: Stock boost pressure with Airaid

06-17-13, 11:27 PM
What boost pressure are you guys seeing on stock cars with just an Airaid CAI? I saw 10 psi with the Airaid Dry filter but after installing the Green filter (brand new) I'm only seeing 8.5 - 9 psi. Surprised to see this considering the fact that the green filter should flow more than the dry filter.

06-18-13, 07:56 AM
Boost pressure is actually a measurement of resistance: the blower is generally going to move a constant volume of air at a given RPM and air density (ie altitude, temp, humidity) under full throttle; with the boost pressure being determined by the efficiency of the blower and the cylinder heads (and cam timing, etc). What you see as "boost" is of course air stacking up inbetween the blower rotors and the cylinders - which is in reality a measurement of air resistance to flow: it is a handy reference point but is not specifically an indicator of power output, though people often make generalities associating the two in engine systems that share many of the same design parameters.

Changing the intake ducting alone should have zero bearing on Boost levels. Porting the blower, modifying pullies (ie the RPM of the blower), reworking the cylinder heads or changing a cam will all effect boost.

I'd wager that there is something else contributing to your perception of lower boost levels.

06-18-13, 08:37 AM
Do not trust that stock gauge. I can understand that you are seeing a big difference but that gauge is really for show.

06-18-13, 08:39 AM
I saw 10#s after the Airaid swap as well. It's a reduction in intake restriction causing the boost increase...you're just improving the intake side efficiency of the blower.

The green should definitely flow more than the dry filter. I used the K&N 1044 and it flowed more than the dry as well.