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      04-26-2020, 04:02 PM   #1
Dr.T
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Lower front grille flaps??

On the M850i, I know the kidney grilles have active flaps that open and close depending on the cooling needs of the engine, but last week I noticed that there were horizontal flaps in behind the lower grille.

However, they seemed to be oriented in different directions....some open, some closed, some flipped up/down irrespective of each other. I was easily able to move them individually independent of each other with finger pressure. And it seemed like the left and right sides moved independently.

Anybody know how they should be oriented? Are they supposed to be open/closed? Up/down? Are they motorized or correlate to the kidney grille flaps being open/closed? Or are they just passive, opening up at speed and supposed to close again once you park. Maybe some of mine are sticky....
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      04-26-2020, 07:59 PM   #2
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Quote:
Originally Posted by Dr.T View Post
On the M850i, I know the kidney grilles have active flaps that open and close depending on the cooling needs of the engine, but last week I noticed that there were horizontal flaps in behind the lower grille.

However, they seemed to be oriented in different directions....some open, some closed, some flipped up/down irrespective of each other. I was easily able to move them individually independent of each other with finger pressure. And it seemed like the left and right sides moved independently.

Anybody know how they should be oriented? Are they supposed to be open/closed? Up/down? Are they motorized or correlate to the kidney grille flaps being open/closed? Or are they just passive, opening up at speed and supposed to close again once you park. Maybe some of mine are sticky....
I never even noticed those but on inspection of my M850i they are wide open which I suspect is what you want. I also suspect they are 100% passive and somehow yours got set to something other than wide open (horizontally flat) prior to delivery.

As for the active kidney grille on the M850i, I consider it a garage only aesthetic, i.e., it sure looks nice in the garage. However, in all but the shortest drives, e.g., if I run to the corner market and back (roughly a 1 mile round trip) it will be wide open as the twin-turbo V8 needs a lot of air to operate. I sum up the active grill in the M850i as gimmicky at best.

According to BMW marketing the purpose of the active kidney grill is as follows:
ACTIVE AIR STREAM KIDNEY GRILLE.
The Active air stream kidney grille knows when engine, brakes and other components need air and automatically opens the air vents. If no further air intake is required, it closes them again. This improves aerodynamics, and fuel consumption falls.
This may work out better in the other models that have 4-cylinders or straight 6s but with a fire breathing twin-turbo V8 under the hood the kidney is open literally 98% of the time. BMW didn't even consider putting the active kidney on the M8/M8C's as unless you were just moving one on your driveway the damn thing would be open.
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      04-26-2020, 08:28 PM   #3
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Not in Canada! Owned mine since Nov and they mostly appear closed while driving and only open concurrent with the electric fan operation for ~2min after I park the car if the engine is hot. But, not if I only drove her for a mile or two...
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      04-26-2020, 09:13 PM   #4
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Originally Posted by Dr.T View Post
Not in Canada! Owned mine since Nov and they mostly appear closed while driving and only open concurrent with the electric fan operation for ~2min after I park the car if the engine is hot. But, not if I only drove her for a mile or two...
Interesting and may be true as the only way I know they are open for sure is when I park the car as well. Unfortunately, when actually driving the car there is no way to no whether they are closed or open. The difference may be that here in AZ even in the winter months we are quite warm during the day (60s to 80s) and now for the past month or so that is 90s to 100s). So unless I mount a GoPro on the front bumper to monitor I have no clue what is going on but like I said it sure looks nice in the garage.
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      04-29-2020, 10:01 AM   #5
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An update on my end is after starting the M850i in the garage for a trip to the grocery story yesterday I realized I had forgot my cell phone. I left the car running and retrieved the cell phone from inside the house. On returning to the garage I was surprised to see the kidney grill wide open. I did check the temperature the car indicated for the ambient air before leaving and it was at 83 F (it was roughly 100 F here yesterday).

