m96 track reliability? (noob question)

[Topless]

Originally Posted by jaykay

No down shifts ?

Careful downshifts.

Allow the oil to settle as long as possible when coming off a long left sweeper under braking. Downshift once only to select your corner exit gear and blip throttle only to 4k. Never ever blip to redline when the oil level is likely low in the pan due to G forces in the previous sweeper. The data on dead m96 engines suggests that the blip to redline under braking is when the oil pump cavitates, oil pressure drops to zero, and then takes out the engine, generally not the banking itself.

[tzincp]

Originally Posted by Topless

Allow the oil to settle as long as possible when coming off a long left sweeper under braking. Downshift once only to select your corner exit gear and blip throttle only to 4k. Never ever blip to redline when the oil level is likely low in the pan due to G forces in the previous sweeper. The data on dead m96 engines suggests that the blip to redline under braking is when the oil pump cavitates, oil pressure drops to zero, and then takes out the engine, generally not the banking itself.

Why left sweepers specifically?
Is there something in the design of the oil sump that causes this?
I was under the impression that the pickup is in the middle of the sump directly under the intermediate shaft?

[JayG]

Originally Posted by tzincp

Why left sweepers specifically?
Is there something in the design of the oil sump that causes this?
I was under the impression that the pickup is in the middle of the sump directly under the intermediate shaft?

high G left sweepers shift the oil to the right of the pan away from the pickup tube

Lots of posts on this

[PaulE]

Originally Posted by tzincp

Why left sweepers specifically?
Is there something in the design of the oil sump that causes this?
I was under the impression that the pickup is in the middle of the sump directly under the intermediate shaft?

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.

[Topless]

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.

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.

[tzincp]

Originally Posted by Topless

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.


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.

I see what you mean with T3: such a long left sweeping braking zone to starve it of oil
https://www.autoclubspeedway.com/~/media/076F3CE929A84DACBD9EF4D9E1E298DF.ashx

Would this imply that in a right sweeper under acceleration the opposite scavenge pump would be starved for oil?

[tzincp]

Originally Posted by Topless

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.



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.

I see what you mean with T3: such a long left sweeping braking zone to cause issues...
https://www.autoclubspeedway.com/~/media/076F3CE929A84DACBD9EF4D9E1E298DF.ashx

Does this imply that in an accelerating right sweeper the opposite scavenge pump would be starved for oil?

[DWBOX2000]

Sorry, how (what) does a baffle work?

[DWBOX2000]

And how difficult to add to a 986?

[Topless]

Originally Posted by DWBOX2000

Sorry, how (what) does a baffle work?

It doesn't solve the scavenge pump problem but it does help to keep the remaining oil centered in the pan so it to does not migrate all the way to the edge. The X-51 windage pan is the one we added once we started running R-Comp tires. A simple bolt-on pan.

https://www.ebay.com/i/283348441283?chn=ps