The goal of a snorkel is to move the point where your engine is drawing in air, to a better location, in hopes of not injesting water or mud during stream and lake crossings. Some snorkels move the point where the air is taken in all the way to the roof. The following design draws air from the rear of the engine compartment, rather than from the original place behind the front grill. I took my ideas from two similar designs I had seen:
In my 4 cylinder 1st generation 4Runner, the air intake is on the inner wall of the air box, not on the outer wall like in the later V6 engines. This made the route through the fender that Allen used impractical. Then I recalled Randy's slick fix of just rotating the air inlet on his Jeep back and up. I tried that and while it did the move the intake point away from the grill, it did not move it much higher and the intake point was right above the exhaust header. After cleaning up the routing of wires and hoses in the engine compartment, it looked like I could run a length of 2" PVC pipe from the stock intake pipe to the firewall, then angle over towards the fender.
To fabricate the snorkle, I used 2" Class 125 PVC pipe, a coupling and a 90 and 45 degree elbow. The longest pipe section is 11" the short one is 5". I cut off the end of the stock air intake tube to get to a round section. The stock tube fits nicely inside a 2" pipe fitting, where I glued it in with Liquid Nails*! The stock pipe is polyethelene, so PVC cement won't work. When the hood closes, it holds the end of the tube down, so it just sits on top of the brake booster. I see no need yet to firmly attach it to anything. This also allows the snorkle tube to be removed if additional working room is needed.
* Attaching the poly tube and PVC pipe is a bit tricky. The PVC is rigid, the poly is flexible. I used the Liquid Nails to to fasten the tube inside the PVC fitting, then added a strip of polyester fabric over that and covered it with another layer of adhesive. Then the assembled tube was baked in an oven at 175°F. for several hours to cure it. It remains flexible yet doesn't pull apart under tension.
The air intake has been moved about 6" higher than stock and back about 2'. In the 2nd picture (below), you can see the 2" round hole behind the grill where the stock intake tube used to sit. The corner of the fender and firewall seems like a good air pocket. I haven't had an opportunity to test the setup in deep water, but at least now I'm ready for it when I get there. The snorkle does not contribute any additional intake noise. Below 4-5000 feet, there is no affect on engine power, but above that, I notice a very slight drop. Since it only takes 30 seconds to install or remove, I think I'll just carry it with me and stick it on when needed. I do notice that if I remove the snorkle and leave the lower end attached, the engine runs a bit hotter (air intake close to the exhaust manifold). This doesn't happen with the full snorkle on, so I guess the intake point is cool enough, but I do notice a bit of power loss at altitude.
Here's what it looks like installed:
2' 2" Class 125 PVC pipe $1 3 2" Schedule 40 PVC pipe fittings 4 --------------------------------------- $5
I plan on making a few changes to this design. Once I get my dual batteries installed underneath the truck, I'll have the old battery try area free. I plan on relocating the air box to the passenger side at that point. This will allow two improvents to the air intake:
These two modifications should allow me to leave the snorkle attached full time, as I'll be taking in cooler outside air, with about the intake restriction of the stock setup. This will also free up the old airbox location to let me install the Premier Power Welder control box and regulator near the shiny new 160A alternator.
At some point in the future, I may go all the way and cut a hole in the fender to allow a full roof line shorkle intake.