Post by
rico05 »
https://forums.nicoclub.com/rico05-u8176.html
Sun Jan 20, 2008 8:33 am
The idea of a BOV is to release the excess pressure when you close the throttle plate. There is a pressure wave that originates from the plate and travels back into the piping, usually dissapating by the intercooler's hot side end tank (diffused in the intercooler). With the BOV on the cold side, you get the valve reacting to the immediate presence of this wave and aggregate pressure increase. With it on the hot side, you effectively empty the entire piping system, and the turbo has to repressurize the system, leading to lag between shifts. Not a big deal on a small turbo, but on larger compressors apparently it is night and day.
Aftermarket bolt on setups usually are found on a mid pipe on the hot side on S13s, as the factory piping is easily replaced with a pipe with a flange on it. It is more efficent to have it on the cold side, but ease of install leads many to have it on the hot. We are just splitting hairs here as most of us are on T2 frame turbos and have no noticable lag regardless.
At WOT, high in the rev band, I get no lag between shifts vented with mine on the hot side. With the vavle recirculated, part throttle lifts are where the benefit is noticed; also when decelerating for a complete, or almost complete, stop. The bigger issue is recirculated or non. I am a ricer (see my Ride of the Month page or website for stickers, lol), and love the sound of my SSQV vented, but for autoX or the like, I recirculate.
Modified by rico05 at 9:04 AM 2/28/2008