I am going to remake my homemade CAI, as I don't feel as though the current filter and pipe being used is allowing enough airflow. I am using a 3" turndown pipe which is smaller than 3" throughout due to the crimp bend and a cone airfilter from Autozone. I am thinking I need more like a 3" 90* mandrel bent pipe to keep the same diameter to allow sufficient airflow. Am I correct on this? I figure the stock 48mm TB has an area of 2 x 18.096cm2 = 36.19cm2 (5.609in2) and a straight 2.75" pipe has an area of 5.94in2. I get from this that I need at the smallest point of my pipe to be no less than 2.75" in diameter to allow enough airflow, and that is if the pipe were straight.

Am I correct on my assumptions on this?
Also, what size cone filter would be ideal to allow enough airflow?

This is more of a temporary setup as I plan to get the Warbird II Hood and switch to a ram-air setup around spring, so I just want to go the cheap homemade route for now.

 

Ressurecting an old post for same answer, but the RamAir setup is going to be held off a little longer than originally thought, I just dont feel like spending over $100 for a CAI.

 

well i would keep the tube the same or greater diameter as the maf sensor.

which is just a hair under 3"

so i would use that as the minimum diameter.

 

I think I just decided on 3.5" pipe. Putting order in Summit now for pipe and filter.