Above is the MerCruiser 4 inch riser, (accepts a 4 inch
exhaust hose). This riser is used on 1983 - 2002
MerCruiser V6 and V8 engines with the center riser
manifolds.
exhaust hose). This riser is used on 1983 - 2002
MerCruiser V6 and V8 engines with the center riser
manifolds.
Above is the MerCruiser 3 inch riser, (accepts a 3 inch
exhaust hose). This riser is used on 1983 -1995
MerCruiser V6 and V8 engines with the center riser
manifolds.
exhaust hose). This riser is used on 1983 -1995
MerCruiser V6 and V8 engines with the center riser
manifolds.
A cutaway view shows the internal difference between
the 3 inch riser (left) and the 4 inch riser (right). The 3
inch riser accepts a 3 inch inside diameter rubber
exhaust hose. The 4 inch riser accepts a 4 inch inside
diameter rubber exhaust hose. The inside diameter of
the exhaust outlet is 2 3/16 inches for the 3 inch riser
and 2 1/4 inches for the 4 inch riser. There is a
performance increase when switching from the 3 inch to
the 4 inch because of the smoother radius of the exhaust
path in the 4 inch riser.
External height is exactly 6 3/4 inches for both risers.
Angle of the exhaust outlet for the 3 inch riser is 15
degrees down. Angle of the exhaust outlet for the 4 inch
riser is 7 degrees down.
the 3 inch riser (left) and the 4 inch riser (right). The 3
inch riser accepts a 3 inch inside diameter rubber
exhaust hose. The 4 inch riser accepts a 4 inch inside
diameter rubber exhaust hose. The inside diameter of
the exhaust outlet is 2 3/16 inches for the 3 inch riser
and 2 1/4 inches for the 4 inch riser. There is a
performance increase when switching from the 3 inch to
the 4 inch because of the smoother radius of the exhaust
path in the 4 inch riser.
External height is exactly 6 3/4 inches for both risers.
Angle of the exhaust outlet for the 3 inch riser is 15
degrees down. Angle of the exhaust outlet for the 4 inch
riser is 7 degrees down.
Both the 3 inch and 4 inch risers have drilled and tapped
bosses to install the shift bracket (left) and the ignition
module (right).
bosses to install the shift bracket (left) and the ignition
module (right).
The 3 inch riser is
attached with
short studs
(included).
The 4 inch riser is
attached with 6
inch long bolts
(included).
attached with
short studs
(included).
The 4 inch riser is
attached with 6
inch long bolts
(included).
Mercruiser 3 Inch Exhaust Riser
Cast Iron # 51110 $89.95
Aluminum # 51115 $145.95
Mercruiser 4 Inch Exhaust Riser
Cast iron # 51140 $89.95
Aluminum # 51145 $145.95
Cast Iron # 51110 $89.95
Aluminum # 51115 $145.95
Mercruiser 4 Inch Exhaust Riser
Cast iron # 51140 $89.95
Aluminum # 51145 $145.95
MerCruiser Engines may come with either a 3 inch
riser or a 4 inch riser.
The size of the riser is determined by the diameter of
the hose that connects the riser to the exhaust pipe.
A 3 inch hose or a 4 inch hose.
riser or a 4 inch riser.
The size of the riser is determined by the diameter of
the hose that connects the riser to the exhaust pipe.
A 3 inch hose or a 4 inch hose.
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