LR. Sorry,confused.
512 bytes is the NTFS sector size. 4Kbs is the standard cluster size. Have you changed the cluster size via disk manager?
For general purpose use, 4K is optimal. You only really see definite performance improvements above this is you do a lot of large file handling.
Yes, the larger the cluster, the more "slack" you have on your disk as every file is padded out to a full cluster size multiple but I don't see the link with error correction?