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Ferraria Effect

Old 11-08-2006, 02:16 PM
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Default Ferraria Effect

Was doing some light reading on the PSD, and it looks like the PSD system on the GT's and newer cars have an accelerometer in addition to wheel speed sensors. Pretty amazing for the day.

Control unit works in three different driving ranges .
1 .Traction while moving off
2.Acceleration from driving in curves
3.Ferraria effect (accelerator pedal released in curve)

1 . Traction While Moving Off
Pressure depending on wheel acceleration is built up in the transverse lock when the control unit recognizes
slip of a wheel through comparison of the wheel speed values . System pressure Is increased
in steps, until the slipping wheel again rotates in the permitted speed range, and then held constant
for a predetermined minimum time . Pressure buildup depends on wheel acceleration, in other
words the pressure will rise faster when wheel acceleration is fast . The pressure Is dropped in small
steps .

2. Traction Regulation for Driving in Curves with High Transverse Acceleration
The driven wheel on the inside of a curve tends ,to slip and propulsion is reduced when driving in
curves with high transverse acceleration . A locking torque depending on the vehicle's transverse acceleration,
road speed and recognized curve is introduced to prevent this .
Locking torque Is lower with a high road speed and high transverse acceleration than with a low road
speed. If cornering stability (lateral control) worsens by way of example due to a change in the road
surface condition (change from non-skidding to slippery surface), this will be recognized from the
rear axle wheel speed values and locking torque will be reduced very quickly in order to prevent loadtype
oversteering due to locking .
This function is effective in the entire speed range above 25 km/h (16 mph) .

3. Ferraria Effect
Rear wheel driven cars tend to oversteer when the accelerator pedal Is released suddenly while driving
in a curve . This oversteering tendency can be reduced considerably through application of correct
transverse locking torque . This function Is activated by transverse acceleration input information
with rightfleft curve identification and a comparison of wheel speed (wheels on inside and outside of
a curve) . The amount of locking torque required Is determined by the road speed, transverse acceleration
and speed of wheels.
Locking torque is reduced in steps as soon as the car is accelerated again or the brakes are operated,
or the activating conditions no longer exist .
The function of ferraria effect works in the entire speed range from 60 km/h (31 mph) on .
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Old 11-08-2006, 03:08 PM
Jim bailey - 928 International
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Yes Porsche was interested in much more than just ice ,snow traction or drag racing.
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Old 11-08-2006, 03:15 PM
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The lateral sensor is mounted under the drivers seat. If your seat has been removed, check to insure that the sensor is oriented correctly. If it's in backwards, or sideways, the G forces in turning will not be reacted correctly.
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Old 11-08-2006, 03:19 PM
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PSD explained video, courtesy 928UK:

Slow server so right-click and 'save as'.
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Old 11-08-2006, 03:32 PM
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Originally Posted by docmirror
If it's in backwards... the G forces in turning will not be reacted correctly.
This enhanced version of lift-throttle oversteer could then be coined the Nine-elevenia Effect.
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Old 11-08-2006, 05:51 PM
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Better quality version of video is up in Youtube. I have it copied from original VHS tape into DVD and MPEG file if someone has space to put it.
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