I've noticed alot of OEM snorkels tend to have the mushroom top design.

Like those found on the Land Rover Defender



Mercedes Unimog



Toyota Land Cruiser



I've even seen some buses come with this style snorkel..

Of course, the aftermarket specializes in the traditional Ram Air design..

Which design do you guys think is best and why? (There must be a reason why manufacturers favor the mushroom type design, I just don't know why)

An example of a Safari Snorkel and how it works.



http://www.4x4connection.com/tech/snorkeltech.htm

The heavier dust and water particles will flow to the outside of the inlet tube and be expelled through the drain slots. Clean air alone should enter the inlet tube. At speed, you may experience a Ram Air effect which should help improve power.

Your typical mushroom snorkel will have angled inlets to promote air swirl, and pulls air from directly below. I can't see this design taking advantage of any possible ram air effect though.

I am actually interested in purchasing a snorkel like this one and my main concern is the effect they will have on your engine at speed.

I know if you turn a Ram Air snorkel backwards, for use in extremely dusty conditions, you are not allowed to drive over a certain speed because you can possibly starve the engine of air. A vacuum effect causes this I believe.

Looking at the mushroom design, do you all think the vacuum effect is possible at highway speeds of 60mph?

I can't imagine any OEM designing a system that would have high speed intake flaws that would cause the engine to starve for air. They put a lot of engineering into their systems. That being said I incorporate a Safari Snorkle into my intake system and really have had no indication of added or detracted performance from the " ram " effect.  My Snorkle had been on my tracker since before I went to forced induction, so I have reference for either way. I got more of a performance boost from replacing my stock air filter with a K+N.
As far as the muchroom top goes, looks like it work great IMO, but I like the way mine looks better. 

The "mushroom" head that 3stage posted uses a centrifugal separation technique to spin dust & water outwards and away from the central air intake, thereby achieveing the same thing that Safari snorkels does with their "ram" head.

As far as running the ram head backwards causing engine damage - not very likely - I've seen test results where someone set a manometer to measure the differences in air pressure in the snorkel at various speeds with the ram head facing both forward and backward and whilst there is a difference, it was not significant - additionally - at no time was there positive pressure to suggest that there was in fact any ram air effect.

If you want "proof of the pudding" however - we have been running a turbo-diesel Toyota Hilux with a Safari snorkel, ram head backwards for several years now with no ill effects.  We do it this way to reduce dust inhalation (which is the reason the vehicle has a snorkel - not for water crossing).

In harsh conditions, I noticed my intake tends to pull in alot of dust / dirt as it sucks from inside the fender (the factory location).

The ability of the snorkel to pull cleaner air from the roof line AND it's ability to separate dust & water from the air is my main reason for buying. (Plus they look hella cool!) I'm not a fan of deep water crossings, so that is not an issue for me.

I know it was mentioned on either Safari or ARB website about not running them backwards, but it is good to know any possible 'vacuum' effect is very minimal. That answers the main question I had about the mushroom design.

Will post pics when I get this thing, it will be a fully custom install..