siggyfreud

The correct answer is C: Not enough information.

HP, and even torque figures will simply not tell you what car is faster. You can make assumptions, but without knowing the details of the car, you could be wrong.

modru2004

true, to really know how fast a car is the weight, aerodynamics, hp, torque, and gearing all play a major role in it.


for comparison purposes though the best things to look at are the hp torque weight and gearing.


as far as hp vs torque, im not an expert on the subject, so maybe im a bit off on this. but ive always though of it like this.

torque is the strength, the force thats applied to move the car, and hp is the speed at which its done.

for example think of using a a crank and pulley to lift some concrete in a pale.

lets say your strong enough to turn the crank at a set speed with one hand lifting hte pale.

now lets apply both hands at the same speed, the task just became easier right but the pale is still moving up at teh same speed.

the "hp" or speed at which you move the pale is a function of the strength "torque" you have to move it.

now lets increase the speed of the pale(hp) by increasing your speed of rotating the crank (rpm) to lift the pale faster. in order to do this you have to meet the necessary strength requirements in order to increase your speed, and the amount of strength you have determines your max speed you can go at a given rpm.

i could be the fastest man on the planet, but only capable of lifting 200lbs.

now lets take someone capable of lifting 500lbs but slower than me in running the 40 yd dash.

were tasked with taking a 150lb object 40yds fastest man wins. i the "fast" one would lose this because i would be at my strength "torque" limits moving the object.

the strong man would have abundant strength for this feat and therefor be able to apply more speed "hp" to it and complete it faster.

i hope that makes sense.

Norm Peterson

Close.

A slightly better comparison would look something like . . .

[AverageTorque] x [Axle gearing] / [CarWeight]

But since most engines make about the same amount of torque per liter of displacement (about 70 ft-lb/liter, give or take maybe 5), your "first cut" could simply replace the [AverageTorque] with [EngineDisplacement]. Keep in mind that cars with engines that have poorish low end torque but good high -end power tend to be geared a bit "deeper" than cars with engines tuned for better low end performance. It's not by mere coincidence, either.


You can carry the mathematical simulation a long way from there as you start to question how much effect things like aero and rolling drag, wheel/tire/flywheel rotational inertia, and actual torque curve shape might have. There's quite a few more things that aren't too difficult to include if you're so inclined.


Norm

onederful100

you also have to look at the curves on each the torque and HP on the dyno graph.
people tend to look at peak hp/tq, but what is more important is where each hits its peak and the total power delivered over time.
measure the area under each curve to find total power.

the most important statistic is et's.

Burns331

Heres a quick analogy.

Horsepower is how fast you hit the wall. Torque is how far you move the wall after you hit it.

jlc41

After reading all this I think I'll have to do a tear down and rebuild on my brain, what ever is left of it. Good stuff...lol

jz

Once this post is all said and done, if anyone is interested in knowing what came first the chicken or the egg send me a PM. The answer will surprise you.

001mustang

My rice bike great HP to weight ratio.
My 351W has nice low rpm torque.

351W feels strong when punch it from cruising rpm.
Bike has no power when punch it from cruising rpm.

JIM5.0

Neither, the Gecko came first!

LordRipberger

Jim5.0,

This will be off topic, but what is the squirrel of death? lol