[loweredram]

Hey guys I've been searching on line and on this forum trying to get a better understanding on how DV's work. I have an 07 335i sport AT with FMIC, V5, UR downpipes and drop in filter. My buddy took a drive in my car and suggested I get some aftermarket DV's. He said the take off lowend was a bit on the laggy side and when he got DV's problem solved. Only problem is when I asked exactly how they work he didn't sound very clear. So I'm asking here . I know you have a nipple side the vaccum is applied to the charge pipe inlet and the bleed back into the manifold but at what points are these active? I did compare his forge to mine and right off the bat they are built well and when I applied vaccum to mine it took very little to open the factory DV and quite a bit more to open his forge. Is this what could be causing the lack of low end snap? Thanks guys

[turb0mik3]

Originally Posted by loweredram

Hey guys I've been searching on line and on this forum trying to get a better understanding on how DV's work. I have an 07 335i sport AT with FMIC, V5, UR downpipes and drop in filter. My buddy took a drive in my car and suggested I get some aftermarket DV's. He said the take off lowend was a bit on the laggy side and when he got DV's problem solved. Only problem is when I asked exactly how they work he didn't sound very clear. So I'm asking here . I know you have a nipple side the vaccum is applied to the charge pipe inlet and the bleed back into the manifold but at what points are these active? I did compare his forge to mine and right off the bat they are built well and when I applied vaccum to mine it took very little to open the factory DV and quite a bit more to open his forge. Is this what could be causing the lack of low end snap? Thanks guys

When you hit the gas your throttle body opens allowing air into the engine. The turbos are in the intake stream and compresses the air and forces it in to the engine at a certain pressure. Well suddenly you need to shift and let off the throttle, throttle plate closes, and the turbos are still spinning. The turbos still spinning are a good thing because it will have less work to catch back up when you reapply the throttle, but... a spinning turbo means it is still compressing air and the throttle body is closed so there is only one way for the compressed air to get out, back the way it came in. Well this is where the Diverter Valve comes into play. The diverter valve diverts the air that would have gone back through the turbo causing it to stop spinning in one direction and spin backwards, to go back into the intake stream pre-turbos so you recycle that air.

Long story short, it recycles the air left over after you lift off the accelerator so you can hold boost better and sends the air back through the intake system. Aftermarket DVs just do their job more efficiently than the stock ones.

[Coolieman1220]

whats the difference between a diverter valve and a blow off valve?

from what i know, a BOV is useless as it just makes noise but it does help release back pressure between the turbo and the throttle body. are they similar, one just puts the air back into the turbo to help it spool faster?

[turb0mik3]

Originally Posted by Coolieman1220

whats the difference between a diverter valve and a blow off valve?

from what i know, a BOV is useless as it just makes noise but it does help release back pressure between the turbo and the throttle body. are they similar, one just puts the air back into the turbo to help it spool faster?

They basically do exactly the same thing. I preferred the blowoff valve because I think it is a little bit more efficient at holding boost rather than re filtering the air back into the intake system. You don't see turbo lambos and turbo GTRs using DVs, although that is a pretty stupid excuse, but still, haha.

[BMW1986]

The N54 motor was designed to keep the air into the motor hence why the DV's are a better option. A Blowoff Valve will give you a better whoost noise.

[Imperator]

Originally Posted by Coolieman1220

whats the difference between a diverter valve and a blow off valve?

Neither help you spool faster. The only purpose of the BOV/DV is to expel pressure on the charge side when the throttle plate closes.

DVs "divert" air back into the intake system and are commonly used to reduce noise and to keep a closed-loop, clean intake tract.

BOVs open to the atmosphere, creating the noise you hear under boost just as the throttle plate closes.

[zeenon53]

So to complicate things more, how would a recirculating BOV differ from a DV? I would assume at that point they are the same?

[TXe92]

just like most platforms.. your probably better off running a BPV ( by pass valve ) / DV.. BOV are for teenagers who want to hear a cool noise when they shift gears..