Bov or Diverter

vivanapoli806 · 05-20-2013, 10:01 AM

Hey guys I just purchased my cobb tune. I haven't used it yet since I'm getting a software update on my car done tomorrow. I plan on getting a new charge pipe soon due to increased boost pressure. My question is which would be better a charge pipe with a bov or one with forge diverters? My car is auto so basically I want to know if I will get the same results out of either of them or is one better than the other. I understand I won't get the loud sound out of the bov unless I'm in manual mode since I'm auto. Just want your guys thoughts

135Pats · 05-20-2013, 01:44 PM

Same results, it's 100% a matter of personal taste. BOV will be louder and more noticeable, I can hear my Synapse clear as day. In terms of loudness HKS>Synapse>Tial.

Eyeman · 05-20-2013, 06:56 PM

Sounds like you have all the facts down and just have to make up your own mind. IMO my car makes plenty of excess noises with diverter valves. I also would not want a BOV sound that might cover up the extremely cool gurgling exhaust sounds that our cars make.

froop · 05-20-2013, 08:12 PM

The function of a diverter valve and a blow off valave are exactly the same in that they are there to release the build up of air pressure when you suddenly release the throttle. This is to prevent sudden deceleration of the turbo compressor wheels. A diverter valve will only really be heard when it's quiet and you're in a carpark etc. I could hear my stock diverters go off on my 6AT with DCIs but only really in those conditions. Without DCIs I found it was virtually unnoticeable.

I have TiAl BoVs on my 6MT 135i and those are clear as day however not an overly obnoxious sound. The sound that you get will vary depending on the brand. Some BoVs have actual cones etc to amplify the noise.

In regards to covering up the gurgling sound of the exhaust it would be quite unlikely. The exhausts generally only gurgle when letting up off the throttle at low load. This generally doesn't build up enough pressure to require air pressure release. At least not in my experience. My car gurgles like crazy because I have a straight pipe set up with only a race muffler but I can't say I've ever heard the BoV drown out any gurgling because they generally just don't happen at the same time.

Stan.mac · 05-21-2013, 07:24 AM

BOV! How do you expect to live your own Fast and Furious life movie everyday you drive? BTW AA's BOV is great!

Freon · 05-21-2013, 07:27 AM

I generally agree with what is posted above, but would add it's nice to have a valve that is adjustable. Either shimming with washers, or turning a screw or whatever.

05-20-2013, 10:01 AM	#1
vivanapoli806 Captain 88 Rep 824 Posts Drives: 2012 535i Xdrive Msport Join Date: Apr 2013 Location: Chicago Burbs iTrader: (2)	Bov or Diverter Hey guys I just purchased my cobb tune. I haven't used it yet since I'm getting a software update on my car done tomorrow. I plan on getting a new charge pipe soon due to increased boost pressure. My question is which would be better a charge pipe with a bov or one with forge diverters? My car is auto so basically I want to know if I will get the same results out of either of them or is one better than the other. I understand I won't get the loud sound out of the bov unless I'm in manual mode since I'm auto. Just want your guys thoughts
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05-20-2013, 01:44 PM	#2
135Pats Major General 456 Rep 6,478 Posts Drives: A few BMWs Join Date: May 2012 Location: Maryland iTrader: (3)	Same results, it's 100% a matter of personal taste. BOV will be louder and more noticeable, I can hear my Synapse clear as day. In terms of loudness HKS>Synapse>Tial. __________________ E88 N54 Alpinweiss/Coral Red/Motiv HTA 3586r Tial .82AR/Other stuff...652WHP F30 N55 XDrive EBII
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05-20-2013, 06:56 PM	#3
Eyeman Colonel 122 Rep 2,040 Posts Drives: 2008 135 blk, blk, step Join Date: Jan 2009 Location: Atlanta, GA iTrader: (0) Garage List 1994 Porsche 968 Cab [0.00] 2017 AMG GTS [0.00] 1994 Porsche 968 Coupe [0.00] 1977 Mercedes 450SE ... [0.00] 2008 135 [8.00]	Sounds like you have all the facts down and just have to make up your own mind. IMO my car makes plenty of excess noises with diverter valves. I also would not want a BOV sound that might cover up the extremely cool gurgling exhaust sounds that our cars make. __________________ Injen, RR OCC, MadDad Whisper, donut spare, 19x8.5et43fr 19x9.5et45r Volk LE37's, rear fenders rolled/pulled, PSS4S 225/35fr 255/30r, KW V1's, AR coated catless dps, Cross strutbar, CF grills and license plate holder, iCarbon diffuser, ETS black anodized FMIC, M3 control arms, Quaife, ER chargepipe, ForgeDV's, Topspeed Custom Tune, V3sims, Braille, Andrey_GTA rear hub mod, Ebay Mstyle front bumper and performance style side skirts.
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05-20-2013, 08:12 PM	#4
froop Colonel 171 Rep 2,682 Posts Drives: 08 AW 6MT E82 Join Date: Jul 2012 Location: Sydney, Australia iTrader: (3)	The function of a diverter valve and a blow off valave are exactly the same in that they are there to release the build up of air pressure when you suddenly release the throttle. This is to prevent sudden deceleration of the turbo compressor wheels. A diverter valve will only really be heard when it's quiet and you're in a carpark etc. I could hear my stock diverters go off on my 6AT with DCIs but only really in those conditions. Without DCIs I found it was virtually unnoticeable. I have TiAl BoVs on my 6MT 135i and those are clear as day however not an overly obnoxious sound. The sound that you get will vary depending on the brand. Some BoVs have actual cones etc to amplify the noise. In regards to covering up the gurgling sound of the exhaust it would be quite unlikely. The exhausts generally only gurgle when letting up off the throttle at low load. This generally doesn't build up enough pressure to require air pressure release. At least not in my experience. My car gurgles like crazy because I have a straight pipe set up with only a race muffler but I can't say I've ever heard the BoV drown out any gurgling because they generally just don't happen at the same time.
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05-21-2013, 07:24 AM	#5
Stan.mac Second Lieutenant 9 Rep 296 Posts Drives: 135i M-Sport Join Date: Aug 2012 Location: NoVA iTrader: (3)	BOV! How do you expect to live your own Fast and Furious life movie everyday you drive? BTW AA's BOV is great! __________________ "I live my life a quarter mile at a time. Nothing else matters: not the mortgage, not the store, not my team and all their bullshit. For those ten seconds or less, I'm free." afe DCI/Greddy Oil Catch Can/Catless DP/ Cobb Stage 2+/Berk Axle-Back(Race)/AAW CP w BOV/H&R Springs/ ALPINA Flash/Helix FMIC/
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05-21-2013, 07:27 AM	#6
Freon Major 81 Rep 1,051 Posts Drives: 2009 135i Join Date: Nov 2007 Location: Indianapolis iTrader: (3)	I generally agree with what is posted above, but would add it's nice to have a valve that is adjustable. Either shimming with washers, or turning a screw or whatever. __________________ 2009 BMW 135i 6MT Sport, AFE intake, Cobb AP, Apex 18x8.5+9.5, 255/275 PSS
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