Helical Camshaft

[throwaway1]

Sorry for posting so many threads, but I have become really interested in valvetrain.

I was wondering what everyone's opinion here was about helical camshafts? What are the drawbacks? Has anyone used them?

The concept is described in the following two links: (although it seems the wikipedia article was written by the same person in the first website)

http://www.helicalcamshaft.com/

http://en.wikipedia.org/wiki/Helical_camshaft

[piast9]

Variable valve timing is forbidden in F1.

[riff_raff]

Sorry for posting so many threads, but I have become really interested in valvetrain.

I was wondering what everyone's opinion here was about helical camshafts? What are the drawbacks? Has anyone used them?

throwaway1,

The design you note only appears to provide variable duration. To achieve variable lift, timing and overlap it would require additional hardware. The device's main limitation is the fixed cam profile geometry on the opening flank. The profile that must be used would seem to produce excessive accelerations at high valvetrain operating frequencies.

FWIW.
riff_raff

[PlatinumZealot]

Sorry for posting so many threads, but I have become really interested in valvetrain.

I was wondering what everyone's opinion here was about helical camshafts? What are the drawbacks? Has anyone used them?

The concept is described in the following two links: (although it seems the wikipedia article was written by the same person in the first website)

http://www.helicalcamshaft.com/

http://en.wikipedia.org/wiki/Helical_camshaft

That is very interesting. I was surprised and impressed at the motion of it - didn't expect that. I think it should be fairly durable, since you have a number of helical timing systems which work on a similar principle. But it's the first I am seeing a variable duration system.

[Bikeracer18]

I have also been watching the progress of this gadget with great interest. It would appear to be very suited to motorcycle racing - maybe even MotoGP - if it legal (a blg "if" maybe?). Ducati uses a very novel valve gear system - so maybe valve gear is "free" in MotoGP?
I don't think the lack of variable lift etc. would be a major drawback for outright performance as in racing - the unlimited (virtually) amounts of duration available I would think make the cam basically unbeatable in racing.
I seem to recall reading somewhere of plans to actually build a version for racing - maybe it was for possibly single cylinder speedway bikes? It would appear to be sensible to prove the basic idea in something simple rather than tackle something like a four-cam 48 valve V12 straight off.