Am i gonna need a blow off valve?

[bluchev]

anyone know if im gonna need a bypass/blow-off valve for that blow thru setup with the whipple 2.3 and the carbed small block? if so what size and what brand would be best? it has a bypass built in butits contorlled by whipple's little computer that comes with the kit...and since i wont be using that-- what to do?

[orange88]

yes put one on

[Sweet35th]

anyone know if im gonna need a bypass/blow-off valve for that blow thru setup with the whipple 2.3 and the carbed small block? if so what size and what brand would be best? it has a bypass built in butits contorlled by whipple's little computer that comes with the kit...and since i wont be using that-- what to do?

The bypass is all you will need.. One port on the bypass will need to be hooked up to manifold vacuum/pressure. So that when the engine is under vacuum it opens the valve, and under boost closes it.. The other port can just go to atmospher....

[bluchev]

sweet thanks

[OffShore]

some one was selling a teil bov for cheap on here a little bit back. do a search. and yes t I would put one on.

[Sweet35th]

some one was selling a teil bov for cheap on here a little bit back. do a search. and yes t I would put one on.

Why? You do realize that a bypass and blow off valve serve the exact same function. They both releave boost pressure with vacuum. The only differance is that a blowoff valve you can utilize spring pressure to controll max boost (to blow off boost past a certain level). But this is not a needed function on a roots style or centrifcal style blower since boost is a function of blower speed. Spin the blower faster, make more boost, slower make less. The blade style bypass used in these kits flow more than sufficient air to bypass at cruise or or after a WOT pull. Since this is a blow through carb set-up. The only thing I would urge to insure is that the bypass is before the caborator. You can vent it to atmosphere, or back into the blower intake if you wish it to be quieter.

[OffShore]

Why? You do realize that a bypass and blow off valve serve the exact same function. They both releave boost pressure with vacuum. The only differance is that a blowoff valve you can utilize spring pressure to controll max boost (to blow off boost past a certain level). But this is not a needed function on a roots style or centrifcal style blower since boost is a function of blower speed. Spin the blower faster, make more boost, slower make less. The blade style bypass used in these kits flow more than sufficient air to bypass at cruise or or after a WOT pull. Since this is a blow through carb set-up. The only thing I would urge to insure is that the bypass is before the caborator. You can vent it to atmosphere, or back into the blower intake if you wish it to be quieter.

So why do I see them all the time on certrifical cars? and roots cars the blower does not sit on the side and blow through the carb either. I thought the bov was to save over pressure on the tb blades?

[Sweet35th]

So why do I see them all the time on certrifical cars? and roots cars the blower does not sit on the side and blow through the carb either. I thought the bov was to save over pressure on the tb blades?

I think your confusing a bypass valve with a blowoff valve, and its easy to do. Most people probably dont even know the differance. As I said above, they basicaly serve the same purpose.......Blowoff valves are designed to be able to be set to open at an ajustable boost pressure to prevent and overboost condition, as well as to open under vacuum to eliminate pressure against the throttle blades, and prevent the supercharger from creating boost in the manifold at low loads.......A bypass valve serves the same purpose, but they are generaly not ajustable (some of them have ajustable stops to insure that they full close, or fully open). These are not ALL designed to open based on boost (specialy the blade style). Some of the cheaper diaphram style bypass valves will open once boost pressure exceeds what the spring behind the diaphram can hold, but they are not designed to do so. Some larger bypass valves are specificaly made to have ajustability to prevent them from opening at specific boost levels, such as a vortech race bypass.

This is all coming from a confusion of terminology.. His system already contains a bypass valve. This vavle will vent boost once the throttle is shut (engine under vacuum) to vent boost from the system. It will continue to be open under vacuum to vent off boost during low load conditions.. It is most likely a blade style valve (may use a diaphram to open it, and boost to hold it shut, but boost pressure is not able to physicaly force it open from pressure against the blade), so excessive boost would not force it open....Its not needed to do so, because boost is in direct relation to blower speed, you dont have to worry about conditions such as in a turbo car which could lead to excessive boost such as in a turbo car (specialy vehicles with non-wastegate controlled turbos)...

Break this all down simply..

Bypass valve. Designed to open under vacuum to vent boost pressure

Blow off valve. Designed to open under vacuum to vent boost pressure, also designed to have ajustable controll to prevent over boost.

Some bypass vales do have ajustability to prevent them from prematurely opening. ALL blow off valves are designed to open at a certain amount of boost pressure...

Since his system already has a bypass valve. There is no need for a blow off valve, since the bypass valve serves the same purpose, and there is no threat of overboost because boost is in dirrect relation to blower speed.

