Mazda's 2019 SkyActiv-X compression-ignition gasoline engine

[Kaido]

https://www.engadget.com/2017/08/08/mazdas-engine-breakthrough-promises-big-fuel-efficiency-gains/

Nice!

Mazda has made the announcement car manufacturers have been working towards for years: it's releasing the first commercial compression-ignition gasoline engine. Dubbed SkyActiv-X, the engine will be available in 2019 and promises up to 20-30% more engine efficiency than the current SkyActiv-G, and up to 45% more than Mazda's 2008 petrol engine.

Current gasoline engines rely on a spark plug to ignite their air-fuel mix. The SkyActiv-X will ignite the air-fuel mix spark-free through compression, like a diesel engine. This, according to the Japanese manufacturer, combines the advantages of petrol and diesel engines to achieve "outstanding" environmental and power performance.

The announcement comes just days after the company laid out its billion-dollar plans to build electric vehicles with Toyota. Speaking to reporters, Mazda's head of R&D Kiyoshi Fujiwara said that while "electrification is necessary ... the internal combustion engine should come first". Electrification and emissions minimization is a major focus of Mazda's Sustainable Zoom-Zoom 2030 plan, and technically SkyActive-X falls into this remit, given its advances in efficiency. But it's still a technology reliant on natural resources. Mazda's electric vehicles and its SkyActiv-X engine take sustainability in very different directions, so it will be interesting to see if, and how, these roads eventually converge.

 

[fleshconsumed]

There have been rumors about HCCI engine for a year, it's nice to see Mazda officially confirm them. Great job Mazda if they manage to pull it off. I just hope my current car lasts until these engines are out.

 

[JeffMD]

I hope they couple it with a hybrid setup, I think by 2019 it shouldn't be to much to ask for a Mazda3 with a hybrid. Electric may be the future but until leeps and bounds in battery tech is made, the closes we will get to a truly ideal efficient setup is the hybrid.

 

[Demo24]

I hope they couple it with a hybrid setup, I think by 2019 it shouldn't be to much to ask for a Mazda3 with a hybrid. Electric may be the future but until leeps and bounds in battery tech is made, the closes we will get to a truly ideal efficient setup is the hybrid.

This is likely why Toyota is taking a stake. This engine coupled with their hybrid technology would likely dramatically increase their mpg ratings.


My only hope is that the engines are reliable and then decent to drive. The current skyactive engines have been reliable and also pretty fuel efficient.

 

[Kaido]

I hope they couple it with a hybrid setup, I think by 2019 it shouldn't be to much to ask for a Mazda3 with a hybrid. Electric may be the future but until leeps and bounds in battery tech is made, the closes we will get to a truly ideal efficient setup is the hybrid.

I really like how the 2nd-gen Volt works: 50-mile battery (more realistic of a range than most of the 10 or 20-mile PHEV setups available today) PLUS a 300+ mile gas engine. So now couple that with like a Turbo 4 instead of a wussy low-power engine & give it some real guts. The hybrid Ford for cops actually looks pretty awesome, as far as the powertrain goes:

https://www.engadget.com/2017/04/10/ford-s-hybrid-cop-car-has-electric-boost-for-high-speed-chases/

 

[fleshconsumed]

From what I've read spark plugs are used at load and more efficient HCCI mode is engaged during idle/cruising. If Mazda gets access to Toyota hybrid patents/technology they could use electric to boost horsepower, let the engine work in HCCI mode almost all the time, and achieve get 50+mpg. Mazda handling, hybrid mileage, and better power, one can only dream...

 

[Kaido]

My only hope is that the engines are reliable and then decent to drive. The current skyactive engines have been reliable and also pretty fuel efficient.

My only complaint with the current crop of Mazda engines is that delay or slight lag from a dead stop. Not sure if that's the engine or transmission. It's very short, just barely a second, but it was enough to annoy me on the test drive because it didn't quite kick in acceleration when I pressed the pedal down. My Jeep Renegade has the same issue (except across all shift points, since it's a 9-speed automatic). Especially since I get to drive various electric cars on occasion, where acceleration is instant, it gets pretty annoying. Reminds me of the older Prius' where they had that slight delay kicking in the motor from electric mode from a dead stop.

