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How the Grail Engine Works

The Basics

Before we learn about the Grail Engine, let's first define some of the concepts behind it so we can fully understand how it works.

Two-Stroke Engine: Unlike most modern car and motorcycle engines, the Grail Engine is a two-stroke engine. In vehicles, it's more common to find four-stroke engines. Here's what that means: On a four-stroke engine, there are four phases to the internal combustion process which causes a vehicle to move -- the intake of air and fuel, the compression of those ingredients, the ignition of air and fuel that forces the piston down and the release of exhaust gas.

However, a two-stroke engine completes that same process in just two steps. The intake and exhaust steps are combined together, as are the compression and ignition steps. Two-stroke engines are lighter and more powerful; but they aren't as fuel-efficient, they tend to break down more often and they also produce a lot of exhaust gas because oil and fuel mix together during the combustion process. This is why two-stroke engines are commonly only used in small recreational vehicles and yard equipment.

Direct Injection: DI is the hot new kid on the block when it comes to engine technologies. It's become a common feature on performance engines, and it's starting to find its way into more and more everyday cars as well. On a DI engine, fuel is sprayed directly into the combustion chamber rather than mixing with the air in a separate manifold. This lets the air/fuel mix burn more evenly and efficiently, resulting in increased power and better economy.

Forced Induction: Even if you've never heard of forced induction, you've likely heard of superchargers or turbochargers. Both do essentially the same job: they force more air into the engine so it burns hotter and harder, producing more power. The Grail Engine uses a unique type of forced induction (which we'll get into in just a bit).

Forced Semi-Homogeneous Charged Compression Ignition: Also known as FS-HCCI, this is a technology carmakers have been chasing after for years, Riley said. This process compresses air and fuel to the point where they nearly combust on their own without spark ignition (similar to the way a diesel engine operates). And when the air/fuel mix does ignite, all the fuel in the chamber burns simultaneously, delivering much better efficiency. That means more power and better fuel economy [source: Green Car Congress].

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