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I have been trying to research this on the MBWorld threads but I can't seem to find a general conclusion.
Does a BOV that vents to air cause a loss of performance? Some people say that the stock system works in a way to recirculate the air so that the turbos stay pressurized and spooled up, and that running a VTA system will cause a loss of power since the C63s does not run heavy boost. Others say that there is not a significant amount of pressure that is lost because it only vents out a small amount of air. I've also read some claims of people saying that they felt the car was lacking after changing to BOVs/VTAs.
I am aware that there are BOV adapters and then the actual mechanical BOV by Turbosmart that bolts on as a replacement. While both of these vent to air, the adapter is purely for sound and while it is claimed that the mechanical BOV provides a performance bonus, I'm not too sure if it would cause any issues if its set to a vent to air system as opposed to recirculate. Even with both these options, the VTA infrastructure pushes out air as opposed to recirculating it. Is there performance loss due to air being vented out?
Does anyone have an answer for this with actual proof?
Last edited by StormHawk; Jun 14, 2022 at 10:50 PM.
I have ZAC intakes which essentially removed the recirculation/diverter valves hoses and the factory BOV vents the excess air to atmosphere.
Couple weeks ago, I ordered PTG race valves and the air now recirculates into the passenger side intake manifold. Its a completely mechanical BOV.
Feels like less turbo lag between shifts and when I step on the gas out of nowhere.
PTG supplied 3 sets of springs that go inside the BOV. I am using the hardest spring as of now so whatever excess air gets pushed out past the springs should be beneficial versus being vented, in my mind.
@miamiboy - sick. I've been considering these. How was the install? I just installed modalwork intakes (the noise is incredible) but wondering if these would be even more beneficial for PTG turbos.
Yes if you vent to the atmosphere with a BOV you will lose all that pressure and boost has to start from zero again. The stock setup uses a bypass valve, so the pressure is not lost. Here's a write up I found with a quick Google search that compares the two. BOVs are mainly for racing and high horsepower applications.
A blow off valve in our testing helps with turbo lag. Venting to atmosphere or venting back into the box as a bypass really does the same thing. It makes no difference. The main reason why a valve is added is to remove what is called compressor surge. This is when the throttle valve closes and the turbo is still spinning at very high RPM's. Compressor surge is the turbo oscillating shaft RPM's and you can audibly hear the noise. This is first off bad for turbocharger longevity and second causing turbo RPM to slow dramatically. When you accelerate again, the turbo has to spool up. A blow off valve or bypass valve will by pass the excess pressure when the throttle valve is closed, allowing the turbo to free spin at a much higher RPM.
We produce a Street Valve which is a spacer made for noise and increased flow. You still maintain the factory electric valve as your control but it just simply vents to atmosphere instead of back in the box. This also takes heat out of the system because this is charge air before the intercooler that is being vented. This is a benefit of venting to atmosphere.
We also produce a race valve as shown above. this removes your factory electric valve and replaces it with a more typical vacuum/boost assisting valve. These can hold more boost and remove some of the ECU's logic to open and close the valve when you don't necessarily want it to.
Hopefully this adds some of our experience to the thread.
@miamiboy - sick. I've been considering these. How was the install? I just installed modalwork intakes (the noise is incredible) but wondering if these would be even more beneficial for PTG turbos.
Install was pretty easy, you just have to loosen the hard plastic pieces a little bit in front of the factory BOV to stick a E10 ratchet in there to remove the screws.
I was also able to stick my hand down the passenger side to remove the stock intake manifold plastic plug to plug in the BOV lines. WD40 and a flat head might needed to wiggle the piece out.
Here's a video that helped me to remove the plug :
Hey man I have these and am mid install but have no idea how to get the boost tap off and also no idea what to do with the electric connectors from the original valves.
Also how did you manage to get the springs in becuase mine fit inside the BOV but not inside the part that attaches to the car.
Hey man I have these and am mid install but have no idea how to get the boost tap off and also no idea what to do with the electric connectors from the original valves.
Also how did you manage to get the springs in becuase mine fit inside the BOV but not inside the part that attaches to the car.
Thanks
you have to reach down into the passenger side and delicately push the plug to unlock it then you pull it out, you can also use a pick if your hands are fat like mine. Becareful because the fins can and I broke mine. I had to use my spark plug angle tool to loosen it more. Next time I know.
For the topside you have to remove the factory BOVs and simply place the new one in and tighten. You might have to loosen the some of the plastic pieces over it to get space.
I have ZAC intakes which essentially removed the recirculation/diverter valves hoses and the factory BOV vents the excess air to atmosphere.
Couple weeks ago, I ordered PTG race valves and the air now recirculates into the passenger side intake manifold. Its a completely mechanical BOV.
Feels like less turbo lag between shifts and when I step on the gas out of nowhere.
PTG supplied 3 sets of springs that go inside the BOV. I am using the hardest spring as of now so whatever excess air gets pushed out past the springs should be beneficial versus being vented, in my mind.
I also have the PTG race valves but i am using the spring that were already installed in the valves
Man whats up with you guys haha you don't need a BOV on these cars why do you guys have them? Is it for the noise or something....
Shiiit I had an HKS BOV on my Evo 7 at the start of this century and it was the bomb when I was 21 years old. But shoot I'd be embarrassed to have that g4y sound now hahaha the f*ck 🥴🥴🥴
⏱️ 700HP Facelift converted C63 S Coupe with Drexler 3.06 plated LSD
Originally Posted by George_1992
Man whats up with you guys haha you don't need a BOV on these cars why do you guys have them? Is it for the noise or something....
Shiiit I had an HKS BOV on my Evo 7 at the start of this century and it was the bomb when I was 21 years old. But shoot I'd be embarrassed to have that g4y sound now hahaha the f*ck 🥴🥴🥴
HKS Super Sequential hahahaha
Imagine having the old vent to atmosphere blow off valves plus a crackle tune. Ultimate f4ggot starter pack
Mercedes SLR McLaren 722 S Is Extremely Rare Example Modified by McLaren
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Does a BOV Cause Turbo Lag/Reduce Performance??
Blow off valves on Mercs haha
