[s-cars] Bypass Valves and Pressure Losses (Uh, Pizzo??)

[Ned Ritchie]

A few of you already know from that for a sacrifice of about 10 hp at
the top I've used a custom turbo from the folks at 3K that will give RS2
power lower in the rpm range like 2400 rpm
For the purpose of comparison here are the specs.  All are RS2
compressors with the 10 mm shaft.  The differences are only in the
turbine section.

K24  2672 GGC  6.13 -- Stock sized S4/S6 turbine
K24  2672 GGC  6.11 -- Custom size between stock and RS2
K24  2672 GGC  6.12 -- RS2 sized turbine

(Yes, I know the numbers appear wrong for the turbine sizes, but that is
how 3K does it)

On a twisty track or in and around town you can't beat the 6.11 turbine

Ned

-----Original Message-----
From: s-car-list-bounces at audifans.com
[mailto:s-car-list-bounces at audifans.com] On Behalf Of QSHIPQ at aol.com
Sent: Tuesday, December 23, 2003 5:36 AM
To: mik at info.fundp.ac.be; gary.m.lewis2 at boeing.com;
s-car-list at audifans.com
Subject: Re: [s-cars] Bypass Valves and Pressure Losses (Uh, Pizzo??)

I agree Minhea.  Look guys, if you are looking for 26psi on the I5, the
RS2 
will hit it.  If you are looking for Flow at 26psi for xxxhp, the RS2
(modified 
cold side) can hit it (I say up to about 480 or so - Minhea?).  If you
are 
looking for 26psi at low RPM's on a 2.3L motor, I can't think of a
better turbo 
for the task (well I can think of one, but Herr Meyer gets a lot of
money for 
it).  If you take a big turbine and try to get it to do big things with
a 
small motor, you will hit the surge line very quickly.  Surge sucks.

Someone really (hey let's get Mikey) should put a couple of these
mongosized 
turbo hybrids on a turbo dyno.  Chassis dynos only give part of the
story, as 
several here are finding out.  I'm intrigued by solving turbo problems
with 
bypass valves.  In fact Gary, using this logic, you are actually going
to 
'increase' pressure losses to get 26psi at 3k.  Part throttle may just
require 
bleeding of boost as several here will find out.  Especially at
altitude, these 
problems are going to get worse, cuz the turbo is spinning faster to
attain the 
same pressure ratio, which means a bigger problem at part throttle.

IMO, you are going to see dual sequential turbos (already here) and
modified 
scroll design (already here) as alternatives to one monster turbo trying
to be 
both a lamb and a lion.

My .02 arbitraged thru the peso

Scott Justusson
QSHIPQ Performance Tuning





In a message dated 12/22/2003 1:52:22 PM Central Standard Time, 
mik at info.fundp.ac.be writes:
Gary,


If you had had a real RS2 turbo (I know the turbo itself is way too 
expensive, I know!), you could have gotten 26 psi at 2.6k in 4th gear
while 
accelerating WOT from 2k RPM.

Just my 0.02 Euros worth of 20vt engines tuning,

Mihnea

At 11:43 22/12/2003 -0800, Lewis, Gary M wrote:
>Hi Hap,
>
>I oriented it from the bottom (pressure side), as the instructions 
>indicated, with 6 shims, as Pizzo indicated.  It works far better than
the 
>old 710N unit from a pressure loss standpoint (I gained 200 rpm in 4th 
>gear).  My current automotive goal in life is to reduce pressure losses
in 
>hope of getting 26 psi at 3,000 rpm.  I'm making progress.
>
>I think the idea you postulate is really a neat one.  It should provide

>far better response than a shimmed-to-the-max BPV.  Uses vaccuum 
>primarily, not pressure and vaccum to open the valve.  I will try it.
>
>Sorry I took so long to answer, but I needed to think about this for a
few 
>days.
>
>That Trevor is something else, ain't he?  The more I talk to him 
>(virtually of course), the more I want to drive his car.  No to mention

>your of course...
>
>Thanks Again,
>Gary Lewis
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