Bertone
Posts: 22
Joined: Wed Jan 22, 2020 9:37 am
Location: Madrid, Spain

Re: Improve aerodynamics for better mpK

Sat Feb 01, 2020 1:39 am

Im testing out a "front spoiler grill add-on" that I've made with spray foam....still in prototype phase....will cone back with more details once finished... :D
2017 94Ah

PVEVman
Posts: 4
Joined: Fri Jan 31, 2020 4:27 pm

Re: Improve aerodynamics for better mpK

Sat Feb 01, 2020 5:58 am

I guarantee you there is nothing you can improve on the aerodynamics, except for the mirrors. This thing has been in the Solidworks modeler for ever, unless you are going to do high speed racing. The best thing to do is drive a little slower :(

Boxbrownie
Posts: 87
Joined: Sat Sep 06, 2014 10:21 am
Location: Pastyland, UK

Re: Improve aerodynamics for better mpK

Sat Feb 08, 2020 1:35 pm

robthebold wrote:
Tue Jan 28, 2020 9:44 am
Boxbrownie wrote:
Sun Jan 26, 2020 12:57 pm
Bertone wrote:
Wed Jan 22, 2020 12:43 pm
Re-opening this topic...

I believe the front of the i3 could have been made more aerodynamic by the BMW engineers.

If you look at the area between the front headlights and "kidneys", it is not a very smooth surface...in fact air will flow between the headlight and kidney and be trapped under the frunk area producing drag.

Perhaps those "holes" could be "filled" with, for instance, polystyrene to form a smooth surface. Also the kidneys can be made more smooth "filling them up"..

The difficulty is to make a perfect fit...but polystyrene is a light and easy-to-work with-material so perhaps it is doable.

What do you think? Just a crazy idea....??
Don’t forget to tape over all the shut lines also :lol:
I think caulk would be even better, combined with taking a green sharpie to the edges of the windows.
Nah, just the duct tape over the shut lines, it’s what we used in the tunnel when tracing flow.......
Best regards........David

If anything in my post offends you please let me know, I may wish to offend you again. ;)

Bertone
Posts: 22
Joined: Wed Jan 22, 2020 9:37 am
Location: Madrid, Spain

Re: Improve aerodynamics for better mpK

Fri Feb 14, 2020 7:04 am

Hi again,

Here are some pictures of my "prototype foam spoiler ":D
Start:
https://m.imgur.com/a/alf7Saa

Finished:
https://m.imgur.com/a/7Blgvti

This afternoon I will see if this "invention" works, I.e. if it decreases power consumption at a constant speed of 120 km/h.

To be continued....
2017 94Ah

Bertone
Posts: 22
Joined: Wed Jan 22, 2020 9:37 am
Location: Madrid, Spain

Re: Improve aerodynamics for better mpK

Sun Feb 16, 2020 5:36 am

So I finally got some figures....
I measured the same trip (with and without the front spoiler) and here are the results;

Without/with: Total average consumption: 16,3/15,3 kWh, average speed: 78/69 km/h, duration: 33/38 min, outside temp: 10/12 degrees Celsius, total trip: 42/42 kms.

Then I also measured at a specific point during the trip traveling at a constant speed with the cruise control on:

Without/with: Consumption: 16,4/15,5 kWh, speed: 120/120 km/h, outside temp: 10t/12 degrees.

So there seem to be a 5% lower consumption in average and at 120 km/h constant speed with the spoiler.

