Question about Weight to power ratio

I am making a word document with various cars from many different makers from 06/07 depending on the most recent versions. In it I list the basic engine type such as I4, V8 etc, Horsepower, and of course, the weight to power ratio (WPR).


My question is say that I have a car with 190 horsepower and a 10.21 WPR and a car with 350 Horsepower and a WPR of 12.1.

Going by WPR alone one would guess that the first car would win in a race, but since the horsepower is so greatly in favor of the 2nd car, wouldnt the 2nd car still pull ahead?

I guess I am asking how can I take into consideration the Horsepower when looking at WPRs.

Also, how can I play torque into this? It would be neat to make a formula to accuratly estimate who theoretically would win.

Moved to correct forum...

Now you may discuss... ;)

There are many factors deciding which car will win, gearing, FWD vs. RWD, etc., etc. But generally speaking with cars that are setup fairly similarly, the better weight/hp ratio will win. Take the C6 Z06 and '06 Viper for instance. Both have 500hp, but the Z06 weighs over 300lbs less than the Viper, which is why the Z runs mid-low 11's and the Viper runs mid-high 11's. The Viper even has more torque, but can't make up for the weight disadvantage. Now the new '08 Viper has 600hp and looks to be running about the same times as the Z06 (C&D got 11.5@126 out of the Viper and 11.6@125 out of the Z06).

So if two cars are the same in all aspects other than weight and power, with a weight to power that is equal, they would in theory tie in a drag style race.
I would guess that the lighter car with less HP would eventually lose ground on the more powerful but heavier car once the heavier car got up a few gears.

Do these look accurate?
I got the weights and horsepowers from howitsworks consumer guide.


2006 Acura RSX I4 201 Horsepower, 13.60 WPR
2007 Acura TL V6 286 Horsepower, 12.66 WPR

2007 Cadillac STS V6 254 Horsepower, 15.18 WPR
2007 Cadillac STS V8 320 Horsepower, 11.83 WPR
2007 Cadillac STS V8SC 469 Horsepower, 8.22 WPR

2007 Dodge Charger DOHC V6 190 Horsepower, 20.10 WPR
2007 Dodge Charger SOHC V6 250 Horsepower, 15.28 WPR
2007 Dodge Charger V8 425 Horsepower, 8.98 WPR
2006 Dodge Viper V10 510 Horsepower, 6.72 WPR

2007 Ferrari 612 Scaglietti V12 532 Horsepower, 7.62 WPR

Power to weight ratio is only one aspect of racing. You need to take into account aerodynamics, power curve, torque curve, gearing, drive train, and power to weight in order to be able to even start to guess who might win.

So if two cars are the same in all aspects other than weight and power, with a weight to power that is equal, they would in theory tie in a drag style race.

You just said they are exactly equal, just used more words. In theory yes they would tie.



Do these look accurate?
I got the weights and horsepowers from howitsworks consumer guide.

Accurate how? Does your WPR all add up? I don't feel like using a calculator right now :wink: If you mean do the numbers compare to them beating a higher numbered car then yes it looks accurate except for the tl vs sts. If its 286hp then you are referring to the A-Spec TL, which I've seen slips for low 14's. The sts clocked in at 14.6 at 97 with car and driver, so its not an exact science. :2cents:

You just said they are exactly equal, just used more words. In theory yes they would tie.





Accurate how? Does your WPR all add up? I don't feel like using a calculator right now :wink: If you mean do the numbers compare to them beating a higher numbered car then yes it looks accurate except for the tl vs sts. If its 286hp then you are referring to the A-Spec TL, which I've seen slips for low 14's. The sts clocked in at 14.6 at 97 with car and driver, so its not an exact science. :2cents:

Yea thats what I meant. The math is quite simple :licka:
I sorted them lowest to highest as well.

