So basically the V8 5,5L Motor is overheating too fast compared to other cars/motors. I think its unrealistic. Other motors wouldn't break in 1 min of driving Top Speed with the High performance radiator. Please change it.
Maybe your radiator was broken. I tested it and it took close to a minute of doing a burnout in 2nd at full boost pressure with drag tires to overheat, and as soon as i let go and it got up to 100km/h it cooled off again.