Dinan Cold Air Intake

A previous owner added a Dinan exhaust system, Dinan cold air intake (CAI) with a 3.5" Hot Film Mass Airflow Sensor (HFM), and Dinan "Stage 2" engine management software; the car runs quite well with the set-up and tune, but the CAI installation was a little too much of a hack job for my tastes.

Most obvious was the adapter and hose clamp party that mated the HFM to an OEM intake boot, and the plastic zip tie mounting of the HFM to a bracket bolted to the strut tower.  Zip ties? Really?  Sure, they work, but I suspect the 3.5" HFM was a very expensive Dinan modification and I'm of the opinion that a better mounting scheme should have been developed.

Dinan CAI Hose Clamp Party.png

I had no idea when the CAI air filter had last been changed or serviced; after finding the Dinan filter stuffed into a hole hacked into the top of the driver's side brake cooling duct, it had obviously been a long time. I selected an AEM 21-204DK dry filter as a replacement:

Dinan vs. AEM 21-204DK Air Filters

Dinan vs. AEM 21-204DK Air Filters

On par with the plastic zip tie HFM mounting; the crudely modified left brake duct:

I suspect the installed Dinan CAI carbon fiber-ish tube (I'm not convinced that actual carbon fiber fabric was used, I think it's black fiberglass cloth) was not specifically designed for a Z3 or an M Roadster; no matter how I clocked the tube it just didn't seem to fit correctly, so I lopped off a chunk, trimming it back to the marked line:

I went with a silicone boot from Cosmo Racing to connect the throttle body, (actually, the Anti Slip Control + Traction (ASC+T) assembly) to the HFM, replacing the OEM boot and adapters.  I would have preferred another rubber boot with a flexible accordion section to prevent engine movement and vibration from being transferred to the HFM, but the Cosmos boot was the only one I was able to find that was the correct diameter, had a barb port in the right place for the idle control valve hose connection, and would work with ASC+T:

Cosmo Racing and OEM Intake Boots.png

A trial fit indicated that the Cosmo Racing silicone boot needed minor trimming to clear the strut tower:

After removing a wedge-shaped slice from the ASC end of the Cosmo boot, everything fits fine; much cleaner with plenty of strut tower clearance:

Cosmo Racing Intake Boot Installed.png

After modifying the tube, the AEM dry filter is positioned behind the bumper opening for the left brake duct; I'm not a big fan of the carbon fiber look under the hood, so I removed the Dinan decal and treated the CAI tube to a coat of semi-gloss black:

 I left the hacked brake duct off for now since I plan to go back to an OEM-style airbox at some point and will need a new left brake duct to connect to the airbox inlet ducting.

As an update, the Dinan CAI is now on the shelf; if someone want's it, feel free to contact me.

 I replaced the Dinan Cold Air Intake with a genuine BMW Z3M S50 airbox assembly, which works with the 3.5" HFM.

AEM 21-204DK Air Filter

AEM 21-204DK Air Filter