What's the top speed on your car?

[NO SLO PK]

Originally posted by jimberg:
Top speed has everything to do with the mass of your car. In order to reach top speed, you need to generate enough force to accelerate the mass of your vehicle to that velocity. Force = Mass x Acceleration.

Let's say that your engine can generate a constant force, which it can't do. The mass of your vehicle will remain constant. As the velocity of your vehicle increases, the force of drag on your vehicle will increase (quadruples for every time the velocity doubles). The force of drag can be subtracted from the force your engine is able to generate and then you can divide it by your mass to determine the rate of acceleration. Your acceleration will constantly decrease until, for all intents and purposes, it reaches zero.

Now factor in the fact that engines don't generate a constant force and force drops off significantly at higher RPMs.

Actually, according to the equation above, top speed is not determined by mass. According to force = mass x acceleration, two cars of different mass will reach the same top speed, all else being equal. The main difference is that the car with greater mass will take more time.

With a greater mass, acceleration is less. But the car will still accelerate until the power it delivers (force) equals the forces of aero drag + friction.


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Russ L
'91 LX
Procharger, 3 row intercooler, extrude honed Cobra intake, Mac full Length Headers, 30# inj., 73mm C&L, 75mm tb, E303 cam, 289 rods, ported E7 heads, MSD, T-Rex w/255 lph Walbro, 5 lug conversion, Cobra R wheels, 3.27 gears and Moser Axles.