[plasticuser]

As a side project I researched here, and looked at my air intake.

At its narrowest point, my air intake is a circle 1 7/8th inch in diameter, which I think is quite small and limiting in an open throttle situation. Regardless of the Cold vs. Warm intake debate going on inside my head, I drew some conclusions, and one was that this restriction had to go.

If you look at the first three attachments,you'll see the intake restriction. I saw on here a "gotts mod" to widen that restriction out to the full diameter of the hole in the side wall. However, I decided to go a different route.

I took some A/C duct material, which is a 1.5" thick fiberglass insulation sheet coated on one side with reinforced aluminum. I removed the restriction, and made an air box like would be found on a cold air intake. I left my air filter arrangement intact.

I did this non-destructively, so when there is good weather, I can do an ABACADA test with and without the obstruction.

Here's my method, theory of what I expect to see:

METHOD:
I will note the temperature, wind and road conditions, and start with a fresh tank of gas with no additives, and a well warmed up truck.
A) I'll ultragauge my consumption at 55, 65 and 75 with the original intake. I'll note the intake temperature, fuel rate, speed, and engine load.
B) Then I will remove the restriction and repeat.
A) I'll replace the intake and repeat.
C) I'll put in the box, to in theory draw in cooler air, repeat
A) I'll replace the intake and repeat.
D) I'll remove the restriction and place some drier hose on the end, drawing air from the radiator, and repeat.
A) I'll replace the intake and repeat.

I will check that each A run is consistent, and create a graph of all the data collected during the runs and publish it here, with a photograph of each configuration.

I expect to see a baseline for A runs, a slight reduction of economy with the C run, and improvements with the B and D runs.

The EPA says that on the freeway, I should get 17mpg. Not knowing their method, I'll get those baseline consumption vs speed curves. From the baseline of 17 mpg, at 68mph that's 4 gallons/hr. That means 58.8 gallons of air would be consumed in an hour at a fuel:air ratio of 1:14.7, or a gallon a minute. That sounds like a lot less than I'd imagined, so I suspect my math is wrong? Anyone in the know want to weigh in?

I'm interested in suggestions for other things to check to improve my method, and also, any other possible configurations I could add to the test? Comments/ideas strongly welcomed!


The other attachments show how bad the underside of the truck is - it's like an aerodynamic grand canyon, and I have some firm ideas of what I'd like to do about it. More on that in a future post.