This is a good question for Psuedo, a guy on another forum I visit was saying his buddy just got a new subby 2.5 RS and he was taking things off and out to cut down on weight. He said he was gaining 2lbs of torque per every pound of weight he lost, is this possible ?

 

Not really true. Your power to weight ratio will be much greater, which in turn translates to better perofrmance, but you're not increasing torque or hosepower in any way.

For example, if you were able to shave say 500lbs off the car, you'd get this:

130hp : 2800lbs = 1hp : 21lbs <--- Stock

130hp : 2300lbs = 1hp : 18lbs <--- With 500lbs removed

As you can see, your engine will only have to move 18 pounds per horse than 21. Thus, you get a performance increase. I hope that made sense.

 

I'm not sure on the formula... Is mine even close to correct?

 

less weight = more power? --> TRUE..why?, becuase you get more work done (distance) faster
less weight = more torque? -->FALSE..why?, you have not changed the performance in the engine, the engine will pull with the same force, given its rpm on any given gear.

What makes a car accelerate faster??? -->torque
but what wins 1/4 miles???? -->horse"power"

so, torque is what I like, to feel the pushback...

please correct me if im wrong...

 

Look at it this way....think of yourself are pulling a sled loaded with bricks. Then take half of the bricks away. You can now pull it faster. Unless you've gotten stronger, you have not gained power, you're applying the same amount of force to a smaller load. Crude analogy, I know.

Exactly.

 

from what i know...its LIKE gaining a couple of HP, but you don't really gain any HP

its like hmmm

stock....same amount of power...pushing more weight
reduced weight.... same amount of power...pushing less weight


so if you have the same amount of power applied to less weight....you basically get more acceleration....but nothing gained in the torque or HP area....just less weight for your wheels to push while moving

 

the only way you'd REALLY gain power (or atleast at the wheels) is if you take weight off the pulleys/flywheel/camshaft... cuz then you'd reduce the energy required to turn those things and hence by the conservation of energy more would be left in the end... another way to think of it for you physics ppl out there, is if you reduce your second moment of inertia (your "I") then it takes much less force to accelerate an object rotationally...

 

okay, so in any case, NOOOOOOOOOOOOOOOOO

your friend is NOT right, you can't increase the torque by reducing weight. What everyone in this thread said is right

power to weight ratio will be better since you're affecting the 'weight' part of that relation...

 

Like I said, it's all about power to weight ratio. If your car has a better power to weight ratio than another, yours would win in a straight line race. Simple as that. (Provided the drivers were of same ability and conditions are both identical.)

 

generally 100lb = 0.1 seconds off of your 1/4

so take of 1000lb, shave a second.

 

So, a stock P5 runs about 17 seconds. It's a 2800lb car. Shave away everything, and you're still left with 14.2 seconds - without a car the damn thing is still slow! LOL!

 

It's like this. (don't you hate it when I say that)

Weight has nothing to do with power. Weight vs. power = performance.

An engine of a given displacement, stroke and compression ratio, etc. has a gross torque output. This can only be measured by torque. (lbs. of force on a lever) Horsepower is calculated by torque, hence horsepower = torque at 5250 rpm.
Then the gross torque is used to turn the alternator, A/C, powersteering, oil pump, camshafts, transmission, etc. resulting in NET torque which is used to move the vehicle weight. Reduce the weight to NET greater performance from your available torque.

Before you argue with this, read Auto Math available from a performance shop near you. It details the formula for deriving horsepower form torque as well as lots of neat little pictures like those you see in a highschool physics book.


Right Psuedo?

 

scotty's pretty much nailed it right on!

which is why shaving a pound from your flywheel or pulleys (or any other component that taps into the available torque) will make a MUCH greater difference than say shaving a pound by not eating McD's for lunch before ya get in!!!

 

Less weight=more power??!!!

 

i think this is what people are saying:

according to newton's second law of physics (i believe it's the second, someone correct me if i am wrong), F=ma. what that means is the amount of force is equal to mass times acceleration. your engine pulls your car with a constant force. this is what your engine is rated as (as for our proteges, it's 130 hp and 135 lbs/ft. torque.)

so if we keep the force constant by not modifying the engine, but lighten the car (reducing the mass), then the acceleration will increase. it will make your car accelerate faster. it does not change the force rating on your engine.

hope this helped.