The Grail engine

Courtesy of Grail Engine Technologies

Grail Engine Design

At just 500 cubic centimeters, the Grail Engine is quite small -- about one-fourth the size of the engine on a typical economy car.

At first glance, the company's prototype looks like any ordinary two-stroke engine, until you notice the large, upward-facing intake valve coming off the center of the piston. That has an important function we'll explore in a bit -- the Grail Engine makes much more use of air pressure than a normal internal combustion engine. The engine is comprised of:

  • A cylinder and a piston
  • A single exhaust valve at the top of the cylinder that lets out exhaust gases after the combustion process is complete
  • Three spark plugs, also at the top of the cylinder. These create the "spark" that drives ignition (Most car engines have one spark plug per cylinder)
  • A "pre-compression chamber" that houses a reed valve, a component that keeps fresh air flowing into the engine in one direction (Reed valves are a common part on two-stroke engines)
  • A single intake valve, which draws in air and fuel, located inside the piston
  • Two vent-to-piston ports and two piston-intake-ports
  • A small crankcase that translates piston motion into wheel motion

[Source: Grail Engine Technologies]