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SKYACTIV-X: first commercial gasoline engine to use compression ignition

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Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#131

Post by cromulent »

fnj wrote: post #110
cromulent wrote: post #63

Earlier quoted context omitted.

It's good work, but I suspect Mahle's TJI (as used in current F1 cars) is a better bet. - Fuel efficiency gains over 17% - over 40% thermal efficiency - over 99% reduction in NOx - significant reduction in CO2 http://www.f1technical.net/news/20316 http://www.mahle-powertrain.com/en/experience/mahle-jet-igni...

- over 40% thermal efficiency - significant reduction in CO2 CO2 production is directly inverse-linearly related to thermal eficiency. It is silly to list both.

Would you mind explaining why (to a layman)? The Wikipedia page on thermal efficiency makes no mention of the CO2 relationship.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#132

Post by cmrdporcupine »

mywittyname wrote: post #115
cmrdporcupine wrote: post #78

Earlier quoted context omitted.

I bet on plugin hybrids, specifically ones with large batteries. This seems to be an unpopular opinion, but I think the Voltec drivetrain shows what's possible here. Pure EV purists dislike PHEVs because they have the complexity of an ICE car + an EV car, but I think there's some serious advantages. Like you say, Atkinson cycle for electricity generation for when the battery drains beyond smaller commute ranges. Some…

> because they have the complexity of an ICE car + an EV car, The irony being that most don't. For example, hybrid synergy drive is basically an alternate transmission design that replaces the complex clutch packs used to control Ravigneaux planetary gears with electric motors. The result is a more simple overall design. Other systems are literally just beefed up starters.

I agree. The Volt to me is a beautiful piece of engineering, and the ICE system is actually simpler than a regular ICE car _because_ of the presence of the EV side of the car, which compliments it.

I think it's more of a political thing -- if you've made the argument that "ICE = pollution = bad" then it's hard to turn around and say "but a little bit of ICE to extend range is good."

The battery + electric motor adds so much good -- regenerative braking, electric torque, good city driving experience, it really feels like every car that is now an ICE should be a hybrid, even if just a "soft" hybrid with no plug, like a Prius.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#133

Post by devy »

ChuckMcM wrote: post #18

A reuters story on how it works: https://www.reuters.com/article/us-mazda-strategy-idUSKBN1AO... So this is 'gasoline' diesel. Or diesel without the NOx. Which, in theory, would give better fuel economy and possibly better torque. And it will ship in cars in the 2019 model year (so possibly as early as late next year). To me, it sounds like a "Don't pass"[1] bet on electric cars. Which they also are working with Toyo…

> To me, it sounds like a "Don't pass"[1] bet on electric cars. Which they also are working with Toyota on electric cars so perhaps it is a fall back plan

The Toyota/Mazda collaboration is a pure compliance play, just like what Honda has done in California for years (read: Honda Fit EV.) The official announcement had a subtle hint:

  From 2019, start introducing electric vehicles and other electric drive
  technologies in regions that use a high ratio of clean energy for power
  generation or restrict certain vehicles to reduce air pollution
as The Verge clarified it in more details here[1], Mazda have to sell EV in regions where regulations are so tough that they can improve the efficiency to pass or in regions where ICE cars are/will be banned altogether.

Also the new Toyota/Mazda auto plant is not going to manufacture only EVs but also other ICE (Internal Combustion Engine) cars.

And yes, without their own EV or the resolve to electrify their model lineups, Mazda might not even survive after 2025 when they plan to use SKYACTIV-X on all of their cars.

For EV, the old saying is true: driving is believing.

[1]: https://www.theverge.com/2017/8/8/16099536/mazda-compression...

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#134

Post by aidenn0 »

greggyb wrote: post #8
coherentpony wrote: post #4

Earlier quoted context omitted.

Are those imperial gallons or US gallons?

I can get 40MPG (US) highway with a 2015 Mazda3 and a somewhat aggressive driving style. City is usually low 30s. The manual transmission is also one of the nicest I've ever driven. These are great cars.

I only wish you could get the 2.5L in a manual with no moonroof. That would probably get me to buy a new car.

I have an 07 Mazdaspeed3 that is getting long-in-the-tooth, and it gets terrible mileage (19 in town, high 20s on the freeway). The best I can say about the shifter is that you get used to it.

I don't think I need quite as much pep as my current car (plus all current hatchbacks that are comparable performance are north of $30k), and the 2.5L engine in the Mazda3 is nice.

I like the Mazda3 better than the Focus, but if I had to get a car today it would probably be the Focus ST.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#135

Post by mbreese »

mohaine wrote: post #89
mbreese wrote: post #38

Earlier quoted context omitted.

> I also wonder if the maintainability of these engines will be the same as with diesel They also include traditional spark plugs and the engine automatically switches between modes. So, I fear that maintenance wise, it may be the worst of both worlds -- but with less wear and tear on the spark side, perhaps it will be better.

I'm pretty sure "wear on the spark side" is an all but solved problem at this point. Most car engines made in the last 15 years have 100k mile lifetime on the entire spark system.

