Do I need a BOV?
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1,862 Posts
Need. No unless the diaphragm is broken and its leaking. Usually no encountered Til boost is raised. Don't freak out the car is supposed to sound like that
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3,541 Posts
you don't need one but you will notice a bit of a difference if you get a BOV in how your boost builds throughout the powerband and how steady boost is held. Also, with an aftermarket BOV, the BOV hack that I came across you will notice a higher peak boost and be able to feel the extra kick in the pants 
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1,488 Posts
Not really. But yes.
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11,457 Posts
That's what she said.
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The AEM/Ingen/Stock/Socks/845 it makes no difference in what BOV/BPV you get. Just look for a BOV that matches the factory 3-bolt flange and you will be all set. If you choose to go the route of a BOV and not a recirculating system, make sure that you get a 7/8" cap or plug to block-off the return on the intake.
The BOV connects to the intercooler and not (directly) to the intake.
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as long as you are using the stock intercooler or the 845 FMIC kit.
If you are using my kit, it uses the Greddy flange, in which you can get a Tial or HKS adapter for it to use those style BOVS
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107 Posts
In addition to this ...what are the differences between running with a recirc bov in our cars and not? I believe stock is recirc. From what I've read on other car forums, it looks like recirc is best unless you have a big turbo. Since we have a smaller turbo (and since it doesn't recirc into the intake), I'm just wondering what each of your opinions are?
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4,298 Posts
Recirc is actually better if you have a bigger turbo as it puts more air into the intake which helps keep the turbo spooled. However the physical difference of spool time between the two I don't have any hard evidence personally. However for the stock setup it's basically choice do you want a Lou sound or something more subtle
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2,798 Posts
Actually, the recirc valve only helps spool time if the air is shot directly at the compressor wheel. This makes sense if you think of air as a fluid like water. If I have a wheel spinning in the water and I direct another blast of water at the wheel it will help to keep the speed of the wheel up when the driving force (exhaust) is removed. If, however, I introduce that blast of water back upstream away from the wheel, the added propulsion from the introduced stream will be lost in the normal incoming stream, and have little if any effect on driving the wheel. As soon as that introduced stream hits any bend or other surface, it will give up its energy.
The main reason most MFG's use a recirc valve, is that they have a MAF sensor. Our car uses a MAP sensor. With a MAF sensor that air has already been accounted for by the ECU and fuel calculated for that Mass of air. If it was not recirculated, the engine would have to rich a mixture and in a worst case could cause the cylinders to wear because oil is washed off the walls by the added fuel over time (Bore Wash). So, for our car the main purpose of the recirc valve is to keep the noise down.
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4,298 Posts
you are correct.. brain fart lol
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639 Posts
What if we don't cap off the hose that is in the intake to the intercooler?
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No. It makes no difference to your numbers. On or off. Just makes noise when you take it off. That's it. It's a noise making mod.
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639 Posts
I am going to ask again lol, what if we don't cap it off? Would this cause a CEL to come on?
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OK, I'm not 100% sure where you are capping/not capping. I think that's why nobody is answering the question.
If you don't cap the return on the inlet piping, you are feeding un-filtered air into the turbo. There is a fair risk of ingesting a solid object. Capping it is required if you are going to run a BOV.
If you cap the outlet on the BPV/BOV you run the risk of back-feeding charge air into the turbine, equally disastrous and also resulting in an end to your commute in an epic way.
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