What is the difference in an interference and non-interference engine?
In order to gain performance, some engine hold the valves open longer and further on the exhaust and compression strokes than others. In each case, the piston is rising as the valve is closing. The engine timing prevents them from hitting, even though they occupy the same place, at slightly different times. If the engine loses camshaft timing, due to a timing belt or chain fault, the valves can hit the pistons causing great damage. In a non-interference engine, there is adequate clearance to prevent this, though such an engine will normally have less performance. See our Detailed Topic article All About Timing Belts for far more details.
