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Re: Holiday Topic - Horsepower Vs. Torque
Posted: Thu Dec 31, 2009 7:53 am
by Els
You really smart types here (David, Geezer, Olaf, etc) know all the formulas about how hp and torque are really the same thing
(huh?) with the numeric values calculated but I'm a bit fuzzy there. I know there is a mathematical equation that calculates this with them equalling the same value at or near a certain point. Confused?....I am.
That being said, I think I want the torque as it ultimately equals HP. SOMEONE WHO KNOWS THEIR ASS FROM THEIR ELBOW ON THIS....JUMP IN!
Elliiot
Re: Holiday Topic - Horsepower Vs. Torque
Posted: Thu Dec 31, 2009 10:14 am
by Elvis
fireice;
there is no hp per se.
only tq
horsepower is a derivative. simplistically said - hp is tq x rpms (divided by unit modifier for nm or ft/lb).
said that - the ability of an engine to maintain tq throughout the rev range is represented best with hp values. that is why hp is provided.
two extreme scenarios:
1. big motor, big heavy internals, low red line - lots of tq down low, low hp due to low redline (remember- hp = tq x rpms). such motor pulls very well at low rpms, has tall gearing to accommodate the low redline and runs out of grunt at high speeds due to said tall gearing
2. small motor, small parts, high red line - not much tq, but whatever it has is carried well into the higher rpm range thus making good hp (again- remember- hp = tq x rpms.. ). such motor does not pull necessary very well at low speeds, but is geared short (can be afforded due to high redline) and pulls very well at high speeds.
two practical examples based on above scenarios
a tractor-trailer is usually an inline 6, is about 10 liters, has 3500 rpms redline and makes 350hp, but 1000+ lb of tq. many gears, but highway gears are tall and roll on acceleration is non-existent.
an f1 engine is 3 liter v8, has 18000-19000 rpms redline and makes 200 lb of tq but manages to maintain it up to 18000 rpms thus making 800hp or so. 8 dense short gears allow excellent torque multiplication over a very wide range of speeds.
generally speaking, hp is preferred for racing as it can be geared short in a light vehicle, tq is preferred for the street as speeds are low and street vehicles are heavy.
hope this helps... there is much more on the subject, but this is the 10k feet overview...
alex
Re: Holiday Topic - Horsepower Vs. Torque
Posted: Thu Dec 31, 2009 1:45 pm
by Ric
I'd like to add something to Elvis's ideas of the Torque vs HP.....
It's a known fact that Budweiser is a better beer than all the other brands you guys drink.
Re: Holiday Topic - Horsepower Vs. Torque
Posted: Sun Jan 10, 2010 12:03 am
by test 2
Re: Holiday Topic - Horsepower Vs. Torque
Posted: Sun Jan 10, 2010 12:24 am
by Geezer
Crazy stuff:
Same thing happen to me in 1964 with a 401 hp 390 Ford.
Clutch came apart at 6000 rpm and took the back of the block
and bell housing bolt flanges..........oh shit................ just missed
my foot by inches.
Not so great memories
PS- Floor board, fire-wall, fender and radiator were toast.........I was a lucky
kid at that time..........
Geez
Re: Holiday Topic - Horsepower Vs. Torque
Posted: Thu Jan 14, 2010 9:09 am
by Toastie
Understanding HP and/or torque is easy by definition.
However, the determining factor will always be measured at either the flywheel or the driving wheels.
A good suggestion would be to measure both.
In this way, one would know how much of the HP or torque is truly getting to the wheels.
There is a parasite between the 2. The dreadful transmission. For years, the efficiency of it has been worked on to improve it.
Without doubt, a less powerful engine could put more down with a good tranny than a more powerful one with a terrible tranny.