Gs Intake Manifolds And Cat Code Plug Hop Up An R1100Rs/Rt - BMW R850 Maintenance Manual

GS Intake Manifolds and Cat Code Plug "Hop Up" An
R1100RS/RT! - Rob Lentini
Many BMW "Oilhead" riders spend big bucks chasing more horsepower with
expensive exhaust systems, magic Motronic microchips, even camshaft and
head modifications. I've wondered whether many of these riders have defined
what it is they want to "improve"?
I don't know about you, but absolute high RPM power is NOT why I purchased a
BMW. Superior broad torque, "user friendly" power delivery and fuel economy is
what I seek in an engine. Top speed advocates often perform expensive
modifications to a BMW for only a modest peak horsepower increase. Then the
machine may be less rideable and reliable on the street. Not my style, thank
you! I prefer strong roll-on power for normal every day commuting, sport riding
and touring.
When I learned about a simple way of getting almost 5 more peak mid-range
horsepower from my '94 R1100RS while increasing and smoothing power
delivery from 3000 to 6500 RPM for less than $35, I was all ears! Here are the
facts...
Anthonie Mans posted an interesting test on the Internet BMW Riders/Oilheads
lists performed by "Das Motorrad", a Euro motorcycle magazine. All that was
done to a stock R1100RS (same engine as in the RT) was to give it a
dynamometer baseline run and then replace the intake manifolds (black tubes
connecting the airbox to the throttle body intakes) with those from a GS. Then
they dyno'd the RS again. Here were their reported results in Newton Meters of
Torque and Metric Horsepower:
RPM Torque (GS tubes) Torque (RS tubes) HP (GS tubes) HP (RS tubes)
2000 86
2500 85
3000 92
3500 90
4000 92
4500 96
5000 102
5500 106
6000 101
6500 92
7000 86
7500 79
87
86
89
89
83
96
99
102
96
92
91
85
87
24 25
29 30
41 39
44 43
52 47
62 62
73 72
82 80
86 81
87 87
86 90
84 90