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In Reply to: what's diff. b/w engine of '94 850 Csi &'93 850 Ci posted by stevie P on July 27, 2000 at 12:42:31:
(1) Displacement difference of 0.2 Liters (5.4 vs. 5.6)from a longer stroke crankshaft providing 79mm vs. 75mm (not positive on these values).
(2) Camshaft lift and duration;
(3) Engine Management Software (Chip Programming); and
(4) Exhaust System: 2mm(?) larger free flow for the CSi.
The two engines are otherwise identical, sharing the same part numbers for the heads, valve train, and other major parts except those identified above. Even more interesting, as some have discovered, changing even the lower displacement 850i 5.0L v12 using bolt-in cams, exhaust, chip and a extrude honed higher-flow intake manifold results in 369hp (per Dinan), only a scant 3 hp short of the CSi in stock form. The 5.4 Ci engine would likely respond in kind. Note that BMW MotorSport engineers did not install the now-famous McClaren dohc heads on the V12 to make the change to 4-valves per cylinder that all previous M-car variants enjoyed over their non-M variants.
The drivetrain of the 6spds and CSi is identical with the exception of the CSi's 2.93LS(25%) final drive gearing vs. the 850i's 2.65 Open rear differential. One small but noticeable exception is that the CSi has a smoother, shorter throw shift linkage. The Ci uses the 5spd autobox which the CSi was never equipped with.
Suspension-wise, the CSi has the plus 1 tires and rims (17" vs Ci and i 16") and the M-technic stiffer shocks, springs and heavy-duty sway bars. All the suspension pieces are available from BMW and replaceable at an expense of about $2-3k.
Otherwise there are cosmetic (spoilers) and other differences, but they are primarily "packaging" issues, except for European models with 4-wheel steering (rear camber adjustment). Some of the other differences include the RPM dependent rev limiter that provides the CSi higher 1st-5th shift points beyond the i/Ci's 6000 rpm limit, and the speed sensitive steering assistance of the CSi.
Overall, the cars are remarkably similar compared to differences between other M versus non-M models for Series such as the e28, e34, and e39 M5s.
Greg K
1991 850 6spd
1988 M5
I understand that 93-97 850ci cars have 322 hp and '94-'96 85Csi cars have 372hp. What contributes to the horsepower increase? Exhaust? Cam? Intake? Displacement? Chip? etc.?
thanks
steve
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