theory: for every 1kg of weight reduced = the equivalent of 1 hp of extra power in acceleration. question: will a 300hp "car" have the same accelleration as a 100kg reduced "car" of equal original weight at 200hp? (this theory does not take into account variables like traction or how the cars get the hp) Comments please -
would it be so linear? ie, would a 1000kg car losing 1kg have the same affect as a 2000kg car losing 1kg I'm sure there would be a long winded formula to have this work. Also. What of the torque? A car thats 100kg heavier might have twice the torque (thanks to turbos etc ), its acceleration will be different. I guess it also depends on the weight distrubution, aerodynamics, traction etc. Or do you just mean, will I for example gain 160hp (abouts), if I drove along without a passenger seat, spare wheel, sub + box, no passenger and drive on light load of fuel saving around 160kgs (again would that work if my car was 1000kgs to start off with instead of 1500kgs or 2000kgs.
Drag racing rule of thumb is every 100 pounds removed is worth a tenth on the quartermile... This is based on an average weight of 1400-1500Kg and engine power of 200-250 horses, (so say 7Kg p/hp). Try to get your hands on a Moroso horsepower calculator or try this online tool...
No Power to weight ratio removes other factors, in particular aerodynamic drag, rolling resistance and so on. Since these things get worse at higher speeds, a lower powered car (but lighter) will not be able to keep up with a higher powered (but heavier) car the faster it goes even if they have the same power to weight ratio. This is why cars with low power but really light (e,g, Lotus Elise) will make it to 100kph in good time, but 100 - 200kph, for example, will be hopeless compared to a high powered, heavy car. Ben
Power to Weight If we assume a 300zx weighs around 1500kg and has around 200KW then thats 7.5kgs per KW. If you had 300KW then thats 5kgs/KW. So in a standard 300zx loosing 7.5kg of weight would be equivalent to gaining one KW.
You're almost right as you said it relates to power/weight ratio so once the weight is reduced the ratio changes since the power output of the car remains to the same. For example lets say you removed the first 7.5kg for the equivalent of 1kw gain the next 7.5kg's will be equivalent to a little more than 1kw and each subsequent reduction will be equivalent to more power gained than the previous reduction. Once the cars weight reaches half it's original weight (750kg) removing 7.5kg will be equivalent to 2kw of power gain. This is theoretical of course and doesn't take in account factors such as the non linier power/torque output of an engine, drag, etc.
