Custom Snorkel Design
The first attempt at a custom snorkel.
There are a lot of good snorkel designs out there, both commercial and
private custom designs.  I was unable to incorporate any of them into my
truck for a variety of reasons.  I still wanted a way to prevent water from
entering my engine in the event of a deep water crossing, so I had to come
up with something a little different.....
The ARB snorkel is an excellent design and probably worth it's rather high price tag, but
I found several  problems.  First it's not available for my model year truck and engine
combination.  Second, I have a police type spotlight mounted right where the snorkle is
suppose to go.

One of the more popular custom snorkels that I've seen is the type that runs a piping
system from the factory airbox in between the engine compartment side wall and fender
and runs the intake pipe up and to the rear of the driver's fender.  This design is also a
good one, but I had several problems with my application.  My inner fender skirt, which
would have prevented water splash from the tire to the intake was removed to clear taller
tires.  The intake tubing appeared to be a bit restrictive to me and I was no longer
running the stock airbox and airfilter, for which this design works best.   A revision of this
design plumbs the intake back into the engine compartment (seen in picture below).  This
does seem to at least solve the issue of water splashing from the tire getting into the
intake.   While this is still a good design, I chose a different route.
A popular custom design, inexpensive,
some drawbacks, but a good design
This picture shows the fender removed
for installation.
ARB design snorkle.  Well made,
works great, but is a bit spendy and
hard to come by for some
models
For my own design, I elected to do something a little different.  I wanted to draw air from
outside the engine compartment, but I couldn't figure out a way to incorporate a poor
man's ARB design, without cutting a hole in my fender or hood.  Something I wasn't
crazy about doing.  In addition, I was concerned that an external type snorkle would get
snagged off my truck, if I went under some low hanging trees or brush.

I settled on a design that incorporated drawing outside air, keeping the design
completely internal, and moving the intake to the highest possible internal location.

My current intake system had already under gone several revisions.  First off, I dumped
the stock intake box a long time ago in favor of a  K&N cone filter and custom (and
cheaply) build copy of the K&N filtercharger system.   While running this system for a
while, it was painfully obvious that it was subceptable to gulping in tons of water given
the right conditions.  I later modified this system by covering the cone filter with a large
plastic cylinder that a had a large opening at one end.   This resembled the factory airbox
with the exception that the filter was of the higher flowing K&N type, the intake opening
was much larger and the opening faced away from the front of the vehicle, where it was
most vunerable to sucking in water.

I later added a 4 inch flexable hose from the intake cylinder housing opening and
plumbed it into the firewall just abovethe clutch reseavor.   I did have to cut a hole in the
firewall.  I chose this location, because the area behind the firewall draws air from
outside the engine compartment.  In addition, cold fresh air is accessed using the vents
behind the hood.  This area is a relatively vast unused space that only houses the
driver's side windshield wiper linkage.   Any water that would enter the compartment, is
quickly drained away.  Water is not allowed to pool in this compartment.   I tested this
theory by dumping a bucket of water into the hood vents.  Within seconds all of the water
that was dumped into the vents, was on the ground below the truck.

The design is not flawless, of course.  If the water level or a front running wave where to
exceed hoodlevel, the amount of water that would dump into the intake compartment
would stand a good change of making it's way into the intake system.   But I have no
desire to drive in water that deep.   I designed the system with  water resistance in mind
rather than the more difficult to attain than waterproofness.  The other drawback in my
origional design is that in like all of the other snorkel designs, the added plumbing
restricts the air intake somewhat.   But this was solved later on....
My original intake
design, plumbing
intake from custom air
box (with K&N cone
filter inside) to the
backside of firewall.
While the intake hose was a decent 4 inches in diameter, the space restrictions required
me to snake it around several unrelocatable items  before plumbing it into the firewall.  
This added length and therefore restriction to the intake system.   While the air intake
seemed adequate, I had just added a header and a new custom exhaust system and I
was looking to make the best use of the freer flowing system.

I decided that if I cut a hole on the top of the custom air box and had some sort of way to
easily close it off before crossing any streams or entering any deep water, I could have
the best of both worlds.   I mounted a trap door mechanism to the air box.  This allowed
me to have a second source of fresh air for the intake system, with the option of closing
the second sourse of air off so that the only sourse of air was behind the firewall.
Click on images for larger view
Second air intake fully open. Allows air
to be drawn in from two sources.
Second intake partly open to illustrate how trap
door works.
Second air intake fully closed.  Only source of air
intake is behind firewall, away from most water
below the hood line.
It's not a perfect design and as I stated earlier, it's not design to be completely
water proof, but I'd be hardpressed to get any water into the system with the
second intake closed.  I don't anticipate crossing deep water, but since the bottoms
of many mudholes and streams can rarely be seen, it wouldn't be unheard of to
find myself in water approaching the hoodline..
For larger view click on pictures
In the end, it's a compromise between good airflow into the intake system for the
99.9% of the time when water is not an issue, with the option of mostly protecting the
intake system when needed.   Closing the second intake is simply a matter of opening
the hood and pushing the trap door shut.

END
Links to other snorkle designs
Update:   This system was later removed to make way for another battery in the engine
compartment.  Would this system have actually worked?  Well, I can't say for sure, but I did test the air
box seperately in water and it turned out not to be water tight.  It certainly would be have been better
than nothing.  I'm leaving this site up to give others who are looking to build a custom snorkle some
ideas to work with.   I later changed again to a "real" custom snorkel.  Write up on that is pending.