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Old 01-11-2013, 05:54 PM
TXFred TXFred is offline
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Location: Austin, TX
Join Date: Apr 2012
Posts: 236
Mein Auto: 2008 335i Convertible
Originally Posted by DT335 View Post
I'm looking to put in something to improve airflow in my '08 E90 335i.

I really like RPi's Ram Air Induction V3 found here. I was wondering if you guys could provide any insight as to whether or not it'd be beneficial to my car, i.e. improve air flow, help with cooling, differences in idle'ing (if any).. This would be one of my first DIY projects on this car, so I'm really looking forward to it if it's worth pursuing.
The car controls boost by comparing boost pressure to atmospheric pressure. So if the ram air system is increasing boost, the car will open the turbos' wastegates a bit wider to reduce the amount of boost that they provide. The end result will be the same amount of manifold pressure you had before.

The turbos won't be working quite as hard, which will translate into a slight reduction in exhaust restriction, which might make for a slight increase in power. However, I don't think you'll be able to feel it.

Unless you're planning to build your BMW into a Bonneville racer, I think you'll be wasting your money with this modification.

This is all assuming that those scoops do anything at all. I've never seen a ram air system that had so many sharp angles on it. Ram air depends on a smooth intake that gradually widens to decelerate the airflow, converting kinetic energy into potential energy in the form of pressure. Those scoops look like a 16 year old made them.

Any idiot can be fast in a straight line. The corners are what separates the drivers from the commuters.

Last edited by TXFred; 01-11-2013 at 05:56 PM.
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