I agree that for the most part engines are extremely reliable. The potential downside here is that the compression mode makes the entire system more complicated. This might make the new system less reliable. I have every confidence that Mazda will do this right, and this has great potential to extend the lifetime of the ICE. However, it isn't without risks.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#136

Post by aidenn0 »

ticklemyelmo wrote: post #88
aidenn0 wrote: post #83

Earlier quoted context omitted.

Almost certainly not, as diesel and gasoline have very different self-ignition properties.

I wonder whether this engine will specifically require you to fill up with NON-premium gas.

I suspect that when operation in compression-detonation mode, it will inject the fuel late enough into the compression stroke that the difference between 87 and 97 octane fuel won't be that big of a deal.

If it does make a difference then I would expect they would design for the higher octane rating gas to prevent user-error.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#137

Post by rootusrootus »

DennisP wrote: post #111
spitfire wrote: post #103

Earlier quoted context omitted.

I believe it's a "luxury/enthusiast" strategy. I believe the auto market will play out something like the watch market did with the introduction of the quartz watch. Most people just want to tell the time, so they buy a quartZ. Similarly most people just want to get from A to B, so will buy an electric (automated) car. Some people enjoy the mechanics of the thing. So they buy a nice mechanical watch. These watches we…

Probably true, but at the same time, some electric cars are pretty darn fun to drive.

Of currently available models, isn't that essentially ... one of them? And only in a straight line. Electrics have a ways to go before they're suitable candidates for things like track days.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#138

Post by usrusr »

borski wrote: post #7
Danihan wrote: post #3

>Compression ignition and a supercharger fitted to improve fuel economy together deliver unprecedented engine response and increase torque 10-30 percent over the current SKYACTIV-G gasoline engine.*3 Wow. I already have a 2016 Mazda 3 that gets around 40MPG (even though it's not a hybrid) and it's already pretty peppy. Probably the best car I've owned, and I've owned several nice sports sedans. Getting 40MPG is too c…

OK, so honest question: I have a 2012 Mazda 3 which, presumably, gets 40mpg. But I can't realistically get anything above 29mpg on average. Am I just an aggressive driver? :) [edit] I agree, by the way, that the cars are incredibly fun to drive, for being "fuel efficient."

The correlation between efficient driving and aggressive driving is far from perfect. The "pulse and glide" method from the wikipedia page linked in a sibling comment would seem quite aggressive for example and on the other end of the scale, I have often seen "moving roadblocks" running their engine at RPM far too high for efficient cruising (e.g. when people drive a manual who are afraid of shifting).

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#139

Post by randomguy23 »

cromulent wrote: post #63
ChuckMcM wrote: post #18

A reuters story on how it works: https://www.reuters.com/article/us-mazda-strategy-idUSKBN1AO... So this is 'gasoline' diesel. Or diesel without the NOx. Which, in theory, would give better fuel economy and possibly better torque. And it will ship in cars in the 2019 model year (so possibly as early as late next year). To me, it sounds like a "Don't pass"[1] bet on electric cars. Which they also are working with Toyo…

It's good work, but I suspect Mahle's TJI (as used in current F1 cars) is a better bet. - Fuel efficiency gains over 17% - over 40% thermal efficiency - over 99% reduction in NOx - significant reduction in CO2 http://www.f1technical.net/news/20316 http://www.mahle-powertrain.com/en/experience/mahle-jet-igni...

Sounds interesting. I'm very curious, though, to see an ignition profile of the compression ignition concept: it seems to me that compression would be even throughout the ignition chamber, leading to a somewhat (within the bounds of statistical deviation in fuel/air pressure) simultaneous ignition of the fuel/air mix. Meaning that I think Mazda's technology would combust more efficiently.

Re: SKYACTIV-X: first commercial gasoline engine to use compression ignition

#140

Post by ouid »

oatmealsnap wrote: post #35
ChuckMcM wrote: post #18

A reuters story on how it works: https://www.reuters.com/article/us-mazda-strategy-idUSKBN1AO... So this is 'gasoline' diesel. Or diesel without the NOx. Which, in theory, would give better fuel economy and possibly better torque. And it will ship in cars in the 2019 model year (so possibly as early as late next year). To me, it sounds like a "Don't pass"[1] bet on electric cars. Which they also are working with Toyo…

Gasoline engines aren't going away for a while; even when every self-driving car is electric, there will be a market for people who want gasoline engines. If it gives a bump in fuel economy to the next (last?) generation of gasoline and hybrid vehicles, great! I also wonder if the maintainability of these engines will be the same as with diesel. That would be another big benefit.

I visited a Tesla store once in mountain view, and they have a great little demo where you can check the cost of charging your car in various states.

Washington DC, for whatever reason, gets its electricity from a gasoline power plant. In Washington, the Model S gets 28 MPG.

This happened a while ago so I could be misremembering, but regardless I don't believe that the environmental value of electric vehicles has been realized. In a lot of places, your Tesla is still coal powered. Efficient internal combustion engines are still a worthy cause, and this will continue until more electricity is being produced than is normally consumed.

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