Hey Stupid guy question

[MyFirst240SX]

Ok i feel sorta dumb asking this but......What exactly is a wastegate/ BOV
I know a Blow off valve is where the excess boost is released, but is it connected to the waste gate?  whats a internal/external waste gate? thanks.

[S13Grl]

Wastegate is what comes stock on your car. BOV replace wastegates, I believe it has more flow.

[MyFirst240SX]

dont SR20DET's come with BOV's not wastegates?or is that why the BOV cost a couple bucks more.....

[S13Grl]

SR20DETs came with wastegates.

[AceInHole]

ummm.... am i hearing this right???

A wastegate dumps exhaust gasses preventing the turbine from being over-sped (and so the wastegate is controlled by a spring or solenoid to control the boost level).
A BOV (blow off valve) dumps boost from the compressed side of the intake, preventing boost from damaging the turbine when the throttle plate is closed (the air would push back on the turbine, causing a shizzit load of stress on the blades, and build up pressure within the IC and compressed side piping).  I believe the stock SR uses a re-circulation valve which simply dumps the air back into the pre-compressed side of the intake....  but don't quote me on that.

The stock SR's turbo comes with an internal wastegate.  Replacing the turbo often requires replacing the manifold, so that an external wastegate can be used (aftermarket turbos often do not have wastegates).  An external wastegate can control boost more efficiently than an internal wastegate (which may disrupt exhaust flow within the turbine section of the turbo, if IIRC).  
Aftermarket BOV's are simply more reliable than stock BOV's, and can dump air faster.  (I have a Bosch replacement for SAAB units in my garage... it's plastic.... and I wouldn't imagine it being able to hold under high loads).

[MyFirst240SX]

Thanks for clearing that up for me

[AceInHole]

LoL... it's tough trusting someone with a sig that says "You're ugly".

(j/k)

[DSC]

</span><table border="0" align="center" width="95%" cellpadding="3" cellspacing="1"><tr><td>Quote </td></tr><tr><td id="QUOTE">Quote: from AceInHole on 1:41 pm on Jan. 17, 2002
LoL... it's tough trusting someone with a sig that says &quot;You're ugly&quot;.

(j/k)</td></tr></table><span id='postcolor'>LOL, ouch

Hey, on that recirculation thing, sounds like pretty good way to kick the turbo back into action. &nbsp;How come more people don't do that instead of getting bov's?

[DragonReborn214]

When using a bov, the air is released in about 1 or 2 seconds, and if you shift quickly, you stay in boost, with the turbo still spooled. With the re circ valve, the turbo has to spool up again.

[grahams14]

It's simple bovs go pssssst/Chiirrrpp................... and recircs don't! Thats all we need to know!!!!! :biggrin:

[AceInHole]

the only thing a recirc valve does is supply the turbo with the excess air in the compressed side of the intake... it does nothing to help spool the turbo. &nbsp;the reason for it is to provide air for the turbo to blow back into the IC piping behind the MAF... otherwise air will have to be drawn through the MAF, making the ECU think air is going into the engine when it isn't, and will cause the fuel mixture to be rich, possibly stalling the engine. &nbsp;a BOV doesn't have to be plumbed like that, and drops boost pressure faster than a recirc valve... which is safer at higher boost levels. &nbsp;plus it makes the cool noise <img src="http://www.zilvia.net/f/iB_html/non-cgi/emoticons/tounge.gif" border="0" valign="absmiddle" alt=':p'>

[DSC]

Ahh, ok. &nbsp;I misread your post.