Comment by blamazon
5 years ago
In addition to what frosted-flakes said, many engines are “non interference” design so that if the belt snaps or jumps a tooth the engine won’t be destroyed, and the belt will just need to be replaced. However, non interference engines are not as compact as interference engines.
Many engines also use a timing chain instead of a timing belt, but this carries extra weight and requires lubrication.
It’s all about tradeoffs!
The engine in one of the vehicles I own has timing gears rather than a chain or belt. Another option, different trade-offs.
Much more common with pushrod engines, where the camshaft is situated close to the crankshaft; less so with overhead camshafts. Though I think some very high-revving sports and competition engines have gears driving overhead cams; IIRC the McLaren TAG F1 turbo V6 (by Porsche) back in the 1980s was one example.
The engine used in the Ferrari Enzo and Maserati MC12 is a notable example:
https://36.media.tumblr.com/8a928fcccf1b41e82be0273ccbe2005a...
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