RC car electronic speed controllers usually offer a setting called turbo that will provide an extra amount of motor timing when at full throttle. This extra timing gives a boost of speed called "turbo."
However, we only want this turbo to kick in for the long straights, as it may make us lose control in the infield, so we use the turbo delay setting to control how long after engaging full throttle the turbo timing will kick in. This allows us to use full throttle briefly in the infield without the turbo engaging and sending us into a wall.
See our article on electronic speed control for more on settings.