bmw s50 turbo ignition

hello unfortunately in my country it is quite difficult to access a dyno, in my city there is only one and has no brake so the ignition adjustment mbt technique is not applicable then how can I adjust the ignition of my car without that technique or is there another way to do it in dyno without brake, also I do not know the factory engine grades I just want to tune my car

Have you checked out the road tuning modules within this course? You can do a reasonable job on engines that are knock limited but you do need to accept the fact that you're not going to be able to optimise the timing to MBT everywhere.