the oil in the crank of a 928GTS is about 7.5Liters according to specs.
During rebuilding of a 928 GTS engine we did some experiments. Aim is finding
out as much as possible about oiling and oil levels in the engine.
Some test results:
- Max level is about 7L in the oil pan. This is where the dip stick shows the max mark.
- Max level is you keep filling it up is about 7.9L. This is where the oil level starts to overflow. It is beyond the acceptable level for the crank which is basically hitting the oil.
- The min level is said to be 1.5L below the max level. This is the min marker on the dipstick.
- At max-2L (so 0.5L below min) the oil level alarm goes off. This only happens when the engine is not (!) running. It seems that Porsche wanted to avoid false alarms.
- With the engine not running, oil seeps back into the oil pan, and as low as 1L the oil pump still picks up oil without air. Obviously a lot of oil is transported into the engine when it runs, so this is not a usable figure.
- at 6000rpm, 100x5,4L=540L air is pushed around in the crank per second. That is a lot. Makes you wonder what the oiling looks like when the engine runs.
Question: how much oil is actually "under way" when the engine runs, or rephrased: how much oil is in the pan available in the pool and ready to pump up at 6000rpm?
Here is an estimation based on not-verified data from the internet:
From a Chevy block at 4000 rpm
Liters Liters (928 adjusted)
5-6 quarts in the small block 5,6 7
1/3 to 2/3 quarts in the valve covers 0,6 0,75
1 quart in the lifter gallery 1 1,25
1 quart in the filter 1 1,25
total 3 3,75
Ok, the suction cup of the oil pump is like this:
it is located exactly in the middle of the lower oil pan square. The square is about 30cm x 30 cm x 9 cm
The suction cup is 9cm in diameter, and has a screen at the bottom of about 8mm.
The screen floats on of barely above the bottom of the oil pan.
Here's a test that I did at cold temp, letting the 928 engine warm up a bit. Goal was to find out how much the oil level drops due to oil traveling in the engine.
- temp 0C. Oil level neatly at max (7,5L, 10W60 oil)
- engine started
- temp 0C Oil level 0,5cm below max, so approx 0,5L on its way in the engine
- temp 10C oil level dropped to 1cm below max, so 1 L on its way
- temp 20C oil level dropped to 1,5cm below max, so 1,5L on its way
- temp 50C oil level approx equal, even a bit higher, 5mm above minimum. Apparently oil flows back a bit quicker.
- temp 50C, rev at approx 2000rpm. It does not make any difference in the levels.
It would be interesting to add to this test when the oil is at 95C.
Taking a fast turn with the 928 will make the oil move to one side of the oil pan and may actually allow air to be drawn into the oil pump. At 26 degrees the oil surface exposes the screen and allows air in. 26 degrees is not much if you imagine what happens on a track.
If your 928 is low on oil, you are bond to run into trouble pretty quickly.
Simple conclusion: keep the oil level to max always !!! Check frequently.
Porsche 928 VDO W0133-1618530 Coolant Level Sensor
(VDO - G1050-83322, W0133-1618530)