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Go Back   E46Fanatics > E46 BMW > E46 Xi Forum

E46 Xi Forum
The E46 XI was produced from 01-05 in sedan and touring body styles. Powered by either a 2.5L inline 6 in the 325xi or a 3.0L inline 6 330xi. Discuss all thing about BMW AWD E46 'Xi' here.

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Old 02-20-2014, 10:18 AM   #41
SamDoe1
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Quote:
Originally Posted by peytonracer4 View Post
If you've actually taken a class in aerodynamics (which I assume you haven't based on your statement) you'd understand that underbody panels are there to reduce drag. Which returns better gas mileage.
Quote:
Originally Posted by alika808 View Post
Second the motion!!!!!!! Good work peytonracer4.
BSME, fluid mechanics/aerodynamics specialty
MSME, fluid mechanics/aerodynamics

I've taken quite a few classes, labs, design studies, design projects, etc. I also do this for a living.

Not quite the answer you were thinking you'd get huh?

Quote:
Originally Posted by alika808 View Post
Check this site, item #26 Front aggregate protective plate
Are you aware what the definition of an "aggregate protective plate" is?

I'm not just blowing smoke guys, your 325Xi is slower and gets worse gas mileage than a late model Toyota Camry without the panels. As much as you'd like to think your 10+ year old BMW is a super car, I assure you the underbody panels are not for aerodynamic reasons or downforce. They are for reducing noise and keeping crap out of the engine bay. Also to hide oil leaks.

Last edited by SamDoe1; 02-20-2014 at 10:20 AM.
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Old 02-20-2014, 05:40 PM   #42
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I have to agree with SamDOe1, the main reasons that the 2 "plastic" covers are on the bottom is to reduce air noise and to protect electronic components from water, ice, snow and other road hazards. They also hide oil leaks, but thats not their true purpose. Yes it makes it more of a PIA to change the oil unless you use a vacuum pump via the dip stick tube (which will remove 90-95% of the oil). At legal speeds, the "covers" have little to no effect on aerodynamics or down force, to be truly aerodynamic or increase the down force underneath the car, there would have to be "shields" from front to back. If you are missing any of the Zerk Screws or their "clips", you can pick them up at a BMW Dealer or even many good car part places, OR you can change them over to sheet metal screws that go into "license plate" type clips that will fit around just like the Zerk Screw clips (lots of parts places that cater to racers will have Zerk Screws and their clips in several different sized as they are used to secure body panels). Leave the covers on, and unless you have lowered your car, the front cover can be removed and installed without even jacking the car up, the drain plug can be gotten to, all you need is a bigger diameter drain pan that has smaller sides.
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Old 02-20-2014, 05:43 PM   #43
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^ We've been agreeing a lot lately...nice change of pace.
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Old 02-20-2014, 06:39 PM   #44
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SamDoe1, yes we have some minor differences, but when you're spot on, you're spot on dude! And since we both have lots of automotive experience, not just as a wrench turning tech, we have some more insight and knowledge. Plus, at some point, I bet we have a difference of opinion again, lol.
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Old 03-20-2014, 02:44 PM   #45
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I added a skid plate

My 330xi did not have one when I bought it. I replaced the altenator a month ago after water got to it. So I added the skid plate to prevent future water damage to the replacement alternator.

Nate
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Old 03-20-2014, 05:49 PM   #46
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Still have them on my 325xi. Best I can tell ya is years ago I took them off my former 5 series and really always regretted it. Went from having a very clean bottom of engine compartment to a filthy one. again, the extra few minutes of hassle putting them on and off, is well worth it IMHO. Besides being neat, I would hate to know that any puddle or anything caused a starter replacement nightmare for myself. Could it lead to that, I dunno, but why even give the elements better odds.
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Old 10-25-2016, 01:49 PM   #47
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I going with...it improves gas mileage.
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Old 10-25-2016, 01:51 PM   #48
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Nice bump, goodmar ^

I have had my skid plates off for about a year/3000 miles since I've been doing constant work on the car. Every time I've taken it to BMW they get on me about it. They say I absolutely should have them on because they protect all of the sensitive stuff while driving AS WELL as help with drag, so you should definitely keep them on!
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a list of parts to replace on these is easy; just replace everything.
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Old 10-26-2016, 05:09 PM   #49
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Must have. I have replaced these very expensive parts several times. If you are keeping your car for any length of time and do any maintenance on it, you must have these. They are on the "insulation" page on realoem.
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Old 10-26-2016, 05:44 PM   #50
e46alfonso
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My middle one is missing and I'm not buying it, fvck that
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Old 10-27-2016, 04:04 AM   #51
Gbro
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I always ditched the plastics and just ran a subframe reinforcement plate such as:

https://www.ecstuning.com/BMW-E46-32...late/ES128604/

It adds some rigidity, has a oil drain window, and protects the underside. What's not to like?
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Old 10-27-2016, 06:53 PM   #52
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No you don't have that thing installed on your car. It's not possible to reinforce the front subframe.
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Old 10-27-2016, 07:33 PM   #53
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No you don't have that thing installed on your car. It's not possible to reinforce the front subframe.

It literally bolts to the front subframe, what are you talking about?
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Old 10-27-2016, 08:12 PM   #54
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On the rwd not the xi
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Old 10-27-2016, 08:27 PM   #55
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Originally Posted by Gbro View Post
I always ditched the plastics and just ran a subframe reinforcement plate such as:

https://www.ecstuning.com/BMW-E46-32...late/ES128604/

It adds some rigidity, has a oil drain window, and protects the underside. What's not to like?

Pics? I have both and XI and RWD and don't see this working on the XI.
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Old 11-01-2016, 02:05 AM   #56
Gbro
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I have this on my RWD, my apologies for the confusion. I've heard that the x5 one will work on XI's, but that seems like a stretch to me
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Old 11-01-2016, 08:36 AM   #57
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I keep all under body panels, and original bracing, unless the new reinforcement won't fit without removing old. You don't want to mess with the airflow through your engine, and it leaves the underside of your engine bay exposed to the elements. How is this a long thread, lol
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Old 11-22-2016, 11:02 AM   #58
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I have a few sheets of 6061 T6 laying around. Looks like a fun project to replace the missing middle pan.
If I do this, it will be reported back.
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