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      11-06-2008, 12:10 AM   #81
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Drives: E30 M3; Expedition
Join Date: Apr 2007
Location: USA

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Originally Posted by exdos View Post
If your car is parked outside in a thunderstorm, where does the rain water go that falls into the hood vent?
It drains from the same "gill-like" opening between 1 and 4.

Also, about the dyno charts. In the case of the M3, I suspect that the baseline dyno charts are being obtained with the stock intake with no flow directed at the car. If that is indeed the case, directing flow at the car with a modified intake would be misleading. The car already has a front facing intake. Whatever gains observed between the two dyno runs could simply be attributed to the functionality of the front facing intake rather than the modification (in the recent case under discussion, scoops). And, of course, as many people, including you, have been saying, it is meaningless to claim that the fan simulates any kind of meaningful real-life airflow to begin with. Airflow increases with rpms and velocity, and there must be dynamic effects in how the engine responds to that. The car/engine will NEVER experience static airflow over its rpm range in operation. The dynos prove absolutely nothing. That cannnot be how BMW has experimented with and tested its intake designs. They must have instrumented the car and driven it around in various conditions. That is the only way to understand what is going on. The rest is false science/rubbish.

At the end of the day, BMW engineers have been thinking about all this much more than any one of us have been, and they are more qualified--meaning they have fluid dynamics experts working on the problem. I have an understanding of fluid dynamics, but I am not an expert. I doubt that any of the posters on these threads are either. The point is, on a recent M car like the E9X, the only way one will achieve gains over the stock setup if one manages to identify and undo a trade-off that has been done by BMW engineers such as noise reduction. That is actually pretty much the basis of almost all engine modification for this car; to identify and undo the design trade-offs that have been made in the stock setup.