RettlerT

Our S6 has piston cooling jets that spray oil on the piston domes for cooling. It's the first time Audi's used this technology and I've never heard of it before.
Is anyone familar with this? I can't figure out how this would work without burning oil.

722maa

then again, my s6 drinks oil a lot !

tenspeed

Using oil to cool pistons has been used on many engines. Even basic Briggs and Stratton lawn mower engines use a splash system. Cooling jets may be new. Some connecting rods have holes in the crank end that allow oil to squirt up toward the piston. Maybe it's something I pick up when I learned about diesel engines in the service.

The oil does not stay on the piston long enough to burn. It hits the piston and carries the heat away. Bob the oil guy say that the oil is around 210*F during normal operation and racing cars have oil temperatures around 300*F. Dino oil starts breaking down around 350*F.

RettlerT

These jets spray right on top of the piston. If it doesn't burn it seems it'd go out the exhaust port. I've got 3k on mine now and the oil level is still max so it's not consuming it. What happens to it after it hits the piston dome?

DeerHunter

Oil spray cooling jets have been used for generations of cars - primarily those with forced induction engines. The original Miata engines, for example, have them, since they were based on the'80s-vintage 323GTX motor, which was turbocharged from the factory.

Oil isn't used because it is sprayed on the underside of the piston, not on top. It they tried the latter, it would empty the sump in very short order and seize the motor. Not to mention making it impossible to meet emissions standards and carboning up the piston crowns.

RettlerT

Yes, you're right, Thank You! I saw the diagram and it looked like it was on the piston top. I couldn't see how that was possible. And...obviously it isn't. The nozzle goes from the top to the underside of the piston.

///M Traitor

The diagram is confusing. The jets are under the pistons for sure. It's a see- through type diagram.

diverdan

It's been used a few years in the Corvette ZR1's LS-9 engine.