A V8 engine that runs on Methane and Vegetable Oil Mix or Ethanol and Vegetable Oil mix, with a stroke so long the engine has a minimum displacement of 1.0L. With the pistons so small the cylinders have to be machined so the connecting rods don't hit it, and the piston rings don't go below the machined part of the cylinders. Make the block with a maximum displacement of 2L. Mount one carburetor per cylinder on 1.0L engines, and one Super Turbo per cylinder on performance engines. One per cylinder because, if you are miles from a dealer and one goes faulty you still have seven more to get you to a dealer.