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I've been following this development for past few years since it was first mentioned, what little info has come out. Seems to me when Mazda does release the HCCI Skyactiv 2, it could really be game changer for the company if the advertised efficiency actually makes it into production. We're talking well over 50mpg for most of the fleet, at a 30% gain. That would be a huge advantage over other brands.

I would expect the biggest hurdle/concern to be reliability with a newly applied combustion tech like HCCI - I know i'd be worried about it, but would have some faith that mazda gets it right.

Also curious what type of power these engines will make - i'd expect similar to current powerplants, or very small gains, but would love to be wrong and see significant (say 20hp) gains. If the mileage and performance is up to snuff, i'd consider a trade in once these cars are available.

So what do you think? Excited? Skeptical? Have any new info on these?
 

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If you look up what an hcci engine is, I don't think their claims are unfounded. We've known about this thermal cycle for a long time now, but so far nobody has built a consumer product based on it.

I'm excited to see if Mazda can pull it off. Hcci is notoriously difficult to control and has other significant issues that they need to overcome. Other big companies have tried to develop one and all have failed. Hyundai and GM to name two. I think Toyota tried as well, not sure.

If Mazda can do this they've outsmarted some of the best engineers in the business. That's very impressive.
 

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Think one issue they run into is the NOx goes up similar to what it does on a diesel. Wouldn't have the soot issues that a diesel has though.

Ralph
 

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I'm excited to see if Mazda can pull it off. Hcci is notoriously difficult to control and has other significant issues that they need to overcome. Other big companies have tried to develop one and all have failed. Hyundai and GM to name two. I think Toyota tried as well, not sure.

Yup, i've been reading this type of stuff over the past year or two, which makes it all the more impressive. I know Nissan is working on variable displacement as well. if HCCI turns out to be successful for Mazda, that's another technology Mazda could potentially pursue with ICE's - assuming the two could work together (don't see why not but i'm no engineer)
 

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I've been following this development for past few years since it was first mentioned, what little info has come out. Seems to me when Mazda does release the HCCI Skyactiv 2, it could really be game changer for the company if the advertised efficiency actually makes it into production. We're talking well over 50mpg for most of the fleet, at a 30% gain. That would be a huge advantage over other brands.

I would expect the biggest hurdle/concern to be reliability with a newly applied combustion tech like HCCI - I know i'd be worried about it, but would have some faith that mazda gets it right.

Also curious what type of power these engines will make - i'd expect similar to current powerplants, or very small gains, but would love to be wrong and see significant (say 20hp) gains. If the mileage and performance is up to snuff, i'd consider a trade in once these cars are available.

So what do you think? Excited? Skeptical? Have any new info on these?
Skeptical.

My feeling is we rarely see new tech result in a game change. Even if the tech should be a game changer in theory, I think Mazda will play it safe as they want their motors to still last, and it will also take a while to get the kind of incredibly accurate control needed to see the theoretical gains.
 

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So what do you think? Excited? Skeptical? Have any new info on these?
Current estimate by Mazda management is an early 2019 delivery. I'm very interested, and I'll consider trading-in when these hit US showrooms.
 

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HCCI will not be the "type" of engine, it will still be a spark ignition engine but with the capability to run in HCCI-mode at certain drive cycles. Right now, the Skyactiv engine is able to run between normal Otto cycle and also Atkinson cycle through drastic retard of the intake variable cam phaser; the main hurdle with something like HCCI at this point is calibration, emissions control and electronics (the sensors and ECU speed required to control HCCI is pretty enormous). However, the tech itself has been in demonstration/prototype mode by suppliers like Continental and Bosch for years.

The other thing to note is that if HCCI comes to fruition, it's very likely you'll see it paired with a CVT (to keep the engine in HCCI mode as long as possible), and/or a turbo.

The technology is probably not additive with variable displacement- as you can probably imagine, HCCI requires strict tuning at a set displacement, I cannot imagine how much more complex the ECU will have to be to also deal with those calculations + infinitely variable displacement. At some point, the gains are not going to be worth the price and complexity, because at some point hybridization will be the easier and lower hanging fruit (especially as many Euro countries start restricting where pure ICE vehicles can run). In any case, I don't expect a screaming high RPM piston engine out of Mazda anytime soon.
 
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