blow-off valve question!!

[98cobraV2_707]

i may sound stupid so i apologize in advance lol but...

i have a 98 cobra running a v2, my question is if i wanted to put a blowoff or bypass valve, would i have to get a blow through maf, and can blowoff valves only be used if you have an intercooler?

 

[Brutal Metal]

Even entry level Vortech kits will come with the Bosch bypass valve without intercooler, the pressurized air needs to be released when the throttle blade closes or your head unit seals are gonna wear out quick... AND you don't need blow through but it's the most effective tuning and range wise for the MAF...

 

[98cobraV2_707]

Even entry level Vortech kits will come with the Bosch bypass valve without intercooler, the pressurized air needs to be released when the throttle blade closes or your head unit seals are gonna wear out quick... AND you don't need blow through but it's the most effective tuning and range wise for the MAF...

great. thanks. i just want that nice blowoff sound but didn't know if i would be messing anything up if i did it lol

 

[02blownGT]

Cant use a blow off valve the spring inside is too stiff you need one setup as a bypass valve so it till be open at idle/low rpm and only close when in boost vs a blow off valve that is closed all the time except when venting boost pressure.

 

[98cobraV2_707]

Cant use a blow off valve the spring inside is too stiff you need one setup as a bypass valve so it till be open at idle/low rpm and only close when in boost vs a blow off valve that is closed all the time except when venting boost pressure.

thanks for the info!

 

[Adiabatik]

I run a BOV purely for the sound. I cant tell you how many comments and stares I get (I run a Big Red BOV).

If you're running a BOV then you really need a blow-through or the car will run like shit.

 

[Brutal Metal]

thanks for the info!

Who installed your supercharger? It should have the Bosch bypass in the area underneath the plastic inlet tubing for the head unit..

 

[98cobraV2_707]

I run a BOV purely for the sound. I cant tell you how many comments and stares I get (I run a Big Red BOV).

If you're running a BOV then you really need a blow-through or the car will run like shit.

thats exactly what i want to use it for, the sound! lol. will a bypass valve produce the same sound without needing a blow through or would a bob and blow through be the way to go?

 

[98cobraV2_707]

Who installed your supercharger? It should have the Bosch bypass in the area underneath the plastic inlet tubing for the head unit..

dealership installed it for the previous owner back in 2000. i believe it does have the bypass valve but it doesn't produce the sound i want.

 

[Adiabatik]

thats exactly what i want to use it for, the sound! lol. will a bypass valve produce the same sound without needing a blow through or would a bob and blow through be the way to go?

Do you understand what a bypass is? A bypass re-routes the air back into the intake pre-blower (there is a tube that connects the bypass valve back into the intake just after the filter). There is no sound whatsoever with a bypass. A BOV vents that air into the atmosphere instead of rerouting it back into the pre-bower intake.

If you want the sound of a BOV, you need a blow-through MAF (an MAF that is designed to calibrate the compressed air being forced through by the supercharger. Factory MAF's aren't designed to handle the increased velocity of air from a supercharger/turbo

 

[98cobraV2_707]

Do you understand what a bypass is? A bypass re-routes the air back into the intake pre-blower (there is a tube that connects the bypass valve back into the intake just after the filter). There is no sound whatsoever with a bypass. A BOV vents that air into the atmosphere instead of rerouting it back into the pre-bower intake.

If you want the sound of a BOV, you need a blow-through MAF (an MAF that is designed to calibrate the compressed air being forced through by the supercharger. Factory MAF's aren't designed to handle the increased velocity of air from a supercharger/turbo

ok i get it now. sorry new to s/c's and all that. still trying to learn. and i wouldn't need an i/c if i put in a bov and blow through?

 

[Adiabatik]

ok i get it now. sorry new to s/c's and all that. still trying to learn. and i wouldn't need an i/c if i put in a bov and blow through?

No need for apologies, everyone has to learn.

By I/c you mean intercooler correct? No.

Any type of power-adder (supercharger or turbo) compresses air and forces it through the intake. When you compress air, it heats up. Heat is kryptonite to an engine.

Feel free to ask any more questions. Im going to bed but I'll pick this up tomorrow :beer:

 

[98cobraV2_707]

No need for apologies, everyone has to learn.

By I/c you mean intercooler correct? No.

Any type of power-adder (supercharger or turbo) compresses air and forces it through the intake. When you compress air, it heats up. Heat is kryptonite to an engine.

Feel free to ask any more questions. Im going to bed but I'll pick this up tomorrow :beer:

thanks for all the info. looks like ill be getting a bob and blow through maf. any other advice when doing this?

 

[02blownGT]

A blow off valve will still have a spring that is too stiff,Unless you go with a company like tial that sells a special supercharger spring.You can vent a bypass valve to atmosphere just as easily if your maf is setup as blow through as previously discussed.Main thing you need to know is your bpv or bov need to be full open by like -5hg of vacuum.Turbo bov (which most are meant for)dont open untill between -8 and -20hg of vac and will cause surging which will ultimately ruin your blower. Here is an example from tial so you can see the different ways the same bov can be setup.
Tial Q BOV springs:
-20 to -21 in/Hg use Pink -11 Psi spring
-16 to -19 in/Hg use Un-painted -10 Psi spring
-12 to -15 in/Hg use White -8 Psi spring
-8 to -11 in/Hg use Black -6 Psi spring
0 to -7 in/HG (or supercharger) use -3 PSI Spring (Pink)

 

[02blownGT]

If you dont want to mess around with all the technical issues just buy a vortech mini race.In a blow through setup you can vent to atmosphere, they sound just like a bov when vented, they are tough units that will last to 15psi+,they can be purchased used for 100$,and best of all they are meant for blowers.I also have an old procharger proflo valve laying around somewhere that you can have if you pay shipping that would be an upgrade to that bosch unit.heres a vid with the proflo to atmosphere Procharger bov sound - YouTube (not my car)

 

[98cobraV2_707]

If you dont want to mess around with all the technical issues just buy a vortech mini race.In a blow through setup you can vent to atmosphere, they sound just like a bov when vented, they are tough units that will last to 15psi+,they can be purchased used for 100$,and best of all they are meant for blowers.I also have an old procharger proflo valve laying around somewhere that you can have if you pay shipping that would be an upgrade to that bosch unit.heres a vid with the proflo to atmosphere Procharger bov sound - YouTube (not my car)

Thanks for all the info. If i went with the proflo valve setup, would i still need a blow through maf? And is it a direct swap from the bosch or would i need to modify?

 

[02blownGT]

Thanks for all the info. If i went with the proflo valve setup, would i still need a blow through maf? And is it a direct swap from the bosch or would i need to modify?

If you want to vent to atmosphere you would still need to go to a blow through setup.Off the top of my head i think the bosch is a 1" valve and i believe the proflo is a 1.5".Almost all valves that you would want to run are going to be around 1.5" inlet.So you would need to get a larger diameter flange/pipe to run the 1.5"(radiator hose).

 

[Brutal Metal]

If your only running 7-8lbs of boost what you have now is sufficent..