Fording Depth vs. Snorkel Height

[Retired Tanker]

At the risk of being branded a heretic...

Do you really need a snorkel intake at the roof level?

I mean, unless you're trying to assault a beach from a landing craft, how often are you intentionally crossing water that washes over the windshield of your vehicle?

And, to be fair, I suppose having the intake that high would keep water out if you stalled mid stream, but then your exhaust would flood back to the heads, anyway...

Or, the only other option my be just over the hood...which may be too low, so the next logical location is at the roof.

And, we're just talking water issues here. Dust is an entirely different issue, which pretty much justifies putting the intake as high as possible.

And lastly, there's the cool factor. And if that were the ONLY factor, just glue / velcro a non-functioning snorkel to the fender and A-pillar, and voila!! You're cool!!

 

[MOguy]

At the risk of being branded a heretic...

Do you really need a snorkel intake at the roof level?

I mean, unless you're trying to assault a beach from a landing craft, how often are you intentionally crossing water that washes over the windshield of your vehicle?

And, to be fair, I suppose having the intake that high would keep water out if you stalled mid stream, but then your exhaust would flood back to the heads, anyway...

Or, the only other option my be just over the hood...which may be too low, so the next logical location is at the roof.

And, we're just talking water issues here. Dust is an entirely different issue, which pretty much justifies putting the intake as high as possible.

And lastly, there's the cool factor. And if that were the ONLY factor, just glue / velcro a non-functioning snorkel to the fender and A-pillar, and voila!! You're cool!!

Every kit i have seen but them at roof height. I have ever also seen allot of homemade ones putting them lower. On jeeps, maybe other vehicles, i have seen people run the intake up through the cowl and have a lower intake. For dust in have seen people use the hummer intake (military) that spins and seperatesout the dust before it goes through the the filter. I suppose having the the intake his could help.

As far as cool factor? There are people who just got for the look, but snorkels can serve as real purpose. If you are going to run deeper water you may need to protect electronics and breathers also.

 

[Johnny Christensen]

My vehicle just have the half-length snorkel. It's standard issue for Geländewagen with fording kit (commercial and military use - not the cafe racers), up to model year 2010 where it got replaced by the full length design. Where I have yet to be in serious trouble with the waterline, after all it can take 1.2m. It is a serious pain in the rear, to have the air intake positioned right at earheight - when you run with open windows.
That's also something to consider.

 

[TeriAnn]

For most people a snorkel is BLING. Their instant statement to their co-workers that they are not trapped in an endless day to day drone rut. Add a roof top tent to go with the snorkel and you have the classic image.

Unless you have an old school diesel with no electronics the deepest you can go is where an electrical circuit controlling an engine shorts out. Alternators do not like to operate underwater and mechanical cooling fans can bend blades when they strike water. Perhaps the image started with the Camel Trophy Land Rovers all with snorkels going up to the top of their roofs. The Camel Trophy Defenders and Discoverys all had mechanical diesels that could run submerged. :snorkel:

Where a snorkel really shines is getting clean air to your engine on dusty trails when you are not the first in a line of vehicles. It has been my observation that dust at radiator intake level can be very thick and the air inside an engine bay can be very dusty. To keep the air filter from filling up quickly you can add an air intake outside the engine compartment above the hood. I personally never noticed much difference in dust levels between the bottom of the windscreen and the top of the windscreen. General Dynamics probably didn't either when they placed the Humvee air intake at the base of the windscreen.

Air has mass and a snorkel is like a long skinny straw. An engine is basically an air pump. The bigger the engine the more air it needs to draw. The harder it is to draw air into the engine the less power it can produce. The larger the diameter and smoother the walls of the intake passage, the less energy it takes to move the air into the engine. It takes energy to change the direction of a moving mass. Ideally your intake passage should have the fewest bends and have enough cross section area to minimize resistance to air flow.

The job of a prefilter is to remove all the heavier dust particles so the air arrives at the air filter about 90% cleaner than when it arrived at the prefilter. This allows the filter to stay clean and minimally restrictive for a much longer time under heavy dust conditions.

I built my intake system from Donaldson parts. Donaldson is a company that provides air intake systems to commercial vehicles and earth moving equipment that spend long hours working in very dusty conditions. My system starts of with a Donaldson prefilter mounted six inches above my front right fender. The prefilter sits directly above my horizontal air filter mounted to the underside of my fender top. There is an about 8 inch straight run to the air filter. The air filter's out tube is inline with the engine's intake so there is a short straight horizontal run from the filter to the engine's air intake. The system starts with cleaner cooler air at the base of the windscreen, 90%+ of the dust gets removed by the prefilter, the rest gets removed by the filter. There is a minimum of air direction changes and the tubes are wide enough for the engine's requirements. And my mini snorkel does not block my vision. Sometimes it is best to focus on functionality to solve a problem and ignore current bling fashion.


You can just see the bottom of my horizontal Donaldson air filter along the top of the wheel arch.

 

[Root Moose]

When you drop the nose of the truck into a hole the height is helpful. Suddenly it isn't that high. Plus the height reduces the "stuff" obstructing the outward view.


