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Discussion Starter · #1 ·
Ok, Total Noob question here but what is the difference between a Blow off valve and a Diverter valves that I see on various sites.

example Go Fast Bits Diverter valve vs. Forge Blow off Valve or are they simply different ames for the same thing?

TIA,

J
 

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They perform the same function, but they are different.
 

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There is something to be said for brevity, but, could you please expand upon their differences? Thanks.

Steve.
 
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Someone can correct me if I'm wrong here, but here's my understanding.

Blow off valves expel pressure built in the intake to the atmosphere. Diverter valves (also referred to as recirculating blow off valves), release that pressure back into the intake upstream of the turbo.

Switching from a diverter valve to the blow off valve effectively creates a boost leak, as air that was metered by the mass air flow sensor by the ECU is expected for fueling purposes. When less air is used than was measured, the O2 sensor reports the engine running too rich and may throw a check engine light for a rich condition. I'm not familiar with whether or not this can be accounted for in a tune.
 

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Someone can correct me if I'm wrong here, but here's my understanding.

Blow off valves expel pressure built in the intake to the atmosphere. Diverter valves (also referred to as recirculating blow off valves), release that pressure back into the intake upstream of the turbo.

Switching from a diverter valve to the blow off valve effectively creates a boost leak, as air that was metered by the mass air flow sensor by the ECU is expected for fueling purposes. When less air is used than was measured, the O2 sensor reports the engine running too rich and may throw a check engine light for a rich condition. I'm not familiar with whether or not this can be accounted for in a tune.
So, I take it that you are agreeing with me, but not with so much brevity. :)
 
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Ah, that's better. Now we know. And the explanation confirmed by a second party. Thank you.

Steve.
 

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Discussion Starter · #7 · (Edited)
So, I take it that you are agreeing with me, but not with so much brevity. :)
Points for being on top of it but I don't read his response as ...the same thing.

Expelling to atm gives you that boy racer Whooooosh sound where as it sounds as if diverting to upstream makes use of the energy.

Aside from the cool sound factor...would there be a scenario where one would be better than the other?

Just curious what anyone in the Fiat crowd thinks.

a little googling provides some description

http://www.eurosporttuning.com/blog/diverter-vs-blow-off-valve/

Benefits of Diverter Valves
The stock valve on your Volkswagen regulates the turbo power. When you are at an idle, the vacuum pressure opens the valve. The turbo boost is activated when the valve is fully closed. Lifting the throttle releases the boost pressure into the air cleaner box. If the valve is defective or inadequate, you will get a loss of boost, extended lag or a throttle response that is sluggish. These problems go away with the installation of an aftermarket diverter valve. If you are running with a chip, you need to put the diverter valve in because the chip will stress the standard valves.

Is It a Blow-Off Valve?
The difference between a diverter valve and the blow-off valve is where the air is delivered. Blow-off valves send it out into the atmosphere and you get a lot of noise, but in some cases, if your Volkswagen or Audi has a complicated engine management system, you may suffer drivability issues or error codes. A diverter valve recycles the air.
 

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Someone can correct me if I'm wrong here, but here's my understanding.

Blow off valves expel pressure built in the intake to the atmosphere. Diverter valves (also referred to as recirculating blow off valves), release that pressure back into the intake upstream of the turbo.

Switching from a diverter valve to the blow off valve effectively creates a boost leak, as air that was metered by the mass air flow sensor by the ECU is expected for fueling purposes. When less air is used than was measured, the O2 sensor reports the engine running too rich and may throw a check engine light for a rich condition. I'm not familiar with whether or not this can be accounted for in a tune.
Woah, that is absolutely not correct when speaking about the 1.4 multiair. No MAF.

Atmospheric or recirculating BOV's will function equally well on these.
 

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Woah, that is absolutely not correct when speaking about the 1.4 multiair. No MAF.

Atmospheric or recirculating BOV's will function equally well on these.
Jon is correct here. The 124 uses a speed density fuel injection system. It's somewhat unusual, but it's excellent, and becoming more common. There is no tuning issue when switching from a DV or bypass valve to a blow off valve.

Greg
 

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I have the GFB dv+ upgrade plus the forge blow off valve. The forge blow off valve is an attachment and bolts to the DV to allow atmospheric purge. Its not that loud but I prefer to hear it knowing that my DV is working properly as I have had some jam up in the past.
 

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Points for being on top of it but I don't read his response as ...the same thing.

Expelling to atm gives you that boy racer Whooooosh sound where as it sounds as if diverting to upstream makes use of the energy.

Aside from the cool sound factor...would there be a scenario where one would be better than the other?

Just curious what anyone in the Fiat crowd thinks.

a little googling provides some description

http://www.eurosporttuning.com/blog/diverter-vs-blow-off-valve/

Benefits of Diverter Valves
The stock valve on your Volkswagen regulates the turbo power. When you are at an idle, the vacuum pressure opens the valve. The turbo boost is activated when the valve is fully closed. Lifting the throttle releases the boost pressure into the air cleaner box. If the valve is defective or inadequate, you will get a loss of boost, extended lag or a throttle response that is sluggish. These problems go away with the installation of an aftermarket diverter valve. If you are running with a chip, you need to put the diverter valve in because the chip will stress the standard valves.

Is It a Blow-Off Valve?
The difference between a diverter valve and the blow-off valve is where the air is delivered. Blow-off valves send it out into the atmosphere and you get a lot of noise, but in some cases, if your Volkswagen or Audi has a complicated engine management system, you may suffer drivability issues or error codes. A diverter valve recycles the air.
They are both blow off valves. One recirculates the air. The other sends it to the atmosphere. As Extreme said. the diverter valve is also referred to as a recirculating blow off valve. The major function is to release excess pressure on the intake side of the turbo. They both perform that function and are interchangeable parts.

You would not say that a quad-tip exhaust is the same as a dual-tip exhaust, but they perform the same function and are interchangeable. Same for the diverter valve and blow off valve. Same function, but different, like I said.
 

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I have the GFB dv+ upgrade plus the forge blow off valve. The forge blow off valve is an attachment and bolts to the DV to allow atmospheric purge. Its not that loud but I prefer to hear it knowing that my DV is working properly as I have had some jam up in the past.
No you don't. You have the Forge Blow Off Adapter Plate ($91.99) with your GFB DV+. You cannot put a GFB DV+ and a Forge Blow Off Valve ($249.49) on at the same time.
 
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Discussion Starter · #14 ·
THANKYOU! 'cuz I read that and my head went huh? I thought I was understanding but now.... ......but i'm back to understanding again ;)

No you don't. You have the Forge Blow Off Adapter Plate ($91.99) with your GFB DV+. You cannot put a GFB DV+ and a Forge Blow Off Valve ($249.49) on at the same time.
 
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