2007 Chevy Corvette V8 505 Horsepower, 6.31 WPR
2006 Ford GT V8SC 550 Horsepower, 6.33 WPR
2006 Dodge Viper V10 510 Horsepower, 6.72 WPR
2007 Ford Mustang V8SC 500 Horsepower, 6.85 WPR
2007 Ferrari 612 Scaglietti V12 532 Horsepower, 7.62 WPR
2007 Cadillac STS V8SC 469 Horsepower, 8.22 WPR
2007 Cadillac XLR V8SC 443 Horsepower, 8.23 WPR
2007 Jaguar XK Series V8 420 Horsepower, 8.48 WPR
2007 Dodge Charger V8 425 Horsepower, 8.98 WPR
2007 Cadillac CTS V8 400 Horsepower, 9.23 WPR
2006 Pontiac GTO V8 400 Horsepower, 9.31 WPR
2007 Jaguar S Type V8SC 400 Horsepower, 9.40 WPR
2007 Jaguar XJ Series V8SC 400 Horsepower, 9.44 WPR
2007 Lexus LS V8ELEC 438 Horsepower, 9.88 WPR
2007 Subaru Impreza H4TC 293 Horsepower, 10.38 WPR
2007 Ford Mustang V8 319 Horsepower, 10.73 WPR
2008 Infiniti G V6 330 Horsepower, 10.77 WPR
2007 Mazda 3 I4TC 263 Horsepower, 10.85 WPR
2007 Lexus G5 V6ELEC 339 Horsepower, 10.92 WPR
2007 Solstice I4TC 260 Horsepower, 11.00 WPR
2007 Chevy Monte Carlo V8 303 Horsepower, 11.06 WPR
2007 Lexus IS V6 306 Horsepower, 11.29 WPR
2007 Nissan Altima V6 270 Horsepower, 11.31 WPR
2007 Cadillac XLR V8 320 Horsepower, 11.39 WPR
2007 Lexus LS V8 380 Horsepower, 11.39 WPR
2007 Infiniti G35 V6 306 Horsepower, 11.44 WPR
2007 Pontiac Grand Prix V8 303 Horsepower, 11.47 WPR
2006 Nissan 350z V6 300 Horsepower, 11.53 WPR
2007 Mazda 6 I4TC 270 Horsepower, 11.64 WPR
2006 Chevy SSR V8 400 Horsepower, 11.75 WPR
2007 Infiniti M V8 325 Horsepower, 11.79 WPR
2007 Cadillac STS V8 320 Horsepower, 11.83 WPR
2007 Honda S2000 I4 237 Horsepower, 12.04 WPR
2007 Honda Accord V6ELEC 253 Horsepower, 12.22 WPR
2007 Lexus G5 V6 303 Horsepower, 12.22 WPR
2007 Jaguar S Type V8 300 Horsepower, 12.53 WPR
2007 Jaguar XJ Series V8 300 Horsepower, 12.59 WPR
2007 Acura TL V6 286 Horsepower, 12.66 WPR
2007 Honda Accord V6 244 Horsepower, 12.67 WPR
2007 Lexus G5 V8 290 Horsepower, 12.77 WPR
2007 Mitsubishi Eclipse V6 263 Horsepower, 12.77 WPR
2007 Lexus ES350 V6 272 Horsepower, 13.16 WPR
2007 Honda Civic I4 197 Horsepower, 13.25 WPR
2007 Lexus SC430 V8 288 Horsepower, 13.33 WPR
2007 Pontiac Grand Prix V6SC 260 Horsepower, 13.37 WPR
2007 Chevy Cobalt I4SC 205 Horsepower, 13.42 WPR
2007 Infiniti FX V8 320 Horsepower, 13.57 WPR
2006 Acura RSX I4 201 Horsepower, 13.60 WPR
2007 Infiniti M V6 275 Horsepower, 13.93 WPR
2008 Ford Taurus V6 260 Horsepower, 14.01 WPR
2008 Mercury Sable V6 260 Horsepower, 14.01 WPR
2007 Ford Fusion V6 221 Horsepower, 14.03 WPR
2007 Nissan Maxima V6 255 Horsepower, 14.03 WPR
2007 Pontiac G6 DOHCV6 252 Horsepower, 14.13 WPR
2007 Nissan Sentra I4 200 Horsepower, 14.26 WPR
2008 Dodge Avenger SOHC V6 235 Horsepower, 14.27 WPR
2007 Cadillac CTS V6 255 Horsepower, 14.48 WPR
2007 Mazda 6 V6 212 Horsepower, 14.83 WPR
2007 Pontiac G6 OHCV6 240 Horsepower, 14.69 WPR
2007 Cadillac STS V6 254 Horsepower, 15.18 WPR
2007 Dodge Charger SOHC V6 250 Horsepower, 15.28 WPR
2007 Nissan Altima I4ELEC 198 Horsepower, 15.42 WPR
2007 Infiniti FX V6 280 Horsepower, 15.51 WPR
2007 Acura TSX I4 205 Horsepower, 15.88 WPR
2007 Chevy Monte Carlo V6 211 Horsepower, 15.89 WPR
2007 Chevy Cobalt I4 173 Horsepower, 15.92 WPR
2007 Jaguar X Type V6 227 Horsepower, 15.99 WPR
2007 Jaguar S Type V6 235 Horsepower, 16.00 WPR
2007 Solstice I4 177 Horsepower, 16.15 WPR
2007 Ford Mustang V6 210 Horsepower, 16.30 WPR
1999 Ford Taurus DOHCV6 200 Horsepower, 16.63 WPR
2007 Pontiac Grand Prix V6 200 Horsepower, 17.38 WPR
2007 Nissan Altima I4 174 Horsepower, 17.45 WPR
2007 Subaru Impreza H4 173 Horsepower, 17.59 WPR
2008 Dodge Avenger DOHC V6 190 Horsepower, 17.65 WPR
2007 Ford 500 V6 203 Horsepower, 17.97 WPR
2007 Mazda 3 I4 156 Horsepower, 18.30 WPR
2007 Honda Accord I4 166 Horsepower, 18.62 WPR
2007 Ford Fusion I4 160 Horsepower, 19.38 WPR
2008 Dodge Avenger I4 172 Horsepower, 19.50 WPR
2007 Dodge Charger DOHC V6 190 Horsepower, 20.10 WPR
2007 Mazda 6 I4 156 Horsepower, 20.16 WPR
2007 Mitsubishi Eclipse I4 162 Horsepower, 20.74 WPR
2007 Pontiac G6 I4 167 Horsepower, 21.11 WPR

Just took a bunch of random cars to see where my car stood.
Not so good, as you can see the 99 car near the end of the list :grinno:

You also have to take into account that some manufacturers over or underestimate their cars.

ex. Cobras. The 99 cobra was often not dynoing at 320hp, it was making less.
The 03 cobra was making more then the advertised 390.

