Vented Two-Stage Valves

Jody Shapiro jshapiro at bit-net.com
Wed Nov 19 02:37:22 GMT 1997


There's a pretty interesting article in the December issue of Turbo
magazine (page 62).

The article is about this guy who came up with the idea of making 2-piece
valves, where the second piece is a "sub-piece" of the main valve surface.
In other words, a center section of the valve face can seperately move
down, effectively giving you two concentric valves that when closed look
like a normal valve (they share the same stem).

Apparently, pretty big gains in volumetric efficiency can be seen as it
attempts to solve the problem of "stacking" (they define it as "intake
runner flow reversion caused by a high-pressure ridge behind and
surrounding the stem and head of each intake valve as it readies to accept
a fresh charge of air/fuel.  Stacking prevents maxiumum fuel atomization
and burn efficiency").

The inner valve pieces is opened closed "by the pressure differential of
the combustion chamber with each induction cycle". 

The guy who invented it (Reggie Huff) has patented the idea and has done
some dyno testing at Western Washington University on a SuperFlow dyno.
He's trying to license the idea to the aftermarket or OEM's.  I sure hope
someone picks it up...

Of specific interest to me was his results on a 96 LT1 motor (from the
photo's exhaust manifolds, it looks to be a Corvette motor):

At wide-open-throttle, the torque curve is up all the way from 1500rpm all
the way across to 5500rpm.  Max torque is up from 328ft-lbs from
276ft-lbs, with a pretty big jump in the 1500-2300rpm range.  Horsepower
is up to 296 from 274.

18% throttle testing showed a 15% jump in torque from off-idle to 3500rpm.
BSFC is also decreased by 10% at WOT.

Very interesting stuff...  for anyone interested in contactinc him, eh's
at:

Acro-Tech Inc.
51377 SW Old Portland Road
Scappoose, OR 97056
(800) 936-9394
(503) 543-8220

-Jody

--
97 Blue Vortech Z28 -  Best ET: 13.100  Best MPH: 111.24 (Goodyear RS-A's)
361 rear-wheel hp @ 6000rpm,  359 rear-wheel ft-lbs @ 4400rpm
http://www.bit-net.com/~jshapiro/z28/  




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