Ok, shows how little I know about sprint cars etc lol........
it's the Chili bowl event, Midget racing, found this from a website ...
"This weekend Michael will race one of two Synergy V8 powered Aggressor Midgets for Simon Longdill at Huntly Speedway?s 40 lap event, as a shakedown for the prestigious indoor Chili Bowl Midget Race at Tulsa, Oklahoma in January 2010. Brad Mosen will be in the second car at Huntly, as the two NZ Midget stars will line up together as team mates against over 250 Midget, NASCAR, and Sprintcar racers from all over the USA, for the biggest Midget race in the world".
He's made his own dry sump bottom end and crank and using heads etc from Kawasaki , more info about his company here..
http://www.synergypower.co.nz/