I had questions about that gizmo too. If it's such a great idea I'm sure
Honda or someone would have bought a license or the patent as it appears to
be a lot cheaper way to vary the valves than using computers and all kinds
of extra gizmos they now use. And you know how car companies love to save
money.
it's probably similar to the 100 mpg carb.
Mike
----- Original Message -----
From: "Marc Sayer" <marc@gracieland.org>
To: <datsun-roadsters@autox.team.net>
Sent: Monday, January 21, 2002 3:09 AM
Subject: Re: Roadster Smart Valves
> 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
>
> /// datsun-roadsters@autox.team.net mailing list
> /// Send admin requests to majordomo@autox.team.net or go to
> /// http://www.team.net/cgi-bin/majorcool
> /// Send list postings to datsun-roadsters@autox.team.net
/// datsun-roadsters@autox.team.net mailing list
|