I have Train Mk4 already and it dont go over 324 km/h what can cause that? i play with Krastorio 2, Space Exploration and AAI Industry, and i use rocket fuel for trains

Hi, train's max speed is based on the "slowest" rolling stock that composes the train. If you have 1 Mk4 and 1 Mk1 locomotive, the max speed will be the same of the slowest, i.e. the Mk1. Make sure to upgrade all locomotives and all wagons in order to fully benefit of the higher speed and less attrition that the better tiers provide

if that isn't the case, it could be another mod in your mod-list that changes that behevior. I tested with K2 + SE + AAI, and Mk4 locomotives go up to ~560 km/h with rocket fuel (lower values if you dont use Mk4 wagons or lower tier anything). Each tier past Mk1 has increasing max speeds, you can check this value by hovering over a locomotive, in the rightmost informative panel, or by opening the prototype inspector (Shift Ctrl E and searching for locomotive)

i didnt know that wagons affect speed, there should be some note for that