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How is it that sometimes cars have 170hp and 130tq or 200hp and 220tq? How do the numbers get so far apart sometimes? Also, if tq is what makes you go then what is hp for?
 

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hp is for top end and the reason why sometimes the numbers are so far apart is the difference in the tuning from the factory(hopefully someone can go more in depth with this eyem not 100% on the details)
 

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If you understand electricity, it can be a good anology,,, horsepower is like voltage, and torque is like amps. torque is the work part, and horsepower carries the torque. There are a lot of variables that cause torque and horsepower to be what they are. such as fuel. diesels have increadible torque with lower horsepower ratings. like big rigs. 350 hp, but 1800 ft lbs of torque.
 

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I assume you are talking about Honda engines. Well the relationship between tq and hp could take a whole semester to explain. But I'll give you the basics. If you go look up the definition of hp you will find a formula that involves the amount of tq. It's tq x RPM divided by 5252 I believe. Torque is what makes the car go, torque is the amount of force applied around an axis, eg. the driveshaft. Horsepower is just another way of measureing torque. Go drive your car and you will notice that after ~4500rpm the amount of acceleration begins to fall, that's because you have passed the torque peek. But it still keeps accelerating because the engine is turning alot of revs(horsepower). So lets take the 1999-2002 Civic Si. It makes 160hp at 7600rpm (I think) but only 111 lb of tq, don't remember at what revs. When it is spinning at 7600 rpm it is producing very little torque but it is doing it very quickly due to the high revs. The only way you can keep the tq numbers and the hp numbers the same is by producing alot of torque through out the rev range, for example- Corvette's, base and Z06 and pretty much any Forced induction car tuned properly. So I hope this helps.
 

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Think of torque as the fat man in the bar with scars and tattoos (not that there is anything wrong with that). Hp as the athlete.
The fat guy hits you once, and knocks you through the wall. Big work.
The athlete hits you once and knocks you down, then proceeds to pulverize you for the next thirty seconds. Lots of work.
They both did the same thing, just differently. The end result is the same.
Seriously, like focus said, torque is a measurement of force and hp is a measurement of work. Also since hp is a mathmatical function of torque, the curves will ALWAYS cross at 5252 rpm. And, the torque will always be greater below 5252, and the hp greater above 5252. Use the above formula and plug in theoretical numbers for fun. Any results to the contrary are dyno error or a product of rounding numbers. And if you look, if there is a difference, the spread will be within the margin of error for the dyno.
Good explanation focus. Very thorough.
 

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A good example of oldschool's work theory is a diesel engine. A cummins truck motor makes 400 to 565 Hp at 2000 RPM. It makes 1450 to 1850 ft. lbs of torque respectively at 1200 RPM! Do the math with the formula above and it comes out right on the money (even though the HP and torque curves will never cross at 5252 RPM).
 

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The formula is also good to see if tuner cars are advertising inflated numbers but didn't have enough sense to make sure it calculate's right.
 

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Geezer,
I'm really not one to argue, but you should plug some numbers in. HP is a mathematical function of torque and rpm. They have to cross at 5252. I can distinctly remeber reading the Hot Rod article on this very topic when I was about 12.
 

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I agree with you completely. What I was trying to explain, and didn't do well, was just that, the equation (mathimatics) works even if the motor in question, physically cannot acheive 5252 RPM.
 

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Sorry about that. I had the same conversation w/my dad this morning. You old guys just love to pick this stuff apart.[thumb] [:D]
 

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Oh yeah, you wanted to know why they are sometimes so far apart? The turbo 2.3 that Ford ran in the SCCA Cougar made 600hp and only 300ft/lb of torque. Incidentally Ford claimed that the stock crank and block were good for the power, but for durability in the longer races they produced the SVO pieces. Just a useless piece of trivia.
 

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oldschool said:
Think of torque as the fat man in the bar with scars and tattoos (not that there is anything wrong with that). Hp as the athlete.
The fat guy hits you once, and knocks you through the wall. Big work.
The athlete hits you once and knocks you down, then proceeds to pulverize you for the next thirty seconds. Lots of work.
They both did the same thing, just differently. The end result is the same.

Great analogy, I got a bit of a chuckle outta that one.
 

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nice engima...when I want to read a novel I'll check that out ;) looks good though...damn its long :)
 
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