The Freightliner ambulance I work in experienced a turbo failure on the Cummins motor in it. It has the larger displacement B series motor. When the turbo failed, it started injecting motor oil into the intake. The ignition was off, keys out, and the motor, with an unregulated fuel source, began a "runaway" condition. It sounded like a jet turbine spooling up. I would bet it made atleast 6k rpm. Smoke everywhere. If you read in you manual, it will tell you to inject a fire extenguisher into the air intake. I would recommend a CO2 type instead of an ABC dry chemical. Just thougt I would let everyone know of this rare, but costly type of failure.