I'm hoping the new Ford 10-speed resolves that...I've read it does a much better job of managing the 4 turbo on the Ecoboost Mustang because it shifts before the turbo lag has a chance to draw out or whatever - one review I read said they actually preferred the 10-speed auto on that car to the current 6-speed automatic.

 

[Kaido]

From what I've read spark plugs are used at load and more efficient HCCI mode is engaged during idle/cruising. If Mazda gets access to Toyota hybrid patents/technology they could use electric to boost horsepower, let the engine work in HCCI mode almost all the time, and achieve get 50+mpg. Mazda handling, hybrid mileage, and better power, one can only dream...

Not to mention the new aesthetics...their whole 2017 lineup looks really great with all of the newer designs, and their red paint is one of the most outstanding reds I've ever seen in person.

 

[Demo24]

My only complaint with the current crop of Mazda engines is that delay or slight lag from a dead stop. Not sure if that's the engine or transmission. It's very short, just barely a second, but it was enough to annoy me on the test drive because it didn't quite kick in acceleration when I pressed the pedal down. My Jeep Renegade has the same issue (except across all shift points, since it's a 9-speed automatic). Especially since I get to drive various electric cars on occasion, where acceleration is instant, it gets pretty annoying. Reminds me of the older Prius' where they had that slight delay kicking in the motor from electric mode from a dead stop.

I'm hoping the new Ford 10-speed resolves that...I've read it does a much better job of managing the 4 turbo on the Ecoboost Mustang because it shifts before the turbo lag has a chance to draw out or whatever - one review I read said they actually preferred the 10-speed auto on that car to the current 6-speed automatic.

That's probably the electronic throttle more than anything. I never really noticed that in the 2 years we had our Mazda 3.

 

[Demo24]

My only complaint with the current crop of Mazda engines is that delay or slight lag from a dead stop. Not sure if that's the engine or transmission. It's very short, just barely a second, but it was enough to annoy me on the test drive because it didn't quite kick in acceleration when I pressed the pedal down. My Jeep Renegade has the same issue (except across all shift points, since it's a 9-speed automatic). Especially since I get to drive various electric cars on occasion, where acceleration is instant, it gets pretty annoying. Reminds me of the older Prius' where they had that slight delay kicking in the motor from electric mode from a dead stop.

I'm hoping the new Ford 10-speed resolves that...I've read it does a much better job of managing the 4 turbo on the Ecoboost Mustang because it shifts before the turbo lag has a chance to draw out or whatever - one review I read said they actually preferred the 10-speed auto on that car to the current 6-speed automatic.

That's probably the electronic throttle more than anything. I never really noticed that in the 2 years we had our Mazda

 

[Yuriman]

I wonder if they mean volumetric efficiency, or thermal efficiency?

A little off-topic, but to me, the Volt is close to the best compromise for a 1-car family right now - it has more than enough electric range for the driving most people will do in a day, and a sufficiently large gas engine that it isn't inefficient to carry the car around once electricity is exhausted (I'm looking at you, i3). The only beef I have with the Volt, is that GM/Chevy cheaped out on the engine because it isn't expected to run on it much. The Accord Hybrid, a bigger car, gets something like 25% better fuel economy when running on gasoline, entirely because it has a better engine. If I remember correctly the Malibu Hybrid also gets better fuel economy on gasoline, because Chevy didn't cheap out as much on the engine in a car expected to use it more frequently.

 

[agent00f]

That's probably the electronic throttle more than anything. I never really noticed that in the 2 years we had our Mazda 3.

Could also be putting trans in N instead of in gear to save fuel. Mazda is generally relatively good for throttle response, esp as they're the holdout against turbos, which is also probably why they're investing in this tech.

 

[agent00f]

I wonder if they mean volumetric efficiency, or thermal efficiency?

"Up to" so it really doesn't matter.

Also on tangentially related noted, new turbo cars are making driving even worse. Tested an ATS recently on twisties which is supposed to be on a decent chassis, and between the auto and turbo 4 it was just a disappointingly disconnected and lifeless experience. Literally even any 90's honda or mazda drives far better.

 

[Yuriman]

"Up to" so it really doesn't matter.

