The Shadow: September 27, 1999

by on Sep.27, 1999, under Shadow

I finally solved the last of the annoying boost gremlins on this car!  I had yanked the Bosch BOV setup on the upper intercooler hose and replaced it with a stock T2 ribbed upper hose.  I have bad boost stacking without the BOV (very bad for this little turbo), but no more boost drop-off or random boost amounts.  Even though I have already tried removing the BOV and plugging the hole with a piece of wood, I wanted to dump this setup anyway.  First of all, I don’t like using that crazy setup with the two restrictors, check valve, and bleed to keep pressure on the BOV to keep it shut.  Second, I know that my IC has quite a pressure drop at high boost, so the BOV would probably be more effective on the lower IC hose.  Since I am not running more than 14psi (nor do I plan to), the stock BOV is perfect and it will also serve as protection because it will blow off the seat above 15psi in case something goes wrong with boost control.

So, I fabricated a new hose connection on the lower stock hose by cutting out a small section and putting a 1-1/2″ copper drain pipe in its place (the stock lower IC hose is 1-1/2″ ID).  I opted for copper because it was easy to solder on a 3/4″ fitting to attach the BOV hose.  It’s a 3/4″ copper T-fitting that I sliced along the back and spread open to match the curve of the big pipe.  It took some bending, hammering, and patience, but it worked.  I then used a short piece of 3/4″ copper pipe in the fitting to connect the hose to.  I connected the BOV to the copper pipe in the fitting with a short piece of 3/4″ I.D. heater hose and then to the air box with another piece.  I already had a 3/4″ copper pipe fitting on the airbox, so I just put a short piece of 3/4″ copper pipe in it to serve as a reducer.  The Bosch BOV used 7/8″ I.D. hose, so the 3/4″ fittings (not 3/4″ pipe) were the perfect O.D.  I squeezed the fittings so the pipe would fit tightly, sanded the surfaces, and then RTVed them in place.  I didn’t want to solder so that I could switch back easily.  The setup works wonderfully and for the first time, my boost is predictable and solid!  This car SCREAMS!!!

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