GFB EX38
External wastegate
instruction manual
Part no. 7003
Ph: +61 (0)2 9534 0099
Fax: +61 (0)2 9534 3999
Email: sales@gfb.com.au
Web: www.gfb.com.au
INSTAlLation
GFB EX38 Packing list:
Assembled EX38 wastegate
10psi spring (installed)
2 x v-band clamps
2 x 1/8” BSPT hose tails
1 x outlet weld-on flange (part # 7043)
1 x inlet weld-on flange (part # 7053)
1 x valve seat
Exhaust in
Smooth flow to
wastegate inlet
Smooth entry of
wastegate gases
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Install the hose tails onto the wastegate. The thread is 1/8” BSP, which is a commonly available thread should you
wish to use a different type of fitting.
Identify the inlet and outlet weld-on fittings. These are to be welded onto your turbo exhaust manifold and exhaust
system, onto which the EX38 is mounted using the supplied v-band clamps.
Please note the EX38 is compatible with TiAl MVS weld-on fittings, so if you already have an exhaust manifold with
a TiAl fitting, the EX38 will bolt straight up using the GFB-supplied clamps.
The inlet fitting, which is welded to the exhaust manifold and supports the weight of the wastegate, is best suited to
1.75” (44.4mm) O.D. pipe with a wall thickness of at least 0.095” (2.4mm). The outlet fitting is designed to accept
1.5” (38.1mm) O.D. thin-walled tube, which is commonly used for exhaust systems and screamer pipes. Of course,
it is possible to use different size and wall-thickness pipes than those recommended, provided a suitable weld can
be achieved. Replacement weld-on fittings are available separately from GFB if required.
The inlet fitting should be welded to the exhaust manifold after all the exhaust runners have merged, and in a
position that promotes smooth flow to the wastegate – fast-moving exhaust gas is reluctant to make sharp turns,
which significantly reduces the flow potential through the wastegate. The diagram below shows a suggested
installation location.
On any street-driven car, legally the wastegate outlet MUST be connected to the vehicle's exhaust system (before
any catalytic converters and mufflers), and should be done in a way that allows the gases to merge smoothly. On
race cars where regulations allow, the outlet can be routed out of the engine bay to atmosphere.
Ensure the valve seat is inserted into the bottom of the wastegate before final installation.
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