Hi! I have a 2009 factory JCW with an N14 engine that I am replacing the piston rings on. I had a friend mic the bores and said they are within tolerances and now it's time to file the rings. I know Mahle recommends a minimum of 0.006" per inch of piston size for normal turbo applications and 0.007" for turbo "race". However, these are minimum measurements and I also know its better to be a little big than too small. I don't plan on building this car to get 400hp but plan to eventually get it to Stage 2 and want to make sure I don't need to worry about the gaps anytime soon.

Does anyone have experience on what gaps I should shoot for? Thanks!

 

Per MINI:
Going from the top down
1st ring: 0.25mm - 0.35mm (0.010" - 0.014")
2nd ring: 0.35mm - 0.50mm (0.014" - 0.020")
3rd ring: 0.10mm - 0.35mm (0.004" - 0.020")