Why do my cams have piston rings?

Rather watch than read? Here’s our Youtube for this page.

Maybe you’ve seen our Pin cams page with a pic of the end of the cam.

If not, check this pic out…
These are located on the very end of the intake cam you can see here. (right cam)

Yes, I called them piston rings, but they’re not really on your pistons, lol… But they sure look like the the same thing! So, what do these rings do and why are they there?

These rings are seals to hydraulic channels that move the cam actuator that is positioned directly over top of these rings. There are three rings to create two channels. One channel acts to Advance your camshaft, while the other retards it. A balance between these two can position the cam anywhere between its fully retarded and fully advanced position. Well, the later cars do this. Early Boxsters, 996s and 996tts have what we call the light switch effect where they are simply on or off, fully advanced or fully retarded. The next gen of cars got to take full advantage of this tech to have complete control anywhere in between as well.

Why are they there?

The actuators on these cams give an incredible range of drivability, increased torque at low end and extended power band on top. Driving a car with and without them is immediately noticeable. A 993 turbo with gt2/Evo cams, twin-plug, 3.8L and all kinds of goodies still lacks the low end torque of a 996 turbo that has cam control, even though the 996tt has the light switch type, and could be further improved with full cam control.

We have applied gt3 tech to the 996tts for a while, and still can, by using a gt3 ecu on a 996tt we could enable full control of the cams. A similarly built 996tt with factory cams vs. a gt3 based ecu setup that could fully retard the cams on top could make an amazing 100-150hp difference in an otherwise identical configuration. First gen gt3s without cam control had terrible idle and low speed drivability. They were basically a full out race car put on the street. The next gen gt3s with cam control had very nice idle, awesome drivability and insane power up top. Porsche continued this further to controlling not only the intake, but the exhaust cams as well for an even better power under the curve.

So what can go wrong?

997.1 turbo owners can probably tell you stories about the dreaded P0016, P0021 and other codes related to cam control. The 997.1 turbo had an issue with an inner sleeve that slipped and blocked off one of the channels forcing the cam control fully retarded, or just super lazy. Replacing the cam with a new one by Porsche didn’t fix the issue since the new production of cams still had the same issue. Pinning those is the best solution, which we offer here.

996TT owners have a different variety of issues with these rings. The first gen rings were cast or ductile iron vs. the stainless rings on the 997.1TT. And these early rings tended to wear badly. Once worn badly enough they’d lose their seal and compromise the control of your camshafts. It’s rare to do damage to the cams themselves, luckily it tends to just wear out the rings. However, getting to them for replacement takes quite a few hours of labor.

So, there’s good and bad with having piston rings on your camshafts… They’re a huge performance and drivability advantage. But do have some technical issues. Luckily none of those issues tend to be catastrophic failures and simply require some maintenance.