P/N: 4GC020-010
©2001 Vortech Engineering, LLC
All Rights Reserved, Intl. Copr. Secured
15SEP01 V1.1
(88-95 GM Lt Trk(4GC))
10. DISCHARGE PLENUM
A. Thread the supplied 90° plastic fitting into the
3/4 NPT bung located on the discharge plenum.
(The fitting should be screwed in until snug,
pointing down & to the right at approximately a
45° angle.)
B. Attach the discharge tube between the plenum
and supercharger with blue sleeves; secure
with clamps as shown.
C. Install the short 1" hose piece onto the 90° fitting
with hose clamps. Attach the supercharger by-
pass valve (vacuum pointing toward the outside
of vehicle) to the short hose.
D. The discharge of the bypass may either be
routed to atmosphere by using the supplied 1"
K&N
®
filter (This installation will produce some
air noise on deceleration), or back to the super-
charger air inlet tube by using the supplied 1" x
10" hose and 3/4" NPT x 1" plastic fitting. If
routing the air bypass back to the supercharger
inlet:
• Mock-up the steel supercharger inlet tube into
its approximate final location.
• Center punch and drill a 59/64" hole into the
inlet tube and thread with a 3/4" NPT tap. (See
Fig. 10-a
for hole position.)
• Thread with the supplied 3/4" NPT x 1" plastic
hose barb into the air inlet tube. Connect the
long length of 1" hose from the bypass to the
air inlet.
E. Connect a vacuum hose to the bypass valve and
a vacuum source.
F. Connect the 5/32" vacuum hose between the
small fitting on the side of the discharge plenum
and the TEE that feeds the pressure normaliz-
ing holes in the spacer block (see Fig. 5-a on
page 5).
Backside of Inlet Tube (Installed)
1-7/8"
Backside of Plenum
Approx.
Center
(Vertically)
Drill:
Tap:
(optional)
59/64"
3/4" NPT
Supercharger
Bypass Valve
Fig. 10-a
11
