Snorkel for Range Rover P38

Introduction
Chris Crompton's Design On Coil-Converted P38
Installation When Retaining Air Suspension
 

Introduction

A snorkel (in the context of off-road vehicles rather than submarines) is a device that raises the engine air intake to the top of the vehicle. Many  off-roaders erroneously assume the main purpose of snorkels is to facilitate deep water fording. A snorkel is indeed helpful for this, although many other measures need to be applied to the engine, especially if it is a petrol/gasoline unit with spark ignition rather than a diesel. However the main reason for adding a snorkel is to get the air intake up out of the dust and sand that fills the air at lower levels on off road expeditions (particularly in convoys). In World War II, the British Eighth Army in North Africa quickly discovered that the conventional engine air intake systems on their tanks and other vehicles ingested so much sand and dust that engine life could be measured in hundreds rather than thousands of miles. Reducing the amount of grit that gets into the cylinder bores is a vital step in prolonging the life of real off-road vehicles.

As of this writing (June 2004) no commercial snorkel exists for the Range Rover P38, so Chris Crompton of Abu Dhabi made his own, after getting his air intake box filled with sand (see photo at left). As the photos show, it looks pretty professional! Chris reports: "So far it seems to be working pretty well. I bought the top “Ram Air” section of a Safari Snorkel for a Nissan Patrol, and made the rest out of plastic drainpipe!! The hardest part was shaping the drainpipe, but with a lot of heating, bending, tacking, riveting and patience, it’s not looking too bad.  I removed the EAS “box” from under the bonnet and ran a pipe straight into the existing airbox.  I had thought about removing the airbox, but for version 1 of the snorkel I thought I’d leave it in and see how it performs. I had to relocate the throttle assembly slightly as the pipe was in the way of this and by this time I had had enough of bending plastic pipes!!"

The description and photos on this page, kindly supplied by Chris, illustrate in detail the procedure he followed.

Chris Crompton's Snorkel Fabrication Project on Coil Converted P38

Chris reports: "I bought the top Ram Air section of a Safari snorkel direct from Australia, this was one designed for the Nissan Patrol. I figured that this one would be designed for a high airflow engine, so in theory should be OK for the air requirements of a Rover V8. The remainder of the snorkel pipe was made out of two different hard plastic water drainpipes, a larger diameter for the outer pipe and smaller for the pipe in the engine bay.

The first stage was to remove the EAS “box” from under the hood. On my coil-converted vehicle the EAS is redundant anyway, so the compressor etc is being kept until I remount it on the other side of the engine bay for my onboard air supply.  With this box out of the way, there is a nice straight run from the existing airbox to the bulkhead, where the pipe can bend towards the inner fender.

I had to move the throttle assembly slightly towards the center of the engine bay, but otherwise, there was no major work required under the hood at all.

The pipe inside the engine bay was made with a single length of plastic drainpipe, cut, and heated to form the required bend, with the end of it positioned at one of the existing holes already in the inner fender, this saved me having to cut another hole in the inner fender, a fiddly job at the best of times, all I did was to make a few small cuts around the edge of the hole so I could bend the metal down around the edge of the hole fixing the pipe in place.

I used the location of this hole as my guide for where to cut the hole in the outer fender, I figured I would make the outer pipe according to where it was best to put the holes in the bodywork, rather than cutting holes according to my pipe design.

The outer pipe was also made out of a single piece of plastic drainpipe, but this one was a bit harder to shape because I wanted a really nice finish.  It took me several hours of cutting and heating until I had formed the right shape around the bodywork.  The clamshell hood is very awkward as I had to make sure the pipe didn’t catch on this as it opens and closes.  Once I had the pipe in the right shape, I used soft steel plate and rivets to form brackets to hold the pipe in the shape I wanted (see photos below). I then heated the pipe and using pre-cut pieces of the same pipe, (to keep the curved radius the same), “melted” these into place.  Some sanding and some filler and the finish on the pipe was very smooth.  This was then sprayed black to match everything else (photo below right).

