RE: Air Flow in a bypass valve

["Lawson, Dave" <dlawson@ball.com>]

As the bypass valve operation discussion progresses...

Steadiboy writes:
If your running a stock turbo the Bosch valve is barely adaquate.....
On 
my car I was Blowing the valve open at 9PSI of boost (Were talking 
DENISTY Here.......)  I had to go to a HKS race valve to get it to 
work....

Qshipq writes:
>DENSITY is not an applicable term to a by pass valve.  PSI and FLOW
are.

Steadiboy writes:
Don't you wish you were right.......  Density is what we are trying to 
achive with a turbo (More O2 molecules per CC), NOT psi.

Qshipq writes:
>9psi is early, the stock k24 turbo cars bypass valve would open early 
>too with this argument if that's the case, it doesn't.  They are rated
at 
14psi+. 
> AIR DENSITY HAS NOTHING TO DO WITH BYPASS VALVE OPERATION.  
>You are NOT, by definition,talking about Desinty (your spelling) you
are
>talking about FLOW and Boost Pressure. 

Steadiboy writes:
The valve on the K24 app is not opening because of a Density problem,  
That little turbo is a heat pump above 10psi in the 10V and 20V app.  
Your not doing your homework here Scott, and in lot's of other places 
too.....You need to look at your PR equations again, there wrong because

your assuming things, Just like your Assuming that PSI and Density are 
the same thing..... They are not, just ask a pilot about Density
altitude 
vs Pressure Altitude.  Thank God your not a pilot 'cause you'd be a 
smoking hole in the ground......


I write:
The first words out of Erics hands is that he was blowing open a Bosch
bypass valve at 9psi, but he is talking "density" here, his own words.
Then
in the reply above he says "The valve on the K24 app is not opening 
because of a Density problem". And I agree with that, it's not a density

problem and I think others agree with that. Now if its not a density
problem, 
then WTF did you mention "density" in the first place? 

The whole idea of a bypass or dump valve is to relieve pressure (PSI)
which
is contained in the intake plumbing when the throttle plate is closed.
The 
events which take place when the throttle is closed have been previously

discussed and include large pressure spike in the intake plumbing, wave 
propagation effects back through the intake plumbing and compressor
stall. 
The idea is to mount a valve close to the throttle plate so when it is
closed, 
the intake manifold becomes a vacum and pulls open the BP valve which 
re-routes the pressurized air, sometimes its dumped to atm or other
times
its routed to the intake of the turbo, pick your method. No talk of fuel
spikes
yet. 

Now these BP valves are designed with different springs for different 
applications, some are 9psi, some are 14psi and some are 18psi or you
can move into the HK$ or Greddy valves which are adjustable. The 
spring is used to keep the valve closed while pressureized air is
pressing 
against it. To open the valve, you can apply an amount of pressure
greater
than what the spring is designed for or pull a vacum on the spring side
of the diaphram.

I know that gas and liquid are different mediums, but this whole
discussion
is about these valves. Lets not even think about pulling a vacum to open
them.
They are designed to open when the applied pressure exceeds the spring 
pressure. If you put 15psi of pressure on a valve designed for 9psi, the
valve
will open. It doesn't matter what the density of the material is
applying the 
pressure, it could be 200 degreeF air or 33 degreeF water or 77K liquid 
nitrogen or your 98 degreeF finger, when the applied pressure exceeds
the 
spring pressure, the valve opens and whatever material is in the valve
inlet
has the opportunity to flow out the other port of the valve.

In Eric's case, he states he is running 26psi in the intake manifold,
and if he 
was using the K24 app BPV, be it 9 or 14psi, it will open up when the
boost 
pressure rises above that point. So his upgrade to the HK$ valve is a
good 
move, that way all the hot air makes it to the intake manifold.


Steadiboy now writes :
>
Do this experiment correctly with a gas and you'll get a higher Density 
at low temp than high temp. Pilot's worry about Hot and High situations,

Why?  Hotter air has less density, less density = less lift and less 
power.  You can go to extremes in the other direction and get too cold 
and too dense, Siberia for instance where an engine will actually make 
less power, This can be proved with Topping charts for helicopters.

>Pretty basic stuff here...   Again.  

IF you understand it, which by example your showing that you 
don't.........  BTW wanna try to impeach my info, get the books first
and 
read up.  "The Art And Science Of Flying Helicopters" by Shawn Coyle has

a very succient section entitled "Helicopter Engines And Their Controls"

page 71 and 72 will be of particular interest to you.

BTW if it's not a density issue why was water injection developed?  I'll

even give you the answer, it's used primarily to increase the DENSITY of

the aircharge.........

Lesson over.
>

(I raise my arm to ask a question of the self proclaimed heicopter
expert). 

What does airfoil theory and lift have to do with bypass valve
operation? And
why is it even mentioned. BTW, in order to have lift, you must have
flow, so with
our bypass valve, there is no flow until the valve opens, so I don't
think 
aerodynamic lift is part of this issue of why your valve was opening at
9psi.

Or have we just been given a glimpse into the SOc Micro-Unification
Theory
which interweaves heicopter rotor operation with turbocharged engine 
airflow optimization?
-
Dave Lawson