[s-cars] While we are on the subject of WGFVs...

[Mark Strangways]

Agreed :-)

My only point was (other than the one on top of my head) you don't want to 
loss 2 or 3 PSI due to friction loss and flow restrictions.

Mark S
----- Original Message ----- 
From: "Paul Gailus" <gailus at mindspring.com>
To: <s-car-list at audifans.com>
Sent: Friday, January 13, 2006 10:47 AM
Subject: Re: [s-cars] While we are on the subject of WGFVs...


>I think we have to be a little careful in such discussions,
> because with air flow you need to consider both the static pressure
> and the dynamic pressure (which is proportional to the velocity squared).
>
> In order to get any airflow from the external atmosphere into
> the compressor inlet, the static pressure at the inlet has to be lower
> than the ambient atmospheric pressure.
> The only way you can get air flow into the compressor inlet without
> having a static pressure there less than atmospheric would be to
> have an external source of dynamic pressure supplying high velocity
> air (i.e., another blower).
>
> I agree that you would want to minimize unnecessary external pressure
> drops in the inlet ducting that restrict the flow. However, near the
> compressor inlet the static pressure is going to be significantly
> below atmospheric at large flows.
>
> To maximize flow, you would want a bell-mouthed transition
> (velocity stack) from the atmosphere to the compressor inlet
> to minimize energy losses along the way.
> The total pressure (static plus dynamic) will then be the same along
> the transition from the external atmosphere to the compressor inlet.
> At the inlet of the bell, there will be mostly static pressure and little
> dynamic pressure (i.e., low velocity). At the outlet of the bell, there
> will be a lower static pressure in exchange for the increased
> velocity (i.e., dynamic pressure) based on conservation of energy and
> Bernoulli's principle.
>
> Paul
>
> -----Original Message-----
>>From: Mark Strangways <Strangconst at rogers.com>
>>Sent: Jan 13, 2006 7:52 AM
>>To: Djdawson2 at aol.com, Eric_R_Kissell at whirlpool.com
>>Cc: s-car-list at audifans.com
>>Subject: Re: [s-cars] While we are on the subject of WGFVs...
>>
>>The last place you want a negative pressure (as related to atmosphere) is 
>>in
>>the inlet to the turbo.
>>It will rob you of boost, and if the turbo is at or near the operating
>>extreme limits it can push it over.
>>I contend that there is not much negative pressure to be found there, this
>>is why I fought so hard over the whole vacuum issue as it relates to the
>>wastegate. Until Dave sprung the little venturi concept on us, that 
>>changes
>>things.
>>
>>Mark
>>----- Original Message ----- 
>>From: <Eric_R_Kissell at whirlpool.com>
>>To: <Djdawson2 at aol.com>
>>Cc: <s-car-list at audifans.com>
>>Sent: Friday, January 13, 2006 7:35 AM
>>Subject: Re: [s-cars] While we are on the subject of WGFVs...
>>
>>
>>>
>>> It would be interesting to see how the vacuum created to the WG by the
>>> venturi effect in the WGFV compares to the vacuum that exist in the line
>>> to
>>> the compressor inlet, i.e. how much bigger is the venturi vacuum than
>>> compressor inlet vacuum?
>>>
>>> I have to assume that the venturi creates more vacuum than the 
>>> compressor
>>> inlet, else the WGFV would not require the venturi effect.  This makes
>>> sense relative to the venturi systems used by "inexpensive shop tools" 
>>> you
>>> mentioned.
>>>
>>> Thanks,
>>> Eric
>>>
>>>
>>> _______________________________________________
>>> S-CAR-List mailing list
>>> S-CAR-List at audifans.com
>>> http://www.audifans.com/mailman/listinfo/s-car-list
>>>
>>
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