2¢

 

[Kevin108]

I've seldom needed one on the trail, but it's bought me peace of mind several times. My snorkels are for getting to work. Tidewater floods several times a year. I'm in a position at work where I'm expected to make it in no matter what. It helps that the vehicles I need for that are justified by my hobbies.

That said, different vehicles call for different snorkels.

My truck was on 4" of lift and 35s. With an intake height over 48 inches, I didn't think it needed a snorkel. Instead, it got a new engine. Doh!

After that, I wised up.

On my XJ, I'd have had to remove the fender and relocate the washer fluid bottle. It got a cowl snorkel instead.

On my FJ, all I had to do was drill a few holes. It got a conventional snorkel.

 

[PIC4GOD]

I hope you took care of the breathers too. Water fording is more than just a snorkel to protect the engine.

 

[Kmrtnsn]

The roof-line location is party because of dust and secondly because you don't always enter the water you are crossing at a level position. Some crossings require dropping nose down over a bank, although the water is only say 36" deep when you start it's 7/8's the way up the hood, nearly to the windshield.

 

[762X39]

I always thought snorkles were to draw in clean dust free air. I have crossed a few rivers in my 404 where I would have preferred a raised intake because of the angle of entry though.

 

[AFBronco235]

I really do hope everyone is also thinking of the axle tube breather lines and similar. The point of these tubes is to prevent air pressure differential from building up inside cavities such as axle tubes and forcing fluids out through the seals. Most will already have a breather line up away from where water and dust can enter the cavity, but its best to run them all up to a point above the engine, with filters on the end to help ensure the longer lines don't get clogged with dust. Its a simple enough mod, but if its not taken care of, or if the original tubes are dry rotted like mine were, water can easily get into components and turn whatever fluids are in them into mud, quickly ruining whatever you have in there.

 

[Retired Tanker]

General Dynamics probably didn't either when they placed the Humvee air intake at the base of the windscreen. .

The USMC actually added an extension to raise the intake, but also extended the exhaust. That was the reason I said "Assaulting a beach" in the original post.



You can see both in this picture.

 

[toylandcruiser]

I always thought snorkles were to draw in clean dust free air. I have crossed a few rivers in my 404 where I would have preferred a raised intake because of the angle of entry though.

404 engines are completely sealed. It'll run completely submerged.

 

[lugueto]

To answer the OP:

I cross rivers that run up to my windshield a few times a year, as well as all of my buddies.

Most of us have gotten stuck mid crossing, with water covering the shifter consoles, and every single time the engine has stayed on thanks to the snorkels. We completely seal the filter housings, though.

If your vehicle stalls mid stream, you're screwed with or without a snorkel. The idea behind having it is to reduce the risk of stalling due to hydrolock as much as possible in the first place, right? Once you stalled, well, you're out anyway.

I believe having an open intake ram on top of the hood will be just as risky as having it in the fender, if not more. Due to the initial wave that goes over the hood when on deep crossings.

Don't think that since a piece of equipment is not a necessity for your conditions and vehicle, it will be so for everyone else.

Also remember that a snorkel serves two purposes, cleaner intake air and safety when crossing water. It must be located as best as possible in order to serve both functions, which is roof height.

 

[87Warrior]

It doesn't take much water to hydrolock a motor. The quantity of water needed to lock up a motor would be dependent on its combustion chamber volume. For instance, if a 1/4 cup of water reached any given cylinder in a Jeep 4.0l it would hydrolock.

A snorkel is an effective way to move the air intake location out of harms way. On a typical Jeep this is right behind the headlights. My thought on a snorkel is they help protect against those accidental front end dunks in a basic water crossing. No matter how well you can read the water's bed, surprises still happen.

I managed to soak the stock air filters in my Jeep TJ a few times with water due to the front end finding a hole. Since I have no desire to drive through water up to the dash I opted for a manufactured cowl intake. This set up is great, but the intake noise is pretty intense and will continue to drone on the highway. When it came time to address the intake on my Jeep Comanche, I went with an ARB style snorkel because it was the most simple and clean alternative to a cowl intake I could find. An intake sticking up in front of my windshield wasn't an option I was willing to consider, so I was left with one option that piped the intake along the a-pillar to the top of my windshield. As a bonus, intake noise is nonexistent!

 

[jeep-N-montero]

I really do hope everyone is also thinking of the axle tube breather lines and similar. The point of these tubes is to prevent air pressure differential from building up inside cavities such as axle tubes and forcing fluids out through the seals. Most will already have a breather line up away from where water and dust can enter the cavity, but its best to run them all up to a point above the engine, with filters on the end to help ensure the longer lines don't get clogged with dust. Its a simple enough mod, but if its not taken care of, or if the original tubes are dry rotted like mine were, water can easily get into components and turn whatever fluids are in them into mud, quickly ruining whatever you have in there.

I have always zip-tied the stock breather lines 6-8 inches above the stock height and been working great so far, and seeing as we live where water crossings are about zero I should be all set. In order to have water crossings you need to have rain, and we just don't get much of that out here. Occasionally you will see flash floods in southern Utah, for those you just park on higher ground and wait for it to pass.