Size of Diesel Generator

no watts = 746 x no of h.p

this means 38 h.p = 28348 watts= 28.35 kw = 35.4 kva

for safety point of view and for future use ur diesel genset should have kva rating of

40 to 45 kva.

i think this solves ur problem.

You should give hp of motors and method of starting and any other loads like lights connected.

A down and dirty way to figure genset sizing for motors is 2KW per motor horse power which would be 76 KW, but that being said you would end up with a system that would work but would over sized and lightly loaded, the best way would be as was said before list your loads and starting characteristics, if you can load the genset sequentially would be better, lighting load first and then limit the motor starting to largest to smallest, soft starts also help, be careful with VFD's they some times cause voltage regulation problems, best to keep the genset running at 60% or better load, most genset suppliers have software that you can use for sizing I would contact some of them, hope this helps