I think some Yamaha motorcycles had what they called a "reed valve" that
functioned in a similar manner to what you describe to give more torque down
low and still open up big for horsepower at the high end. I think it was a
passive type system though ( not 100% sure). Don't know if a similar setup
could be fabricated for a Holley TB. Remember the motorcycle carbs are
sidedraft. Don't know if this would have an impact on feasibility or not.
Bob
Pennsville, NJ
-----Original Message-----
From: Shaun.Hendricks@bergenbrunswig.com
<Shaun.Hendricks@bergenbrunswig.com>
To: dakota-truck@buffnet.net <dakota-truck@buffnet.net>
Date: Tuesday, August 10, 1999 4:29 PM
Subject: DML: Throttle Body Mod idea
> Been watching things for a bit on the whole TB mod issue. DMLer X vs
DMLer
>Y vs DMLer Z vs Standard Production... etc. It seems to me that you can
only
>do so much before you've hit the wall. No matter what, with each different
>approach you're going to get different preformance benefits. It's a great
>thing, but what about a single TB mod to fit variable needs.
> An idea for the truely experimental ones of you, take some lessons from
jet
>aircraft. You need a variable geometry TB follower plate. Essentially a
TB
>is just an air intake orifice and the butterfly valves control the amount
of
>air allowed through the orifice. The problem with "enlarging" the orifice
too
>big is a loss of torque because the air velocity into the cumbustion
chamber
>is decreased. The problem with them being too small is that a horsepower
loss
>happens due to a smaller amount of fuel/air being available. This is just
>general talk, I don't need a full technical detail made to me, I'm in
>conceptual mode.
> You can't have a variable orifice because the butterfly valves can't
adjust
>sideways. An iris valve isn't as fast as butterfly valves for response so
>they're out. In order to keep the butterfly valves and a large orifice TB,
>you need to have a post TB adjustment plate, something that can "narrow
down"
>or "enlarge" the opening as necessary for different sections of the power
>curve. The idea is to take the design from a jet which controls it's
thrust
>by a set of vanes that open and close to change the geometry of the thrust
>(it's called a thrust cone). A small set of these just under the TB,
mounted
>on a separate plate (so it becomes a mod unto itself) with a solenoid or
cable
>controller could adjust the airflow for high velocity at the low end and as
>more horsepower is needed, open to allow maximum air flow.
> Obviously this is not a simple toy, but it is possible. For you "gotta
>squeeze every last ounce of power" guru's out there, it might be a cool
item,
>but me personally, if I modded for horsepower and then went to tow, it
would
>be a great thing just to engage with a pull knob. Have a matching buddy in
an
>expanded exhaust system to provide the needed backpressure for max torque
and
>you have a great combo for developing torque on demand... It would be
>interesting to see if something like this could be made, and just how
>effective it would be.
>
>Shaun H.
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