in term of acceleration....
ever since I replaced my tires...which made me gain about at least 5lb on the wheel....I can feel that my car does not accelerate as fast...I can feel it so bad!!......

it is like when I put 3 passenger in my car....
humm....
light wheel with good traction = acceleration friendly

good for straight line fun?
thank you.

 

static weight, 1 pound of rotational weight=5-7 pounds of static weight.

 

effects on acceleration is to think of it in terms of a loss of engine torque. If you add 1 lb more to the wheel right at the wheel/tire interface of say a 16" wheel, that's (16/12)ft*(1)lb = 1.33 ft-lbs of torque that acts AGAINST the engine. Since you have two drive wheels, that'd be a 2.66 ft-lb loss of torque total for 1 lb heavier wheels. Your 5 lb heavier (each) wheels would result in a 13.3 ft-lbs loss of torque in this scenario. That's a loss of 13.3 from, what, 180 ftlbs at the wheels or something like that? (180-13.3)/1800=0.926 You now only have 92.6% as much torque at the wheels as before. If you did 0-60 in 6.8 sec before, know you'll do it in roughly 6.8/0.926 = 7.3 sec. That's a BIG loss.

One thing this quick and dirty calculation doesn't consider is the effect of larger diameter wheels (going from 16" to 17", for example), in which case you can assume the torque losses will be 17/16=1.06 times that of the weight increase alone...or, if you don't want to have any loss, the 17"ers will need to weigh W/1.06 (where W is the weight of the 16"ers), i.e. a little less (lb or two) than the 16"ers.\

Make sense?

 

It's not THAT simple...too bad...hehehe

 

1 pound of unsprung weight (wheel) is equal to 9 pounds sprung (suspended) weight. This doesn't take into consideration rotating mass of the wheel (smaller or larger), just wheel weight.

 

so how much slower will my max be with 300 pounds of gear added in my trunk?

 

A lot. Its like having two friends with you all the time.

 

The addition of 300lbs on a relatively small engine really takes a toll. A Z28 or Mustang won't be as affected because of their huge torque. Be glad you don't drive a Honda because you would be a LOT slower. Adding 300lbs to your Max will probably drop you overall 1/4 mile time by .7 seconds and take about 2-3mph off your trap speed. So if your car is running 15.2@92 without the stereo, you're now in high 15s barely 90mph. I'm glad I'm not a stereo guy like I was back in high school (before I knew how much slower it makes your car). Having a good stereo and trying to have a sporty car is a oxymoron.

I'm all about keeping my ride as light as possible without getting rediculous (ie driving without a spare or jack, stripping the interior).


Dave