eNate wrote: ↑
Sat Feb 22, 2020 4:31 pm
I've seen this opening myself, and wondered the same. However, I can't imagine that the Bavarian Aerodynamikers in charge of this project missed this little detail?
Regarding road noise, I will tell you this: I've driven a few trips with the cover removed, and the electric motor is incredibly loud. Earplug-wearing loud, to be exact. I wondered if, as opposed to keeping road noise OUT, this area was left open so as not to keep motor noise IN.
Whatever you try, be sure the front lip is attached well to something of substance. I drove one of my cars with the front splash guard removed and the piece immediately behind the splashguard became a giant wing with its front edge suddenly exposed, and pulled down at 40 MPH making some sort of "oh sh*t" racket. You wouldn't want to send a plexi Frisbee through the windshield of the car behind you!
hehehe, yes! Definitely no throwing 90mph plexi frisbees! But I do really think the opening was designed to provide cooling to the ICE and associated components.
Makes sense that it lets motor noise dissipate. However I've already addressed the area with sound treatment, so hopefully noise is absorbed and cancelled instead of getting amplified. I'll report back on findings once everything's fab'd and mounted. Nice thing is the triangle opening has predrilled holes for attachment points for a cover. Just need to leave a bit open for that one engine mount that hangs below the motor.
i3 BEV rear underside showing large triangular opening:
This has to be intentional. Visible are openings in the panel below the bumper that would allow some air that enters the open triangle to exhaust. It would be nice to understand why BMW didn't enclose the entire underside as with many very aerodynamic vehicles. I've wondered about this since purchasing our new BEV in 2014 but decided against closing it because I don't understand why BMW left it open. Not sure that we will ever know…
Awesome picture, thanks Art!
Intentional yes, for ICE cooling. I brought a few friends to get under and check things out with me. We couldn't figure out a valid reason for having the opening. If anything I've found the opposite of beneficial when the opening is left open. Obviously water and debris gets into the 'motor bay' and I've seen countless posts of people finding corrosion in the connectors that go in and out of all the components on the motor.
But when all that air rushes into that opening, and only has a few little slits in the rear bumper to escape from, you create a very beautiful parachute effect. by definition
Am I trashing it?, absolutely, but with love, like every other BMW I've owned.
Rondel stands for something, and I fully utilize all the non neutered abilities its got.
Takeaway. This is an amazing piece of engineering. And I'm not impressed with 'stuff'