Ram Air Part II

Setup

The second part of the ram air effect investigation involves covering the opening of the Eventuri air scoop.

Air Scoop Opening Covered
Air Scoop Opening Covered

The drive speeds were repeated as with the first test and results compared.

Results

Mk7 GTI Ram Air Test II Results
Ram Air Test II Results

The results are not conclusive, but there seems to be a VERY slight improvement in pressure with the opening unobstructed.

In the chart above the solid red line is with the scoop opening clear and the solid blue line is of the opening covered.  The dashed blue and red lines represent the margin of error for each test case, based only on pressure sensor measurement error.  The margin of error has significant overlap.

The difference between the two test cases on average is 0.1 inches of H2O, which is approximately 0.004 psi.  The maximum difference is 0.2 inches of H2O, approximately 0.007 psi.

Conclusion

There is a very slight increase in air pressure at the intake inlet with the scoop opening clear, but there is a substantial overlap in the margin of error between these two test cases.

References:

8 thoughts on “Ram Air Part II”

  1. We were doing our own “air scoop” testing on a BMW N55 engine car over the weekend. We found no measurable change in boost pressure nor airmass flow. Maybe “ram air” works on naturally aspirated engines but it has no impact on turbocharged applications.

    1. The more that I look at the part and its placement I believe the design may have a fundamental flaw in the location. If I were designing the front end of an automobile I would not want air ramming into it. I suspect just enough air goes into the grill to support combustion and cooling, and no more. I think it is likely that the majority of airflow that might enter the grill does not because the shape of the front end is designed to not have air enter the grill.

      I’d be interested in knowing if an intake scoop that disrupts the airflow to direct air into the intake would be more effective, at the cost of aerodynamic efficiency.

  2. Maybe it would make sense to see if a test could be done with an area of higher pressure, for example in the area of the FMIC or to the left of right of it, where the fog lights would be. My hypothesis, it may still not yield a large ram air effect, but it may reduce IAT like on other cold air intakes. The Seat and Golf TCR also seem to get the air from a different location than stock.

    1. I’ve pulled the driver side fog light out at one time with the intent of trying to make a scoop to feed the airbox from below. The more I thought about it the less confident I became that it would be beneficial and the effort has stalled. It might be better to try and measure the pressure in that area to try and get an idea of the amount of potential positive pressure, if any.

      1. I didn’t get a notice of a reply, so pardon the late response.
        You could check the pictures for the Golf GTI TCR and see the routing, but I only see the brake ducts at the bottom. When searching CFD info, you find substantial evidence that the frontal area where the cooling happens, seems to have the highest pressure, maybe also the reason that the GTI TCR has the brake cooling located more towards the center.

        1. I’ve seen a diagram of airflow across the fascia of another car and in the area of the fog lights, also near the outer edge of the bumper, the airflow is more perpendicular to the bumper cover than into it. I might still try making something, but it’s a lower priority as my confidence in it making a difference drops.

  3. Just to finish this off: Verus Engineering has a rear diffusor for the Golf VII (as you probably know), and in the information pack, it also has air flow of the frontal area. It is the best information I have found thus far: https://www.verus-engineering.com/web/content/2077?access_token=633eada3-3607-4496-b84c-16194daf607f&unique=957cd7c14c840e881e85d24614538633aae7b911&download=true

    If the link doesnt work, just check the “Information pack” on the product page for the Golf VII Diffusor.

    In general, have you looked at modifying the aerodynamics with the stock parts for the underbody from the various models?

    1. I haven’t looked into these. So far I just drive on the street and I don’t see much benefit in that application.

Leave a Reply

%d bloggers like this: