Exhausts and Engine » Silent chain cam drive

I note that the new 1250 engine uses a "silent chain", or BMW's term "toothed chain". I wonder why? Could it be that this type of chain does not require a tensioner system?

I recall that the Japanese switched from a roller chain to a silent chain to drive their camshafts and as a primary drive to the clutch on some of their engines around the late 1970's, I believe. I think the brand name was "Hi Vo". It was supposed to be a very durable chain drive system that would last the life of the engine and would run quieter than a roller chain, but I never really noticed due to the noise that the engine and exhaust would make. But a few years later the Japanese went back to using roller chains inside their engines. Perhaps due to cost or maybe roller chains had increased in durability?

So my question is: I wonder why BMW switched from a roller chain to drive their camshafts in the new engine? I have tried to do some research regarding silent chains, but I haven't really come up with much. Any thoughts?

I don't know the reasons why, but I found the 1250 engine running a lot more silent than my 1200. And also smoother and less vibrations, so the 1250 is a big step forward in quiet running. Some people won't like that, and prefer the "character" of the 1200, but most new buyers will like the new engine...

Technically, BMW is not using any chain drive to the cams. It is using gear drive to the cams. The chain drives an intermediate gear.

My guess is that there may be some "shock" loading to the driving gear as the inlet cams move from low speed to high speed and the Hy Vo chain may be better at absorbing "lash". However, this is just a guess.