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BMW 3-Series (E90 E92) Forum > E90 / E92 / E93 3-series Technical Forums > DIY Guides > 335i Free BOV DIY



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  335i Free BOV DIY
Red Star Rising
04-06-2007
Since Active Autowerke insists that their BOV is worth $750, I think this little DIY is great. Not extremely loud. But noticible, and nice. Member JOEVISTA clued me in on exactly how to do it. Thanks!
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  #198  
By danilloe90 on 11-26-2010, 12:13 PM
not smart....trying to make your BMW sound like a ricer is a bad idea. Want to make a whoosh noise go get a Subaru. Thats just my $.02 Plus doing this wont hurt the car, you are right BoostedBMW the MAP sensor will prevent any damage.
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  #199  
By corb on 01-18-2011, 03:57 PM
fyi, if you're having a problem removing the hose, it's most likely because the car is COLD (not cooled off, but cold). In the winter this will be nearly impossible to do by hand, and will most likely result in something snapping, or at least some raw fingers. To fix this, just warm the engine up, let it cool for a few minutes, and you'll have no problems at all
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  #200  
By RUS0628 on 02-21-2011, 05:29 PM
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can some1 do this mod for me. I ll give u 10$ for your time. I am in the bay area. Thanks
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  #201  
By Dr. G on 03-17-2011, 12:31 AM
Is there a better option rather then plugging the bungs?

Anyone find a cap you can put over them like the BOV kits come with instead of having to stick something inside?
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  #202  
By MeinBMW on 03-19-2011, 02:49 PM
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Quote:
Originally Posted by Dr. G View Post
Is there a better option rather then plugging the bungs?

Anyone find a cap you can put over them like the BOV kits come with instead of having to stick something inside?
Forge Motorsport makes blanking plugs ... I'm actually using them on my car right now ... just need 2 of I believe the 20mm ones and a small piece of silicon hose + 4 clamps ... just call them up and ask for Mike ... tell him you need the same setup I am running

-Eric

http://forgemotorsport.com/content.a...oduct=FMTB052K
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  #203  
By Marcanthony04 on 04-20-2011, 10:16 PM
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I just did this on my e90. Worked perfectly, sounds good. I put everything back though. Just wanted to try it out. Nice DIY.
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  #204  
By wahooooman on 05-08-2011, 06:55 PM
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harmful or not ??

just trying to clarify, ive heard mixed things by reading this DIY. i know this is a do at your own risk thing but will there be a chance i will be harming my car. thanks
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  #205  
By hiter202 on 07-15-2011, 11:52 AM
can this be done on a 2011 335i xDrive Coupe E92??? and if so, please let me know if there are any pictures of it?
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  #206  
By FirstBMWLA on 07-15-2011, 04:55 PM
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My question about this is wouldn't any BOV whether it be a genuine AA one or this simple DIY cause the car to run richer after a shift vs using stock diverter valves?
Does the car not car that this air is not being fed back into the system?
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  #207  
By eninety88 on 07-25-2011, 02:37 PM
tried doing the mod, but couldnt find the second hose. well i found it i think, but not sure if it's the right one. i know its behind the airbox... can someone post a picture of the second hose? the first one is clear. thanks!
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  #208  
By craesq on 10-18-2011, 08:40 PM
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The Final Say...

I've turbocharged many cars and here's the facts:

1. BOVs prevent boost spikes when throttle bodies close suddenly, protecting the engine from overboost and the turbochargers from air backflow.

2. When the throttle bodies close suddenly, OEM BOVs route the surplus air back to the pre-turbo air intake piping for two reasons: (1) emissions compliance; (2) reduce noise.

3. This "BOV mod" does not change in any way shape or form the function of the BOV. It is still going to vent the excess boost. The only difference is that the excess boost is going to vent to the atmosphere, not back to the intake piping. By doing so, you can hear it better when it happens.

4. The intake piping will still show vaccuum when not under throttle/boost.

5. The ONLY potential impact of this mod is that, immediately after the throttle bodies reopen, the a/f ratio may be slightly rich because there is less air in the intake piping than BMW calibrated. This is not a safety/reliability issue.

6. All of the above assumes that you have adequately plugged the intake piping hole so that it is airtight.
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  #209  
By G-Bus on 10-26-2011, 12:27 AM
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BMW Free blow off DIY

Here is a video of how mine sounds. My door was open when I recorded. Also I tried it on but put them back together.
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  #210  
By aj555 on 10-26-2011, 12:39 AM
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Quote:
Originally Posted by Dr. G View Post
Is there a better option rather then plugging the bungs?

