|
"To each his own".
You need to make these decisions based on knowledge and experience. You are the builder and you are responsible.
These decisions need to be decided on what parts you have in front of you. How is the oil feed to the rod bearings? What is the crank speed? Crank rotational speeds determine how the oil is feed to the rod bearings. What oil pressure you want at the bearings.
Oil directed straight off the mains does not require grooving but has shown good results. This type of design can withstand crank speeds typically seen in these Porsche engines. However, high speed cranks will be feed internally as ell. The later 991.2 engines are feed from the front nose as well. Porsche must have felt that the 9000 RPM required this. Race engines with crank speeds over 12000 RPM typically have center feed oiling due to the oil's inability to find its way to the rod bearings, due to centrifugal forces. All the high speed F1 engines I have seen had this oiling.
These Porsche cranks definitely in my opinion need all the help they can get to oil the rod bearings. To read the attached doc has to be done in reference to the type of crank in play and the engine type. To say its a blanket statement for all engines is in my opinion somewhat closed minded.
But to each his own I say.
|