Blow-off Valves

SyTyJedi

SyTyJedi

Jedi Council
On 2002-01-18 22:02, turbojimmy wrote:
The BOV's only purpose is to vent boost when you don't need it.
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Let's not confuse anyone here. The BOV's only purpose is to open and release boost when there is a difference in it's pressure signal from it's vac port and the pipe it's on.

To answer a few more questions, the BOV and flange (get a steel one) easily weld onto a metal turbo to IC pipe. HKS is the preferred brand. A smaller valve, such as GReddy Type-S, is too small for our application IMO.
 
M

MadPSI

Member
I talked to John Craig (Limit Engineering) about the importance of a BOV a couple years back. He told me that they aren't really necessary anymore. Turbo technology has reached the point that the "blade chattering" is not harmful at all. The turbos are designed to withstand it all day long.

What BOV's are still sorta-useful for is to keep manually shifting cars spooled up between shifts. As the air rushes out of the turbo the wrong way, it can slow down the spinning of the blades and thus decreasing maintained boost pressure between shifts. The BOV lets the air escape another way so it doesn't cause that.

Plus they sound cool

Brandon
ASM Sy #1151
 
jhacking

jhacking

Hacker
I have a question if you have a external wastegate is it ok to run a BOV,or is it not necessary to have both.
 
S

smeagol

Active member
Completely unrelated.

External wastegate is for boost control, BOV is not used for boost control at all, just venting excess boost when throttle closes.

So yes, you can have both. You can have just one or the other. You can eat your green eggs & ham in a car too.
 
jhacking

jhacking

Hacker
So why does everyone say you will have over boost problems.So if i go and put one on,am i going to have to tune it in,or is it just a simple mount it and run it. Those green eggs and ham sound good.
 
S

smeagol

Active member
On 2002-01-21 10:35, jhacking wrote:
So why does everyone say you will have over boost problems.
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I have no idea. A BOV should not open while you have the throttle open at WOT.
 
SyTyJedi

SyTyJedi

Jedi Council
Make one or get one from Bob Galla (assuming you have stock turbo and intercooler)

I chose to make one.
 
ParTyBoy

ParTyBoy

New member
On 2002-01-21 09:44, mr.sparkle wrote:
Completely unrelated.

External wastegate is for boost control, BOV is not used for boost control at all, just venting excess boost when throttle closes.

So yes, you can have both. You can have just one or the other. You can eat your green eggs & ham in a car too.
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! —x‚é!
 
blownamigo

blownamigo

TYed Up Member
With the BOV you don't control your boost, you only control the trigger point for it's venting function via the bolt. So if you run a stock truck you can set it 2 to 3 Psi above the stock 14.7 Psi. This is because if you let off the throttle the boost that remains between the now closed throttle and the turbo can easily reach 4 times this pressure searching for the easiest way out...the turbo. This is when your truck sounds like a horse. The turbo stalls for a moment and therefore if you need to build up boost quick again you will feel a lack of response cause the wheel basically has to start spinning from scratch. With a functional BOV you allow the system to get rid of this unused boost before the turbo get's slowed down too much or stalls. Needless to say that this helps your turbo to live longer.
 
Silly

Silly

Banned
it is very easy and i am kind of confused on why the hell a simple topic like this is taking of 3 pages of space?

In a turbo you will see the compresser wheel. this compresser wheel has little fins on it. When you are on the throttle and into boost and you let off the throttle you will hear a compresser surge which is the excess boost going back through the compresser wheel and out of your K&N. Compresser surge is BAD for a turbo. After too much of it you will see the fins on the wheel beginning to bend back out of the turbo and therefore you will have a dead turbo. BOV will not make you go faster or slave overboosting. they will just make the life of your turbo longer.
 
ParTyBoy

ParTyBoy

New member
21_brian_walski.jpg


blowin off some steam are we???
 
spooldup

spooldup

Super Member
So to sum this up. BOV's are GOOD to have. They DO NOT CONTROL BOOST. They aid in turbo life. The BOV to get is HKS with a Steel flange for welding. Now, where do we get this BOV? Turbo imports sells that valve for $205 and the flange for $49. Also where do you get the pipe to go from the turbo to the intercooler and if you had to make a custom one like i do where do i get the materials and what shoul i/we use?
 
J

JoeLutz

New member
I use the Turbo XS SSBOV and it works flawlessly and sounds great. You MUST know how to hook it up right though. The vacuum line goes to a good vacuum source on the intake manifold.
If you try to use a BOV for boost control, you can be doing more damage to the turbo than good because it can overspeed, destroying the bearings.
 
jhacking

jhacking

Hacker
Thats what kind of ajustable boost control i have now.I will get there BOV as well,what is the propper way to to install this explane.
 
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