Turbo delay is the time from the throttle trigger is moved to the full throttle position and stays at that point to the moment Turbo Timing is really activated. If you set this item to “INSTANT”, then the Turbo Timing will be activated right after the throttle trigger is moved to the full throttle position. If set it to any other values, then you need to hold the throttle trigger at the full throttle position for a while (as you set) till the Turbo Timing initiates.