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Krombacher replied to JG07997's topic in 997-1 Series (Carrera, Carrera 4, Carrera 2S, Carrera 4S)For use on the track, fix the oil pressure problem these cars have. A 2qt deep sump isn’t enough though. Check your oil pressure on a 270 degree highway on ramp with rpms at or above 3400 rpm and 15 min of highway driving speeds immediately beforehand. You will see what I mean.
Mark, Put a oil pressure sensor in a oil filter sandwich plate - if you have a screw-in oil filter adapter. In order to achieve good rpm and oil pressure relationships - the oil pressure readings need minimal lag.. putting the sensor near the filter will put it the closest to the pump. Then find a 270 degree (3/4 circle) highway on-ramp, with continuous constant radius curvature..your Rpms at 3400 rpm or above, 15 min or highway driving immediately before hand, and hard cornering then look at your data. I can’t wait to see your response once you see the data.. email me if your interested in a better oil pan than currently available. I’ve tried them already. firstname.lastname@example.org accusumps won’t get rid of air bubbles sucked into the pump btw. -Pete
Could you shoot a video with your smart phone and show us the front wheel spinning on snow or ice (or anyone else)?
You're right, and the Haldex system would have been the right technology, a good match for the 911s layout... Which is now used by cars like the Bugatti Veyron, etc.. It would require inputs from steering angle sensor, a gear selection sensor , parking brake switch, brake pressure sensor, or at least a brake light switch.
After further review, I think Porsche intentionally chose a relatively weak viscous coupler (compared to the BMWs and Volvos above), to avoid understeer. The stronger the link is between the front and rear driving wheels (i.e. the stronger that viscous coupler is), the harder it is to turn (esp. on pavement, will increase understeer). Considering Porsche's customers probably find street/track performance more important than going through deep snow and ice, compared to volvo and bmw owners, and since 911's are decent in the snow with their engine on top of the driving wheels, and p-car owners probably have a 2nd car for nasty winter days, they probably didn't want to trade off too much increase understeer for winter traction. Of course, when they went to the electronically controlled centre differential in the 997.2 (no-more viscous coupler), they could increase winter traction without harming understeer (because they could actively control the "strength" of the link between the F & R tires). I think the very nature of the simple viscous coupler design makes the designer make huge tradeoffs between avoiding understeer on pavement vs. increased winter traction. Wouldn't an actively controllable viscous coupler replacement upgrade be welcomed for all 996 and 997.1 AWD 911's? Maybe a stronger AWD in just first & reverse gear, and rear wheel drive for 2nd gear and up? What do you think?
there are a few videos on the 996 4wd system - which don't look very impressive. watch how the front tires of don't spin: porsche 996 turbo - 996 c4s - another 996 c4s - Re: the delay associated with the system in the c4 (due to the viscous clutch (VC) fluid), there are plenty of videos showing there really is very little delay (below). I think either: a) Porsche's choice for their 996 Viscous Clutch was designed to transfer very little torque, or b) there are a lot of worn out VC's in 996's out there. Here's a few videos of people testing the functionality of their AWD cars' viscous clutches. When their VC's were not worn out, they worked very well. older AWD bmws in parking lot on rollers - older AWD bmws in parking lot on a fork truck - older AWD bmw on ice - AWD volvo wagon on a hoist - AWD volvo wagon climbing a very steep hill (watch the rear tires) -