Blow off valve install - VACUUM SOURCE

[reventon]

Hi all,

As we know the valvetronic does not produce negative vacuum pressure in the intake manifold so a typical blow off valve setup *shouldn’t* work. However, I’ve seen two videos of a 330i and a mini cooper both with the B48 platform utilising a blow off valve successfully.

I’m in the middle of an upgraded turbo (and t51r mod), intake piping and bigger custom intercooler and just toying with the idea of welding on a bov flange.

*Would it be possible to tap the vacuum pump/brake booster line to feed the blow off valve?*

Yes, it’s a rice mod. Yes, I just want cool noises, always loved the HKS ssqv.

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[tracer bullet]

Burger / BMS sells a pipe for it, I think, someone might have a DIY or installation guide for the hookups.

 

[i3igpete]

The manifold DOES pull vacuum, but you need a bov with swappable light springs (turbosmart or tial). Ssqv does not, which is why hks has that controller thing which reads pedal input.

You may need to buy a few different springs, start with the default one and keep going lighter until the bov operates properly. For reference, the b58 pulls ~2 inHg at idle and ~10 inHg when letting off at high RPM.

On the b58, the evap line that runs over top of the manifold can be tapped for vac/boost. It looks like the same part can be used for the b48.

REV2 Controller - Boost Take Off Fitting (OEM Intake Manifold) - For B – protuningfreaks https://www.protuningfreaks.com/pro...OR7GngHE_Tr_-AKwr4U62mJdLx99CAY33-i4Q8dY3cE8d

 

[jnoremac]

I’ll be following this!
What turbo did you end up going with?

 

[reventon]

The manifold DOES pull vacuum, but you need a bov with swappable light springs (turbosmart or tial). Ssqv does not, which is why hks has that controller thing which reads pedal input.

You may need to buy a few different springs, start with the default one and keep going lighter until the bov operates properly. For reference, the b58 pulls ~2 inHg at idle and ~10 inHg when letting off at high RPM.

On the b58, the evap line that runs over top of the manifold can be tapped for vac/boost. It looks like the same part can be used for the b48.

REV2 Controller - Boost Take Off Fitting (OEM Intake Manifold) - For B – protuningfreaks https://www.protuningfreaks.com/pro...OR7GngHE_Tr_-AKwr4U62mJdLx99CAY33-i4Q8dY3cE8d

thank you for the detailed reply! I will consider buying a blow off valve with a spring in the range of less than 10inhg. Would I risk the valve opening prematurely if the spring rate is too weak? Or the pressure differential will keep it closed?

 

[reventon]

I’ll be following this!
What turbo did you end up going with?

hi, I bought a g30-770 and sent it to ocd works for the t51r inlet machining. This will be run with an external wastegate, my tuner is setting it up.

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