Coldwater In Your Veins

Easy concept.  Race starts at 6 am.  You have 2 hours to complete the 7.7 mile lap.  You take all the aid you need with you.  There's no pacers, help or other aid that you don't get from yourself or another racer.  If you finish under 2 hours, that's the time you have to rest until the next loop starts at 8am.  You finish over the 2 hour limit, DNF.  You're not in the runner's corral when I count down to start the next lap, DNF.  How long can you go?