Variable oil pressure on 997. ?

[Polome]

I'm always interested in the engineering/technical side of cars . My 997 has variable oil pressure...monitoring the gauge during driving shows the pressure fluctuations. This is more linked to throttle openings than revs ( iie more throttle = more pressure) and not at all like older engines where high revs gave high oil pressure.Easy to understand as the engine needs more protection with greater loads irrespective of revs. Just wondering if anyone knows how the system works. I assume it's some sort of electronic relief valve but would like to know for definate. Thanks.

[Magic919]

One of the oil pumps is electronically controlled. The ECU makes the decisions. The remaining four punps are simple mechanical ones.

[Pope]

The MA1 engine was the first Porsche flat six to have a demand controlled oil pump. The pump has one fixed plane gear and one that is controlled by a hydraulic solenoid; the controlled gear slides along the fixed gear giving a larger or smaller pump capacity, the gear is sprung 'full mesh' as a failsafe.

Edited by Pope on Sunday 12th July 22:31

[WindyM]

Hi Polome
I'm like you - I love instrumentation. It's part of the 911's appeal to me - all those gauges. My old Lotus Elan +2 had 8 gauges and I felt as though I was flying it! However, I was a bit disappointed when I first started my 997.2 from cold and the oil-pressure gauge didn't go off the scale at 5bar+!
Magic and Pope have explained how the system works (I believe its covered in the owner's manual too), but of course the reason for it is reduced fuel-consumption by spreading the smaller pumps out to where they're needed. Have you ever got yours to read 5bar?!
Windy

[Polome]

Pope said:

The MA1 engine was the first Porsche flat six to have a demand controlled oil pump. The pump has one fixed plane gear and one that is controlled by a hydraulic solenoid; the controlled gear slides along the fixed gear giving a larger or smaller pump capacity, the gear is sprung 'full mesh' as a failsafe.

Edited by Pope on Sunday 12th July 22:31

This sounds really interesting...when you say "plane gear" do you mean a standard twin lobbe or sliding vane type oil pump? Any pics or schematics to show what you describe.? Regards.