HP to Weight Ratio?

[John R-]

For those who don't know, divide the cars weight by the cars crank horsepower. This is how many pounds 1 horsepower is in charge of moving. The smaller the ratio, technically the faster the car is.

Does AWD effect this? Reason I ask is because I was doing some numbers crunching & noticed that some AWD vehicles don't have a very good ratio on paper but in real life fare very well?

For example...
Stock C5 Vette 3250lbs/ 350hp= 9.2:1 ratio
16G AWD DSM 3250lbs/ 320hp=10.1:1 ratio

Despite the slight advantage to the Vette, we know that this isn't much of a race in real life? I guess traction is everything?

[V8SpankR]

I'm a few tenths quicker than a stock ZO6 and with my 18g at only 17psi I know I don't have over 400hp like the Vette but I do weigh over 100lbs less but I know it's traction that is winning my races. Just look at the traps,I'm at 101 while the Z06 is over 106mph.

[Dallas J]

HP is all good and dandy...A good way to see if your mod is doing you good, and something that should stay constant in all gears(with the exeption of something like spool time in different gears).

But if you really wanna find out you would have to go into the real power (torque) to weight ratio. And to do that you would have to individualise each gears ratio.

The Vette does what in 1st gear? like 45, Ours does about 30. So the vette would have to have about 50% more torque to keep up with us to 30mph. Then we get to about 60 in 2nd...and we would have to have more torque to match his acceleration...

To figure out exact accelerations would be so much of a hastle..Just hit the track and get real numbers:p

BTW, this all makes sense in my head :D
-Dallas J

[v413nc3]

Power to weight ratio is exactly that, and nothing more. A point or two doesn't make all that much difference when you can throw in other factors... but take a look at this, your power to weight ratio on my bike is 2.3:1... that gigantic power to weight ration difference allows me to propel it to 9 second 1/4 mile times with limited traction, and trust me, it's VERY limited traction.... Taking one factor or annother to try to determine how fast you are isn't going to work, although power to weight ratio does help a great deal... you want to know how fast you'll be, figure all this out

Power vs weight
Traction vs surface
Driver skills

[John R-]

I couldn't agree with you more. It's just one of many different ways to compare vehicles. It's like those who just compare the peak HP numbers of two cars with out seeing a dyno graph? There's alot to be told by the plots on the graph, you just need to know what it is you're looking for. This just one piece of the whole puzzle. I was just trying to get a better understanding of this concept or see if there was anything I was missing?

[v413nc3]

Very good points, on N/A cars you can basically take Power to Weight as a solid acelleration scale. How fast can the car get to speed? Dallas you make a semi-valid point but always remember that torque is indicitive of horse power, and vice versa. With the advent of All Wheel Drive, and forced induction models that introduce lag (turbo charging) we have changed the dynamic in which cars should be measured against each other. Naturally a FWD car with 400bhp with a turbocharger and an AWD with the exact same setup will loose to the AWD (not accounting for drivers, from a stop) because of the fact that AWD's have an advantage of launching the car at a high enough RPM point that Turbo lag is minimalized or almost completely eliminated (in the case of stutter boxes), which you almost surely can NOT do because of lack of traction in a FWD (read Wrong Wheel Drive). I believe that we have actually entered an area of automotive racing where we are comparing apples to oranges even though it's mere hp to wt ratio to hp to wt ratio. It is nice to have club members that actually race so that we can compare numbers that we used to attempt to glean from such numbers as P/W ratio and Torque curves, etc etc etc... these amazing things are 60' times, 1/8th mile, 1/4 mile times, trap speeds, and things that help us understand differences in driving, such as reaction time, trap speed vs known traction characteristics, etc... You've asked a question that has a simple answer that can turn into an iceberg of data...

[John R-]

So basically...run that shit & see what happens:p

[v413nc3]

LMAO!! Basically, yeah. The variation in setups on our cars are so wide that there is nothing left of a measurment but to simply run it. Our power curves are not "linear" so to speak so might as well just go on the old fassioned, lets run 'em...

[hoffman]

i have to go with the theory, half car- half driver.

i've seen kids post up times on other forums with more mods than my car at a way lower elevation (my last and fastest runs were at 4,800 asl) and im still running the same if not slightly faster. of course my traps are always about 3-6mph slower, but i think driver has alot more to so with a cars performance than people give credit to.

[v413nc3]

I fully agree with you there...