Well, I have talked about this for awhile now but never really made any real progress until recently. Presently the Ram Air Intake Scoop is located under the bumper on the passenger side of the truck. A lot of people have said that the scoop is in an area of negative pressure and I even read a few websites that made this claim as well. However, I noticed that none of these websites made the statement in relation to pick-up trucks, and no one I talked to had actually tested it. I tested this location, along with several others, with a homemade manometer and found it to be in an area of high pressure.
Tundra Fuel Economy: Manometer
I knew that moving the scoop up in the bumper would place it in even higher pressure - and hopefully, cleaner air. In its present location it gathers quite a bit of grit from the road and salt during the winter. I also had an inordinate fear of the scoop being torn off by parking space concrete sleepers or high sidewalks.
I managed to score a nice sized sheet of black ABS plastic to use to fabricate the scoop out of. Tonight I took the resin bumper cover off of my truck to get my eyes and hands on the innards so that I can better understand what I have to work with in there. I created some patterns based on the available space in there and will begin drafting up some designs over the coming week. I will fabricate some mock-ups out of cardboard and test fit those possibly this weekend. The final design will be out of ABS plastic.
In designing Ram Air Intake Scoops there are several design considerations to be taken into account. The first consideration is the amount of air that needs to be gathered. Based on empirical testing data generated over the last several years I have come up with a a formula to calculate the scoop face area based on engine size, RPM's and MPH. The second consideration is the shape of the scoop. In order to create a true "Ram Air" affect the scoop needs to have a wide face that converges to the rear with walls that are smooth and with acute angles in relation to the forward travel of the truck - less than 30 degrees is ideal. The third consideration is the volume and depth of the scoop. The deeper the scoop the better. Last is how to get that air from the scoop to the air box and there really are not many attractive options here - just a lesser of the evils.
So, here are some preliminary pictures and I will continue to document the process as it moves along. I need to have this finished in a few weeks as the next project more or less fell into my lap. A long time member here and reader of my blog contacted me to see about donating a set of stainless steel JBA headers to me as a means of supporting my testing and research. The headers will be here in about a week and as soon as I have the gaskets, studs, and extra tools (torque wrench) the headers will go on the truck.