Mahle Piston Gaps

[tiger_e30]

The machine shop I used didn't return the documentation that came with my Mahle oversized pistons(84.48mm) below is their response when I contacted Mahle but it really doesn't seem right to me. Is what they are saying correct? And second question for a turbo application should I open up the gaps?

"The BMW #11251714810 being given is the OE replacement #. Our Mahle # is after market # 0811502
If that is the # being used, Ours are Factory replacement pistons & rings & they are drop in & no filing is needed.
These are not file fit rings. "

[ForcedFirebird]

Apologies, falling behind on PM's.

They actually should be a little over gapped out of the box based on my experience. If you are going to be turbo/SC/nitrous, then open the gaps according to this literature:

http://blog.wiseco.com/everything-you-need-to-know-about-ring-gap

Gaps on the big side are safer than the tight side. Ideally the rings should almost close (but not touch) at operating temps - hence the gaps when room temp.

[tiger_e30]

No worries. I am going back and forth between the Racing with Nitrous/Turbo or Modified/Nitrous. I think based on my reading I will be better off going with the bigger gaps even though it will be a street car.

[tiger_e30]

I found the Mahle sheet and it has 0.006 as the multiplier on both. I am going with 0.020 gap on both both rings

[tiger_e30]

Anyone know where I can get a mahle oil ring in the usa? Can't quite stomach paying more for shipping then the part

https://www.schmiedmann.com/en/11251713195MO-mahleoriginal-pistonringkit

[tiger_e30]

Amboss Corp will sell just the rings. Only $8.