Craig Blome wrote:
> - --- dg50@daimlerchrysler.com wrote:
> >
> > Uhh, there aren't ANY cars with "computer controlled
> > camshaft timing" out there,
> > in the sense where a computer directly controls the
> > lift/duration of the valves.
...
> Not exactly...the Toyota VVTL-i system in the 2000
> Celica GT-S continuously varies cam timing by rotating
> the cam relative to its drive gear, in addition to
> switching between two cam profiles. As you say, not
> equivalent to switching cams, but it is the equivalent
> of adjustable cam sprockets.
Basically similar in concept to BMW's VANOS. Cam timing is advanced or
retarded continuously by the computer. Depending on the model and what
part of the world you're in, either the intake, or both intake and
exhaust cam timing is controlled by the computer.
Aftermarket tuners can take advantage of this and remap the timing
changes. No, it won't change the total amount of lift or duration, but
it can change the amount of lift at any given crank position by
advancing or retarding the cams. That seems like "computer controlled
camshaft timing" to me.
> Also, we're not too many years away from engines that
> do away with camshafts entirely, actuating valves by
> high speed solenoids instead. There are power
> consumption and speed limitation problems to be solved
> yet, but they will be solved, and the resulting
> engines will be devilishly hard to police.
It's was done in F1 years ago. Not sure if it was outlawed, or just
faded away, but there was a team (a French manufacturer I believe) that
ran pneumatically activated valves. Valvetrain inertia is obviously
decreased substantially meaning extreme RPM levels are possible. Cost,
complexity, and reliability are probably more of a limiting factor than
power consumption or speed.
--
Ron Katona
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