What is exit speed and how much of a difference does it make?
That’s what we are going to answer in this lesson.
It is stunning to see how exit speed benefits stack up over a lap…
Overview of Exit Speed
Let’s make sure we are all starting on the same page.
Exit speed is how fast you are going as you leave the turn. Simple enough.
Exit speed is important because many turns lead onto a straight section of the track. When we get more speed out of a turn we get to carry that bonus speed the entire length of the straight.
That means if you sacrifice a little speed going into a turn, and then exit with an extra 2 mph, you will have an extra 2 mph at the end of the straight.
Which would you rather have: extra speed through the beginning of a turn, or extra speed for hundreds of feet after a turn?
The second option is clearly the better deal. Let’s look at some numbers to get a better sense of the impact.
An Example with Numbers
In Figure 1 you will see a simple right turn followed by a long straight about 660 feet long (⅛ mile). This is similar in length to straights you see on Laguna Seca.
Let’s say that our car has enough acceleration to add an extra 70 miles per hour between the exit and the end of the straight. Think Corvette type of acceleration or other high-end sports car.
So we leave the first turn going 50 and end up at 120 mph before slowing for the next turn.
The straight would take roughly 5.3 seconds for this base case.
How much time would we gain if we went just 5 mph faster out of this corner?
In other words, we start the straight with 55 mph and end with 125 mph.
A few magic presses of the calculator and…the math says 0.29 seconds.
We are talking several car lengths from just a 5 mph difference. Not bad at all.
Let’s pretend this is one of our worst turns and we decide to practice a bit. Maybe driving a better line gets us an extra 10 mph out of the turn.
How much does a 10-mph bump affect the time? It saves roughly half a second!
And this is just one turn. Most tracks have 6 or more turns leading onto straights. It’s easy to see how focusing on exit speed can save 3 or more seconds. Pretty cool, right?
You should now have a deeper appreciation for what better exit speeds can do.
If you would like to learn more about how you get that extra speed out of a turn join the Keys to Speed program.