[OffShore]

I think your confusing a bypass valve with a blowoff valve, and its easy to do. Most people probably dont even know the differance. As I said above, they basicaly serve the same purpose.......Blowoff valves are designed to be able to be set to open at an ajustable boost pressure to prevent and overboost condition, as well as to open under vacuum to eliminate pressure against the throttle blades, and prevent the supercharger from creating boost in the manifold at low loads.......A bypass valve serves the same purpose, but they are generaly not ajustable (some of them have ajustable stops to insure that they full close, or fully open). These are not ALL designed to open based on boost (specialy the blade style). Some of the cheaper diaphram style bypass valves will open once boost pressure exceeds what the spring behind the diaphram can hold, but they are not designed to do so. Some larger bypass valves are specificaly made to have ajustability to prevent them from opening at specific boost levels, such as a vortech race bypass.

This is all coming from a confusion of terminology.. His system already contains a bypass valve. This vavle will vent boost once the throttle is shut (engine under vacuum) to vent boost from the system. It will continue to be open under vacuum to vent off boost during low load conditions.. It is most likely a blade style valve (may use a diaphram to open it, and boost to hold it shut, but boost pressure is not able to physicaly force it open from pressure against the blade), so excessive boost would not force it open....Its not needed to do so, because boost is in direct relation to blower speed, you dont have to worry about conditions such as in a turbo car which could lead to excessive boost such as in a turbo car (specialy vehicles with non-wastegate controlled turbos)...

Break this all down simply..

Bypass valve. Designed to open under vacuum to vent boost pressure

Blow off valve. Designed to open under vacuum to vent boost pressure, also designed to have ajustable controll to prevent over boost.

Some bypass vales do have ajustability to prevent them from prematurely opening. ALL blow off valves are designed to open at a certain amount of boost pressure...

Since his system already has a bypass valve. There is no need for a blow off valve, since the bypass valve serves the same purpose, and there is no threat of overboost because boost is in dirrect relation to blower speed.

Cool, thanks for the great info!

[bluchev]

Cool, thanks for the great info!

yeah no shit--very informative thanks alot no ones really explained it all for me

[Sweet35th]

yeah no shit--very informative thanks alot no ones really explained it all for me

Yah, half this stuff usualy comes down to the aftermarkets confusion on terms...

Intercooler/aftercooler for example......Somehow the aftermarket got these two terms mixed up at some point and now everyone is confused....

I personaly have never seen a vehicle with an intercooler.......An intercooler is a cooler placed between two power adders.. Yet because the aftermarket has thrown the term around so much, most people dont know the differance anymore.

[orange88]

I think your confusing a bypass valve with a blowoff valve, and its easy to do. Most people probably dont even know the differance. As I said above, they basicaly serve the same purpose.......Blowoff valves are designed to be able to be set to open at an ajustable boost pressure to prevent and overboost condition, as well as to open under vacuum to eliminate pressure against the throttle blades, and prevent the supercharger from creating boost in the manifold at low loads.......A bypass valve serves the same purpose, but they are generaly not ajustable (some of them have ajustable stops to insure that they full close, or fully open). These are not ALL designed to open based on boost (specialy the blade style). Some of the cheaper diaphram style bypass valves will open once boost pressure exceeds what the spring behind the diaphram can hold, but they are not designed to do so. Some larger bypass valves are specificaly made to have ajustability to prevent them from opening at specific boost levels, such as a vortech race bypass.

This is all coming from a confusion of terminology.. His system already contains a bypass valve. This vavle will vent boost once the throttle is shut (engine under vacuum) to vent boost from the system. It will continue to be open under vacuum to vent off boost during low load conditions.. It is most likely a blade style valve (may use a diaphram to open it, and boost to hold it shut, but boost pressure is not able to physicaly force it open from pressure against the blade), so excessive boost would not force it open....Its not needed to do so, because boost is in direct relation to blower speed, you dont have to worry about conditions such as in a turbo car which could lead to excessive boost such as in a turbo car (specialy vehicles with non-wastegate controlled turbos)...

Break this all down simply..

Bypass valve. Designed to open under vacuum to vent boost pressure

Blow off valve. Designed to open under vacuum to vent boost pressure, also designed to have ajustable controll to prevent over boost.

Some bypass vales do have ajustability to prevent them from prematurely opening. ALL blow off valves are designed to open at a certain amount of boost pressure...

Since his system already has a bypass valve. There is no need for a blow off valve, since the bypass valve serves the same purpose, and there is no threat of overboost because boost is in dirrect relation to blower speed.

im going to have to wait and see if les says this is a ture statment

[RyanM]

im going to have to wait and see if les says this is a ture statment

Is what he will say

[Sweet35th]

im going to have to wait and see if les says this is a ture statment

That actualy made me laugh....



Alot