You also have to take into account that some manufacturers over or underestimate their cars.

ex. Cobras. The 99 cobra was often not dynoing at 320hp, it was making less.
The 03 cobra was making more then the advertised 390.
Yea thats true.

Would you say that this chart would atleast give a general clue to some one 2 days into their life in the world of automobiles? Such as myself? :grinyes:

I suppose the list is accurate but you have to take it with a grain of salt not all of those numbers are correct and just because car X has a better W/P ratio does not mean the car will be faster. When you race a car you have to look at the total package no one thing is more important than any other.

There is no exact science to predicting a race. For one, nothing is ever equal. You can throw an awesome driver in a low 14 second car and a pissant driver in a higher 13 second car...more than likely the 14 is gonna win. Power to weight is only one factor of many. You can't depend on power to weight alone to figure out a car's performance.

Exactly, there are too many factors to think about.

Crunching numbers and bench racing only go so far, at some point you gotta get your ass out on the asphault and get at it.

You also have to take into account the aerodynamics of the car... You could put a 1000+hp in almost any car, but if its not aerodynamic it wont do much good. Thats the difference between a 600+hp Skyline and a mclaren f1, the Mclaren will win mainly on accord of its shape etc...

WPR is a good way of estimating performance, but definitely not absolutely conclusive. Its probably even more useful in non-drag racing. In drag racing, lighter cars will generally have a slightly easier time launching, but will generally lose out in the long run to a stronger car. On a track however, a heavier car generally won't be able to corner as quickly as a lighter car, so the weight element of WPR is more important.

A Bugatti Veyron is a monster in a straight line because of its monstrous amount of power, but on a road course the Pagani Zonda F, Koenigsegg CCX, or possibly even an Enzo will probably win.

just remember horsepower sells cars torque wins races

could you try doing a WPR with torque instead of HP?

You also have to take into account the aerodynamics of the car... You could put a 1000+hp in almost any car, but if its not aerodynamic it wont do much good. Thats the difference between a 600+hp Skyline and a mclaren f1, the Mclaren will win mainly on accord of its shape etc...

Aerodynamics are for people who can't build engines
-Enzo Ferrari

just remember horsepower sells cars torque wins races

could you try doing a WPR with torque instead of HP?


Ya sure, ill post it when ever I finish it.

just remember horsepower sells cars torque wins races

could you try doing a WPR with torque instead of HP?


...

Kawasaki ZX-14: 102 lbft of torque
Dodge Viper SRT-10: 535lbft

Who do you think is going to win?

Torque may win races, but it is a function of Horsepower. With no horsepower, you have no torque. So again, it has nothing to do with just one factor.

okay but massive weight difference there
and no horsepower is torque at speed

Torque=(5252xHP)/5252

So if HP is 0, then Torque = 0/5252, and that is 0. Torque is a function of horsepower.

So again, it takes far more than just any one given number to determine the outcome of any contest of performance.

http://member.rivernet.com.au/btaylor/BMWText/technical/EnginePower.html
heres a dandy article about it( although long probably best to just skim through it)

and your right in that it takes more than one factor to determine performance

I tried to play with the equation and put torque into it. I got some interesting numbers and posted them here. Heres a link. Take a look at it.

http://www.automotiveforums.com/vbulletin/t700356.html

Torque=(5252xHP)/5252

So if HP is 0, then Torque = 0/5252, and that is 0. Torque is a function of horsepower.

So again, it takes far more than just any one given number to determine the outcome of any contest of performance.
that can't be right. multiplying something then dividing it by the same number doesn't do anything.

to find the power at a given rpm you take the tq times the rpm you're looking to find power at, then divide that by 5252. for example my car makes 220 lbs of wtq at 2,000 rpm so 220x2000/5252=83.777 whp at 2,000 rpm. to find torque you multiply hp at a specific rpm x 5252 and divide that by the rpm you found hp at to see what the torque is.

you're right though the two are directly related. look at any dyno the hp and tq always cross at exactly 5252 rpm.

Torque=(5252xHP)/5252

So if HP is 0, then Torque = 0/5252, and that is 0. Torque is a function of horsepower.

So again, it takes far more than just any one given number to determine the outcome of any contest of performance.

Um... you're almost right.. but slightly off bro!

This is how you get Torque:

T = 5252 x HP

rpm




And Horsepower:



HP = rpm x T(torque)
5252(constant)

Meh, close enough. I was never good at memorize equations.

Ha, I had to google it to make sure I was right.