Ok, so the thought here was that if the engine gets less air it will have to lower the amount of fuel it uses to maintain normal air/fuel ratio.
Less gas will be less power but possibly higher mpgs at cruising speed.
So here is my mass airflow sensor.
My thinking is that all I would have to do is block up the air filter box to do the trick.
So out comes the box cutter and the coroplast and a hacking I go and come out with this abomination.
Sorry about the pic quality, it was 1am at a gas station. :\
So on the right side you see the top of the air intake is being blocked about 3/4 by a piece of coroplast.
Then on top of that is the big piece of coroplast with a small hole in the center about 1/3 the side of the air intake tube.
Then on top of that mess I put the air filter and then latch the box closed.
The box was still air tight and with the filter on tip I didn't have to worry about anything getting sucked into the engine.
I did my runs between 1 - 2 am so traffic was no issue, though I probably confused the hell out of the guy at the gas station I used to stop and record numbers at.
Temps were 45 - 47F and I did my best to hold 45 mph though my car doesn't have cruise control so it was a bit hard.
Had a 1.5 - 2 mile stretch of road with gentle ups and down.
Heading west with my restricted air intake my runs were 52.4, 53.0, 53.4 for an average of 52.93 mpg.
Heading west with the normal air intake my runs were 52.9, 52.9, 53.7, 53.3 for an average of 53.2 mpg.
Heading east with my restricted air intake my runs were 50.6, 51.7, 51.5, 52.5 for an average of 51.57 mpg.
Heading east with the normal air intake my runs were 52.7, 52.1, 53.3 for an average of 52.7 mpg.
Variance heading west was 0.9 mpg but the variance heading east was much larger at 1.55 mpg.
Heading west the standard air intake was 0.27 mpgs better then the restricted intake.
Heading east the standard air intake was 1.13 mpgs better then the restricted intake.
I know the sample size was very small that that it looks like the restricted air intake didn't work but going both directions the variance was larger then the difference of averages.
I plan on giving it a try again on a different road once I need to replace my air filter so I can mod the filter itself and then run a comparison between a clean filter and a dirty one modded to be more restrictive.
Thing I don't know is how long does it take for the cars CPU to modify the air/fuel ratio?
I did do a quick 5 minute drive between normal air intake and restrictive air intake but I'm not sure if that was enough for the CPU to actually change the mix.