Roscco

Just been wondering about power to weight.

Would a car weighing 2 tonnes with 400bhp be faster than a car weighing 1 tonne with 200bhp?

Assuming torque is also proportional.

I'm confused.

Ryan

they would be the same

Lambchop

iTrader: (1)

The bmw would win

Matt_16v

Surely there's lots of other factors to consider other than just power and torque though? Aerodynamics, gearing, FWD or RWD, do you mean acceleration or top end, etc etc.

joffy

iTrader: (1)

if you went purely by power and weight and everything else was identical then yes,

Lambchop

iTrader: (1)

what if one was a turbo?

or the other was a 5litre v10?

Luca

iTrader: (2)

Also depends whos driving

Roscco

cheers

joffy

iTrader: (1)

doesnt matter what engine, if the power was delivered in the same way and only the weight and the power changed then it would be the same, f=ma

force is 200=(mass)1000x(acceleration)0.2

and

400=2000x0.2

both the same acceleration, but ONLY if everything else is identical

Alps Pacino

i have always been under the impression that the lighter car will be on par upto say a tonne then more power always seems to be quicker at the higher speeds. Very general summery but you get what i mean

Benni

Me too.

foreigneRS

indeed

too generalised. would work if the vehicles were driving in a vacuum.

something like that. at low speeds, you are only accelerating the weight of the vehicle whilst aerodynamic resistance is minimal. as speed increases, the drag increases (both wind and tyre, bearings etc) and you need a certain amount of power just to maintain the speed that the vehicle is travelling at, leaving less to accelerate.

it requires something like 80 bhp to achieve about 100 mph, so the vehicle with 200 bhp has 120 bhp left to continue accelerating the 1000 kg mass with, but the 400 bhp vehicle has 320 bhp to accelerate 2000 kg (you do the maths, but 320 is clearly more than 2x 120)

Alps Pacino

Thats exactly what i was trying to say lol

joffy

iTrader: (1)

vacum wouldnt matter aslong as they were identical, i assume your talkin about drag co efficents etc but as i stated aslong as everything else was identical i wouldnt matter if they were on the moon they would accelerate at the same speed

Lambchop

iTrader: (1)

nah if it's turbo'd it has to be quicker surely?

the one with the most horsepower has to win. isn't it obvious?

joffy

iTrader: (1)

the only thing that makes a difference in reality is stripes, loud stereos and halfords spoilers

Lambchop

iTrader: (1)

funny you say that!

my mate with a fiesta st has white stripes and he says his car is quicker than his mates identical car that has blue stripes.

i'd have white stripes for sure just in case.

joffy

iTrader: (1)

white has less coulour pigment in it so its lighter and faster,

Alps Pacino

Is he being serious ? i think a pimp slap is in order

Lambchop

iTrader: (1)

read all my posts on this thread and report back your answer soldier