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Subject:Re: cutting out bottom of airbox to increase air intake and add HP
From:Robert Keezer
Date:Thu, 25 Dec 2003 00:25:02 -0800

<<i was thinking the same thing - but  wont drawing in warm air from the
engine compartment reduce HP?    isnt cold air more dense, and colder,
denser air
is better for fuel/air mixture?>>

Wait! Before you get out the Dremel there is something you should know about
airboxes.

First, if your engine is carburetted you will throw off the fuel jetting.

The air/fuel ratio is calibrated by the amount of air/fuel metering. If you
increase the air intkae, you need change the jet sizes to maintain the
fuel/air balance.

Airboxes also contriibute to the Venturi effect, that is , air that is drawn
thru a smaller opening lowers the air pressure inside the airbox. This air
pressure differential "sucks" the air into the intake . You are ridding your
self of a benefit if you omit the airbox.

Also the airbox dampens intake noise.
As Chris points out, the air thru the intake is cooler and denser than the
warm air in the engine compartment.  The denser air increases combustion
effeciency.

Finally, the airbox protect the filter element and prevents large pieces of
dirt and debris from damaging or obstructing the airflow.

I noticed that a Jetta airbox that had holes bored in it was much dirtier
inside that ones left alone I saw in a junkyard.

The air box was engineered with all this in mind and ridding yourself of it
all is a slap in the engineers face- Ok just kidding- but you know they had
to figure this out and not by accident.

Merry Christmas!

Robert

1982 westfalia

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