm what's better torque or horsepower
 
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Horsepower = Torque x rpm / 5252 so if rpm is constant only way to increase power is to increase torque, doesn't make any difference if you are concerned with 1000 rpm or 6000 rpm.
 

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Making more power in the range you want is difficult. Sheesh, the motor doesn't start to make real power until 2000 rpm's plus. It doesn't get a chance to make usable torque just off idle because it hasn't "spooled" (for lack of a better term) up yet. Why do you want more hp/torque in that power range anyway?
 

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They've got it right... Torque is a direct realation to Horsepower... visa versa.

What you should do... is just get the most power out of the motor... then and only then will you get what you are specifically looking for...

Paul
 

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dgc333 said:
Horsepower = Torque x rpm / 5252 so if rpm is constant only way to increase power is to increase torque, doesn't make any difference if you are concerned with 1000 rpm or 6000 rpm.
i dunno dude... i was watching C&D 2-3 weekends ago and they had some import that had 200hp but only like 150or 180ft.lbs. i thought that was really odd....
 

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Evilsizer said:
i dunno dude... i was watching C&D 2-3 weekends ago and they had some import that had 200hp but only like 150or 180ft.lbs. i thought that was really odd....
Yeah stoock hondas pull 120-130 hp, and not enough torque to properlytighten our lug nuts.
 
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Evilsizer said:
i dunno dude... i was watching C&D 2-3 weekends ago and they had some import that had 200hp but only like 150or 180ft.lbs. i thought that was really odd....
Horspower is a straight mathematical calculation related to torque and rpm as I stated above. It is what it is and isn't open for debate. If you put your car/engine on a dyno the only thing the dyno measures is torque and rpm, horsepower is calculated from the formula above.

So what's you issue with an import making 200HP and a relatively low peak torque?

The horsepower peak and torque almost never occur at the same rpm. You didn't state the rpm's that the HP and torque were generated at. But, if you assume that the 180 ft-lbs of torque was being made when the 200HP was being made that had to be happening at 5835 rpm's. If the torque was 150 at the point of 200HP then the rpm's had to be 7002.

If torque is constant then horsepower will continuely increase with rpm until you reach the mechaincal limits of the engine and it blows up. If torque decreases at the same rate as rpm increases then the horsepower will stay constant. If the torque decreases faster than rpm increases then horsepower will decrease. The ideal situation for a car engine is to create max torque right off idle and have it saty constant to the mechanical limits of the engine.

All of this was set in motion way back in the late 1700's when James Watt defined 1 horsepower as lifting 33,000 lbs in one minute so he could compare the work his steam engines could do to a horse. After that it's all just math.
 

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If torque were the whole answer to our prayers, we would all be driving diesels. I usually think of it like this - Torque gets you moving quickly and horsepower gets you there quicker.
 

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The torque v horsepower debate aside; about the only way to make solid lowend power with a 4.7 is to supercharge / turbocharge it.
 

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oO_Rogue_Oo said:
The torque v horsepower debate aside; about the only way to make solid lowend power with a 4.7 is to supercharge / turbocharge it.
You could move the power band down (speed) with 4.10 gears. Forced induction, especially turbocharging doesn't take care of low end until you get the rpm's up there.
 

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N56629 said:
You could move the power band down (speed) with 4.10 gears. Forced induction, especially turbocharging doesn't take care of low end until you get the rpm's up there.
Well I disagree, you can tune a turbo to produce full boost at any RPM you choose, though a SC's power will be more linear you can still tune for lowend. As far as 4.10's go thats an increase in mechanical advantage, not power. His power STILL wouldn't come in till 2500 RPM's he would just be doing that 2500 RPM's at a much lower speed (and yes I know YOU know this but he may not).

I stand by my original statement, if you want any REAL increase in lowend power in a 4.7 you need forced induction.
 

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oO_Rogue_Oo said:
Well I disagree, you can tune a turbo to produce full boost at any RPM you choose, though a SC's power will be more linear you can still tune for lowend.
Hmmm, full boost at idle? I suppose it's possible, but that would depend on what you mean by "full boost."

I put "speed" in perenthses to indicate that more torque would be realized at a lower speed. I didn't think anything I said would indicate an increase in torque.
 

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dgc333 said:
Horspower is a straight mathematical calculation related to torque and rpm as I stated above. It is what it is and isn't open for debate. If you put your car/engine on a dyno the only thing the dyno measures is torque and rpm, horsepower is calculated from the formula above.

So what's you issue with an import making 200HP and a relatively low peak torque?

The horsepower peak and torque almost never occur at the same rpm. You didn't state the rpm's that the HP and torque were generated at. But, if you assume that the 180 ft-lbs of torque was being made when the 200HP was being made that had to be happening at 5835 rpm's. If the torque was 150 at the point of 200HP then the rpm's had to be 7002.

If torque is constant then horsepower will continuely increase with rpm until you reach the mechaincal limits of the engine and it blows up. If torque decreases at the same rate as rpm increases then the horsepower will stay constant. If the torque decreases faster than rpm increases then horsepower will decrease. The ideal situation for a car engine is to create max torque right off idle and have it saty constant to the mechanical limits of the engine.

