Oil Control

[Taylorman]

I was reading Popular Hot Rodding last night about the engine that won the engine masters challenge. The builder was speaking about how he hones the cylinders to reduce friction. He said he prefers a fairly rough stone and then uses a brush to knock the peaks off the honeing cross hatch. He said when they used fine stones they lost all the oil control. What oil control is he referring to?

[Rocket-J]

It is about how the rings seat. Al

[Moneypitt]

The "grit" of the finish hone is critical to maintaining oil on the cylinder walls. And of course the ring you choose to run also has a "grit" that is compatable with the hardness of the rings. In order to understand this you need to look at the surface as though you had a microscope. The microscopic peaks and valleys left on the surface will be a deciding factor in ring seating and the oil control mentioned. Overall life is also affected, based in part on how the tops of the peaks are finished. Some grits will mearly bent them over, while others will in fact create a flat on the top, and several choices in between. There has been much industry discussion on this subject as even the new car people search for better ways..........I have a artical Dan sent me from Utah, I'll see if I can find it and somehow pass it on to you, or better yet, email him and ask if still has it.........Ray

[DetroitJim]

They are referring to "plateau honing", where the cylinder walls are rough enough to retain oil an assist the ring seal, but the highest peaks are knocked down in a type of burnishing process. This is a departure from old thinking that the cylinders needed to be a smooth as possible. I'm no authority so I'll let others explain in detail.
DJ