View Full Version : Does reducing/ removing air intake restrictions lower or raise the boost?

04-30-2015, 11:36 AM
Might be an obvious question, but I've never known the answer--does reducing/ removing air intake restrictions lower, or does it raise the boost?

04-30-2015, 11:49 AM
It should increase the boos amount as most restrictions arent large enough to over take the stock TB and MAF. Where people start seeing high boost numbers is when they enlarge the intake and SC, but do nothing with the heads and IC, which means more air is being moved, but also it is being restricted causing Boost numbers to be higher. That is the 500,000 feet view.

David Neibert
04-30-2015, 12:05 PM
I agree..removing restrictions prior to the supercharger will usually increase boost. Removing restrictions after the supercharger will usually lower the boost.


04-30-2015, 12:56 PM
Next question--if one were to fabricate a ram air duct into the front, would/ should that then raise the PSI on the boost gauge?

04-30-2015, 01:15 PM
I don't think it would raise it by an easily measurable amount...unless you have a huge scoop and travel at 100mph! :p

04-30-2015, 01:24 PM
:D The reason I'm asking, is because I'd fabricated a custom ram air duct that goes to the front of the car, to try and see what would happen. The car appears to have lost maybe a 1/4 to half a psi, and the low end torque seems to be reduced a bit......but the car seems like it pulls a little bit harder in the upper end. I'm still tinkering around with it--I've sealed the tube (bought some Mole Pipe at the local hardware store), and it's great for staying straight when you don't want bends, but it's also super great for bending when you need it. I've sealed it off at the intake box, but other things I was thinking of trying was to not seal it up and then see if the air wouldn't draw itself from the slight areas around the piping where it would otherwise be a "leak", where the air may draw quicker from to not lose a little low end torque.

Edit: though the psi seems to have dropped a small bit, it doesn't appear to affect the 0-60, as I timed a 6.89 last night (with an automatic trans) and other times I had tried (with the temperatures 20 degrees colder), I'd got about a 6.98-7.1 or so 0-60. It's tough to tell, because the temperatures are changing, but it doesn't appear to lose any upper end power with hotter temps outside.