I keep my tools in a Platt box and when I keep it organized
it does really well.
I keep my most-used tools in the slots and ready to go. My ratchet always has the
sparkplug socket on. My 1/4" allen for the motor mount is always right there. I bought a
battery powered ratchet and carry it to the start grid with sockets to change the starter assembly
and it's already saved us once. Carry a spare plug just in case (I've only needed it once.)
I don't carry everything I could possibly use/need to the track because there's never
enough time to do major work before the next race. My philosophy is that if you have to
do major work at the track in order to race (barring a wreck or catastrophe), you were not
ready to go to the track.
You could probably do most races with an impact for tire changes, tire pressure guage,
a screwdriver, sparkplug wrench and a 1/4" allen.
I leave my dyno and boring bar at home.