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Whats A Good Bolt On Plumb Back Blow Off Valve?

drifta1600

By drifta1600,
in Engines & Forced Induction

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drifta1600 Contributor

drifta1600

Posted
Posted

Hi all. Im not after a swoosh or a fluter, I just want a good performer.

My std one has a hole in the bottom of it (its supposed to be there) but it leaks like a sieve for some reason.

any one used an after marker one that has been good with no leaks? Needs to be good for upto 20 psi.

Blackkers Experienced

Blackkers

Posted
Posted

the bov has the same pressure applied to either side of the valve + a spring holding the valve shut. So I don't really know how it would leak unless the unit wasn't sealed properly or the gasket is a bit old.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

I run the Kompact, other than having no adjustment and needing to buy springs from Turbosmart for fine tuning the noises out, they are a very good product. Mine has been flawless for years.

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Ben C34 Grand Master

Ben C34

Posted
Posted

the bov has the same pressure applied to either side of the valve + a spring holding the valve shut. So I don't really know how it would leak unless the unit wasn't sealed properly or the gasket is a bit old.

stock rb25 bovs also have a small hole for some reason. It leaks when you pressure test the system, but I can't see how the tiny hole would have an impact on the amount of air the engine uses when under high boost.

scotty nm35 Grand Master

scotty nm35

Posted
Posted

Mine gained 4psi on the dyno with the hole blocked. What a waste of boost. :P

It is there to help smoothen out the transition from boost to cruise, good tuning can help with this too, so the hole isn't really required. It is easy enough to try, as you can remove the grubscrew if you don't like it. (or drill a smaller hole through the grubscrew to fine tune the amount it bypasses)

drifta1600 Contributor

drifta1600

Posted
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yer, I have solved a number of issues, just from blocking that hole. fixed slow to boost issue, surge and creep issue, (which I thought it was a waste gate issue) flat spot after 4800 and before 6000 issue. low idle issue. sooo many thing were happening just because of that stupid hole. I fixed it (temporarily) with elect tape! I will get a gtr one I think. or a compact.

thanks heaps for all the info!


stock rb25 bovs also have a small hole for some reason. It leaks when you pressure test the system, but I can't see how the tiny hole would have an impact on the amount of air the engine uses when under high boost.

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