cajerseyboy

Recently picked up a 2011 RS and noticed at startup the oil pressure readout is at a 5 (highest level). It then very slowly (very slowly) comes down after warm up but will go back up to 5 with any throttle whatsoever.

Oil level is high but not overfilled.

Is this an issue to bring in for service or normal?

Bxstr

I have a 3.6 997.1 GT3, I haven't paid attention to what it does at startup, but I can confirm when driving any acceleration makes oil pressure go to 5.

Fisher

This is normal for a dry sump engine.

cajerseyboy

Bxstr and grizfish - Great! Thanks for chiming in.

Hella-Buggin'

That's why I went for the Mezger to replace my m97 as a track car.

cajerseyboy

Is there a benefit to the high oil pressure on the track?

Hella-Buggin'

A oil in a non dry sump engine can wash up along the side of the case during high load corners allowing the oil pump to ingest air.
This leads to oil starvation and accelerated engine wear and eventually, failure. A dry sump forces oil everywhere.

cajerseyboy

Thanks for the education! I did some additional reading on Porsche dry sump vs wet sump engines. Interesting. Here is an article from a 2008 that has a video link if anyone is interested.

https://www.caranddriver.com/feature...-test-feature/

Mike Murphy

For what it’s worth, my 996 is a wet sump engine and I also have 5 bar of pressure, even when hot, at any RPM above 2500. It’s essentially always pegged while driving.

While it’s true that dry sump systems are almost always better in design than wet sump, especially on the track, oil pressure is really just a function of the size of the tolerances inside the engine combined with viscosity. My engine, your engine, have tighter tolerances, which leads to higher oil pressure than a more relaxed engine.

Smallblock Ford vs Chevy engines from the 60’s through the 80’s met enthusiasts with banter back and forth as to which design was better: Ford v8 engine had higher oil pressure than the equivalent Chevy v8s. There was no correct answer, other than, a properly designed engine should have the right amount of pressure. The Chevy engines had larger bearing surfaces, which allowed for less pressure to achieve a similar result. If pressure goes down on an engine design, you can design for slightly better fuel economy because it takes power to drive an oil pump faster and takes power to pressurize the oil.

Some engines only require 5-15psi of oil pressure (1949 Chevy 216 inline-6). In fact, for a plain bearing to work, no oil pressure is needed. However, oil will eventually seep out and will need to be replaced.

In a modern engine, the oil will eventually get very hot and will need to be cooled down, so the pressure keeps the oil moving along so that it can be cooled. The higher the pressure and volume, the faster oil can be cooled through the heat exchanger, a huge benefit, as our engines use the oil to cool nearly 1/2 of all heat generated.

And of course, it depends on where we are measuring and how many oil passages and oil accessories the oil pump must drive. Oil pressure off the pressure side of the oil pump should be a lot higher than any accessory toward the end of the delivery passage (such as the tensioners in the M96 engine).

On average, across every car in the world, the saying goes: 10psi for every 1,000 RPM is ideal. But that’s a generalization and doesn’t always apply.

bubba928

Thank you. I enjoyed your comments.

JS

Dry Sump Love ! ! !