[s-cars] MAF screen removal-please explain

CaptMagu at aol.com CaptMagu at aol.com
Sat Apr 19 12:46:24 EDT 2003

[ Picked text/plain from multipart/alternative ]

I'd like to make a minor correction here. The author of the Negative Boost
articles was not trying to get more boost. His main objective was to get it
quicker. He was attempting to lower his boost threshold. In fact, he built a
DIY boost controller that did credible battle against waste gate creep but
retained the stock boost levels. By removing any of the negative boost
nasties and cleaning up the intake tract he was delivering the air to the
compressor section with less effort. This may in fact translate to higher
potential boost but more impotantly it will lower boost threshold.

In my experiences as an aeronautical engineer, mostly limited to looking at
and admiring beautiful airplanes;-), I have never seen any benefit to a scren
as an airflow tool. The egg crate affair on the RS2 MAF does provide a
benefit to flow stabilization. The same can be said of the long tube that is
hidden in the top of the airbox and that connects to the MAF. Both of these
devices are attempts by the Audi engineers to reduce turbulence and
straighten out the air flow as it proceeds through the MAF.

In the case of the Pederhousen Big MAF, it is directly mounted to the top of
a Ford snorkel type aircleaner. The MAF we use does not have the egg crates
but does have screens. I have removed mine but I believe Mike still has his
in place. I did remove them one at a time and noticed a 100 rpm reduction in
threshold overall. With this set up I have no drivability issues whatsoever.
A lister who recently drove my car noted that it was easier to drive around
town than his stock 97 S6. It had a lot more grunt down low. His car felt to
him like it was going to stall during gentle starts. According to him mine
felt much more substantial.

I really can't understand why we're having all this discussion about a very
easy DIY mod. The proof should be in the results. Remove your MAF and remove
the screens. You might want to establish some sort of baseline test before
and then test again after. I like to use a 6th gear pull up an incline. I
establish at what rpm I develop full boost. I start the pull at 2500rpm and
go to full throttle. I simply note at what rpm I develop full boost. Right
now, I'm at 3200rpm. If things are better great leave the screens off. If not
put them back in. HTH

Hap, wonderin in Everboost, Maguire

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