Horsepower To Weight

[Silverback51]

Sure glad some of you guys are not engineers.

[TerrysSPF]

Silver-I may not be an engineer, but I did stay at a Holiday Inn Express once!

Alright..............let's look at it this way:

If we take the Vipers figures (3400 lbs w/ 650hp), divide the hp into the weight, we get the 5.23 figure. If this figure equals HP, then (as pointed out above by Anthony) the Viper would have 18,000hp - which it doesn't.
Let's say that the Viper only has 550hp instead of 650hp. Take 3400 and divide it by 550 and we now get 6.18 (a higher number than the 5.23 when dividing by 650).
Using Tim's method/logic (that the figure equals HP), and that the higher figure equals the faster car, that would mean that the 550hp Viper would be faster than the 650hp Viper.

Using MY method/logic (that the figure equals weight), it would mean that the lower HP car (550hp) would be SLOWER because it now has to push more weight = 6.18lbs for ever HP it produces instead of the 5.23lbs that the stronger (650hp) car has to push.

[RICK LAKE]

sparks Forget the 600HP. It's about torque.... This is what moves the car. My cobra is 2705 lbs without a 200+ me inside it. 368 HP and 448ft of torque. With pilot tires of the 335/35 17 size my car runs a 12.59 at 110 mph. The motor is all done at 5,700 rpm. It's built for torque not HP. The viper makes a ton of torque down low in the rpm range. It also has traction control. The Viper cut through the air alot better than the cobra. To the best of my knowledge at Run&Gun not cobra has run on just motor a 9.99 second run. We have a 9.86 at 138 mph with a blue bottle and 3.07 gears. Cobra has a shorter wheel base than the Viper. The weight if transfered will only hurt it by .3-.5 in a 1/4 mile. A Viper should have a higher mph than the flying barn door. If both cars have the same torque and HP numbers, the viper should edge out the cobra in the lights. You have a big opening in the front of a cobra and a windshield than acts like a sail at high speeds. Remove the windshield the cobra would win. Rick L.

[TerrysSPF]

Rick- Your explaination was more confusing than all of the others here, put together!

-Now I'm confused!

[sparks]

Even Barac no that viper aint got no traction contro!!!!!!!!!!!!!!

[RICK LAKE]

TerrysSPF COME ON Terry, If this is about the new viper, it beat the cobra. The older viper looses. If both cars are even in HP and torque, I would hope for a cobra to win by a bumper. Rick

[sparks]

Yeah TERRY, whats the matter w/you?

[Silverback51]

Originally Posted by TerrysSPF

Silver-I may not be an engineer, but I did stay at a Holiday Inn Express once!

Hey, that's where I got my degree.

[sparks]

the cobra wins because its a cobra!the end

[TerrysSPF]

Rick- If both cars were equal in HP and TQ, then the Cobra would spank the Viper because of the huge weight savings it has over the Viper.
-But that isn't the case here..........which is why/how we got into the math in the first place!

[eschaider]

I think you have to take the number of whacks you used to tighten the spinners on the left side of the car only multiply it by the square root of the age of the driver divide by engine displacement add 2 for wind drag subtract the wattage of the head lights unless they are HID units in which case you have to factor in the spring rate for the pressure plate.

In short order the answer will be self evident.

By the way, for each 100 lbs of weight, the general rule of thumb is you should add or subtract (depending on heavier or lighter) 0.1 seconds from the quarter mile time all other things being equal (which they are not).

Wow! I'm even more confused. More beer and fresh horses ...

Ed

[Anthony]

Here's a youtube of a cobra vs a GTS. Cobra wins. 11,000 hp beats 18,000 hp.

http://www.youtube.com/watch?v=GJPwxLZGzlM

[Tim Brewer]

OK, ALRIGHT, I know were not talking about thousands of hp here. I admit I didn't mean 4.73 hp per pound, (I based it on 2600 pounds). But somehow I think you guys get what I'm trying to say here. But I can tell you that Viper will spank the Cobra. Come on now, doesn't someone here know how to figure this out?

[Silverback51]

Well this has been fun to watch, but I guess we better straighted it out.

