dizzyj

I see one for a 928. Having a machine shop cross drill, but want to make sure we are doing the right thing. The work is only done on the rod journal, correct?

Dougs951S

The mains are drilled too.

dizzyj

is there a diagram of what is done?

Dave W.

The holes are drilled all the way through. Here's a stock crank, note there's no hole in this side of the rod journal.

Voith

Is there any real world proof that this mod actually helps? Early cranks had cross drilled journals from factory, but on later cars they abandoned this practice.

When crank is made, cost of drilling trough the journal instead only half of it is almost zero.

That means that benefit of doing it must be worth even less.

MAGK944

...or maybe just cross drill #2 & #4 as those are the two that are known to have issues:

http://newhillgarage.com/2013/06/25/...tem-explained/

Voith

Ive read this before. Still, making two holes instead of one lowers the pressure of oil at the hole, that IMO means there is less oil pressure on the power stroke and bigger chance that the film will break.

I dont remember of the top of my head, but is the crank designed so that the rod oiling holes are turned up on every power stroke? That would make sense.

Mains have oil grooves in bearings, so no need to drill them.

harveyf

I wondered why there was a surge of interest in my website yesterday

My personal opinion is that cross drilling has no advantage. I would agree with the above comments regarding "the factory tried that and then stopped" and "we want to maintain the oil film, not more flow". Save your money and use it for a good quality oil that is designed to be "low foaming".