| The
engine of a high performance vehicle can be compared with the lungs of an athlete. To
function efficiently, it is essential that they can be fed with sufficient quantities of
clean, fresh air. For a standard production vehicle, the design of the air filter box is
controlled by a number of constraints. Obviously, it must contain an adequate filtration
medium to prevent dirt & foreign objects being fed into the engine. It must be fitted
in such a positon that allows simple plumbing from it to the inlet of the engine. It
should not be expensive to produce, and the filtration medium used should be simple to
change, and cheap to manufacture (to control service costs). It should also suppress the
noise generated by the induction air as it enters the engine or turbocharger. Finally, it
should be capable of passing sfficient volumes of air for the engine to produce the
required level of power. The
route that the air is forced to take through a standard Cosworth air box is rather
convoluted. It enters the base of the air box through a square hole with a small cross
sectional area. Once inside the air box, the cross sectional area expands greatly to allow
the air to pass through the flat, air filter element. When the air reaches the far side of
the filter element, it is then sucked back out through a small outlet hole, and via a
rubber hose, into the turbocharger inlet.
Another restriction that the air
faces when it tries to enter the engine is the air filter element itself. As explained
above, this is manufactured to a strict (low) price policy, and because of this, it does
not have a very high level of efficiency. When it is totally new, the airflow rates of a
standard filter are acceptable, but as it works, it becomes choked with small dirt
particles. These dirt particles then prevent the air from passing through this part of the
filter, reducing the effective area,and restricting the airflow.
The GGR cone & trumpet
induction kits are another item on offer that we originally designed for use in the
Touring Car. With power outputs in
excess of 500BHP, the standard air box restricted the volume of air to the engine,
reducing the power available. For our new filter assembly, the design priorities were
slightly different.
Our filter assembly must have
excellent filtration qualites to prevent damage to the fragile turbocharger compressor
wheel. Pass sufficient air for power outputs in excess of 500 BHP, (even when slightly
dirty), and offer no restriction to the incoming air. The filter that we use is conical in
shape, and has an overall surface area that is capable of flowing sufficient air for power
outputs in excess 750 BHP (which should be sufficiant tor most applications). This filter
is made exclusively for GGR by K&N filters, and carries their usual million-mile
guarantee.
The best (&unique) feature of
our induction kit is the part to which the filter is fitted. To channel the incoming air
from the large diameter of the filter, down to the smaller size of the turbocharger inlet,
we use a trumpet style adaptor. The shape of this was designed to give the optimum
aerodynamic profile for air to flow from the largerm into the smaller diameters. |
