Dry-sump S.B.C / wrist pin oiling

[swampbuggy]

When using a high vac. dry-sump oiling system ( 4 to pan, 1 to lifter valley, 1 pressure section ) probably 22 plus or minus vac., does this have a negative effect on wrist pin oiling, if so what is done to insure plenty of oil gets to the w-pins ? Thanks Mark H.

[Roundybout]

I was just reading a blog by JE on this very subject.

https://www.google.com/amp/blog.jepisto ... s_amp=true

I like the DLC coating and forced pin oiling via the oil control ring on an endurance application. Drag engine I believe you could get away with a DLC coating only. Not a big fan of opening up the clearance to allow more oil and a big fan of using a high quality synthetic. A lot of times it can appear to be an oiling issue when in reality there is too much clearance and/or the pin or piston boss is flexing causing issues. If it is a lack of oil problem the coating would be my first step even if it means a more expensive option than other remedies available.

[swampbuggy]

THANKS Roundybout for putting the information on this forum about w-pin oiling, i read it carefully and thought it was very informative. Mark H.

[Kevin Johnson]

High vacuum changes the distribution patterns of oil from the rod bearings on the cylinder bore. The oil will tend to land orthogonally to the normal collection zone at the scraper ring. This suggests schema that take advantage of the new pattern and these are mentioned in the blog (use your deductive powers).

Positive pin oiling via EDM drillings to the rod bearings is a possibility as well. I do not like that the pressure gradient and volume in the film are sacrificed.

[swampbuggy]

Thanks Kevin for the input. I must say when reading your replies i usually have to get the dictionary out to get the drift of your comments, but that is ok it is GOOD to learn ! Now tell me where in the crankcase the area is that is orthographically located from the scraper ring ? Mark H.

[Kevin Johnson]

The thrust and counterthrust surfaces of the bore.

The scraper ring is circumferential but two arcs are the source of oil feed to the ends of the pin.


Slots on the rods aimed at the underside of the piston is another economical way to get the oil to the pins. It just increases the probability of drops hitting there.

[swampbuggy]

Thanks Kevin for the answer, Mark H.

[Dan Timberlake]

A few decades ago an SCCA GT1 champion explained to me that EDM's surface finish and changes to material properties can clobber many steels' fatigue strengths, if fatigue strength is important for the application. As usual, he was correct. Turns out there is list of EDM's negative surface effects.

(as a rule theses are not my favorite tech references, but this one seems remarkably thorough)

https://pdfs.semanticscholar.org/f3f0/e ... 20b39b.pdf

https://link.springer.com/article/10.10 ... 010-2751-y

[Kevin Johnson]

A few decades ago an SCCA GT1 champion explained to me that EDM's surface finish and changes to material properties can clobber many steels' fatigue strengths, if fatigue strength is important for the application. As usual, he was correct. Turns out there is list of EDM's negative surface effects.

(as a rule theses are not my favorite tech references, but this one seems remarkably thorough)

https://pdfs.semanticscholar.org/f3f0/e ... 20b39b.pdf

https://link.springer.com/article/10.10 ... 010-2751-y

One topic that does not appear to be discussed is how the complex interior topology of a machined part is to be shotpeened effectively.

[englertracing]

I have also read that rods with the edm passage arent the best solution.

Oil jets are probably the best really.
If you have thick pin bosses, bottom drilled holes would provide a direct path.