Newb question.

[HKSenilyks]

This doesn't have anything to do with dsm's, or turbos for that matter. But does anyone know why supercharged cars don't need Blow off valves?
I recently bought a supercharged Buick Park ave. and always wondered. Is it because as the t.b. butterfly closes as the supercharger slow down err....?

[User Name]

A bov is made protect the compressor section of the turbo from damage due to pressure surges, not applicable on SC's.

The supercharger recycles the boosted air back into the intake, so as to minimize parasitic loss.

[Goat Blower]

Superchargers are a little more robust, but the real reason is your car is an automatic. The engine doesn't immediately drop into vacuum from a boosted stated when you let off the gas on an auto. Buick GN's didn't have a BOV from the factory and they were turbocharged, and all were autos.

[HKSenilyks]

Yea I had a turbo sunbird that didn't come stock with a B.O.V. it was also an auto.

[311evo]

you can technically use one, but they wont do much unless ur running alot of boost. there kind of pointless as the main point of having a BOV is to save your turbo from compressor surge.

[Super Bleeder!!]

Depends on the application. Your car has roots blower and its located after the throttlebody.

A lot of the med-hi boost centrifugal kits these days (vortec) do inlcude bovs.

[Kracka]

Originally Posted by Super Bleeder!!

A lot of the med-hi boost centrifugal kits these days (vortec) do inlcude bovs.

Yup, a lot of the supercharged S2000 guys are using BOV's.

[tpunx99GSX]

actually i dont think even our dsms dont need a bov. I was actually thinking off blocking mine off when i go to the track, that way it holds a little more boost between shifts. (not sure if this will work or not on our cars) My buddy with the S15 Silvia (yes a real one) doesnt run a BOV when he goes to the track and hes on higher boost (17-20).
sure it wears the turbos compressor a little, but for how many times we change turbos, we arent going for longevity anyways.

[Shane@DBPerformance]

I was going to say something, but this thread is retarded.

[Halon]

^
That made me chuckle

[RichardBBY]

actually i dont think even our dsms dont need a bov. I was actually thinking off blocking mine off when i go to the track, that way it holds a little more boost between shifts. (not sure if this will work or not on our cars)

I think this would be a bad idea. When you shut the throttle during shifts that air that is now pressureized and flowing through all of your pipes will have no where to go other then back towards the turbo. That rush of air back towards the turbo will cause the turbo to violently slow down, which is exactly the oppisite of what you said your trying to acomplish.

just my 2 cents.

[1ViciousGSX]

Originally Posted by ecoli

I was going to say something, but this thread is retarded.

Love it!!

It really has to do with location of the TB in relation to the supercharger or turbo. Close the TB on a supercharger and you immediately have vacuum on both side of it. And the supercharger speed is based directly on crank speed. Turbo chargers stay spooled longer and need a place to release the excess pressure between shifts to maintain high turbo shaft speeds. This helps reduce turbo lag between shifts and removes excess stress on the turbo.

[crazy_skier]

Originally Posted by RichardBBY

I think this would be a bad idea. When you shut the throttle during shifts that air that is now pressureized and flowing through all of your pipes will have no where to go other then back towards the turbo. That rush of air back towards the turbo will cause the turbo to violently slow down, which is exactly the oppisite of what you said your trying to acomplish.

just my 2 cents.

This is true, but at the track people are also shifting much quicker, or if using dsmlink there is nlts and then the throttle will not be closed at all. I have haerd of removing the bov for the track also though on high boost applications, since it does keep the pressure in the pipes and makes cars a little more responsive when shifting quickly. I would reccomend feathering off the throttle after crossing the mark for whatever distance your running so you dont cause huge compressor surge

[RichardBBY]

Your right, i could see how No Lift To Shift would make this a worth while modification for track use. He didn't mention using nlts. If anyone has ever driven a SRT4 with out any blow off valve, like they come from the factory, they have felt how badly that car falls on its face during the 1 - 2 shift. I would imagin the same problem would be felt if you were to unhook your bov. Unless of corse when you say high boost, you mean 25 to 30 pounds, in that case I would not know sence I personaly have never driven a car with that much boost.

theres a few more cents for ya!