Re: Another reason Audi doesn't go

["Graydon D. Stuckey" <graydon@apollo.kettering.edu>]

On Fri, 13 Mar 1998, Ned Ritchie wrote:

> every input & output on the engine. The lab scopes showed a slight
> ripple in the output from the Mass Air Flow Meter and reduction of pulse
> width on the fuel injectors.
> 
> In previous experiments with other S4 enhancement systems they had
> installed a K&N cone air filter.  They didn't think the ripple was
> enough to worry about but one tech said "hook back up the stock air
> box."  Going back to the stock air box that had the plastic air
> straightening passages corrected the problem!

In my testing of HVAC ducting, I have found that I can flow more air 
through a duct if I reduce the turbulence.   Its also quieter.  I even 
went so far as to place a piece of aluminum honeycomb in the inlet to the 
main blower of the new Seville HVAC system.  It worked, so we built a 
plastic version of it.  You can check it out at your local dealer.

> Apparently the cone filter when supplying enough air for over 25 PSIG of
> boost created just enough turbulence to upset the reading from the hot
> wire and cause the engine computer to reduce fuel and reduce maximum
> allowed boost.

I imagine the turbulence would cause the hot wire to cool unevenly, 
thereby giving a false, lower airflow reading.

> This also makes me think about the "?power tubes?" that are placed in
> the air intake track, and that I now see being advertized in "Turbo &
> High Tech Performance" magazine.  I guess I'll have to test one.

Or the "hurricane" vortex generating devices?   :-)

Interesting find, Mr. Ritchie.

Later,--------------------------- -   -   -   -
Graydon D. Stuckey		 / \ / \ / \ / \
graydon@apollo.kettering.edu	|Mr. Muffler... |
810 733 0255			 \ / \ / \ / \ /
--------------------------------- -   -   -   -