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Discussion Starter #1
This may seem like an elementary question, but I've always wondered about it. I've seen turbo cars running without BOVs...what does a BOV do that a wastgate doesn't? And what is meant by running an open wastegate and what are the benefits? Thanks, people!
 

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wastegate limits boost by opening at a preset psi so turbo will not overboost and blow the engine

BOV blow off valve whent he throttle closes( ie let off the gas) the pressureized system against a closed valve can cause backpressure against the turbo impeller ( compressor surge) which can damage the impeller
 

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talltrini10 said:
This may seem like an elementary question, but I've always wondered about it. I've seen turbo cars running without BOVs...what does a BOV do that a wastgate doesn't? And what is meant by running an open wastegate and what are the benefits? Thanks, people!
The wastegate vents some of the exhaust around the turbo to regulate boost. running a open wastegate in a supra means pulling the control hoses off so the waste gate only opens when the pressure overcomes the spring that normally holds it shut.

The BOV vents boost out of the intake side when the throttle plate closes to prevent the compressed intake from pushing the turbo's backward. Running without a BOV isn't good for the turbos unless you are only running very low boost I think.
 

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talltrini10 said:
This may seem like an elementary question, but I've always wondered about it. I've seen turbo cars running without BOVs...what does a BOV do that a wastgate doesn't? And what is meant by running an open wastegate and what are the benefits? Thanks, people!
The two other guys gave good explinations. Here is a little more, that would have helped me when I was learning. The turbo has two sides of corse. The two valves/gates we are talking about are located on different sides of the turbo. The wastegate is located on the exaust side of the turbo. And it is used to keep the turbo from spinning too fast. It does this by goving the exaust an other path to take then just thought the turbo. The BOV on the other hand is located on the intake side of the turbo, between the turbo and the intake manifold of the motor (or there abouts). When the motor stops excepting intake (like when you release the throttle) the pressure between the turbo and the motor would grow too big. So they have a BOV there that will release the pressure and keep the turbo nice and safe. I hope this helps. I needed to look at a picture before I really understood the difference between the two.
 

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Re: Re: Difference between Wastegate and BOV

Running an open wastegate means venting the wategate to the atmosphere instead of venting in back into the exhaust.

An open wastegate makes a very loud "shhhhh" sound when it opens it. Sounds like a jet :D:D

Josh S said:


The wastegate vents some of the exhaust around the turbo to regulate boost. running a open wastegate in a supra means pulling the control hoses off so the waste gate only opens when the pressure overcomes the spring that normally holds it shut.
 

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Discussion Starter #6
Ok...

Thanks for all the responses, folks. I think I have it now...I saw a car dyno with an open wastegate once, and the noise was unbelieveable!(It did look cool when fire shot from under the car, though!) I also have another friend with no boost controller running a modded wastegate for increased boost, and I was just wondering how that worked...
 

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Well, some wastegates have an adjustment that varys the spring pressure which can be used to adjust/set the desired max boost level. Another crude way is to shim the wastegate spring which shortens the spring travel. Wastegates actually do not open precisely at a given boost pressure but start to open earlier in a progressive fashion. This is why a proper manual or electronic boost controller can help spoolup time by not allowing any pressure into the wastegate actuator until the desired max boost is hit.
 
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