Weight

[Redline686]

How much does weight affect performance? It seems that if just one of my friends (200 pounds) gets in the car, it's much slower...feels like a loss of 10-15 horsepower. And with a full car (~500 pounds) it feels like a normal ION QC. Is this normal?

[clownhair]

Originally Posted by Redline686

How much does weight affect performance? It seems that if just one of my friends (200 pounds) gets in the car, it's much slower...feels like a loss of 10-15 horsepower. And with a full car (~500 pounds) it feels like a normal ION QC. Is this normal?

at the drag strip I was running .5 seconds slower from having my brother in the car with me.

[WopOnTour]

Originally Posted by clownhair

at the drag strip I was running .5 seconds slower from having my brother in the car with me.

Yikes, fallowing the old rule of thumb (100lb=0.1) your bro better lay off the Big Macs!!
j/k of course (shouldnt talk I'm quite the lard ass myself! So I need mucho carbon fibre to offset, then if I drop a few lbs... )

[clownhair]

--double post---

[clownhair]

Originally Posted by WopOnTour

Yikes, fallowing the old rule of thumb (100lb=0.1) your bro better lay off the Big Macs!!
j/k of course (shouldnt talk I'm quite the lard ass myself! So I need mucho carbon fibre to offset, then if I drop a few lbs... )

heh he weighs 200 lbs I guess the rule isn't quite spot on as it was quite consistent.

[Get_Sum]

maybe you didnt throw best of gears that run with your brother in the car. its very difficult to do back to back identical runs. . .

[ender]

I thought it was 10lbs per hp but my kenne bell book is lost in a file so I am not for sure....so if I lost 30lbs I'd be healty and faster.

[CarNut]

If we assume constant acceleration, the old physics formulas f=ma and x=1/2at^2 (distance traveled from standing start) will give a good estimate. Rearranging to eliminate acceleration you get t = sqrt(2xm/f). Ignoring the effect of weight on friction, the force applied at the tires should be constant. Quarter mile times should change in proportional to the square root of the weight change. If your passenger weighs 200 lb and you normally run 14.5 then you should run 14.5 x sqrt(~3200/3000) or about 14.97. So .5 sec for a beefy passenger is about right. Add 500 extra pounds and your high 15s / low 16s. But the .1 sec per 100 lbs rule would be about right for cars twice as fast.

[clownhair]

Originally Posted by Get_Sum

maybe you didnt throw best of gears that run with your brother in the car. its very difficult to do back to back identical runs. . .

not if your good, I am extremely consistent when drag racing.

[Redline686]

Originally Posted by CarNut

If we assume constant acceleration, the old physics formulas f=ma and x=1/2at^2 (distance traveled from standing start) will give a good estimate. Rearranging to eliminate acceleration you get t = sqrt(2xm/f). Ignoring the effect of weight on friction, the force applied at the tires should be constant. Quarter mile times should change in proportional to the square root of the weight change. If your passenger weighs 200 lb and you normally run 14.5 then you should run 14.5 x sqrt(~3200/3000) or about 14.97. So .5 sec for a beefy passenger is about right. Add 500 extra pounds and your high 15s / low 16s. But the .1 sec per 100 lbs rule would be about right for cars twice as fast or 1/2 as heavy.

you know...i was thinking that same thing no but i was trying to think of a formula but after a minute i realized that it was summer and that i shouldn't have to worry about math for at least another month