I'm not to knowledgeable about all of the components that are on turbo systems. Like the blow off valves and the intercooler.From what I know......when you buy a second gen turbo 7, it is just the turbo and intercooler......My ? is, what exactly does the bov do...what is the purpose of it? And what would I have to do if I wanted to add 1 to my turbo....or what mods would I have to make?

 

On a turbo car, when you let off the throttle after boosting, there is pressure, IE boost, between your throttle plates and the turbo. This pressure just bounces back and forth, which is bad for your turbo. So, the BOV vents the excess boost when you lift off the throttle.

 

It makes a whoosh sound........... gotta love it.........

 

If you are doing a blow-thru turbo I can see the need for a BOV as the turbo is upstream and closing the throttle plates will block the flow..instantaneously. If you are doing a draw-thru, do you need a BOV? If you close the throttle plates on a draw-thru you are instantaneously starving the turbo (which is downstream) of air. Does the BOV "suck" in this instant??

I have what appears to be an old Rayjay aftermarket turbo setup and it has a BOV yet is a drawthrough type. I cannot figure out for the life of me why a BOV is needed for drawthrough. Help explain, thanks.

 

howstuffworks.com

 

here's one way of looking at it... think about a blow-thru weber sidedraft setup for a second; lets say it doesn't have a strong return spring. you romp the pedal and make 10psi or so and let off without a bov to vent the pressure... well it's going to push the throttle plates open and slam left over boost in to the block. this is bad. atleast going thru the carb it can still register the air and give fuel with it.

on a drawthru setup the boost is bypassing the carb. when you let off and that turbo is still spinning and blowing air... it's going to go straight for the intake ports. a bov can help.

this is all just a quick thought, i've never personally messed with a draw thru setup but this is why i think a bov would help on one.

 

search function would work awesome for a topic like this...although I don't think anyone on this forum has used a BOV on a turboed rx...I don't...but then again not done the engine build so probably will...BOV saves the life of your turbo...as explained before it releases the pressure after you let off the throttle...

 

look at the picture above your post of FBII's car. See the blow-off valve?

I'm just messin with you but I had to point that out.