MitchAlsup

There are three different arenas where weight and HP can be traded off.

A) dead stop to (say) 60 MPH. This is the traction limited case (for a Z06). There is essentially no amount of HP that can make spinning tires spin faster and gain time in 0-60. Here, weight is pure king. Also note: tires that are more heavily loaded have reduced traction per unit weight.

B) power limited acceleration. This is the power limited domain from about 60-140 MPH and the arena where there is some correspondence between weight and HP that is fairly linear.

C) speed limited. This is the aerodynamic drag limited case. Here, as long as the weight is not adding drag to the vehicle, top speed remains the same (however, it might take a few more seconds to achieve top speed.)

0GHL Exhaust

I think it's 7lbs for every 1 hp.

LEAVINU

They should have at least left the intake and exhaust on so there were no "engine mods" but we all know a car like that won't gain much but still gains something. Either way 500lbs off any car will make it move pretty damn good.

PRE-Z06

Aero and gearing of course have to be taken into account also when comparing 2 different vehicles. The rule of thumb 10hp=100lbs=.1 is somewhat accurate in the realm of 13 sec vehicles, it doesn't apply in the 10sec arena

40YRW8

Comparing a Mustang to a Corvette in terms of power to weight will never work due to an endless number of variables. As far as trying to pin down exactly how much weight will equal a certain power gain is a little easier but also no clear answers. The best thing you can do is add power until you are done with engine mods then start reducing the weight as far as you can reasonably go and live with the results. The weight reductions, though small and expensive give you a performance edge not only in accelleration but also in lateral grip and stopping power. They also don't use any gas and give you those benefits every time you move your car for ever at no further cost. The bottom line should be, "Who cares! Just do it!"
Gary

NORTY

Sure, for every 20 lbs of weight, it takes 1 add'l viagra. I'm just guessing here since you didn't state for what purpose...

Halltech

So that's why my 2950 lb Z06 with 700 HP goes sideways in second gear at half throttle. 4.13lbs/hp. Now every 4.13lbs of weight savings equals 1 HP, but I'll have to recalculate often, since it is a moving target.

Believe it. Power to weight ratio is everything in racing. Now imagine our stopping power, with the Carbon Ceramic ZR1 brakes with 375 less pounds to stop than the ZR1. I weight 169. If I was a fatty, I would likely not be on this power/weight kick. I would just add Nitrous.

Jim

novaz06

i remember reading a article in hot rod maybe twenty years ago where they took a stock dodge polara I think, which was body on frame, and removed the entire car except for the rolling frame and engine, and it ran I believe in the 12s

naradz06

except traction is a function of normal force, related by coeff of friction. So unless you have spikes on your tires, you'll need some weight.

40YRW8

Not quite true. If you move weight to the rear, you will in fact pick up more accelleration. However, just adding weight might not. With a rubber tire, if you double the weight on the tire, you don't quite get double the traction. That is why it works to tune a chassis by changing the tire loading. The most traction comes with the minimum amount of weight on a tire, not the most.
Gary

naradz06

*yawn*....ya, I was just tryin to be a smarta$$ because you can't reduce the vehicle's weight ad finem.

But I completely understand your rather over simplifed view of some complicated stuff. Oh, and you get the most traction when your wheels slip a little too...

sadunbar

QUOTE=Painrace;1577705748]I used to race against a guy named Jerry Dunbar. Jerry was faster than the thunders of hell, but, Jerry weighed more than double what I did. The cars were weighed without driver so the cars had to weigh about the same (2,450# to 2,600# depending on engine displacement and type of transmission). Jerry was a great qualifier but all you had to do was keep up with him and toward the end of the race Jerry's tires would start to give up because of the extra weight. Weight matters a lot in road racing. You don't see many fat pro racers. Take a look at the Corvette guys, Ron fellows, Andy Pilgrim, etc. The more weight you can shed the faster you will go. It is simple physics.

Jim[/QUOTE]

You mean this guy?

Greywolfe

99% of the posters on this thread are

'Not smarter than a 3rd grader'

juanvaldez

http://www.stealth316.com/2-calc-hp-et-mph.htm

Quarter mile times are primarily a function of weight and horsepower.

On the Corvettes 6 - 7 lbs = 1 hp.

The only reason Danika Patrick is a driver is because she weighs 100 lbs and she is good looking. I think the Indy guy got smart and made the weight rules car + driver.

Vette @ 71

Interesting calculators

http://measurespeed.com/

juanvaldez

Interesting. For 1/4 mile, 3,000 lb/500 hp 10.6, 3,100 hp/500 hp 10.7.

Vette @ 71

With perfect shifting, driving and traction ..

hyteck9

juanvaldez

The calculator is a little optimistic giving 10.8 for 3,200/505 hp . . . say a Z06. Maybe half a second.

hyteck9

It is all relative. Obviously if you add 500 lbs to a motorcycle you have a world of challenges ahead of you to make up for it.

If the weight you are adding is only 10-20% of the vehicle weight, the 10/.1/100 rule is a great place to start planning.