benefits of a slave cam over a true dual cam?

[nialloftara]

So I've owned 2 16 valve dohc engines however both have utilized a slaved cam. The 4afe's was geared directly to the main while the beta1 has a chain drive system. What are the advantages and disadvantages to these kinds of systems vs both cams being driven directly from the timing belt/chain?

[Daffyflyer]

You know, I'm really not sure... I have 2 Mazdas of a similar era and one of them (KF-DE V6) has a slave gear driven cam, and the other (BP 1.8) has both belt driven.

I can't really think of any reason not to use the slave gear setup, besides the fact that it'd be reaaally hard to do VVT with only one cam pulley per bank.

[nialloftara]

I'd always figured both being driven off the belt would give more response due to less system drag. Is there aanother term for this? Searching Google for slave cam gets bdsm websites and searching for both slave cam and dual cam is all about bow hunting.

[Daffyflyer]

I don't think that the drag of driving the camshafts either way really is an appreciable power loss compared to all the other friction in other parts of the engine, and I'm not even convinced that the both driven by belt system is the lowest drag anyhow.

I'd say maybe the slave gear system is better for packaging reasons, but it'd impose a limitation on how far apart you can have the two camshafts, thus limiting valve angle and how well flowing and smooth your port shapes can be? I'm pretty sure that's why the 4age has seperate cams, but the 4afe doesn't (4age has a waaay wider valve angle)