mmarshall

No. HP alone does not determine top speed. Many factors do...HP is only one of them.

S8B

This comparison is so odd. First, I usually try comparing RWD with RWD, and AWD with AWD. Its not as simple as 1, 2, 3...etc.

From your choices, I would assume that:

0-60:

1) Evo
2) STi
3)335i
4) IS350
5) Mustang GT
6) Z
7) G35

I would say 3-7 would be a VERY close call. Each of them within a few tenths of each other.

1/4:

1) 335i
2) EVO
3) STi
4) 350Z
5) IS350
6) Mustang GT
7) G35

Once again, 1-4 close call, and 5-7 close call, with an estimated 0.5 difference from 1 to 7

After 100, From my knowledge, I would say:

1) 335i
2) 350Z
3) G35
4) IS350
5) Mustang GT
6) EVO
7) STi

A bit ironic how everything changes after 100. Evo's and STi's are known to lack acceleration after 100. But have a massive advantage in the 0~70 area.

.
IS350 v. 335ci v. mustang GT v. STi v. Evo v. Z v. G35C

S8B

Wow, I hope this was intended as a joke.

What about the other important facts? Weight? Drag Coefficent? Traction? Driver?



.

lobuxracer

iTrader: (2)

Weight doesn't matter to top speed. Aerodynamic and mechanical friction are the enemies of top speed. Frontal area and Cd are the biggest concerns. Driver is meaningless as long as the driver can keep the car going straight.

Horsepower does = top speed after you factor in frontal area and Cd.

S8B

We're talking about all around performance here. (All around as in 0-60, 1/4 mile, top speed).

In order to get top speed, you need to go through everything other stage.

Everything I mentioned matters in all around performance on the straight.

.

thetopdog

Are you saying that a car that can hit 170mph with one driver on board can hit the exact same speed as the same car with a driver and 1000lbs of passengers on board? It doesn't make intuitive sense but maybe you know something I don't

GSteg

iTrader: (15)

Weight does not have an influence on top speed. Mass will only affect acceleration. The time it takes to get up to top speed will take longer with 1000lbs of passengers than it does with just one driver, but it will eventually reach top speed. When you're traveling at greater speed, mass means less. The aerodynamic factor will be a bigger concern rather than weight.

GSteg

iTrader: (15)

I was just going to post this. These 3.5L are quick!

LexFather

They are correct. Weight is not top speeds enemy, drag is a cars biggest enemy and cars need more and more power to push them through the wind.

You will notice that is why engineers go through all the trouble of creating cars that go over 200mph without huge wings and they have flat underbodies.

The 9ff top speed 911s have a lower roofline to combat drag.

The Bugatti simply OVERPOWERS drag. It does not have a low CD and it weighs what 4500lbs.

A McLaren F1 weighs literally, 2,000 lbs less, at under 2500 lbs and has a lower top speed as the engine and gearing have no more room.

thetopdog

I know drag has a bigger influence on top speed but I'm still trying to get it through my head that weight has no influence on top speed at all. I went to an Ivy League school and took 2 physics classes so I really should be ashamed of myself for not knowing this

Somebody put the relevant equations up or something. F=ma is about all I can remember from physics class, which is pretty sad. I'm not sure if you can equate horsepower directly with force either, but if you can, wouldn't it make sense that in order to accelerate the car from 169 to 170mph for example, you need more force for a 5000lb car than for a 3000lb car (assuming all other factors are the same?). So if a car tops out at 170mph, the same car travelling 169mph with an extra 5000lbs would need more force to accelerate the car that extra 1mph, and the engine may not be able to produce that force, leading to a lower top speed?

I probably have that all wrong, but let's just throw out an extreme example: My car, a 2006 Corvette that weighs about 3200lbs with 400hp can reach 186mph. If I load up 100000 bs of weight into my car (assuming my car doesn't collapse), will I be able to still reach 186mph eventually?

This is actually pretty relevant because I want to do a top speed run with my car. Apparently if you fold the side mirrors back and tape over the headlights, the C6 Vette can hit 300km/h (187.5mph) and I was thinking about bringing my friend along to film it (I don't want to try to play with a camera doing 3 miles a minute . I figured his extra weight might cause me to fall just short of 300km/h but if it makes no difference then we're golden.

13loody

Weight is mass times gravitational constant. What you have to remember is weight is a "downward" force. Also recall the law of inertia; where an object at rests tries to stay at rest and an object in motion tries to stay in motion. Have you ever pushed your car when it broke down for whatever reason? Getting the car to move initially can be quite difficult, but once the car starts moving, it's quite easy to build up more speed with the same amount of force. What you're primarily fighting against is friction and air resistance, hence where the drag coefficient comes in. I'm not sure if you ever saw or experimented in physics class with vacuums, but a feather and a bearing ball in a vacuum tube will fall at the EXACT same rate. That is ONLY in a vacuum. Another thing car engineers have to consider is the balance between a low drag coefficient and downforce. Without enough downforce, the car will lift, thus negating any further "push" from the engine spinning the wheels. Too much drag and it will take more power to accelerate through. That is to say that weight absolutely has no effect, it does, FRICTION! What allows your car to accelerate also affects how fast it can accelerate. Why do you think electromagnetic monorails are so fast; very low drag coefficient and virtually no friction.

Sorry for the long paragraph.. I was too lazy to break it up and make it look all nice and 'purty.'
--
Forgot to ask if 1 mile is even enough for those cars to reach their top speeds. Also, what's the point of having a straight-line race? I love the Evo Unfortunately, the 335ci has heating issues on the track.

thetopdog

Thanks for the reply. I understand what weight is, and the feather/ball bearing example is pretty elementary, at least give me a little more credit than that!

But from what you're saying, weight does matter, just not a lot, which is kind of what I was thinking.

13loody

Sorry, I wasn't trying to offend/demean you in any way. However, seeing how the only thing you mentioned was F=ma, I thought I'd be a bit more thorough in my explanation and ensure that you understand it, even from an elementary perspective.

thetopdog

haha, no offense taken. I learned what I needed to learn for my physics exams and as soon as the exams were done the information left my brain for good.

So after all that, is it correct to assume that if my car can hit 186mph, my same car loaded up with 10000lbs of weight will not be able to reach 186mph?

13loody

With that much extra weight, I highly doubt it. If it were more like 1000lbs, then yeah, I believe you would. It would just take a bit longer. Also, with all the advancements made in aerodynamics, supercars can easily reach 300mph from a drag coefficient stand point.

That's enough for me tonight; time to go work out and then crash, peace out.