Need portable/wireless dragrace timing system arduino or pi based

Voulounteering for a nonprofit motorsport organisation on my spare time. And in an attempt to lower the illegal races of the public roads we arrange controlled meets. Today we have a old unreliable wire based system. Now i want and started building one based on arduino or pi's and on loramodules & rtc clocks to keep the time in sync, So need a prototype drag racing timing system with reaction time, finish speed and to display in lcd at the start and end of the track. I'll build it together myself from whatever schematics which is proven to work.