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- Sep 28, 2006
- #2
turbo2g111
15+ Year Contributor
- 298
- 6
- Nov 9, 2005
- Moraga,California
Absolutely no problem at all... in fact, thats how they came from the factory. The wastegate opens once your turbo has hit a specified boost level so that your turbo does not keep increasing pressure until your injectors can't take it any more. On the other hand, the BOV opens when the throttle is closed (ie, you step off the gas and push in the clutch to shift), and this prevents compressor damage. They actually perform different functions, and are both vital to a turo system. The lag you experience is the time that it takes for the turbo to fill your entire intake system with pressurized air. Kinda like filling a balloon up, it takes a while to get to full size.
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- Sep 28, 2006
- #3
Denji
Supporting Member
mrxchan said:
When people seen my engine, they question me why do I have a combination of both wastegate and blow off valve. They said it makes no sense having both because both do the same thing. They also said it may be the reason why my turbo sometimes stops for a spilt second when I floor it, basically the turbo laggs. Does anyone know anything about this? Should I remove my BOV or wastegate? And could this be a problem for my turbo if I have this combination of the two? Thanks for any advice at all.
wastegate= bypasses turbo so it doesnt overboost
blowoff valve- releases whatever pressure is seen when you let off the gas and positive pressure is lost.
You dont really need a blowoff valve, the air would just back into your turbo, however, if you value your turbo then you know it should only spin one way.
Blowoff valve cant control your boost while a wastegate cant vent excess pressure.
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- Sep 28, 2006
- #4
Stainbox12
15+ Year Contributor
- 378
- 7
- Jan 3, 2006
- Panama,Central_America
Im not sure, from who you heard this, but they are absolutly wrong. The wastegate is a
device that by-passes the turbine wheel of the turbocharger, limiting the
shaft-speed of the turbocharger. Therefore, limiting the boost
(pressure) that the compressor generates and keeping the turbocharger
from over-speeding. The blow-off valve is more commonly used to keep the turbocharger spinning when the throttle plate is suddenly closed. When the turbocharger is
generating maximum boost pressure at full throttle and then the throttle
is suddenly closed, compressed air coming from the compressor slams
against the throttle, generating extremely high pressures that travel
backwards to the compressor stopping the compressor from spinning. Now, turbo lag depends on what kind of turbo you got, but if you got a 16g or a stock turbo you might want to do a boost leak test, because you might be leaking boost somewhere causing turbo lag. check for usual things, sparg plugs and their gap, timing, fuel mixture, etc. good luck. 
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- Sep 29, 2006
- #5
tstkl
15+ Year Contributor
- 3,881
- 64
- Feb 10, 2005
- SoCal,California
sorry, here, look at these
its a 3000gt, so theres two turbos and two intercoolers, but as you can see, the wastegate alleviates extra pressure built up from higher rpms and your engine flowing more air. Without a wastegate, your turbo will see all of the exhaust gases created by the engine, and they will all accellerate the turbine wheel faster and faster. This will cause the compressor wheel, which is attached to the turbine wheel, to pressurize the intake charge more and more, and "force feed" the engine with more and more air. The more air the engine is "feed" the more it expells as exhaust gases. If the wastegate wasn't there, your turbo would never stop creating more and more pressure in the system. (this doesn't happen in real life due to friction, but in ideal conditions, it would.)
as for the bov, this is a greddy rs (simple) bov. The picture explains most of it, but basically, as your turbocharger pressurizes air, and you close the throttle body, the extra pressure SURGES back towards the turbocharger, and the blow off valve alleviates the extra pressure built up and helps prevent damage to the turbocharger from the extra pressure spinning the turbocharger backwards.
The reason they think they are the same, is because they both perform similar functions. They both alleviate extra pressure, but their main functions are drastically different. Removing either of them could end in a very large bill. Either a new turbo or a new engine. Which would you like?
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- Sep 29, 2006
- #6
Defiant
DSM Wiseman
- 34,753
- 202
- Jan 13, 2003
- glorious Galt,California
mrxchan said:
When people seen my engine, they question me why do I have a combination of both wastegate and blow off valve. They said it makes no sense having both because both do the same thing.
Upon entering the world of turbocharged engines, you will find that the world is rife with uneducated, inexperienced, myth-fed, bottom-feeding, mouth-breathing troglodites.
Do your best to avoid becoming one of them.
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