Does the VK engine have cast iron cylinder liners or is it an all aluminum bore.....

Wikipedia says they're Cast-Iron Cylinder Liners.

http://en.wikipedia.org/wiki/Nissan_VK_engine

The VK56DE is a 5.6 L (5552 cc) version built in Decherd, TN. Bore is 98 mm (3.9 in) and stroke is 92 mm (3.6 in). Output is 305 hp (227 kW) at 4900 rpm with 375 to 390 ft·lbf (509-522 Nm) of torque at 3600 rpm. It has aluminum-alloy block and heads and low-friction molybdenum-coated pistons. The valvetrain is a dual overhead cam (DOHC). It has 4 valves per cylinder with microfinished camshafts and cast-iron cylinder liners for increased durability.

I don't think there's many true "all" aluminum blocks. Chevy had disastrous results. I read recently though that some manufacturer was going to give it a shot though......something about a coating (maybe zinc?) being as good, but saving weight.

Honda makes one with a liner of aluminum silicate and something else. Its that hard stuff used for the abrasive on sandpaper. It's tuff, but you can't bore it.

^ maybe that's the one I was thing of! Thanks!

Yeah, I was thinking about this when I was putting some new rings in my mower...........

Some small engines, such as on chain saws, had aluminum or magnesium blocks with a hard chrome plating on the cylinder bore. This keeps the weight down. I had a Homelite chain saw with the chromed bore.