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  #1 (permalink)  
Old 11-15-2008, 09:11 AM
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Question Horsepower To Weight

ME AND MY FRIEND R ARGUING THAT A 550 HP (fe)COBRA WILL KEEP UP WITH HIS O8'(650HP)ACR VIPER.I TOLD HIM THAT A 500-600LB. DIFF. IS HUGE. WHAT IS THE GENERAL RULE FOR HP LOSS DUE TO WEIGHT????
THE RACE WOULD ONLY GO TO AROUND 125 OR SO.
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Old 11-15-2008, 09:23 AM
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A lot has to do with tires and suspension. The heavier car may stick to the track better. The lighter car can have all the horse power in the world, but if it can't get the tires to hook up its useless.

Put the Viper next to the Cobra and see who draws the crowd!
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Old 11-15-2008, 09:27 AM
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Craig- The weight difference should be a lot more than 500-600 lbs. It should be closer to 1000 lbs difference since Vipers weigh in at around 3400 lbs.

Where Vipers, Vettes, etc....usually get Cobra's is off the starting line. This is mostly due to their superior tires (I think Vipers have sticky, low profile 345's on the back). We Cobra guys have to keep from spinning our tires too much when taking off. In my experience, I usually end up overtaking them by the time I'm thru 2nd gear.

Stick some BFG drag radials, or some sticky AVONS on the back, and you will be good to go!

Last edited by TerrysSPF; 11-15-2008 at 09:30 AM..
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Old 11-15-2008, 09:33 AM
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The New Acr's Come W/a Track Tire.they Make You Sign Something That Says U Will Not Drive Car In The Rain!!!!!i Usually Would Race From A Roll On.your Rite About Which Car Would Get More Att. And Def. Sound Better. A Viper Sounds Like A Johndeer W/ Bad Exhaust.
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Old 11-15-2008, 09:38 AM
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2 years ago, I was given the oppurtunity to drive a hennessey viper, i think venom 650. No comparison to my cobra. Viper was actually disappointing. My cobra was so much more explosive, "out-of-control" type acceleration than the viper.
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Old 11-15-2008, 09:40 AM
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but there is a general ratio,rite??
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Old 11-15-2008, 09:47 AM
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Weight has no effect on horsepower
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Old 11-15-2008, 09:54 AM
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then why a 4000lb. car is not as fast as 3000lb car w/ same engine?????
or r you gettin all engineer on me?
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Old 11-15-2008, 10:08 AM
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Quote:
Originally Posted by sparks View Post
then why a 4000lb. car is not as fast as 3000lb car w/ same engine?????
or r you gettin all engineer on me?
He is correct, that weight has no relationship to HP.

It does however take more HP to move a heavier car at the same rate of acceleration as a lighter car.
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Old 11-15-2008, 10:17 AM
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OK,that being said!how much more hp would it take to move a 3k lb. car vs a 4k lb car??
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Old 11-15-2008, 10:23 AM
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If the Viper weighed 3500 and the Cobra weighed 2500, it would take 40% more power in the Viper for it to have the same power to weight ratio (and acceleration, all else equal, which it's not) as the Cobra. If your friend has a 550 HP Cobra, the Viper would have to have 770 HP to have the same potential for acceleration (assuming no wheelspin and similar traction).
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Old 11-15-2008, 10:29 AM
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not to mention he drinks alot of bud lite and he is about 50lbs. hev. than me!
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Old 11-15-2008, 10:39 AM
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Weight has EVERYTHING to do with comparing speed vs. horsepower. To compare, you divide the cars' weight into it's hp. So, your Cobra's power is 4.73 per # and it doesn't matter what kind of engine you have, and your buddy's Viper is 5.23 per #. So I wouldn't race him, he'll eat you up. I've been told that 13#'s equals 1hp.
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Old 11-15-2008, 10:54 AM
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Tim,
It's 4.73 lbs per horsepower for the Cobra. 5.23 lbs. per horsepower for the Viper.

The Cobra has the advantage.
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Old 11-15-2008, 10:56 AM
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A minor correction, weight has a lot to do with acceleration vs. horsepower, not speed vs horsepower.
If the Cobra has 4.73 lbs/HP, it will out accelerate the Viper with 5.23 lbs/HP. Lower lbs/HP is better in this case.
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