Anyone find a cap you can put over them like the BOV kits come with instead of having to stick something inside?
Yeah, go to home depot and buy a pack of those rubber chair leg protector caps. There like $5 for 4. They fit right over it, then clamp it down with a small metal tightening clamp.
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  #211  
By Lulz_M3 on 10-26-2011, 07:56 AM
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Quote:
Originally Posted by craesq View Post
I've turbocharged many cars and here's the facts:

1. BOVs prevent boost spikes when throttle bodies close suddenly, protecting the engine from overboost and the turbochargers from air backflow.

2. When the throttle bodies close suddenly, OEM BOVs route the surplus air back to the pre-turbo air intake piping for two reasons: (1) emissions compliance; (2) reduce noise.

3. This "BOV mod" does not change in any way shape or form the function of the BOV. It is still going to vent the excess boost. The only difference is that the excess boost is going to vent to the atmosphere, not back to the intake piping. By doing so, you can hear it better when it happens.

4. The intake piping will still show vaccuum when not under throttle/boost.

5. The ONLY potential impact of this mod is that, immediately after the throttle bodies reopen, the a/f ratio may be slightly rich because there is less air in the intake piping than BMW calibrated. This is not a safety/reliability issue.

6. All of the above assumes that you have adequately plugged the intake piping hole so that it is airtight.

Good info, but #5 is incorrect.

The n54 does not have a MAF sensor, therefore the A/F ratio is not affected by a BOV that vents to the atmosphere.
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  #212  
By Haus_07 on 11-02-2011, 12:19 AM
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Quote:
Originally Posted by Lulz_M3 View Post
Good info, but #5 is incorrect.

The n54 does not have a MAF sensor, therefore the A/F ratio is not affected by a BOV that vents to the atmosphere.
+1

Speed density on the 335i's. I've had my car setup like this for months now. One of the main reasons I did this mod was to keep some of the engine oil from re-entering the intake system. I know that's how BMW designed it for emissions, but after just a few weeks of running the car in this configuration, I can plainly see how much oil is now not being fed back into the intake, and it sounds pretty good too. Here's a pic of the way I have mine setup:
Attached Images
  
Last edited by Haus_07; 11-02-2011 at 12:26 AM.
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  #213  
By Lulz_M3 on 11-02-2011, 07:15 AM
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Quote:
Originally Posted by Haus_07 View Post
+1

Speed density on the 335i's. I've had my car setup like this for months now. One of the main reasons I did this mod was to keep some of the engine oil from re-entering the intake system. I know that's how BMW designed it for emissions, but after just a few weeks of running the car in this configuration, I can plainly see how much oil is now not being fed back into the intake, and it sounds pretty good too. Here's a pic of the way I have mine setup:
What do you have the diverter valves venting to? I can see where you have attached tubes to route the air that is being bled out of the DV's but i cant make out what they are feeding into.

WRT the oil in the intake, i wouldn't think venting to the atmosphere vs pre-turbo intake would have any significant benefit vs stock set-up. Are you seeing alot of oil being vented from the DV's? To really eliminate this you should look into a catch-can set-up (if you havent already).
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  #214  
By Haus_07 on 11-02-2011, 01:10 PM
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Quote:
Originally Posted by Lulz_M3 View Post
What do you have the diverter valves venting to? I can see where you have attached tubes to route the air that is being bled out of the DV's but i cant make out what they are feeding into.

WRT the oil in the intake, i wouldn't think venting to the atmosphere vs pre-turbo intake would have any significant benefit vs stock set-up. Are you seeing alot of oil being vented from the DV's? To really eliminate this you should look into a catch-can set-up (if you havent already).
They aren't feeding into anything. I tied them together so that they both exit in the same place, but basically they are just dumping into the atmosphere. As far as a catch can is concerned, I've read many a post of people having issues with the pcv system after installing one, so I opted not to.
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  #215  
By az335idesi on 11-03-2011, 06:18 PM
anyone who tried this, did you guys see any long term negative effects?
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  #216  
By m thriller on 05-06-2012, 10:55 AM
Well i just did this mod today and for some reason my car actually feels more free revving and slghtly quicker!
I'm sure its not a placebo effect and come from a long line of modified turbo cars but its deffo an improvement and can not feel any delay or slight jolt between gear changes like i could before.
can hear the spool up nice but wish it was a touch louder but hey ho will end up buying one now!
P.s.. my cars a auto and has over 140k on it now!
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  #217  
By kollegga on 06-21-2012, 04:46 AM
I can't see any pictures on page 1...

Can anyone help me?
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  #218  
By Bavarian Made on 06-30-2012, 07:08 PM
So can It be done with only the front part? I've been trying to get the rear clip off for about 30 minutes with no luck and I don't feel like taking everything apart.
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  #219  
By E90Company on 07-11-2012, 10:56 PM
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When you are removing the dv hose from the intake nipple, do you twist? how is it done? The gray thing isnt moving and I think I broke it...
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