variable cam profile/timing (was: Twin injector system?)

[Adrian Teo]

On Mon, 29 Jun 1998, Chris Conlon wrote:

> I didn't know Nissan had a scheme called VVT or VVT-i. Toyota has
> two that have exactly the same names. They don't switch cam profiles
> though. VVT switches between one of 2 predetermined advance/retard
> settings, but the cam of course stays the same. VVT-i (incremental)
> allows a finer selection of advance/retard, again within preset
> limits. All the Toyota motors that I know of that use VVT or VVT-i
> are twincam models, and I think that some of those vary only one of
> the two cams, to save money I guess.

Well, I think I could have gotten the designations mixed up. Nissan's
system is called VVL or something. It's very similar to the Honda VTEC
system but instead it uses locking catches to mesh rocker arms versus
Honda's locking pins.

It's currently used on the Nissan Pulsar VZ-R (or something like that) on
the SR16-VVL engine. Too bad we don't get these beasts over here...

...that's why some of us build our own.

> I always thought it would be way cool to have the valves activated
> hydraulically, controlled by solenoids or something. But I have no
> real idea how to do this. I would think that a completely flexible
> "cam" profile would be a real big advantage, and since I haven't
> seen it anywhere I assume it must be a very difficult thing to do.

Allow me to point you to Racecar Enginnering, a UK publication. A recent
issue featured electronically (solenoid activated) valve technology.
Apparently at the experimental stage, it does solve a lot of problems
associated with conventional valve technology. There was a working model
featured but, as with prototypes, it wasn't pretty.

:)

-AT

------------------------------------------------------------------------
Adrian Teo                               e-mail: adrian.teo at asu.edu
System Administator                              falconer at falcon.asu.edu
Instruction Support Lab, Arizona State University                           
Ph: 602.965.6739                         http://falcon.asu.edu/hybrid
Fx: 602.965.2724     Pg:602.204.1831     e-page: adrian at falcon.asu.edu
------------------------------------------------------------------------