Variable Cam Stuff

[Andrew W. Macfadyen]

The Porsche device was neat, Alfa also had a really simple system on some models,
a little oil pressure driven accuator in the centre of the cam sprocket  which
retarded one cam on a DOHC  engine to increase  the timing overlap --- it was
simply activated by a centrafugal trip vavle in the cam sprocket releasing the
oil pressure at a given RPM.
Sadly Rover are going to halt production of the VVC version of the  excellent 16
valve K series  used in the MGF next year because of emmision problems.
Even without variable timing its worth while experimenting with the relative
timing of the cam on  DOHC engine with hot cam as by changing the overlap you can
sometimes get a big boost in low speed torque without  too much loss at the top
end.

Adrian Teo wrote:

> On Mon, 29 Jun 1998, Sandy wrote:
>
> > Saw the idea in the 60's hot rod mags where some gizmo was attached to the
> > timing gear of the cam and it did some magical adjustmet by letting the
> > assembly slip and slide to alter the cam timing. Never saw one in action or
> > knew if they really worked, the idea was good.
>
> That's how Porsche implements the VarioCam mechanism. Slack in the timing
> chains are altered with moving tensioner guides such that the timing of
> the camshafts change relative to the main crankshaft.
>
> -AT
>
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