Quote:
Originally Posted by saunders1313
I've heard that reducing the weight by 10% will increase the fe by 4-5%, does anyone have any data on this? Also, how much luck has anyone had with actually lowering the weight enough to make a difference. My car is around 3500 pounds so I don't know if I can drop 350 pounds out of it, I might try anyway though.
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Depends on specifics. Assuming optimal engine efficiency over your route, your car is roughly 4088 square inches which is about 2.64 square meters and supposedly has a drag coefficient of .36. At 3700lbs (200lb driver/stuff) curb it's about 16460 newtons, and assuming a typical rolling resistance of .012 needs ~198N to roll. To move through the air at 55mph or 24.6m/s, ya need, about ~352N. So... since you're at ~550N right now, shaving off 300lbs in a 3700lb car would decrease the force needed by ~3400/3700(198N)+352N=~533N, so your mileage would go up by ~550/533=1.03, aka 3%. Now, the problem is this is assuming the engine is operating at otpimal efficiency, and if it's not, which it tends not to be for most cars, then you'll see less than a 3% gain. Naturally as your average speed drops from 55mph, the gain is greater, and as it rise, it's less. On the other side of the spectrum, if you have 14" wheels available (j-yard?), you could run LRR 14" tires (rolling resistance of ~.008), and gain around 13-14% assuming ideal engine efficiency or less w/o it.