Also on tangentially related noted, new turbo cars are making driving even worse. Tested an ATS recently on twisties which is supposed to be on a decent chassis, and between the auto and turbo 4 it was just a disappointingly disconnected and lifeless experience. Literally even any 90's honda or mazda drives far better.

Reason I ask is, I'm skeptical of the implications of such huge thermal efficiency gains - 45% would be practically impossible unless Mazda was pathetically behind with their 2008 engines. Honda and Toyota have had ~39% thermally efficient (peak) gas engines since the late 90's, which is better than a lot of diesels on the road and close to theoretical maximum for a gasoline engine. Honda achieved this over a wide RPM range using offset cranks, roller cams, shot-peened pistons and coatings, VTEC cam profiles for low RPM operation, indexed plugs, exhaust heat scavenging, lean air/fuel ratios and stratified charge - in other words, tons of tech, making their engines complicated and relatively expensive. Toyota achieved this largely via running Miller/Atkinson cycle instead of OTTO, and keeping the engine at ideal load and RPM, using electric motors to vary speed, rather than changing engine RPM (Prius/CVT "drone").

However, 45% more volumetric efficiency can be achieved by slapping a turbo on any old engine, as it's basically just how much air you can stuff into your cylinders. Volumetric efficiency can have an impact on economy, but it's just as often a negative as a positive one. Granted, there is reason to applaud if Mazda is getting almost 50% more power out of the same displacement without revving to the sky or using a turbo.

 

[agent00f]

Reason I ask is, I'm skeptical of the implications of such huge thermal efficiency gains - 45% would be practically impossible unless Mazda was pathetically behind with their 2008 engines. Honda and Toyota have had ~39% thermally efficient (peak) gas engines since the late 90's, which is better than a lot of diesels on the road and close to theoretical maximum for a gasoline engine. Honda achieved this over a wide RPM range using offset cranks, roller cams, shot-peened pistons and coatings, VTEC cam profiles for low RPM operation, indexed plugs, exhaust heat scavenging, lean air/fuel ratios and stratified charge - in other words, tons of tech, making their engines complicated and relatively expensive. Toyota achieved this largely via running Miller/Atkinson cycle instead of OTTO, and keeping the engine at ideal load and RPM, using electric motors to vary speed, rather than changing engine RPM (Prius/CVT "drone").

However, 45% more volumetric efficiency can be achieved by slapping a turbo on any old engine, as it's basically just how much air you can stuff into your cylinders. Volumetric efficiency can have an impact on economy, but it's just as often a negative as a positive one. Granted, there is reason to applaud if Mazda is getting almost 50% more power out of the same displacement without revving to the sky or using a turbo.

Their existing skyactiv engines are already relatively efficient with 13+ compression ratios and pretty sophisticated chamber/scavenging design. About as high as thermal delta of the otto thermodynamic cycle as reasonably possible with existing tech.

 

[_Rick_]

If they can make this work while keeping an aluminum block, I'm all for it. The main problem with Diesel was always weight.

Oh, and I wonder what they plan to do with the exhaust treatment. Auto-ignition with gas will probably not burn as hot as Diesel, but still, I'd expect NOx issues to arise.

 

[Yuriman]

If they can make this work while keeping an aluminum block, I'm all for it. The main problem with Diesel was always weight.

Oh, and I wonder what they plan to do with the exhaust treatment. Auto-ignition with gas will probably not burn as hot as Diesel, but still, I'd expect NOx issues to arise.

There are plenty of small block aluminum diesels in Europe and Asia, you just don't generally see them in the US.

 

[ChronoReverse]

If they can make this work while keeping an aluminum block, I'm all for it. The main problem with Diesel was always weight.

Oh, and I wonder what they plan to do with the exhaust treatment. Auto-ignition with gas will probably not burn as hot as Diesel, but still, I'd expect NOx issues to arise.

Apparently, HCCI actually yields lower temperatures than normal spark ignition. This is because it burns homogenously (complete gaseous mix that can burn at once) unlike diesel which is stratified (the fuel spray droplets are microscopic but still exist so there's a hot flamefront around every speck).

 

[postmortemIA]

Wonder if these engines will last longer than their rotary ones...