About corner exit speeds and illusions

People just getting into performance driving are almost entirely focused on getting the big horsepower numbers. They fail to understand that in the real world and on a road course, it takes a lot of horsepower to make up for the lack of real driving ability. That means being able to sustain high speeds in corners, not just in a straight line.

Richard Shelquist has written a nice article explaining the importance of corner exit speed:

As you can see, Car number 2 is at a distinct disadvantage due to only a 2 mph difference in corner exit speed. At the end of 1000 ft from the corner exit, car number 2, which had the slower corner exit, is 0.103 seconds behind car number 1. At their speed of 94 mph, that will be a distance of about 14 feet.

He also has some interesting observations:

Now, imagine that you accelerate exactly the same as the car ahead, and that you exit with exactly the same cornering speed, keeping exactly 0.34 seconds behind the other car. As you accelerate down the straight, keeping always exactly 0.34 seconds behind, the distance between the two cars increases. For example, if you stay behind by exactly 0.34 seconds, when you reach 4500 rpm in fifth gear, about 110 mph, the cars will be travelling 161 feet per second, and your separation will become 54 feet. It looks like you need a new motor, but its just an illusion, you were a constant 0.34 sec behind.

Link