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Weight vs HP?

Old 02-14-09, 08:19 PM
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Weight vs HP?

How much weight must you lose to overcome HP? Say one car has 200hp and the other has 400hp. How much lighter would the other car have to be to make up the Difference? I'm sure this has been asked before. Sorry if so.
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Old 02-14-09, 09:22 PM
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It depends on a lot of things, such as suspension, tire size, drag, etc.

For instance you have 2 identical cars, but one has half the hp and half the weight, the heavier car will have a faster top speed and faster acceleration at speed because it'll have the same drag as the lighter car, but more power to overcome it. The lighter car will have better grip than the heavier car, so it'll handle better.

Within reason, a bigger, heavier, more powerful car will be faster than a light, less powerful car on a race track given appropriately sized wheels and tires. Corvettes are faster than Miatas (even turbo ones) because they've got more power, not a heck of a lot more drag and they can fit massive tires.
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Old 02-14-09, 09:59 PM
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There has to be a point where being light would make a difference in acceleration, stopping distance and would be equal to or better than the car with more Hp in speed. How much would it take?
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Old 02-15-09, 12:20 AM
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I already told you, it depends. You seem to be looking for a simple answer to a complex problem, but there is none. It depends on many, many, many different variables, I listed only a few of probably a hundred different significant variables. On a shorter, tighter, more technical track the lighter weight will be a greater advantage than on a longer, faster track where hp/drag will be more of an advantage than on the other track. So even taking all the car variables out of the equation the answer is still that it depends.

All else being equal, lighter is better, but all else is almost never equal. HP/weight tells only a very small part of the story as far as speed potential goes.
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Old 02-16-09, 04:29 PM
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Originally Posted by Mid_KnightFD View Post
There has to be a point where being light would make a difference in acceleration, stopping distance and would be equal to or better than the car with more Hp in speed. How much would it take?
if you're talking just drag racing, its all about power to weight. although its probably not 100% linear. for instance a 200hp/2000lbs car would probably slightly still beat a 400hp/4000lbs car even though they both have the same power to weight ratio.

if you include cornering the answer gets really complex, power doesnt matter at all. in a corner, its all about how the driver uses the car/suspension to manipulate the contact patch. in odd cases adding weight can actually HELP cornering. the suspension/tire/driver interaction is really complex.
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Old 02-16-09, 08:41 PM
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Originally Posted by j9fd3s View Post
if you're talking just drag racing, its all about power to weight. although its probably not 100% linear. for instance a 200hp/2000lbs car would probably slightly still beat a 400hp/4000lbs car even though they both have the same power to weight ratio.
No, it's not only about power to weight, that only really affects LOW SPEED acceleration, assuming you have sufficient traction. For HIGH SPEED acceleration, power to drag is the important factor, this is where the heavier, more powerful car will likely be a lot better than the lighter, less powerful car.

THERE IS NO SIMPLE ANSWER, EVEN FOR DRAG RACING!!!
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Old 02-19-09, 04:27 PM
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I agree completely with Black91n/a
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Old 02-19-09, 05:44 PM
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the less a car weighs the less force its gonna take to move it so if u have a 2000 lbs car wit 200 hp compared to a 4000lbs 400 hp car in a perfect world they will both cross the 1/4 at the same time
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Old 02-19-09, 08:52 PM
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Originally Posted by trakshuhn View Post
the less a car weighs the less force its gonna take to move it so if u have a 2000 lbs car wit 200 hp compared to a 4000lbs 400 hp car in a perfect world they will both cross the 1/4 at the same time
You don't get it do you? HP/weight affects acceleration predominantly at LOW speeds. As the speed increases, so does the drag, which is what gives many cars their top speed, and that is why the car accelerates less and less enthusiastically as you go faster. If those two cars had the same drag, the heavier, more powerful one would be faster in a drag race.

That said, lighter is ALWAYS better, all else being equal, but all else is NEVER equal.
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