MINI2 - MINI Forum - View Single Post - Reduce Unsprung weight = Increased Horsepower?

pocketrocketowner · Jan 24th, 2005, 03:37 PM

Quote: Originally Posted by lwlam

I need a little help with theory, please.

I understand that a reduction in unsprung weight (specifically I am thinking about wheels and tires) will result in an increase in a car's acceleration by reducing the amount of mass that the engine has to turn. The car becomes faster without any true gain in torque.

Is there a practical mathematical formula to derive the equivalent gain in torque/ horsepower from a reduction in unsrpung weight? For example, if I can reduce unsprung weight from each corner of the car by 8lbs (total reduction of 32lbs), how much more "power" would that feel like?

I am hoping that is some rule of thumb out there that someone would care to share. Otherwise, I think this could be figured through examining the delta in acceleration times for a car before and after the weight reduction. A pretty standard rule is that a 10hp gain will reduce your 1320ft time by .1sec. If a car can reduce its 1/4mi time by X seconds after the unsprung weight reduction, then we could say that the equivalent horsepower gain from the weight reduction is equal to X times 100.

Is there a better way?

Thanks

Answer to question # 1: NO
Answer to question # 2: NO
Answer to question # 3: Yes, but I'd have to kill you if I told you......

Jan 24th, 2005, 03:37 PM	#8
pocketrocketowner Best Personal Regards Join Date: Dec 2004 Location: Ile de Vaux, France Local Time: 08:04 AM Posts: 2,023 Offline	Quote: Originally Posted by lwlam I need a little help with theory, please. I understand that a reduction in unsprung weight (specifically I am thinking about wheels and tires) will result in an increase in a car's acceleration by reducing the amount of mass that the engine has to turn. The car becomes faster without any true gain in torque. Is there a practical mathematical formula to derive the equivalent gain in torque/ horsepower from a reduction in unsrpung weight? For example, if I can reduce unsprung weight from each corner of the car by 8lbs (total reduction of 32lbs), how much more "power" would that feel like? I am hoping that is some rule of thumb out there that someone would care to share. Otherwise, I think this could be figured through examining the delta in acceleration times for a car before and after the weight reduction. A pretty standard rule is that a 10hp gain will reduce your 1320ft time by .1sec. If a car can reduce its 1/4mi time by X seconds after the unsprung weight reduction, then we could say that the equivalent horsepower gain from the weight reduction is equal to X times 100. Is there a better way? Thanks Answer to question # 1: NO Answer to question # 2: NO Answer to question # 3: Yes, but I'd have to kill you if I told you......