alright I've been arguing with this kid on another site. We've been discussing whether or not you need a blow off valve. I say that it doesn't really matter if you have one, and he's telling me that you need one for sure. Anything that you guys can post to help either side of the arguement would be great. Hopefully I get more posts to help my side!;)

Yes you need one, it is not there for sound, if you do not have one, then every time you shift, the pressure has to go somewhere. If the throttle plate is closed, then it goes back and hits the turbo stalling it making have to re spool after the shift. The BOV vents it out so the turbo can free spin until you hit the gas for the next gear.

Well, technically you don't HAVE to have one. You can make a turboed car work without it. Some turbocharged cars don't come with blowoff valves. My friend has an old 300Z turbo with no BOV. But it's definitely not a good idea to run without one. If there's no BOV to vent the boost pressure between shifts, it tries to spin your compressor wheel backwards, hence "compressor surge."

dont those cars just come with a by-pass valve if its stock turbo?

i like my turbo-xs rfl bov.

Yes, most cars with stock turbos have bypass valves. Turbo cars equipped with a MAF (mass air flow sensor) instead of a MAP (manifold air pressure) will have to vent the air back into the intake tract because the MAF measures the amount of air that the valve is bypassing to the intake. This is why many MAF-equippeed turbo cars who vent out their bov will experience cels and rich fuel conditions.

>i like my turbo-xs rfl bov.

hehehe, with a 60mm tb :P sounds so crazy

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96 talon esi-t
san clemente, ca

Uberingram> I bow down to the Geo

You don't need one if you want your turbo to fail. Pressure being force back into the compressor is not a good thing. So, YES, you need a DV or BOV.

So do 4G63's come with blow-off valves or bypass valves? When I drove one I never really got the chance to get on it (dealership guy was in the car).