Quote:
Originally Posted by Daox
After treatment is a difference. However, Mazda's skyactiv direct inject engines have pistons quite similar to a diesel.
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There are a wide variety of piston bowl shapes, but it you put that thing in a diesel it would smoke like a chimney. Here's a more typical diesel piston
In a direct injection gasoline engine the fuel is injected a long way before top dead center, with the goal being to vaporize and mix the fuel before ignition. In a diesel the piston bowl distributes the burning fuel plume. For this reason, a gas direct injection injector is pointed almost directly downward. A diesel injector is typically more horizontal than vertical, because the fuel in injected near TDC and the shape of the piston spreads out the fuel to mix with the air.