All of this was set in motion way back in the late 1700's when James Watt defined 1 horsepower as lifting 33,000 lbs in one minute so he could compare the work his steam engines could do to a horse. After that it's all just math.
im not tring to say anyone is wrong but i find it quite odd that imports make more HP then Tor. C&D never said at what rpm on the show. I normally read Mopar muscel where they show the different HP made at such rpms and tor. and mostly they make more TOr. then HP. I found it quite odd that I saw a import with more HP then tor. that is all.
 

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Evilsizer said:
im not tring to say anyone is wrong but i find it quite odd that imports make more HP then Tor. C&D never said at what rpm on the show. I normally read Mopar muscel where they show the different HP made at such rpms and tor. and mostly they make more TOr. then HP. I found it quite odd that I saw a import with more HP then tor. that is all.
I think you are failing to grasp the whole picture. I don't know of any Mopar that makes more horsepower than torque(numerically). I think that's what you are referring to, numerical numbers. The reason torque can fall off and horsepower continue to climb is because rpm continues to increase. Remember, horsepower is a function of both torque and rpm. Horsepower will increase no matter whether you increase rpm's or torque.

Small engines can reach high hp numbers, even though they have low torque, because they do it at the expense of high rpm's. As you can see, your comment that "imports make more HP then Tor" makes no sense. It is just the way they were designed to make that horsepower, namely by being capable of high rpm.
 

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Evilsizer said:
im not tring to say anyone is wrong but i find it quite odd that imports make more HP then Tor. C&D never said at what rpm on the show. I normally read Mopar muscel where they show the different HP made at such rpms and tor. and mostly they make more TOr. then HP. I found it quite odd that I saw a import with more HP then tor. that is all.
You will find that most (and I say most) engines that have a longer stroke than than bore diameter will have produce more torque than horsepower when compared the same motor with the opposite configuration. For the most part, the "throw" distance of the crank influences torque. That is why import motors produce more h/p the tq and why big block, stroked v8's produce more tq than h/p. (generally speaking).
 

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So you want h/p and torque? Here ya go!

The cylinder bore is just under 38" and the stroke is just over 98". Each cylinder displaces 111,143 cubic inches (1820 liters) and produces 7780 horsepower. Total displacement comes out to 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version.

Some facts on the 14 cylinder version:
Total engine weight: 2300 tons (The crankshaft alone weighs 300 tons.)
Length: 89 feet
Height: 44 feet
Maximum power: 108,920 hp at 102 rpm
Maximum torque: 5,608,312 lb/ft at 102rpm

Fuel consumption at maximum power is 0.278 lbs per hp per hour (Brake Specific Fuel Consumption). Fuel consumption at maximum economy is 0.260 lbs/hp/hour. At maximum economy the engine exceeds 50% thermal efficiency. That is, more than 50% of the energy in the fuel in converted to motion.
For comparison, most automotive and small aircraft engines have BSFC figures in the 0.40-0.60 lbs/hp/hr range and 25-30% thermal efficiency range.

Even at it's most efficient power setting, the big 14 consumes 1,660 gallons of heavy fuel oil per hour.


 

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Yes, but that is a measly 42.233 lbs/hp compared to around 17 lbs/hp on a Dakota. What will all that torque get you in the quarter mile?
 
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N56629 said:
If torque were the whole answer to our prayers, we would all be driving diesels. I usually think of it like this - Torque gets you moving quickly and horsepower gets you there quicker.
I have heard that quote before but you are missing the point. You have to perform "WORK" to make something move and work is expressed as ft-lbs (well at least here in the US). Horsepower is just the rate at which work is done. It could be expressed as ft-lbs/hour or ft-lbs/rev or horsepower. They are linked you can't have one without the other.
 

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dgc333 said:
I have heard that quote before but you are missing the point. You have to perform "WORK" to make something move and work is expressed as ft-lbs (well at least here in the US). Horsepower is just the rate at which work is done. It could be expressed as ft-lbs/hour or ft-lbs/rev or horsepower. They are linked you can't have one without the other.
I guess I don't see your point. I seems that you just restated what I've already said. You can get more horsepower without increasing torque by simply increasing rpm. The problem is, it won't get you moving very quickly. Lot's of torque, like in a diesel, will get a heavy truck moving rather quickly, but it won't get you down that quarter mile very fast.
 

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N56629 said:
I think you are failing to grasp the whole picture. I don't know of any Mopar that makes more horsepower than torque(numerically). I think that's what you are referring to, numerical numbers. The reason torque can fall off and horsepower continue to climb is because rpm continues to increase. Remember, horsepower is a function of both torque and rpm. Horsepower will increase no matter whether you increase rpm's or torque.

Small engines can reach high hp numbers, even though they have low torque, because they do it at the expense of high rpm's. As you can see, your comment that "imports make more HP then Tor" makes no sense. It is just the way they were designed to make that horsepower, namely by being capable of high rpm.
no i was using the mopar muscle as comparasion, showing [email protected] and c/d didnt. im still learning about engines, mainly from reading about build ups in mopar muscel.. but if someone know of good reading /links. plz post them for me. sorry if i took this off topic...
 
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