Re: Fire in the hole... Ross please read

[QSHIPQ@aol.com]

In a message dated 97-06-14 05:40:40 EDT, you write:

<< > The blowoff valve serves 2 perposes
 > 1-keeps pressure out of the pipes during 
 > shifts.
 > 2-keeps the turbo freewheeling
 > The reason it's not routed back into the
 > system is,Who wants Hot air back and the kjet 
 > really sucks!
----------------------------------------------  Then Phil write: 
 >I'm gonna have to think about this ...
  
 >In theory, dumping metered air from the system will cause enrichment.  The 
 >timing of this could be interesting, because (I presume) the purpose is to
up-
 >shift - the engine's revs will be falling to match the new gear, and the 
 >mixture will be rich for a very short period as fuel arrives without some
of 
 >its air.
 
 >This sounds very interesting.  The system would have _very_ different
short-
 >term characteristics from a system that retained the air by recirculating 
 >compressed but uncooled air back into the turbo.  In such a system you
would 
  >>
Phil is correct in his thinking.  Ross, the air you are putting back into the
intake side of the turbo has already passed thru the IC, so not sure you
really have to worry about the heat problem.  More specifically, I would
worry about a backfire problem.  The rich fuel spike can eat O2 sensors, and
cats (assuming this not to be a problem), and it can burp fire back into the
intake tract, stalling the turbo or worse case going all the way back to the
CIS.

The accepted theory of fuel and air measurement, is that all measured/metered
air should stay closed loop, important to both CIS and Mass Air and Dense Air
systems.  Rich fuel spikes are easily avoidable, and any empirical test of a
closed loop system won't support the notion that a dump to atmos is a good
idea.  For more discussion on this, a quick visit to the talon list has some
measurements of atmos dump vs closed loop.  Those boys (and they play in the
350-400hp range) indicate that open only gives a tenth or two on quarter mile
times, so most run open ONLY at the track, closed loop everywhere else.  And
that is on a very sophisticated MAS computer.  With the CIS, I really doubt
you would get any improvement at all, in fact I would (btdt) bet just the
opposite.

Hope this helps you go even faster.  Phil's point well taken, short term
fine.  Long term, you are literally playing with fire.  

HTH

Scott