2013 Shelby GT500 to have improved 5.8 liter supercharged V8 According to several sources, including MustangsDaily and Fox News, the 5.4 liter supercharged V8, currently in the 2012 Shelby GT500, will be replaced by a 5.8 liter supercharged V8. The recently negotiated labor agreement between Ford and the UAW includes language regarding a $50 million investment in the Romeo Engine Assembly Plant that will include production of a 5.8-liter supercharged V8 for the 2013 Shelby GT500.