Re: [alfa] re: 147 knock-off (Mazda 3)

["Benjamin" <budweiser@xxxxxxxxxxxx>]

I'm pretty certain Porsche have a system where the cam lobes for
both the intake and exhaust valves are moved according to various
conditions eg RPM, rate of change of RPM, torque etc.

I was talking to a mechanic the other day at a machine shop, and he
has a bit of experience with motor cycle engines. Some engines even
have 8 (yes eight!) valves per cylinder. Also rotating heads where a disk
with a hole in it rotates to the intake and exhaust position, but this is
not
very good because the port is only open for 1 degree for each rotation.

I've also seen rotating spheres with slots cut in them that rotate in the
heads.
I have no idea how effect this is, but to me it makes sense as there is not
up/down movement, just simple rotation. There is a US company than
manufactures these heads (I think mostly for racing) but the website did
show it fitted to a straight 6 Mercedes engine. Interesting, but I'm sure if
it was worth while, Ferrari might have been using rotating valves for a few
years now if it was :)

I'll shutup before this gets too off-topic :)

~Benjamin


> Are you talking about the cam-less designs that use electronic controlled
> actuators to move the valves? I didn't know anyone had taken that into
> production yet. I remember reading about it a few years ago though, so it
> has been long enough for it to go into production use. At the time, if I
> remember the article, they first did it to see if they could, then they
> were going to try racing with it. I just wish I could remember who "they"
> was. It's been too long.
>
> On Thu, 2 Oct 2003, Benjamin wrote:
>
> > Yes, but don't Porsche now have a system where its completely variable,
not
> > like an on/off switch?
> >
> > ~Benjamin
> >
> > The ultimate car : designed by Italians, built by Germans
(Lamborghini?!)
> >
> > > > Yes, the VVT used by Alfa, Porsche, etc. in the '80s just
> > advanced/retarded
> > > > a pretty normal intake cam.  The neat thing about the Honda system
was
> > that
> > > > it could switch between two totally different cam lobes to vary
lift.
> > >
> > > That is neat.
> > > --
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