Creating a Ram-Air System with Stock Airbox
From: Andy Gajewksi (gajewski@tuns.ca)
There has been a lot of controversy on whether to use the cone shaped K&N air filters or retain the stock air box with a K&N filter element. The controversy relates to the air that is drawn into the air filter. In the cone shaped element, it is theorized that warm air is drawn into the filter from the engine compartment and in the stock set up, cooler air is drawn from behind the headlight. As most of you probably know, colder air is denser, thus contains more molecules per volume than warm air. The more air you can get into the cylinders, the more power your car can produce (Look at the forced induction systems of superchargers and turbos. Most use Intercoolers to cool the air).
One can do several modifications to both systems to improve the quality of air entering the filter. In the cone shaped filter design, one can create a shield of some sort to shield the filter element from the engine heat. One can also add extra ducting to channel some cooler outside air in the filter area. However, I will in the procedure below show you how to improve the air supply to the stock airbox.
Ram-air is referred to as a system of air induction where the air is being forced into the filter element. The simplest way of creating such a system is to create piping where one and is just below the filter and the other end is in the front of the car. As the car gains speed, air hits the front of the car at close to the velocity of the car (depending on the natural wind speed and direction). Some if this fast moving air will hit the piping and channel the fast moving air to the filter element. At this point, the air is being forced through the air filter and is readily available for use by the engine.
You will most likely not even notice the difference if you go through with this set up. I do not have any data of before and after measurements of any kind. The cooler air theory is the part that sounded best to me and that is why I chose to create the ram-air system. For those of you who want to be extremely hard core, you may even get some engine heat insulating material and wrap it around the airbox.
You will need to obtain several nuts and bolts, 3" vinyl flexible ducting, a tool to cut through the air box., screen door mesh, a foam type of insulation material with adhesive tape on both sides (about 1/8" wide), bendable metal bracket (about 5" long), some electrical tape and some of your more common standard tools.
Next, follow the procedure listed below (it may slightly vary for VR6 cars):
- Undo the clamp that holds the supercharger hose to the top of the air box and undo the hose.
- Undo the top part of the plastic cover behind the light.
- Undo the clamps that hold the top of the air box to the bottom of the box
- Lift the top of the air box off to expose the filter.
- Remove the filter element (inspect it and replace/clean if necessary
- Undo the 2 rubber rings that hold the bottom of the air box in place
- Take out the bottom of the air box. Make sure you don't loose the rubber bushings on the bottom of the box
- (Optional) remove the long tube that connects the box with the back of light. This was hard to remove on my car.
- Stick on the insulating double-sided sticky tape to the perimeter of the hole.
- Cut the wire mesh screen to fit that opening and stick it to the insulation material. This will prevent flies and other things from entering the air box.
- Undo the charcoal canister and push it through the hole in the frame. Don't worry, the attached wires and tubes will be long enough.
- Take a nut and bolt and create some long plastic spacers (about 2/3" inch long) for it. Insert the bolt from the top into the stock mounting hole closest to the back of the car. Place the spacer from the bottom, attach the mounting bracket of the canister and tighten it up with the nut.
- Now push the canister towards the back and side of the car. An opening for the ducting should appear. Take your metal bracket and attach it to the other stock mounting hole from the bottom in the frame of the car. Bend the bracket to make it fit to the canister bracket. The canister should now be secure.
- Outline with a marker where you should cut the air box. to allow one end of the piping to enter. (make sure its right above the hole in frame). Cut a hole slightly smaller (~2.5" in diameter) and make sure the ducting fits snugly in the bottom of the airbox.
- Direct one end of ducting from the bottom towards the airbox. Install the air box in place and push some if the ducting into the air box. Cut a circular shaped piece of the screen door mesh and fit it over the end of the ducting. Secure it by a rubber band and then use electric tape to attach it firmly in place. This will prevent flies from entering the air box.
- Re-assemble the air box and all related components.
- Cut the ducting to a desired length, just enough to bend it under the lowest part of the bumper. You may attach the screen mesh here as well, I did. Get some heavy wire and wrap it around the end of the duct and attach it to one of the bolts that holds the spoiler under the bumper. The ducting can now be aimed forward. Mine is angled at about 45 degrees down-word instead of straight on. This way, you can hardly see it if one looks straight on at the front of the car.
- You may also secure a piece of wire to the bottom of the canister and attach it to another bolt closer the wheel well. This way it will prevent any potential movement of the canister at the bottom.
Note: The pictures here are obviously without the bumper so you can see how it was done. You can do all this without removing the bumper.
