Quote:
Originally Posted by PaulE
I'm no expert on this, isn't it also due to the location of the oil scavenge pumps in the cylinder heads. The M96 uses the same cylinder casting on both sides. They're not interchangeable though because there is some different machining on each side for something. So the timing chain for one side of the engine is on the front - where the serpentine belt, etc. is located and the timing chain for the other side is on the back - where the flywheel is. Inside each cylinder head is a scavenge pump, and on one side it's in the front and on the other side it's in the rear. Those left sweepers can cause the oil to move by centrifugal force away from the scavenge pump in one of the cylinder heads - or maybe the asymmetrical nature affects both scavenge pumps on left handers, there doesn't appear to be an issue with right sweepers.
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Yes.
The scavenge pump in the right bank is at the rear of the engine in a Boxster. On a long hi G Left sweeper oil accumulates in the right bank head and when you go to the brakes, the oil moves forward, away from the scavenge pump leaving the pan with very little oil left. Now zing the throttle to redline with an overzealous heel/toe downshift and the oil pickup cavitates causing temporary zero oil pressure and connecting rods sticking out of uncomfortable places on the casing. A bad day.
The 996 has the same motor configuration but reversed 180* so the long R sweeper is the one to adapt your driving style to.
When Porsche developed the 9A1 they went back to the Metzger design with 4 scavenge pumps in each of the 4 corners for much better oiling under high G forces. Now the engine runs safely under hi G just like the GT3, 993, 964 etc.
If you keep your oil topped off, run street tires, and stay well away from redline in the sweeper you have little to worry about. An SPBOX driver racing in a pack on fresh comp tires, not paying attention to his oil situation is likely to get bit at Fontana. At least a dozen Boxster Spec motors have been sacrificed entering turn 3 Fontana with a big redline (money) heel/toe downshift while reaching for 2nd gear.