can anyone tell me wat the orientation for the famous bosch bov is? is it the vacuum line to the top? or to the side? thanks

 

the port just south of the vacuum line is the source....

the port that's perpendicular to the vacuum line is the blow-off port.

 

i have one on my setup, but have no idea what you are trying to ask? If you are trying to figure out which side is in and which is out, it should be oriented so the flat side of the cylinder is parallel to the charge pipe. The vacuum line needs to be hooked up to a manifold vacuum source or it will not blow off. In the picture below, the Horn would vent to atmosphere.

 

beat me to the punch scott

 

If you look at how its implemented on most OEM turbo cars, the source is the side and the relief is out the bottom.

 

VW/Audi are like Wideoepentuning mentioned, Saabs are the opposite if I remember correctly. In other words, doesn't really matter.

 

When I had one installed, I found recommendations both ways. I finally decided that the best way for me was to have boost pressure hold the valve closed and the vacuum line pull it open. This way there would be no chance of boost pressure leaking.

 

Boost will hold it closed and pull it open regardless of how you have it oriented.

When we used to make a diaphragm replacement for the Bosch valve we recommended to install it with boost entering from the bottom. Installing it with boost entering the side port increases the amount of lateral loading that the diaphragm sees and can have a negative effect on the longevity of the diaphragm. Boost entering the bottom keeps the loading axial (except for the slight lateral loading caused as the pressure is discharged unevenly along the face of the valve as it is vented through the side port...).