How Blow Off Valves Work

[sw20kosh]

Originally Posted by Huehuecoyotl

a malfunctioning BOV could cause the results the OP of the boom thread we all just saw, tho he seemed pretty sure his BOV was working fine.

The only thing a malfunctioning bov can create is boost leak or compressor surge.

It can never cause a boost spike as it plays no part in controlling boost. That is solely the waste gates job.

[King Tut]

Originally Posted by ATSAaron

1. throttle shut, zero boost. AKA idle or light cruise. This is when your engine creates the most vacuum. The hose going from the engine to the BOV is actually trying to suck the BOV open at this point. It is the job of the spring to prevent this. I have seen a couple threads on here about bad idles caused by BOV's being sucked open. Get stronger springs people (venders too).

I have the stiffest spring Tial makes for the 50mm Q BOV, and it can still open under high vacuum conditions.

[RedLeader]

So wouldnt a diverter valve (ala VW's TSI motor) that recirculates the compressed air from the pressurized side of the turbo back to the intake side be more reliable and more efficient since it's using the already compressed air sent back to the intake side of the turbo to keep the turbo spooling? Or am I getting a recirc system confused with an anti-lag system?

[sw20kosh]

Originally Posted by RedLeader

So wouldnt a diverter valve (ala VW's TSI motor) that recirculates the compressed air from the pressurized side of the turbo back to the intake side be more reliable and more efficient since it's using the already compressed air sent back to the intake side of the turbo to keep the turbo spooling? Or am I getting a recirc system confused with an anti-lag system?

Install bov before the maf. Problem fixed.

[RedLeader]

Originally Posted by sw20kosh

Install bov before the maf. Problem fixed.

That failed utterly to address the question or point of my post. But thanks for trying.

[sw20kosh]

Originally Posted by RedLeader

That failed utterly to address the question or point of my post. But thanks for trying.

No it addresses your post just fine. Recirculating the bov like you mentioned does not spool a turbo.

Since you mentioned reliability I gave you a safe and reliable way to not have issues with venting metered air. I assumed (wrongly) that you knew the very basics of turbocharging or would at least take the time to read up on how turbocharging works. As such I left out explanations.

By placing the bov before the maf (filter - turbo - bov - maf - throttleB) you avoid metered air from being lost. The air that is released was never metered by the maf.

People use recirculation valves (filter - maf - turbo - recirc valve - throttleB) because they want silent bov operation or they want to comply with emissions regulations. The recirc valve dumps metered air right in between the maf & turbo so metered air is not lost.

[superpilun]

I don't mean to derail this thread but there is considerable debate over whether bov's are necessary and the extent to which not running one is detrimental to the turbocharger. There are many who believe that the fluttering sound heard when shutting the throttle with no bov is absolutely perfectly fine for the turbo, including Corky Bell and Crawford Performance. The theory is that the compressor surge which is harmful for a turbo occurs under load. For example:
[ame="http://www.youtube.com/watch?v=nCj6Spwl1CU"]True Compressor Surge - YouTube[/ame]

Those who choose to run without a bov also claim benefits such as less boost loss during shifting and better driveability.

[sw20kosh]

Originally Posted by superpilun

I don't mean to derail this thread but there is considerable debate over whether bov's are necessary and the extent to which not running one is detrimental to the turbocharger. There are many who believe that the fluttering sound heard when shutting the throttle with no bov is absolutely perfectly fine for the turbo, including Corky Bell and Crawford Performance. The theory is that the compressor surge which is harmful for a turbo occurs under load. For example:


Those who choose to run without a bov also claim benefits such as less boost loss during shifting and better driveability.

If it wasn't detrimental to the turbo, OEMs would not use recirc valves.

[Tansey86]

They are both harmful, but the surge under load will destroy a turbo much quicker. They are both making the same noise, doing the same thing.

I would never buy a turbo kit without a BOV, or a valve of some sort. Look at how many use them, and how many don't.

[audixieboy]

Alot over my head. I am just going to find some experts to put this in. Costly but thought I could save on the products they put in. I do alot of shopping on this site and the shirts, ties and such are very nice at the price.

http://www.aliexpress.com/item/Hong-...713915465.html


Can anyone tell me if this BOV would work?
Does it need a turbo to work?
And would i just be better off getting a UNIChip?

[King Tut]

So let me get this straight. You want to buy a cheapass knockoff HKS BOV from a Chinese website, but you don't know if you need a turbo.

1. No.
2. Yes.
3. For you, UNIChip would probably be the best option.

[audixieboy]

man, sorry if I hurt your feelings man. Take it you feed your family by selling expensive BOVs. Was just asking a question. Thanks for response. ****

[jamesm]

Originally Posted by audixieboy

man, sorry if I hurt your feelings man. Take it you feed your family by selling expensive BOVs. Was just asking a question. Thanks for response. ****

an extremely, incomprehensibly stupid question, yes. why the hell would you need a BOV without a turbo? it seems as if you have no clue as to what the purpose of the piece your asking about is. many people find this annoying, and for good reason. you could've answered your own question just by reading the same thread you posted it in.

[King Tut]

Originally Posted by audixieboy

man, sorry if I hurt your feelings man. Take it you feed your family by selling expensive BOVs. Was just asking a question. Thanks for response. ****

There is an Alabama joke to be made here, but I won't make it. Enjoy showing off your BOV.