I'm just pulling the numbers out of my butt, however you will understand the concept.

Viper

3600 pounds with 600 HP. 3600/600 = 6 pounds per HP


Cobra

2500 pounds with 500 HP. 2500/500 = 5 pounds per HP


What this means is that the every HP for the Viper has to move/accelerate 6 pounds of mass. For the Cobra it only has to move/accelerate 5 pounds of mass.

If all other things are equal, the Cobra would win. However there are a lot of other variables that could affect the outcome.

[nevermind65]

Personally, I doubt the hp figures are even going to matter in this case. Traction, gearing, and torque are the big factors especially since we are only talking about going to 125. Beyond that number, horsepower and wind resistance start to take over.

Anybody ever watch that Bugatti Veyron video on how much hp it takes to get to 253 mph?

[TerrysSPF]

And probably the BIGGEST variable in the outcome would be the DRIVERS of the two vehicles.
It doesn't matter how much power your car has if you don't know how to use it properly. This simply comes from practice / experience behind the wheel of your car.
If you go out with either one of the cars in question (Viper or Cobra) and simply dump the clutch and hope for the best, you're most likely going to lose.

Geto to know your car. -Practice makes perfect (plus it's FUN)!

[Jerry Clayton]

BIG VARIBLE----how many of them HORSES are PONIES?????

[greg schroeder]

Originally Posted by sparks

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.

Here's my opinion.

I've seen quite a few cars of guys I know from assorted Ferrari including Enzo, Assorted Porsche including Carrara GTs and GT2, Ford GTs, Vipers, Supras, assorted Lamborghini including LP640, Mercedes including SLR and SL65 AMG, Vipers, Corvettes and such stock to having assorted mods like NO2 and turbos run in street races and at the strip. There are quite a few variables, but not much will beat a good higher wheel HP Cobra on drag radials from a low speed punch through 3rd gear. At higher speeds over 100 - 115 mph the Cobra starts to show the lower HP and huge wind drag.

You really need to know wheel HP of the Cobra. A 400 wheel HP FE should pull ahead of a new stock ACR Viper from a low speed roll. Most the 550 engine HP FEs aren't making over 400 at the wheels though. Both the cars are probably good for mid to high 11s in the 1/4 on an average day with out having drag radials.

The 475 wheel HP Superformance with a small block that I recently sold would beat the ACR Viper 1st gear to half way through 4th gear(125 mph) without question.

[eschaider]

OK guys here is a simulation that assumes both cars are driven correctly, no cross eyed drivers, no stupid driving mistakes just two cars correctly operated and measured through a qtr mile. I'll let you look at the specs in the individual pics but they are publicly availably from various sources mfgr/internet etc.

Bottom Line is more HP/Lb always wins. The Cobra has 0.213HP/# while the Viper is only 0.171HP/#. The Cobra has 25% more HP for each # of car it has to accelerate and it is lighter! The outcome of the match up is pre-ordained. The Viper is no match for the Cobra! The only way the Viper can win is if the Cobra driver is a wus or doesn't know what he is doing.

Absolute power is not as important as HP/#. In fact it can be a detriment when the vehicle is heavier. Light cars can run just as big a tire as heavy cars. The difference is they are lighter, launch harder and do not have as many traction problems as heavier cars.

Here are the simulations:

First the Cobra



Then the Viper



The Cobra spanks the Viper by almost a second through the quarter and 4MPH despite a worse coefficient of drag and a larger frontal area! By the way a one second difference in ET is like watching two different races that's how bad it is.

If you really have 550 HP in your Cobra, know how to drive it and have the stuff to drive it, there are precious few cars that can keep up with you. Even fewer can outperform you!

Ed

<Begin Edit>p.s. This fictitious Cobra is probably very similar to Greg's Schroeder's car in the post just before mine.<End Edit>

[Ant]

There isnt a lot of cars even today that can beat a good Cobra, but if you have the money or have been vetted by Ferrari, then this little limited car called the FXX (860bhp) will make any Cobra look very very slow on race circuit,

http://www.youtube.com/watch?v=nfF1Fzx8tmA

But I still like my Cobra, because it is simpler and I can build and repair it!