[s-cars] Re: [200q20v] intercooler

[Calvin & Diana Craig]

Question.....was Audi as aggressive as I think when designing the S4 boost
map?  I regularly run 16 lbs under hard throttle through gears 3-5 at 6k
feet.  That's a PR of 2.33...awful close to the 2.4 we are relying on here.
This is not to mention the "overboost mode which I can pull for longer than
6 seconds for sure at 20 psi.  This yields a PR of 2.67.  This is a TOTALLY
STOCK S4.  What gives with the 100% failure rate?  I know of at least 2 more
people that are running more boost than this at this altitude by a couple of
psi.  One of them happens to be my Audi mechanic who has a K24 on a 5K with
tons of miles on both the K24 and the engine running between 20 and 23 psi?
This also says that the standard chip upgrades only (which run 18 psi at
this altitude) have a PR of 2.5....now how many people on this list have a
chip only upgrade with the stock K-24 and live in Colorado?  I would guess a
BUNCH.

What am I missing here, as I am thinking about chipping my S4 with a Lehman
chip but certainly don't want to sacrifice the K-24!

--Calvin Craig
Parker, CO
'92 S4
'91 200 TQ
'89 200 TQW
'72 Formula Firebird

-----Original Message-----
From: qshipq at aol.com [mailto:qshipq at aol.com]
Sent: Tuesday, December 04, 2001 3:56 AM
To: brianl at starsys.com; mlped at qwest.net; b.m.benz at prodigy.net;
brett at cloud9.net
Cc: 200q20v at audifans.com; s-car-list at yahoogroups.com
Subject: [s-cars] Re: [200q20v] intercooler


Brian:
Remember that turbos are mathed and Mapped using Pressure Ratio.  Pressure
ratio is:
PR = Boost pressure + ambient/ambient
So, if you are running 20psi in CO, say denver
PR = 20 + 12.7/12.7
PR = 2.58

Looking at the k24 turbo Map, 2.57 isn't listed, which means you are
overspinning the turbo, and your 130F inlet temp is prolly way low.  In CO,
I'd target 18 as the maximum boost pressure, 16 will keep your turbo within
the designed Map @ 2.26PR

The biggest risk you have right now is that you have no room for error.
Check your bypass valve recently?  Any hoses leaking?

HTH

Scott J

In a message dated 12/3/01 3:22:26 PM Central Standard Time,
brianl at starsys.com writes:


Im using a peak flow 19.7 lbs/min (.85 VE) as the mass flow rate.  I'm
using an inlet air temperature of 130F (wag).  Up here in CO.  I'm spinning
my k-24 at 140,000 at 20 psi????


Brian





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