Dyno Chart is vehicle engine performance evaluation tool, which provides you the information of max power and torque vs RPM. Dyno Chart app uses OBD II interface on your vehicle to collect sensor data and build the chart. Please follow the app instruction for compatibility check before you purchase and unlock the in-app chart function. The app needs an ELM compatible Wi-Fi or Bluetooth Low Energy (for iPhone4s and later) adapter to work. You can check Developer WebSite for Adapter Guide: http://www.outdoor-apps.com/enginelink.html Drop us an email for any suggestions/questions you may have at email@example.com. We will answer.