What Car? Q&A - Why is a chain-cam engine better?

Can you tell me if Toyota VVTi engines are chain-cam engines. If so, what are the benefits?
Darren Neill

A: The camshaft opens and closes the valves of an engine, so it's vital that its timing is correct for the engine to run smoothly and efficiently.

It is turned by the engine's crankshaft, and connected to this either by a belt or, in the case of Toyota's VVTi engines, by a chain.

A belt will slacken over time, causing the engine to misfire. It needs to be replaced at this point (from about 50,000 miles generally) and this can be a time-consuming and costly job.

You shouldn't ever have to face this hassle or expense with a chain-driven engine. While the chain might need to be adjusted, it shouldn't have to be replaced in the life of the car.