A RWYB test day on 8th August yielded a first run of 1.13 to 60′ (our best ever), 3.13 to 330′ then rev limiter and then wheelspin – 7.7 @ 145mph. There was a loud pop as the limiter came in and smoke from the exhaust in the shut down area which turned out to be a broken ball-bearing race in the small turbo, so game over for the day.
2 weeks later we were back at a Peak Performance day (better track) with a rebuilt turbo from Owen’s only for the same thing to happen again. Even with Owen’s help, this was getting expensive at a turbo per run!
Both turbos had failed in exactly the same way, a broken bearing on the compressor side.
Close examination of the datalog however revealed that hitting the limiter was caused by clutch slip, not wheelspin, so for the next time out we would add more weight to the clutch and modify the limiter to cut fuel only instead of fuel and ignition.