It is a souped up VW engine, the engine, trans (bus) and chassis were special built by Southern California's premiere Baja racing folks.
We know the chassis was built by Chenowth, this engine may have built by Don Hatz, I have an inquiry to them now.
The trans-axle was built buy ether ITS or Mendeola.
EDIT, sorry it has the bus 6 rib 4 speed transmission and it looks like the engine will be somewhere from 2100 to 2200 CC, will not be certain until I can measure the bore.
I will have to pull the head to do that but need a couple days to clear a permanent indoor spot for it before starting to rip it apart.