If is true that I've only got 2 samples so far and that there was 2 degrees of temperature difference that could impact the measurements. Also the average figures samples are not exactly the same circumstances...shorter trip and higher speed in average...but seems that the spoiler do improve aerodynamics and lower the consumption to some extent... :)
2017 94Ah

Boxbrownie
Posts: 87
Joined: Sat Sep 06, 2014 10:21 am
Location: Pastyland, UK

Re: Improve aerodynamics for better mpK

Fri Mar 06, 2020 3:34 am

Which direction was the wind in either direction/test run, what speed was the wind in either direction/test run what was the road surface temperature during each run including tyre temperatures, do you know the logging error parameters of the BMW onboard read out?
Best regards........David

If anything in my post offends you please let me know, I may wish to offend you again. ;)

Bertone
Posts: 22
Joined: Wed Jan 22, 2020 9:37 am
Location: Madrid, Spain

Re: Improve aerodynamics for better mpK

Fri Mar 06, 2020 9:18 am

No idea...the samples were taken on different days but with rather similar conditions, i.e, more or less same ambient temperature 10-12 degrees celcius, non windy conditions, same 2 persons in the car, samples taken at the same road spot at 120km/h constant speed, etc...Obviously I did not attempt a scientificly rigourus test. just a simple comparison test with as much as possible similar conditions.

Next week I will try to obtain 2 more samples to see if the initial result is still valid.
I do these tests driving to my weekend house in the outskirts of Madrid :D

BTW it has been rather windy today when I drove the car, and I've noticed that the i3 is very wind sensitive....
2017 94Ah

Boxbrownie
Posts: 87
Joined: Sat Sep 06, 2014 10:21 am
Location: Pastyland, UK

Re: Improve aerodynamics for better mpK

Fri Mar 06, 2020 11:39 am

Bertone wrote:
Fri Mar 06, 2020 9:18 am

BTW it has been rather windy today when I drove the car, and I've noticed that the i3 is very wind sensitive....
This is something I hear a lot from i3 owners, but I can honestly say ours is very stable at high speed (70 mph) in very high winds including crosswinds, they get very strong down here.
I can only assume ours has either spot on wheel alignment/geometry and dead on tyre pressures (always checked) or the geometry is a bit different but works for stability, did need new set of tyres at 18K miles or so maybe if that’s the case for me it’s worth every penny :lol:
Best regards........David

If anything in my post offends you please let me know, I may wish to offend you again. ;)

robthebold
Posts: 110
Joined: Sat May 11, 2019 5:09 pm

Re: Improve aerodynamics for better mpK

Fri Mar 06, 2020 12:10 pm

Boxbrownie wrote:
Fri Mar 06, 2020 11:39 am
Bertone wrote:
Fri Mar 06, 2020 9:18 am

BTW it has been rather windy today when I drove the car, and I've noticed that the i3 is very wind sensitive....
This is something I hear a lot from i3 owners, but I can honestly say ours is very stable at high speed (70 mph) in very high winds including crosswinds, they get very strong down here.
What magnitude of high wind do you mean? I find even a 35mph crosswind very noticeably buffeting me around.

Boxbrownie
Posts: 87
Joined: Sat Sep 06, 2014 10:21 am
Location: Pastyland, UK

Re: Improve aerodynamics for better mpK

Wed Mar 11, 2020 5:03 am

robthebold wrote:
Fri Mar 06, 2020 12:10 pm
Boxbrownie wrote:
Fri Mar 06, 2020 11:39 am
Bertone wrote:
Fri Mar 06, 2020 9:18 am

BTW it has been rather windy today when I drove the car, and I've noticed that the i3 is very wind sensitive....
This is something I hear a lot from i3 owners, but I can honestly say ours is very stable at high speed (70 mph) in very high winds including crosswinds, they get very strong down here.
What magnitude of high wind do you mean? I find even a 35mph crosswind very noticeably buffeting me around.
Down here in Cornwall we get storm force winds slightly inland as well as coastal, say around 50-60 mph winds, easily enough to lift the windscreen wiper off the glass and fold it back on itself, first time that happens it’s a bit of a shock........I do admit though at those wind speeds (not very often thankfully) you do have to hold the steering wheel securely, and although you can feel the wind buffeting the car it never feels like it’s causing instability issues at speed.
I think there is a big difference between buffeting (caused by the relatively slab high sides of the i3) and instability felt through the steering at speed which we never find an issue.
Best regards........David

If anything in my post offends you please let me know, I may wish to offend you again. ;)

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