How to influence files (pre)allocation steps (max growing value) in MongoDB 3.4 with WiredTiger
WiredTiger does not preallocate data files. Only journal files are pre-allocated (at 100MB per pre-allocation), see journaling process.

The disk exhaustion you're seeing is likely due to these journal files. Journal files are optimized for quick writes, and their contents will be persisted in a more permanent manner on a WiredTiger checkpoint which occurs every ~60 seconds. Typically, once persisted in data files, you should see less disk used, since now the journal files can be removed. Note that the journal files are only removed by WiredTiger following a checkpoint and at no other times.

I would suggest you to allow for some temporary extra space during this restore/data load process. Once the database is in a steady state, you would see a more accurate size.

The power-of-2 preallocation is specific to MMAPv1 storage engine, which is deprecated. This is not relevant to WiredTiger.