# explain foot pounds to me

Discussion in 'The Garage' started by tecton, Apr 3, 2004.

1. ### tecton1/2 ton status

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it makes no sense to me at all

what is a foot pound

2. ### velocitiiiRegistered Member

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ft-lb is a measure of torque or twisting motion.
1 ft-lb is the amount of twist you would have if you had a 12 inch wrench on a bolt and you put a 1 lb weight on the very end of the wrench.

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the amount of torque applied by that many pounds on a lever one foot long, or one pound on a lever that many feet long, or any combination thereof.

So for 100 ft-lbs, you could put 10# on a 10 foot lever, or 100# on a 1' lever, or 1# on a 100' lever, which in theory should all apply the same torque.

This is why if you can't yank off a lug nut, say, you get a cheater pipe, which gets you a longer lever for you to jump and down on.

The scientific types will jump in and give you more details, but I think that's the basic idea.

And is it foot pounds or pound feet? I always get it wrong.

-- A

4. ### sandawgk53/4 ton status

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I have always had it explained as the amount of energy to move 1 pound 1 foot straight up i.e. lbs-ft. That is how you can calculate horsepower based solely on a torque number.

5. ### tecton1/2 ton status

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that explains alot

so lets say my truck makes 300lb ft or tourque...my truck puts 300lbs of force on the end of the hypothetical 12inch wrench?

that cant be right

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Well, the engine might do 300 lb/ft at the flywheel -- if it's a big one, or a diesel -- but then the gear reductions of the tranny, transfercase and diffs increase that.

So my stock 350 which puts out something like 250 lb/ft goes through the TH350 low gear which is what, ~3:1 and then the NP203 in low gear is 2:1 and my diffs are 3.73:1... so net is somehting like 5600lb/ft applied to the wheels. If I were flooring the poor girl in low/low in an ideal world of no loss, slippage, etc etc.

This is why you can snap axle shafts /forums/images/graemlins/laugh.gif

-- A

7. ### Paxx1/2 ton status

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[ QUOTE ]
This is why you can snap axle shafts /forums/images/graemlins/laugh.gif

[/ QUOTE ]

This just cracked me up when I read it /forums/images/graemlins/rotfl.gif

I think it was the smiley that did it lol /forums/images/graemlins/histerical.gif

8. ### Highjaxx1/2 ton status

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/forums/images/graemlins/laugh.gif

Nice

9. ### mike reeh1/2 ton status

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I think everyone pretty much covered it. An interesting tidbit- if you ever look at a torque/hp curve chart, they should always be equal (torque and horsepower) at 5252 rpm.

mike

10. ### duece211/2 ton status

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New cat they are puttin in freightliners and kenworths

How bout them foot pounds. For a truck engine at least, twin turbo. So now when they break people can pay \$3,200 for new turbo's instead of 1,000.

Cylinders In-Line 6
Bore/Stroke 5.4 x 6.75 (137mm x 171mm)
Displacement 15.2 L (928 cu in)
Weight 2890 lb (1311 kg)
Horsepower 435 to 550 @ 2100 rpm
Torque 1350-1850 lb0ft @ 1200 rpm

All for more power &amp; Higher emissions standards /forums/images/graemlins/rolleyes.gif

11. ### 84gmcjimmy1 ton status

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12. ### Highjaxx1/2 ton status

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I drive a truck with 500HP and about 1500ft/lbs /forums/images/graemlins/laugh.gif

Coming out of a Detroit 60 Series turbo, with a 3 level engine brake.

Really makes me want to buy turbo diesel pick-up.

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