What Is A Flat-Plane Crank And Why Is It So Loud? An ExplainerJason Torchinsky11/17/14 3:01pmFiled to: Car Tech2015 Mustang CObra GT35024386EditPromoteShare to KinjaToggle Conversation toolsGo to permalinkGIF One of the things you may have noticed among all those big, exciting numbers and words we used to talk about the 2015 Shelby GT350 Mustang were these three words: flat-plane crank. Many of you may be wondering just what the hell that means, and why you should give a rat's rectum. Here's what and why.ShareTweet Kinja is in read-only mode. We are working to restore service.