11 thoughts on “Airflow Testing “Open” Intakes”

  1. Really like to see the modded stock setup with the addition of the silicone hose vs. the stock accordingly. Great work…keep it up!

    1. Adam, I did a couple variations that weren’t in the chart, that was one. With the stock airbox (aFe filter & no grate) and MST hose and TIP the setup flowed 383 CFM.

  2. so i was just looking at this video and comparing it to some previous tests you have done in the past and i am confused how your “stock tests” done today are flowing significantly less CFM than your stock tests completed on Sept 7 2018.

    there is a significant difference in numbers (486cfm to 371cfm today.) can we go back and re flow test the stock airbox?? I am assuming it has to do with the adapter plate you made to mimic the turbo.

    1. Those tests don’t appear to use the turbo inlet pipe like the later test so that must cut down the flow.

    2. Hey Nick, that’s correct, the adapter was made with the same inside diameter as the inlet to the turbo compressor, which is a good bit smaller than what I tested with in Sept 2018. Also as Adam noticed, this latest test utilized a turbo inlet elbow that the initial testing did not.

      Looking at the two tests really shows how much the turbo inlet elbow cuts down the airbox airflow potential.

  3. jmd5500@yahoo.com

    Would love to see you flow bench test popular mufflers for the GTI and compare with stock. Also would be interested to see if chambered mufflers really lose power compared to straight through types. It seems like they would but the proof is in the pudding.

    1. It has crossed my mind. The challenge is getting my hands on the parts, and then getting them out of my garage. The flow testing part is relatively easy.

  4. Can someone, please, explain me why generic tip with stock airbox top half performs better than a generic tip by itself?
    As Nick said, it would be nice to see a stock airbox re-tested.

    Great work, Jeff!

    1. Alex, air is being draw in because of a vacuum that is inside the flow bench (or turbo on the car). The air outside the TIP (atmosphere) is equal pressure all around, so that anywhere around the edge of the TIP the air can be pulled in. The pull of the vacuum diminishes with distance so you get sort of a half circle of suck at the entrance to the TIP. The area of pull in fact extends around the lip of the inlet, more than the half circle, making the area of influence (pull) to the sides of the TIP. The result is that air is being pulled in from the sides as well as in front of the opening. Air coming from the side direction is mixing with air from the front creating turbulence. The air from the side also has to change direction. All in all it makes for a messy entry into the pipe. In the case of the half airbox there is a radius at the inlet, sort of a bell-mouth, that permits the air to enter in a more orderly fashion. The result is that even though there is a bit longer inlet path the orderly entry by the air reduces the drag inside the piping compared to the relative chaos at the entrance to the bare inlet elbow. So you get more air going through the airbox top than the elbow by itself.

  5. Thanks for explanation, Jeff – it makes sense. For some reason, I was not expecting to see so much difference between those two.

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