There isn't really a maximum load average. It can increase based on other resources besides pure CPU processing such as waiting for IO a whack of other stuff.
But you'd expect see 1 per core on a fully utilized system when it is CPU bound.
4 core = 4 load avg
With hyperthreading, you'd hope for
4 core hyper-threaded = 8 load avg
But things can be more complicated, since they aren't real cores: Linux Load Averages and HyperThreads
What goes into figuring out load averages
Load average is the average of the load number for a given period of
time. It takes into account processes that are:
Actively running on a CPU.
Considered runnable, but waiting for a CPU
to become available.
Sleeping: i.e., waiting for some kind of resource
(typically, I/O) to become available.