Sorry for bumping this old thread.

Are inteference designs related to fuel economy?

I mean, Mazda engines are known to be gas guzzlers, and I was thinking it's related to the non-interference design.

Basically, AFAIK, non-interference engines have deeper combustion chambers (please verify) and more clearance. I thought it takes more gas to combust inside to complete the four strokes, which consequently equates to poor fuel economy.

I'm quite confused.



Maybe someone could shed light on this.