LAST EDITED ON 09-Feb-01 AT 05:30 PM (PST)

Just to be clear on this, I will go the _same_ speed as Chris (or anyone else here) in the same gear at the same engine rpm, assuming equal tire diameters.

The problem here is that aerodynamic drag increases as the cube of the velocity. Remember how the power curve starts dropping off after 6000rpm? Well, we start not being able to drive the car faster because the aerodynamic drag exceeds the power output of the engine. Turbo'd 2GNTers can drive their cars up to the limiter in fifth (good for 160something) because they are making a lot more power. 1G turbo guys with ToddzModz can hit somewhere over 175mph at 8000rpm. If you modded correctly with NA and improved your high rpm power output (ported everything, free intake/exhaust, etc), you should be able to get more speed out of the car. One point though, a GS-T and possibly GSX driver would likely have a higher maximum speed regardless of what we do to our car, as they have 'taller' gearing.

More succinctly, the theoretical vehicle speed in any gear is determined only by:

- rpm
- transmission gear ratio
- final gear ratio
- tire rolling diameter

In the real world, aerodynamic drag may prevent the car from reaching maximum speed as determined by redline in top gear from this equation.

This is why some 6 speed cars can be faster in 5th than 6th, if the 6th gear is an 'overdrive'. The car may not be able to overcome the drag in this gear at very high speeds, as they are designed more for cruising at highway velocities with lower rpm. This happens with Corvettes, as one example. In a vacuum, the car would of course be fastest at the top of 6th. But then, you'd have other problems, like breathing, or providing O2 for combustion...


I once proved a roomate that the Porsche 959 was incapable of driving at 245 mph, like he insisted it could. I dug up from my CRC Handbook the equation for aerodynamic drag, and calculated the 440hp that car generated made it top out at somewhere just over 200mph. I was glad to prove him wrong, cos he was a complete dumbass...

juan