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

www2.mazda.com

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

#61

Post by vvanders »

toast0 wrote: post #37
vvanders wrote: post #22

Earlier quoted context omitted.

Yes, however common diesel fuels tend to be higher in NOx and particulates. My understanding is that because gasoline is refined to a higher degree it burns a fair bit cleaner in similar environments(and also makes it a PITA to store for more than a few months). [edit] We've got a pair of tractors around the house here, '81 diesel(pre-emissions), and '47 gasser. I can tell you which one I prefer to run from an exhaus…

NOx emissions from a diesel engine are from atmospheric nitrogen and oxygen, not from the fuel. I welcome further clarifications, but my understanding is that this engine will not produce NOx like a standard diesel because the fuel/air mix will be tightly controlled like in a gasoline engine, and temperature and pressure will be significantly less than a standard diesel. Additionally, it seems the timing of the fuel…

According to wikipedia the fuel can be a large source of nitrogen for NOx: https://en.wikipedia.org/wiki/NOx#Fuel

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

#62

Post by elihu »

Maybe this is old news to people who pay attention to car news, but the most interesting thing to me is this line from the press release:

> 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

I've been kind of disappointed that Mazda hasn't gotten into the electric car market yet; I'm glad to see they're coming around.

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

#63

Post by cromulent »

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...

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

#64

Post by pedrocr »

Technologies are always at their best when they're already being obsoleted. Just as electric cars become practical ICEs are getting great and so are the transmissions, making for great modern powertrains.

There were rumors last year in F1 that one of the manufacturers was doing HCCI for it's engine (the same that Mazda has done here). I don't think any actually did but Ferrari did introduce a jet ignition system[1] that allows them to run much leaner. I wonder if anyone is thinking of adapting that to normal road cars.

[1] http://www.motorsportmagazine.com/opinion/f1/ferraris-formul...

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

#65

Post by seanmcdirmid »

elihu wrote: post #62

Maybe this is old news to people who pay attention to car news, but the most interesting thing to me is this line from the press release: > 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 I've been kind of disappointed that Mazda hasn't gotten into the electri…

Mazda is kind of small, it would be like expecting an electric vehicle from Subaru. Ya, it will happen eventually, but the big guys are going to have the resources to go first (well, and startups built on the concept itself).

Also, hydrogen was supposed to be the big clean fuel in Japan, but that fell by the wayside when the bigger Chinese market decided it would be electric.

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

#66

Post by tannhauser23 »

serpix wrote: post #36
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…

That is horrible mileage. I remember averaging that on a 1997 Opel Astra.

You're trolling, right? 40mpg is pretty great.

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

#67

Post by aphextron »

serpix wrote: post #36
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…

That is horrible mileage. I remember averaging that on a 1997 Opel Astra.

As long as we're one-upping, I'll jump in here to say that my Nissan Leaf gets 140 MPG ;)

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

#68

Post by mikeash »

serpix wrote: post #36
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…

That is horrible mileage. I remember averaging that on a 1997 Opel Astra.

Any chance your MPG was measured on imperial gallons? Looks like 40MPG imperial would be normal for that car, but 40MPG US would be a fair bit more than expected.

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

#69

Post by rm445 »

mikestew wrote: post #19
stirkac wrote: post #2

Mazda is one of those companies just don't stop revolutionizing. First they got rotary to be actually usable. Now this.

The rotaries leaked oil and got terrible mileage, and good luck finding someone to work on them. Other than that, they were zippy. "Usable" they might have been if you keep a low bar, but "practical" they were not.

I've had Mazda's last model of rotary-engined car, the RX-8, as a daily driver for the past five years (sixty thousand miles). It has served me well and my local garage have performed regular servicing and mechanical repairs with no problems.

So I think your opinions are a little bit overcooked.

But I don't want to overdo mine in turn. The fuel consumption is excessive by modern standards (but comparable to other vehicles of similar performance). The engine consumes oil by design and needs to be topped up every few weeks. The whole car is in a high state of tuning, and has given me a few large service/repair bills - but never stranded me at the roadside. My garage once admitted incomprehension and sent me to the main dealer for diagnostics before they could begin repairs.

All in all I think Mazda pitched the RX-8 well as a sporty car for enthusiasts, whose reliability might have come in under par in the market for, say, small family cars. I just want to fight the impression that having a rotary-engined car is a drastically different, worse, experience than one with a piston engine. Generally you just get in and drive.

Wankel engines are just one of (surprisingly many) technologies that were more-or-less viable but just not able to become dominant. Like, we would all still manage to drive around if the only technologies developed happened to be opposed-piston engines, or two-stroke diesels, or axial-cylinder engines with a swashplate. We might even see a few of them come back if the market moves towards series-hybrid vehicle setups. A light little rotary always running at its peak-efficiency speed might be a reasonable choice for a range-extender/series hybrid.

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

#70

Post by quake »

IgorPartola wrote: post #17
quake wrote: post #16

Earlier quoted context omitted.

More or less usable. They did have a tendency to blow apex seals after 80k miles, which was could end up as a full rebuild of the engine. As far as how finicky a rotary can be, the biggest thing to do is let them warm up before driving, and let them cool right down after you're done. They were never an engine to replace the standard fourbanger, but they weren't any more finicky than say a BMW or Audi at the time of t…

Heh. I mean an engine rebuild at 80k seems kind of crazy. I am both continually amazed at the ICE and at the same time can't wait for it to die out. It's such an archaic technology. Hell, a turbine engine would be so much more fun to have in a car!

Turbos are definitely taking hold in the American auto industry as well, with stuff like the Chevy Sonic and Fiesta/Focus really making good use of them with tiny engines. The 2015 Focus had an option for a 1L, 3 cylinder engine with a turbo for commuters. Great stuff.
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