If it's going to run LeMans, then it'll have to last 24 hours.
Kidding aside, it's not unusual for a race car engine to get rebuilt / replaced after every race. Heck, F1 used to use different engines for qualifying and the race. The qualifying engines were so lightweight and high strung they only lasted 12 to 15 laps. (F1 races are around 60 laps, depending on the track)