SkyActiv Technology – Market Hit

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SkyActiv Technology

MyCarma reports have been producing interesting results (in a good way) with Mazda’s SkyActiv technology. We decided to investigate further and look into how SkyActiv actually works. The technology has managed to develop a high compression ratio of 13:1 (in North America) with low octane. Avoid buying premium and save a lot on fuel!

What makes SkyActiv different from other cars? The engine! Or at least it is a big part…

For many years engineers worked towards raising compression ratio while avoiding knocking. Knocking (premature combustion) is caused by high temperature cooking off the fuel earlier than intended. Increasing your compression ratio raises the fuel temperature to one high enough for unintended combustion to occur. So how do we avoid knocking? We try to keep the intake charge as cool as possible.

Mazda does a few things to generate a cooling effect:

  • Its variable valve timing (VVT) uses aggressive cam timing profiles to purge hot exhaust gasses.
  • It also has a long 600-mm 4-2-1 exhaust system, which removes exhaust out of each cylinder without pressure interference and moves the catalyst further away (this helps reduce emissions by making it difficult to light off quickly).
  • Direct injection is used from cold start (temperature of cold start) to stimulate easy ignition. It improves compression because it uses fine fuel atomization. The fuel is directly sprayed into the combustion chamber which causes a better cooling effect.

Stable combustion is ensured by injecting a portion of the fuel during the intake stroke and then some more fuel during the compression stroke.  Stable combustion allows for a delayed ignition at cold start.

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If we compare a Mazda 6 with and without Skyactiv technology, we notice large differences in torque, horsepower, fuel economy and curb weight. The SkyActiv Mazda is lighter and also has about 9% more horsepower, 9% more torque and is about 8% more fuel efficient. Considering the vehicles would be taking in the same amount of fuel and air (notice the displacement is similar), these differences are large enough to provide great fuel savings!

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