Originally Posted by 5speed 
I find it a little amusing when people are saying the trap speed at the end of the quarter mile is a better measurement of hp than a dyno. I would say they are both flawed, and the trap speed mph is even more so.
And here’s why, the top speed at the end of the quarter is affected by even more variables than the typical dyno. First, your top speed will be affected by traction, whether the car is on street tire or slick, track surface temperature, and track surface prep, whether it’s greasy, grippy, sandy. You also have to consider the track condition such as air temperature, humidity, barometric pressure, elevation of the track, and wind condition, whether it’s a 10mph head wind or tail wind. If you didn’t have enough variables to think about, you have to also factor in the weight of the car. At least the dyno has a weather station and correction factor to take out some of these variables.
Let take an example car with 200hp and run it on different tracks. One track is in LA at sea level and in the winter, and the second track is in Denver in the middle of summer.
Will the top speed be different between the two tracks?
The answer, Hell Yes. Any racer will tell you they run different top speed depending on the condition of the track.
So why are we trying to compare top speed from different cars from different part of the world at different time?
That’s why I like dyno days. All the cars at the same place and time.
Agreed, a lot of guys think power is all that its about, gear ratio also plays one of the biggest roles in this equation.
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