Aluminum Stage II Block 4.1 Liter - Very Rare
Casting number NONE

GM Performance made a few blocks (not sure of how many) and these WILL have a casting number on them. However, when the project was abandoned, GM sold the tooling to M&A Casting - Brighten Engineering in Colwater, MI. Aluminum blocks made by them do NOT have any casting numbers at all. These only have the raised power 6 logo. - Thomas Carter



86-87 Production Block Top View
86=-87 Production Block Side View
Features of Note:
  • Notice the solid lifter valley.
  • Notice the reinforced lifter bosses
  • Notice "oiling tube" casting into the valley
Features of Note:
  • Notice the six bolt holes per cylinder
  • Notice the cylinder liners



86-87 Production Block Bottom View
86-87 Production Block Front View
Features of Note:
  • Four bolt mains (not cross bolted)
  • Notice no oil pickup cast in, set up for dry sump
Features of Note:
  • Notice the blocked off bosses for the cam oil galleries
  • Notice the beefy front main webbing



Features of Note:
  • Notice reinforced freeze plugs
  • Notice power six casting on the bottom of the bellhousing
    casting (right rear of the picture
Features of Note:
  • Reinforcement ribs cast into the block
  • Notice extra thick bell housing casting

Submitted by:

Todd King