Doc: "Marty, the new gauge on the dashboard will tell us the boiler temperature. It's color coated to indicate when each log will fire: green, yellow and red. Each detonation will be accompanied by a sudden burst of acceleration. Hopefilly we'll hit 88 miles per hour before the nedle get's much past 2,000."
Marty: "Why? Wha... What happens after it hits 2,000?"
Doc: "The whole boiler explodes."