Need help in calculating high speed run potential...

blue00gt · 06-07-2001, 05:55 PM

One thing people need to remember is that weight does not have that much to do with top speed, only how long it takes to get there.
As for being able to predict how fast a given car will go, it's just too complicated without knowing all the details of that particular cars setup - it really depends on the final drive ratio, the amount of change in gearing in shifting from one gear to the next at high speed (i.e. if you shift from 4-5 at redline in my stock geared '00GT it comes out of the powerband because 5th is so tall and you are screwed), and what the engine's powerband looks like. After all that then you figure in wind resistance and other friction factors.
I say run that turd and then let's hear about how fast it can go.
We can all agree that in general for a given aerodynamic configuration, the wind resistance increases as the square of the speed. Thus an approximation would tell you that is a stock CRX with 108hp can do 125mph according to the car mag, then to go 150mph you better be packing almost 50hp more than stock, which is no small feat for an engine that size. (150/125)^2 x 108hp = 155.5hp.
The trick here though is that the car needs to be able to make that horsepower at the exact rpm that it would be going that speed.
That is the main reason why people's cars won't go as fast as they think they will.

And that's all I have to say about that. ;-)

And please don't question my education.

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06-07-2001, 05:55 PM	#1
blue00gt Mustang Addict Join Date: Jan 2001 Location: McKinney, TX Posts: 1,294	One thing people need to remember is that weight does not have that much to do with top speed, only how long it takes to get there. As for being able to predict how fast a given car will go, it's just too complicated without knowing all the details of that particular cars setup - it really depends on the final drive ratio, the amount of change in gearing in shifting from one gear to the next at high speed (i.e. if you shift from 4-5 at redline in my stock geared '00GT it comes out of the powerband because 5th is so tall and you are screwed), and what the engine's powerband looks like. After all that then you figure in wind resistance and other friction factors. I say run that turd and then let's hear about how fast it can go. We can all agree that in general for a given aerodynamic configuration, the wind resistance increases as the square of the speed. Thus an approximation would tell you that is a stock CRX with 108hp can do 125mph according to the car mag, then to go 150mph you better be packing almost 50hp more than stock, which is no small feat for an engine that size. (150/125)^2 x 108hp = 155.5hp. The trick here though is that the car needs to be able to make that horsepower at the exact rpm that it would be going that speed. That is the main reason why people's cars won't go as fast as they think they will. And that's all I have to say about that. ;-) And please don't question my education.