I decided to use the existing airbox and route the new air supply through this as this would avoid having to mess around with the airflow sensor and also finding a new filter.  The original plan was to discard the whole airbox and use “elephant” tubing to re-route the air pipe with a straight through filter, this may happen in the future, but for now I decided to use as much of the existing air supply system as possible. The pipes were then fitted in place, first the internal pipe, into the airbox and bracketed in place and sealed with more silicone (picture below left).

The airbox was sealed using another piece of soft steel and riveted in place and I cut a hole in the bulkhead side of the airbox for the new air supply pipe.  The sealed hole was surrounded by a liberal coating of silicone sealant (picture above right). How well this will hold up I don’t know, but I will test it and see!

The outer pipe was fed into the hole in the fender and I used a section of radiator hosing from a truck to join the two.  The radiator hosing was slightly conical in shape, and made of extremely tough rubber and allowed for the change in pipe diameter between the outer and inner pipes.  I mounted this in the end of the outer pipe using industrial adhesive and sealant, making sure that it wouldn’t affect the airflow too much.  This was cut to shape and jammed, glued and sealed into the inner pipe as far as possible, with more silicone applied liberally between the inner and outer fenders.

The bracket for the top of the pipe was made out of a soft steel trim also taken from the truck body (photos below). This was bent into shape and screwed into the body frame on the outside of the rubber seal running down the edge of the door.  The pipe was then secured in this with two small bolts and given a coat of black paint.

The top “Ram air” section was then screwed into the top of the pipe (photo above right) with a small amount of silicone used, (avoiding the drainage holes), to seal this in place.

I have used a small plastic plug at the lowest level of the outer pipe to provide drainage for any water or debris that will collect there, although I am not totally sure about this bit, so I may change this and just put some screws into the bottom of the pipe which can be removed to provide the required drainage."

Installation When Retaining Air Suspension
Chris offers the following advice on installing the snorkel on a 4.0 without removing the EAS compressor and control box:

"The approach would depend a lot on whether you want to retain the original air filter box. My original idea was to leave the EAS box in place and re-route the air supply from the end of the airflow sensor using “elephant” tubing and a straight through K&N type filter.  This would then also allow me to have removed the airbox and moved the EAS box slightly towards the front of the car, allowing enough room for the tubing to pass behind it.

"Another option would have been to continue the pipe further down the outside of the fender, and cut the hole either directly through the fender into the existing airbox intake, or use a smaller diameter pipe in between the two fender sections to join the outer pipe and the airbox, but this would be seriously fiddly and I didn’t want to get into this.

"One more option that did cross my mind was to mount the snorkel on the RHS of the car instead of the left.  On the Rover V8, the whole plenum section is reversible, the bolt pattern is exactly symmetrical, so I did think about turning the plenum around, moving the throttle assembly, and routing a pipe and snorkel out through the RH fender where there is lots of space in the engine bay (on LHD vehicles).

"If you didn’t want to go this far, then there is space to move the EAS box slightly towards the center of the engine bay without disturbing the air lines too much.  This will then allow enough space for a “slightly flattened” pipe to be passed alongside the outer edge of the EAS box towards the bulkhead in a similar way that I did.  This will allow you to keep the original airbox in place and just seal up the existing intake hole above the wheel arch.

"These are the four main ideas I considered before going ahead with the option I chose – of course I was heavily influenced in my decision by the fact that I didn’t need the EAS box in place anymore, so it made life a lot easier for me.  One thing I never really looked at was how easy it would be to move the EAS box to a new location, ultimately all there is going into the airbox are 8 airlines, (I think it’s 8, but I need to check !!), and the two control and sensor cable bundles.  These have quite a lot of slack on them anyway, so it may be possible to turn the EAS box clockwise by 90 degrees and move it right down next the airbox.  This would provide quite a lot more space to play around with."