std::unordered_map lock the bucket count

I am trying to do a performance benchmark on C++11's std::unordered_map container.

I want to see how the load factor of the container affects performance for insertions. Specifically because I am interested in using a hash table as base data structure for finding pairs in a huge set of numbers.

As I understand the documentation, this does not seem possible. I can set the amount of buckets with a rehash() but this is done automatically any time the max_load_factor is exceeded.

I can set the max_load_factor but as I understand it, this only determines when a rehash is performed, it does not allow the table to be placed under heavy strain, which is what I want to do.

Is there any way for me to hard limit the amount of buckets in a hash table?