Granted the car was stationary for roughly 5 minutes so without moving air it may had no choice but to open the kidney. Of course no way of knowing whether it closed once I was on my way but sure enough it was open and electric fan blowing when I parked it in the grocery store parking lot.
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      04-29-2020, 07:46 PM   #6
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I’m probably like the only one on this forum with an 840gc and I still haven’t been able to catch my vents opened. Although I really only just started actively looking for it about a week ago and haven’t done any aggressive driving. It’s also not hot yet here in Chicago.
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      04-29-2020, 08:06 PM   #7
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Originally Posted by gustovier View Post
I’m probably like the only one on this forum with an 840gc and I still haven’t been able to catch my vents opened. Although I really only just started actively looking for it about a week ago and haven’t done any aggressive driving. It’s also not hot yet here in Chicago.
I believe ambient temperature has a major factor in whether the active kidney grill can stay open vs closed. Just my operating theory given my experience here in AZ. In IL the temperature is still in the 40s/50s and with an inline 6 (vs a fire breathing twin-turbo V8) that may be the difference. It will be interesting when the IL summer months hit in the upper 80s/90s with the humidity (I spent 20+ years in IL during my tenure at Motorola/MSI) as to how that impacts your 840gc and active kidney grille.

That aside welcome to the 8-series and enjoy that glorious 840gc! Can you post some pics and elaborate on the your build, etc.? All part of sharing everyone's 8-series experience here on the forum.
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      04-29-2020, 08:28 PM   #8
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At the time of sale, my BMW sales consultant explained to me the flaps were to assist in managing engine temperature. Keeping them closed at start up until engine warms or keeping them closed for periods in cold weather and then doing the opposite in the heat. When I return my car to the garage after a decent drive and turn off my engine, the fans continue to run for a period of time with the flaps open which I assume is the cool down phase. My flaps cannot be opened manually.
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      04-30-2020, 12:21 AM   #9
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Quote:
Originally Posted by Ozzie8 View Post
At the time of sale, my BMW sales consultant explained to me the flaps were to assist in managing engine temperature. Keeping them closed at start up until engine warms or keeping them closed for periods in cold weather and then doing the opposite in the heat. When I return my car to the garage after a decent drive and turn off my engine, the fans continue to run for a period of time with the flaps open which I assume is the cool down phase. My flaps cannot be opened manually.
The thread has taken a bit of a different turn but the OP was asking about the "flaps" in the lower grill of the M850i vs the active kidney grill itself. Mine are wide open and suspect that is to design as per my original reply to the thread. As far as the "active" kidney grill goes on an M850i here in AZ, I suspect it is wide open due to the ambient heat and the fire breathing twin-turbo V8. The only time I see it shut is when I approach the car in the garage before taking it out for a spin.
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      04-30-2020, 09:04 PM   #10
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I can see I've confused myself.

Yes my flaps (the rubberised ones) are open.
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      04-30-2020, 10:12 PM   #11
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Originally Posted by Ozzie8 View Post
I can see I've confused myself.

Yes my flaps (the rubberised ones) are open.
No worries as the thread took a different turn. Back to that turn my quick run to my local mini-market (aka Circle K for those of thus in the US) which is roughly a 1/2 mile round trip the active kidney was closed the entire time (including when parking back in the garage). It was only 90 here today so apparently with that ambient temperature and short distance there was no need to open it up.

Side note is the quick run was to pick up some beer so I can enjoy a few while catching up on the forum.
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      04-30-2020, 10:21 PM   #12
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My grille flaps open when it's feeding time, prefers snacking on MB, Audi, and Lexus badges...
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      05-02-2020, 09:21 PM   #13
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I can confirm that running a 2019 m850i in winter time, the flaps are closed almost all the time. even in sport plus or adaptive modes.

That said, it's a convertible, so it's mostly summer time. and the flaps are almost always open in summers.
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      05-02-2020, 11:09 PM   #14
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Originally Posted by Resjudicata View Post
I can confirm that running a 2019 m850i in winter time, the flaps are closed almost all the time. even in sport plus or adaptive modes.

