Subject: UrQ Bypass Valve - How To Add One.
This Friday was the day after Thanksgiving for us here in the good ole US of A and a perfect day to poke around the junkyard while millions flock to the malls to mass consume. My goal was to add a bypass valve to my '83 UrQ with no major alteration to my the car. After poking around BAAS 900 turbos, 9000 turbos and OVLOV turbos I found enough pieces to complete the job. Here's what you need.
1) From BAAS 9000T - Junkyard Aluminum intake pipe that runs from intake manifold under the air box to the intercooler This has a 3/4" pipe sticking out the side, the bypass valve outlet connection.
2) BAAS 9387607 - reducer hose to connect this aluminum pipe to the UrQ aluminum intake cap that sits atop the airflow plate.
3) BAAS 7526288 - coupling to connect baas aluminum pipe to the metal right angle pipe directly in front of the UrQ turbo inlet.
4) BAAS 9389446 - Right angle hose that connect the 3/4" connection of the BAAS aluminum pipe to the Bosch bypass valve outlet.
5) BAAS 7533185 - This is the most important piece. It's from a BAAS 900T with an intercooler and it is a hose that takes the 3/4" inlet to the bypass valve down to the same size as the little UrQ hose that runs directly off the major pressure side turbo hose, back to the emissions stuff. (here I'm not too sure what it is) Get this above all else.
6) The bypass valve. I forgot to get the Bosch PN, but it's off a 9000T and is similar to the S4 one and all the Bosch valves. Someone else posted all these PNs before. All I know is that the BAAS 9000T can easily handle 15psi.
7) A T plastic hose coupler. I took mine from a BAAS 900T right off the intake manifold. This is a part you could find from any autoparts or hardware store. It's approximately 1/2" in OD and is simply a T piece.
8) Assorted hose clamps. You'll need a bunch of big ones for the intake side connection.
9) Long section of vacuum hose, braided or cheapo autoparts variety, say 3 to 4 feet.
10) T connection for this hose to an existing hose leaving the back of the intake manifold on your UrQ.
Here's the scoop. You replace the accordion wire-reinforced UrQ intake-side hose with a section of the 9000T aluminum pipe. Cut the pipe to within 3/4" of an inch from the 3/4" outlet stub and cut the other end to fit. The whole aluminum piece is approximately 10" long when cut correctly. Join the pipe to the UrQ air box end with No. 2. Connect the other end to the UrQ right angle pipe directly in front of the turbo inlet with No.3. Connect the bypass valve outlet to the aluminum pipe with no. 4. You need to trim this to fit the valve next to and rearward of the throttle position sensors. Connect the bypass inlet end to no. 5. Trim the large end of No. 5 to allow a T connection of the small end of No. 5 just in front of where the small UrQ rubber hose that is connected to the large throttle body hose meets a 4 or 5 way metal connection near the back of the intake manifold. The T connection you are to make will have the No. 5 hose meeting the UrQ hose from below. Add a T connection to this UrQ rubber hose using a 1 1/2" long piece of 3/4" OD heater hose from an autoparts store. Point the 3rd leg downwards. Connect this third leg to the bypass valve via No. 5.
The final step is to T into any small vacuum line running from the back of the intake manifold. Run this line to the small nipple on the front of the bypass valve. To keep the bypass valve from interfering with the throttle position sensors run the No. 5 hose through the existing hose retaining clamp on the airbox that used to retain the small rubber UrQ intake hose mentioned above. Use a slightly larger piece of hose to wrap around the No. 5 line and a hose clamp over this to pull the No. 5 hose, and ultimately the bypass valve, rearward.
Voila. You have a bypass valve. Please email me directly if you have questions. This is a 4 hour job or less, but it difficult to describe.
HTH.
Andrew Finney
1983 UrQ.
