Neil Harvey

FYI, the only reason to recut the camshaft and in doing so the DLC is removed, is, the solid valve motion requires a different lobe design. If you want to see fingers get destroyed, run the Hydraulic lobe with solid finger motion. After the cam lobes are re profiled, they are re coated with DLC. The cam mod is not the "fix" as you suggest. Its a result of going to a solid valve motion to allow a gap, ( lash) to be included in the valve geometry.

Someone posted a photo of a horizontal line across the backside of the finger. This is from the finger contacting the base circle of the cam lobe all the time. Same contact stress the finger follower sees from the same cause.

This conversion is not for all. Some will stick with what they have, some will decide to swap out for same new parts. Some will change over to solid. Its all about what you decide.

Choices.

Neil Harvey

Actually the 991.1 engines do have Hydraulic Lifters. Maybe the design is not a typical lifter that acts directly on the end of the valve stem or on a rocker arm. But the definition of a lifter is a two piece hydraulic cylinder that eliminates the need for valve adjustment. This is what the .1 engine has. In engine design terms it is a Hydraulic Lifter which ever way you look at it.

Cay_PI

Ah, you re-coat them. Interesting. That makes sense. Can you also run more powerful cam timings when re-cutting anyway?

The basic difference to a classic hydraulic lifter design is, that porsches construction doesn't move the hydraulic elements. And thats a gigantic difference compared to a classic hydraulic lash adjuster. Call it how you want, I'm not used to english tech-vocabulare. But in fact the MA175/MA176s valvetrain design is completely different compared to that of a 9A1 Carrera engine and the lash adjusters of the GT3 might kill the lash/clearance as you said. But argumenting with moving masses is just wrong.

Neil Harvey

Indeed, maybe the translation to your language makes the description different. There are 3 parts to the Lifter. An inner that when filled with oil pushes against the bottom part of the outer. This then pushes the middle section that the finger pivots off, upwards stopping the whole assy from collapsing.

Cay_PI

.. and in a normal car engines valvetrain, that whole thing would sit somewhere inbetween the cam lobe and the cam and would move on every rotation cycle, creating a lot off moving masses. Not so in the GT3, where it just sits in its mount and alters the finger followers position. The original design idea is smart... just to ambitious.

Is it a standard hydraulic element? The interesting thing is, that they drilled oil sprayers into the top cap.