Oops - forgot about four wheeling.
I always forget the off road thing - I'm an old Trans Am/IMSA racer and such things didn't bother us. I have to agree with the Sunk - who sounds like he ought to know something about snorkels - wheeling with a cone funneling any available fluid - gaseous or liquid - into the filter box can't be a good idea. I've seen a post were the dude cut a hole into the area in front of the windshield and used PVC and dryer fittings - but the mudders around here would drown that too. Something sexy right up beside the windshield would look cool?
Let me stop right here and say this - the questions you have about the sensors and the fact that you are talking about your friends truck leads me to suggest you be real careful - you could loose a friend in the process of trying to entertain your bored self. (Do they not have girls where you two live?)
The most thing about building a cold air box - something I spent a lot of time trying to do with the help of a NASA engineer - is that it's sort of an exercise in futility. It is, that is, if what you are trying to do is improve on what the factory did or you are trying to improve horsepower. A lot of things that seem like they would work, won't
I'm currently running a temp gauge in my cold air box - stock one - just measuring temp differentials. The temp inside the box from a cold start will stay within two or three degrees of the outside air until you hit stop and go traffic or stop and let it heat soak. Remarkably, the air cools down very rapidly after the engine starts. It will stay within a few degrees of outside air for a long trip only rising when I hit heavily traveled freeways. You might enjoy trying this - I used the indoor/outdoor digital thermometer that was sitting on my kitchen table - measuring the temp by my pool. I believe it was under $20 at Walmart.
A running engine at between 60 -70 highway, at partial throttle draws, about 2 water column inches of vacuum. Coincidently, the pressure at the front of a Ranger doing 60-70 miles were hour is about 2 water column inches of pressure. The differential is quite low - just enough to work well. These tests were done last week on 75-90 degree days in Texas. The stock cold air box works well because is sits behind the headlight, which catches most of the bugs and spray on a wet day. The pressure on the front of the car, keeps relatively clear air on the front of the little cone that sticks into the CAI - thereby assuring good air flow.
I've done testing to try to raise the pressure inside a cold air box at speed. The problem is the constantly varying speed of a typical car or race car, the changing throttle position and therefore vacuum, head wind, tail wind, drafting, etc. Some have claimed to have accomplished this only on the top end. F1 cars in the 70's had a odd shaped box on top of the intake of the rear engine cars that claimed to do this. It sat way up high into the clean air stream. I've seen the same shape on a few blown drag cars. - all in all a pretty impractical shape for the street or off roading - in my opinion. And - this only worked well at rather high speeds. You would think just building a big funnel on the front of the car would work - but if you did some testing you would find the air begins to bounce off of itself as it stacks up in the funnel - no appreciable pressure gains can be had in that manner. If you know an air conditioner technician who has a gauge (called a Magnehelic) to measure water column inches of pressure he could loan you - you can test this yourself. Make yourself a scoop out of cardboard, change designs, Duct tape the thing on the side of your Ranger bed, sit back there with it (check State law about riding in the back) and change the shape and size of the scoop and check it out. You may expect the air to read out in pounds - but it won't.
You may be asking yourself - why was he doing all this testing if he already knows the answers? I'm a writer, I thought it would make a nice article after I try a few other things. I may come up with the complete list of things that promise to improve your horsepower and are guaranteed absolutely, positively not to work. Who knows?
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