Installing a snorkel onto your 4WD is definitely in the list of top five things to do to make a 4WD more capable off road and,unlike other modifications, it is relatively inexpensive.
Most manufacturers build engines that have air intakes that are facing forward in the car's engine bay or inner guard, as close to the grille as possible, because this is where the air is coolest. A snorkel lifts your 4WDs air intake, normally to around the car'sroof height.
There are a few reasons why a snorkel is an effective performance enhancer for a 4WD. Whether your car has a petrol or diesel engine, it uses an air/fuel mixture to create combustion.Because installing a snorkel raises the air intake to roof height,where the air is cooler and therefore denser, you can burn more fuel more efficiently.
Another great advantage of the air intake being at roof height is the fact that up there you will get less dust. This will reduce wear and tear on your whole engine because your air filter doesn't have to work as hard, which also means it will need replacing less often.
In terms of improving off road performance, where your 4WD draws air from determines how deep it can go through water. If you have not modified your car's air intake and it is at the front of engine bay facing forward, you can only drive through water of that is half a metre deep before you are likely to get water in the engine, an activity that we all know that can be very expensive. Because a snorkel drastically lifts the air intake, then you should be able to drive through much deeper bodies of water, as long as the connection was well sealed during installation.
As well as providing easier water crossings and cleaner, cooler air, both the major brands of snorkels available offer what is called an 'air ram'. The air ram is the component that sits on top of the snorkel and it does two things.
First, because it is facing in the direction of travel, the snorkel is forced through the air and creates a ram effect which can improve engine performance.
Secondly, the air ram separates any water or moisture that enters the snorkel before it gets to the engine. Because water is heavier than air, the 90° bend of the air ram causes the heavier water to move to the outside surface where it can drain out.
When it comes to buying a snorkel, there are two major brands,Safari Snorkel and Airtec. They are both made of polyethylene and models are available for most popular cars.
The advantage of commercially available snorkels is that they have been flow tested for each model, so you are guaranteed that it won't restrict air flow to your engine.
Your other option is to get a snorkel custom made. There are some great examples of custom snorkels out there, from stainless steel to PVC pipe, and they do the job well. I would recommend getting-your snorkel professionally fitted, as it is useless for water crossings if the connections aren't watertight.
Source: Camper Trailer Australia #51