The longest installment of the series currently is the most recent, Furious 7, which clocked in at 137 minutes.
This would be ludicrous (pun intended), by Fast and Furious standards.
Though it is fairly interesting to note that the Furious movies have gotten longer with each respective installment, and took a leap from the fourth Fast (107 minutes) to Fast Five (130 minutes).
We have reached out to Universal Studios for confirmation on the final cut of F. Gary Gray’s The Fate of the Furious, but the runtime on the IMDB page for the next Fast is 160 minutes, or two hours and 40 minutes of Furious action.