[CloNeGTS]

Alright, I have to admit that I don't know many details about turbo systems. Of course I know the function of blow off valves and wastegates, but I don't know much about the types of both or what are considered the better brands/styles.

Anyone have any good info? I've tried finding FYI sites on search engines to no avail.

 

[4MLA1FN]

Cars/Comparisons

Of course I know the function of blow off valves and wastegates...

maybe we could start with basic definitions for those (like me) that have little experience with turbo engines...

a bov relieves boost pressure to protect the turbo. when you lift off the gas, the throttle slams shut and boost pressure quickly builds. the bov releases this pressure. some bovs pass this excess pressure to the air (the "pssht!" or chirping sound you here on wrc); some bovs recirculate the boosted air to the input side of the compressor (the side that is normal air pressure).

a wastegate relieves pressure on the turbine (exhaust) side. it is used to allow exhaust gases to bypass the turbine. this is necessary to prevent the turbine from over revving at high RPMS. (the diverted gases just goes out the tailpipe and don't contribute to spinning the turbine.) therefore the wastegate is what determines the max boost you can make. wastegates have cooling fins since they manage hot gases.

in summary, both are used to protect the turbo. the bov protects the turbo when you quickly get off the gas; the wastegate protects the turbo from over revving when you refuse to get off the gas. the bov is located on the on the input side; the wastegate is located on the exhaust side.

okay, where am i wrong?

 

[CloNeGTS]

It looks like a lot of you are thinking like I am.....

No, that's very good. The only change I would add is that instead of a blow off valve, the stock system on most cars, including the WRX, is a bypass that feeds back into the intake. This really isn't a valve from what I understand. It simply operates off of pressure differential. So when this pressure builds in front of the throttle body, this pressure is passed back in front of the turbo.

And wastegates can be internal or external. Our turbo, and most replacements, are internal. Some larger boost setups will use an external wastegate to do the same job and they will wire the internal wastegate shut. External wastegates are larger, allowing more pressure to flow by the turbine.

There are some discussions on nasioc I'll probably copy over some time...but for now it's off to bed with the fiance! :wink:

 

[4MLA1FN]

...but for now it's off to bed with the fiance! :wink:

so you know, you put that one high and slow over the plate. i could make all kinds of jokes about blow-off valves and wastegates. but i'll be good, i'll resist. [quick, somebody knock this outa the park...] 8)

 

[CloNeGTS]

HAHAHA.....I never would have thought about that....but that's some good thinking man!

 

[CloNeGTS]

Alright, here are some of the links I found on NASIOC that are decent reads about BOVs in general and how they perform on a WRX

http://forums.nasioc.com/forums/showthread.php?s=&threadid=303662&highlight=blow+off+valve

Here's the Scoobymods install on removing the silencer people are talking about.

http://www.scoobymods.com/forums/showthread.php?s=38a569e83b0ce878484f85687be9b667&threadid=113

Here's another discussion

http://forums.nasioc.com/forums/showthread.php?s=&threadid=295256&highlight=blow+off+valve

Anyone have their own input with their WRXs? It would be nice to get some general info on BOVs from people that have been around for a while in the WRX community and have followed most of these discussions. It's so hard to find documented information.