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Proper diffuser option for the ///M

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GuidoK
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Proper diffuser option for the ///M

Post by GuidoK » Tue Sep 19, 2017 9:13 pm

Steve84N wrote: Sun Sep 17, 2017 9:21 pm They only work when they're fed smooth air but the underbody is not blanked off.

Their job is not to tidy up turbulence but to create a larger exit than the opening. This creates a pressure difference which creates the downforce.
Totally true. A diffuser must be fed undisturbed/unturbulent air, and only then the lamellae can create an underpressure as the size of the cavety grows.

With the e85/86 z4, it has a huge windtrap on the underside in the shape of the gearbox area which is not covered up which'll create a lot of turbulence.
On the e46 and e89 bmw did cover up this area with a plastic undertray. But even with these cars the exhaust isnt covered up, so its not 100% flat.
The only thing a diffuser can do for the z4 (like the aero kit diffuser) is filling up the holes between bumper and chassis, reducing another stock windtrap
Z4 3.0i | ESS TS2+ | Quaife ATB LSD | Brembo/BMW performance BBK front/rear | Schrick FI cams | Schmiedmann headers+cats | fully polybushed | Vibra-technics engine mounts | H&R anti rollbars | KW V3 coilovers | Sachs Race Engineering clutch

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