I don't know, maybe its just me, or maybe they don't explain it well, but it
sounds like a bunch of crap. How a floating auxiliary seat will in anyway alter
valve *timing* is beyond me. I can see how it would affect flow rates and other
variables, but the valve opens when it opens and that floating seat isn't going
to change that. If the floating seat stays with the valve as the valve moves off
the seat, it becomes part of the valve and the sealing zone is between the
regular seat in the head and the outer surface of the floating seat. If it stays
with the seat in the head, it becomes part of the functional seat and the
sealing zone is between the inner surface of the floating seat and the valve (at
least until the valve moves beyond its floating range). But in neither instance
does it alter when the valve (be it just the valve or the valve & the floating
seat combo) comes off the seat (be it just the seat or the seat & the floating
seat combo). To do that it would have to change thickness, maintaining a seal
with the regular seat in the head *and* the valve as the valve moved off the
seat. I don't see how what they describe can do this. All I can see it doing is
lowering flow at small valve openings and ruining your control over turbulence,
two things we try hard to avoid. And that would be the case at all engine
speeds, a constant, not a variable, so it still doesn't make for a variable
anything. Maybe they're trying to claim that the floating seat would prevent
flow between itself and the valve if it was within a given distance of the
valve, acting as a variable thickness valve and thereby altering valve timing
based on some sort of pressure signal. I suppose this is possible, but it seems
like a damn sloppy approach that violates KISS and is not rpm indexed, which
variable valve timing ought to be. I assume there must be something keeping the
floating seat attached to the valve at all times, that also limits its range of
movement (which I assume would be that magic range where it can prevent flow
between itself and the valve) and keeps it properly centered on the valve,
otherwise you could have some serious problems. Whatever it is that serves this
function better be *really* reliable. And on top of all this, you now have *two*
sealing surfaces per valve to deal with. I'd rather go with an inertia based
sprocket for an OHC motor and a hydraulic bleed-down lifter for a push rod
motor.
Just my .02
Dat2000srl@aol.com wrote:
>
> I got this reply from the maker of Smart Valves
> <A HREF="http://www.aatap.bigstep.com/generic.html?pid=6";>aatap - Sample
>Performance Graphs - variable valve timing solutions for car
> eng</A>
> http://www.aatap.bigstep.com/generic.html?pid=6
>
> Mr. Coughlin,
>
> Manufacturing and preliminary development of the parts is expensive (aprox
> 8k-10k per vehicle make, model, displacement, and valve size; amd that is
> just for the prototypes), so obviously, a good amount of folks have to let us
> know this is something they would want. Please feel free to share this with
> other Roadster enthusiasts. Once again, the more requests we get, the better
> chance an applications will be made. Thanks again, and hope to hear from you
> very soon.
--
Marc Sayer
82 280ZXT
71 510 2.5 Trans Am vintage racer
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