Tumbler polished cranks

[Steve.k]

Are you guys seeing any gains in windage losses or friction with the polished cranks?

[ProPower engines]

Depends on the finish. Smoother the better to shed oil as the surface gets slick and oil retention on the crank
surface is much harder then on a rough surface.
There is some coatings offered these days by the crank manufactures that shed oil very well.

[Steve.k]

Thanks i was just curious a friend of mine did his it shined up like the bearing surfaces. Interesting to see difference.

[mag2555]

Most Dyno's are hard pressed to measure the 2 hp difference that there is likley to be!
A Crank scrapper with Telflon edges that ride right on the Crank can be worth 18 hp above 6K rpm when you have a a lot of rotating mass area so they say.