Whats the estimate of how much HP gained per lb. of weight lost?

Question

Roughly how much hp do you gain per lb of weight dropped?

Answer 1

I guess we are talking a race car here..Like a AA fuel type..??? Anyway as far as all that is concerned it takes horsepower to make the weight move...lets say your car has a weight of 1100 lbs and you want 10 sec quarter miles,,,, the accelleration is constant all the way to the end and the horsepower being made is measured at the rear wheels as a unit in ft.pds. of torque...well it takes 1 hp to get 550 pounds to move one foot in one second so it takes 2 hp to get 1100 pounds to move one foot in one second ...if you wanted to move 1100 pounds 10 feet in one second it would take 20 horsepower....now a quarter of a mile is 440x3=1320 feet or 132ft/sec is the average speed (not the acceleration)..so to get 1100 pounds to move 132feet in one second it takes 264 horsepower...this gets the car to top speed and holds it there... divide 1100 by 264 =4.1 pds per horsepower....so with our imaginary car if you throw the cat out you gain the use of another horsepower....That was pretty easy ....now I said all that to say this...Horsepower is a smoke and mirror thing...torque and weight and wind drag ,fuel mixture , timing , gear ratios ,rolling coeficients and even pitch and yaw go into the calculation ..And then if you add catalyzing agents like nitromethane or NO2 you have even more problems with HP CALCS.... just change the flywheel from 10" to 12 " and you add so much inertia to the car that is usable you wouldn't believe it but then at top end you loose power because of the extra power required to keep it spinning...Dual boost turbo and air pumps of all types are great but at what speed do they work?? and of course RPM.... at what rpm do you want this engine working anyway ????...One of the best things a racer can do is get a good friend who has been doing this for awhile and ask lots of questions..why make all the mistakes over again??..get a good program on HP curves and mess with the variables...like carb cfm vs fuel vapor btu content. and fuel inlet vapor pressures...I guess throwing the cat out is one way to make a little horsepower but to really be a constant winner it takes a lot more.......from the E...

Answer 2

Divide the horsepower rating of the engine by the number of pounds that the car weighs.

300 HP/3000 Lbs = 0.1 hp/lb.

Answer 3

It is the ratio of HP to weight that determines acceleration. The significance of a one pound weight change depends on how much weight there is.