RE: Airbox Info

[Marc Gallagher <mgallagher@Langan.com>]

of course we are talking about an airbox INSIDE the hood without 60 mph
eddies.  the way you cut a hole will affect the flow through it, but based
on the slight negative air pressure we are talking about, I am not sure it
would be noticeable.  I can certainly understand on a bike since the air
outside is moving at a high velocity over the holes, essentially blocking
more air from entering the box.  But enough of this horse.

Marc
97'  GLX - Red/Black


-----Original Message-----
From: Bill Hussey [mailto:list_squid@hotmail.com]
Sent: Wednesday, June 27, 2001 7:48 AM
To: jettaglx@igtc.com
Subject: Re: Airbox Info


>From: TRedGLX@aol.com
>Date: Tue, 26 Jun 2001 22:53:06 EDT
>
>In a message dated 26-Jun-01 21:16:53 Central Daylight Time, 
>ONELOMNE@aol.com
>writes:
>
><< The previous owner of my 97 JETTA VR6 decided he wanted to make swiss
>cheese out of the lower 1/2 of the stock air box.  >>
>
>Actually, you can leave it that way. I t won't hurt a thing, and will
>somewhat improve the breathing of the VR6. My airbox is missing the entire
>lower-front, for example. Makes a nice throaty roar on hard acceleration, 
>and
>it breathes much better besides.
>
>It's one of the first 'cheap' mods that many VR6 drivers do.

This is completely incorrect.  The airflow into, and through and airbox can 
change a torque curve rather drastically.  If drilling holes is what you are

doing, then the proper size, placement, and smoothness of the holes 
themselves will affect air flow velocity, air box pressure, and depending on

where the holes are drilled ... air temperature.

I brought my '97 VFR750 to a specialist in Canada for dyno tuning.  After 
the custom jets were installed and the K&N filter cleaned ... he brought out

a moving box filled with VFR air box tops that were all modified 
differently.

The one with a bunch of holes drilled into it made decent power, but the 
because the air flow was from multiple directions it made for very erratic 
airflow within the box and the the dyno chart was funny, there wasn't a 
smooth part to the power curve at all.

The cover he tried with the top completely cut off was the worst of the 
bunch.  It made more HP and torque than the others with the dyno fan on low,

but as he cranked up the air speed on the fan (a mini wind tunnel if you 
will), the lower pressure area around the bike sucked air from inside the 
bodywork where the airbox was.  Without squeezing the remaining air through 
a hole which increases the velocity of the air, the air being sucked in was 
very slow moving and was having a hard time being sucked through the filter.

  So the result was that when the fan was pushing air at 60mph or so, the 
bike made less power throughout the entire rev range than with any other air

box cover.

The one we settled on, the one that made the smoothest power with the best 
numbers was a stock airbox cover with the snorkel removed and the snorkel 
hole slightly enlarged and smoothed with a dremel.  The differences we saw 
in HP between the different air box covers was 5 at the rear wheel ... which

I consider to be a lot when we're only talking about an 88 RWHP bike (in 
stock format, it made 100.2 when we were done).

Bill
'98 GLX for sale
'01 325Ci absolutely unreal
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