That said, it's a convertible, so it's mostly summer time. and the flaps are almost always open in summers.
It will be interesting to see what happens when the DC temperatures raise this summer along with the added humidity. Thanks for confirming though that presently your's are shut as it tracks to my theory that ambient temperatures play a big role in the functionality. I suspect to the OP's point the lower grill is able to supply enough air so the active kidney is staying shut.

With our 100 degree temperatures here in AZ that doesn't appear to be the case. The irony is this reminds me of my Dad whom for serveral decades did not buy cars with power windows. His rationale was just another thing to break vs the simplicity of manual windows. Fingers crossed the active kidney in the M850i doesn't break as otherwise with the AZ heat and the fire breathing twin-turbo V8 that will be a recipe for disaster.
May need to make this argument with the wife so I can get a M8C coupe as no such concern on the kidney grill front.
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      05-02-2020, 11:28 PM   #15
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Quote:
Originally Posted by bloozemanAZ View Post
Quote:
Originally Posted by Resjudicata View Post
I can confirm that running a 2019 m850i in winter time, the flaps are closed almost all the time. even in sport plus or adaptive modes.

That said, it's a convertible, so it's mostly summer time. and the flaps are almost always open in summers.
It will be interesting to see what happens when the DC temperatures raise this summer along with the added humidity. Thanks for confirming though that presently your's are shut as it tracks to my theory that ambient temperatures play a big role in the functionality. I suspect to the OP's point the lower grill is able to supply enough air so the active kidney is staying shut.

With our 100 degree temperatures here in AZ that doesn't appear to be the case. The irony is this reminds me of my Dad whom for serveral decades did not buy cars with power windows. His rationale was just another thing to break vs the simplicity of manual windows. Fingers crossed the active kidney in the M850i doesn't break as otherwise with the AZ heat and the fire breathing twin-turbo V8 that will be a recipe for disaster.
May need to make this argument with the wife so I can get a M8C coupe as no such concern on the kidney grill front.
always something. it's the price you pay to play with new toys. There isn't any good way around it.

maybe follow the 3 F rule. If it flies, floats, or F. renting it. Don't buy it.
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      05-03-2020, 12:53 AM   #16
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Originally Posted by Resjudicata View Post
always something. it's the price you pay to play with new toys. There isn't any good way around it.

maybe follow the 3 F rule. If it flies, floats, or F. renting it. Don't buy it.
LOL on the 3 F rule and new toys as my watch broker contacted me yesterday on an opportunity to try once again in securing a GENUS GNS1.2 for my watch collection. However, in the watch game there is no renting, leasing, etc. but only cash on the table.

My last attempt at #2 in the series of 8 up for auction at Sotheby's earlier this year failed as my ceiling was 30% over the original price given I wanted to absolutely double my money no questions asked over the long run as an asset in my Estate. Apparently #5 is coming on the market and I get another go at it. The details are forthcoming but regardless of COVID-19's impact on the economy it will take top dollar and an easy 50% over the original price.

However, based on that and its position in the industry as literally a Rembrandt, Monet, etc. in equivalent the longevity of value will vastly exceed any price paid. Thus, now I just want it no differently than the M850i with the caveat I'll never get to enjoy it on a daily basis no differently than the other investment watches in my collection. The upside of the M850i is I can enjoy it every day as no matter how I take care of it, etc. it's a quasi asset with straight line depreciation to zero.

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      05-09-2020, 10:01 AM   #17
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The kidney grille active flaps are actually quite genius. At highway speeds when the added cooling isn't needed, they can close. This shunts air over the hood instead of through the radiator, which in turn 1) reduces air turbulence and therefore reduces aerodynamic drag, and 2) creates downforce (reduces lift) by converting turbulent air to high-pressure air at the front of the hood.

This provides subtle benefits to both high-speed handling and highway fuel economy. This technology absolutely blew me away when I first saw it. (No I'm not an engineer, but my nephew is head aero engr at Penske, and I learn from him whenever I can.)
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