With your air filter just sitting inside the engine compartment, isn't it fed with hot air from around the turbocharger & exhaust?
Why do you offer trumpets with, or without, takeoff pipes?
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 position 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 sufficient 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 500 BHP, the standard air box restricted the volume of air to the engine, reducing the power available. For our new filter assemble, the design priorities were slightly different. Our filter assembly must have excellent filtration qualities 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 sufficient for 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 larger, into the smaller diameters.
If the car was stationary, this could be true! Once the car is moving, there is a considerable quantity of air that comes into the engine compartment, through gaps in the panels, and round the headlamps for example. In our Touring Car applications we did construct a cold air box for the filter, and feed this from the front bumper. This would be the ideal solution, but the costs involved in fabricating this cold air box are usually considered prohibitive for a road car application. The benefits in airflow of our system outweigh any small detrimental effect that it may have. Customers who have fitted our induction kit in place of their standard systems have reported a noticeable improvement in engine response. Also, at an independent test of induction systems, our induction kit was found to give an 8 BHP increase in power to a standard Escort Cosworth.
The standard air box is also used to route the oily fumes from the crankcase breather system back into the engine. They are then burned and expelled into the atmosphere, via the exhaust system. We offer trumpets with take off pipes for customers who wish to rout their breather systems in the standard way. For cars with significantly higher than standard outputs, we recommend that the breather system be allowed to vent to atmosphere at the back of the car. In this application, a trumpet without takeoff would be specified.
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