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Requires DI to work right. Which means it may run afoul of clean air regs, the way DI engines are turning out some side effects. Still the concept is very interesting from a technical perspective. Something to keep an eye on.
 

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Discussion Starter · #3 ·
Requires DI to work right. Which means it may run afoul of clean air regs, the way DI engines are turning out some side effects. Still the concept is very interesting from a technical perspective. Something to keep an eye on.
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I've been watching from the wings, so to speak, to see IF and HOW HCCI engines would be deployed ... not to mention When.

I'm still interested to see if that approach to power generation will find a home in mass-produced cars.
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I'm very encouraged by what I'm learning about this variation on the ICE engine.

Question though:

Does the relationship Mazda now has with Toyota help in the development / implementation of this....OR does Toyota's historically conservative nature serve as a roadblock / speed bump?

Too bad FCA doesn't have this....I think the company desperately needs SOMETHING "distinctive"...to separate themselves from the competition...and give people a compelling reason to buy FCA...and this would be it.
 

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In layman's terms, HCCI is a gas powered engine that operates like a diesel, IE no spark?
 

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Not quite. HCCI engines can run on diesel too, in theory, but I suspect you'd have a lot of soot to deal with...

There's two factors: how you ignite the explosive "charge", and how evenly the fuel is mixed when it's ignited.

In HCCI the fuel mix is evenly distributed throughout the combustion chamber in the way you see in a carburettor-fed gasoline engine (hence "Homogenous Charge").

Traditional compression-ignition engines (and also "lean-burn" DI gasoline spark-ignition engines) create a stratum of fuel-rich air in the chamber, with the remainder being fuel-lean (this is a "Stratified Charge"). Using a stratified mixture creates very high ignition temperatures, and higher efficiency (and lower soot for diesels), but it also results in higher NOx emissions.

The thing that makes compression-ignition efficient is that it burns all of its fuel in one short instant, whereas in a spark-ignition engine, the fuel is set on fire, and a flame-front travels through the mixture as it burns, converting some of the fuel's energy into waste heat. This progressive burning is the reason why gasoline engines are "smoother" than diesel (the energy is released over a longer period of time rather than in one big "thump"), but it's also why they're less efficient.

So, "Homogenous" not "Stratified" charge is why a HCCI engine has lower NOx emissions, and "Compression" versus "Spark" ignition is why it has better fuel consumption.

I believe HCCI is, overall, less efficient than SCCI ("diesel"), but SCCI will produces much more NOx.

@romalerig - Firefly does run at a very high compression for a gasoline engine (13:1), but it's still spark-ignited. Mazda's engine runs at 18:1, higher than a small diesel engine. Not a million miles apart, though.
 

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Ah... :)

But now you've got me thinking about whether Firefly was designed with some kind of plan for HCCI in future.
 
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