The
FTZ Correct-Crimp will do 8AWG to 4/0... the
bench-mount version is what I use here to make cables. Can't recommend it highly enough. Be advised that you can likely get better prices from other sellers, tho... FTZ sells these things a lot cheaper to companies moving a lot of them than they do to us, who only sell a few a year... so look around for your pricing, but I
highly recommend this above all others I've ever used.