# Mazdas new petrol engine doesn't need spark plugs and is 30% more efficient.



## CAPSLOCKSTUCK (Aug 8, 2017)

Its fuel economy potentially matches that of a diesel engine without high emissions of nitrogen oxides or sooty particulates.

Mazda's engine employs spark plugs under certain conditions, such as at low temperatures, to overcome technical hurdles that have hampered commercialization of the technology.

*HOW IT WORKS*
A homogeneous charge compression ignition (HCCI) engine ignites petrol through compression, eliminating spark plugs.

Its fuel economy potentially matches that of a diesel engine without high emissions of nitrogen oxides or sooty particulates.

Mazda's engine employs spark plugs under certain conditions, such as at low temperatures, to overcome technical hurdles that have hampered commercialization of the technology.

To keep the temperature low at compression, the system reduces the amount of hot exhaust gas inside the combustion chamber.







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To keep the temperature low at compression, the system reduces the amount of hot exhaust gas inside the combustion chamber using a 4-2-1 exhaust system

In the Skyactiv-G, for example – the predecessor to the Skyactiv-X – Mazda uses a 4-2-1 exhaust system.

This relies on a pipe with a length over 600mm to elevate actual-use torque, and a loop shape to save space.

As the long distance cools the exhaust gas before it reaches the catalyst, which would then delay the catalyst’s activation, the system delays ignition timing after engine-start for stable combustion.

A piston cavity is used to optimize fuel injection further, to formulate a stratified air-fuel mixture around the spark plug, according to Mazda.
















http://www.mazda.com/en/innovation/technology/skyactiv/skyactiv-g/


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## GoldenX (Aug 8, 2017)

As a motor fan, this is great news, but as a rotary fanboy, Mazda, gimme another RX-7 please!


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## therealmeep (Aug 9, 2017)

CAPSLOCKSTUCK said:


> *HOW IT WORKS*
> A homogeneous charge compression ignition (HCCI) engine ignites petrol through compression, eliminating spark plugs.
> 
> Its fuel economy potentially matches that of a diesel engine without high emissions of nitrogen oxides or sooty particulates.
> ...


 So in a nutshell its a diesel engine running on gas with some new fiddly bits to help it with mpg and the works.


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## Melvis (Aug 9, 2017)

so its a diesel engine with extractors that doesn't run on diesel?


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## HD64G (Aug 9, 2017)

Melvis said:


> so its a diesel engine with extractors that doesn't run on diesel?


Much more complex since it burns petrol (=gas for US). And it has spark plugs for when combustion isn't high enough to induce the burning procedure. The achievement is spectacular, especially for such small company, but Mazda is a rare occassion in motor industry which has given the motor enthusiasts some special cars and technologies in times. Many cudos to them for giving decads of life more in internal combustion engines.


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## Melvis (Aug 9, 2017)

HD64G said:


> Much more complex since it burns petrol (=gas for US). And it has spark plugs for when combustion isn't high enough to induce the burning procedure. The achievement is spectacular, especially for such small company, but Mazda is a rare occassion in motor industry which has given the motor enthusiasts some special cars and technologies in times. Many cudos to them for giving decads of life more in internal combustion engines.



I am guessing the spark plugs kick in when it is at idle RPM when the compression is at its lowest. Mazda is well just Mazda I wouldn't say there anything special but alot better then some other company's, we can thank them for the Rotary engine thats for sure.


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## FordGT90Concept (Aug 9, 2017)

I read an article in truck trend that compression ignition is possible with gasoline but the compression ratios to make it happen are ridiculous.  In short, the fuel economy improvements are offset by the weight of the engine to compensate for the high pressures (this is why diesel engines tend to be much heavier than gasoline engines).  Increasing fuel economy standards may lead to requiring the development of compression ignition gasoline engines (surprised Mazda is first).



Melvis said:


> Mazda is well just Mazda I wouldn't say there anything special but alot better then some other company's, we can thank them for the Rotary engine thats for sure.


Wankel engines are kind of crappy though (dirty and inefficient).


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## GoldenX (Aug 9, 2017)

Combustion engines in general are dirty and inefficient.


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## dorsetknob (Aug 9, 2017)

FordGT90Concept said:


> compression ignition is possible with gasoline but the compression ratios to make it happen are ridiculous.



In the moter trade This is known as Pinking  and is Caused by faulty ignition Timing  Not Good for Engines as it Damages Pistons


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## FordGT90Concept (Aug 9, 2017)

That's knocking (premature combustion), not compression ignition.  Compression ignition engines (largely diesel) use a high pressure fuel injector which forces fuel into the cylinder at maximum compression.  The energy from this causes the fuel-air mixture to ignite.


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## CrAsHnBuRnXp (Aug 9, 2017)

Love my Mazda. Hopefully when I trade in my 6, this new engine will be in it.


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## Brusfantomet (Aug 9, 2017)

That reminds me of the Wärtsilä dual fuel engines. Originally a diesel cycle (burning MDO or just straight crude oil) they could change over to run on natural gas after is was started on MDO. the trick was to use a small pilot injection of MDO at the start of the power stroke and then follow up with natural gas during the rest of the power stroke.


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## HD64G (Aug 9, 2017)

FordGT90Concept said:


> I read an article in truck trend that compression ignition is possible with gasoline but the compression ratios to make it happen are ridiculous.  In short, the fuel economy improvements are offset by the weight of the engine to compensate for the high pressures (this is why diesel engines tend to be much heavier than gasoline engines).  Increasing fuel economy standards may lead to requiring the development of compression ignition gasoline engines (surprised Mazda is first).
> 
> Wankel engines are kind of crappy though (dirty and inefficient).



That's why Mazda made it. They are pushing the development of higher compression ratio engines more than any other car manufacturer for a decade now instead of bringing to the market diesel-gate engines or small turbo gasoline ones that irl burn much more fuel than advertised, and now must get bigger and bigger to get lower emissions. Mazda's longtime strategy is proven brilliant now.

As for Wankel engines, they are also monstrous in output, revving sky-high and sound great. Engines for enthusiasts.


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## GoldenX (Aug 9, 2017)

Brusfantomet said:


> That reminds me of the Wärtsilä dual fuel engines. Originally a diesel cycle (burning MDO or just straight crude oil) they could change over to run on natural gas after is was started on MDO. the trick was to use a small pilot injection of MDO at the start of the power stroke and then follow up with natural gas during the rest of the power stroke.



Here in Argentina we still use common engines modified to run on natural compressed gas (with a huge canister on the back), it's way cheaper, very popular with taxis.


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## dorsetknob (Aug 9, 2017)

GoldenX said:


> Here in Argentina we still use common engines modified to run on natural compressed gas (with a huge canister on the back), it's way cheaper, very popular with taxis.


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## Totally (Aug 9, 2017)

So they're using performance/race longtube headers, and deliberately inducing combustion through high compression called 'engine knock' when it happens otherwise. Where's the breakthrough?


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## niko084 (Aug 9, 2017)

I look forward to seeing what it can do but have my doubts/concerns, primarily on reliability and power output.
--- There are already a number of gasoline/petrol small low power cars available that achieve near the fuel economy of a diesel.

There are a few problems, greatly increasing compression will increase wear. I'm curious as to what the power band will look like.
I assume this will also require a high pressure fuel pump on the rail which adds more drawback. 
I believe this will also increase CO emissions (per unit of spent fuel), total emissions maybe down due to increases in efficiency.

I do not intend to sound like a downer on what sounds like could be a great development to carry over until electric is ready for mass markets.

****
Then the motor head side of my brain boots up and says NO! Blown big block or go home!



Totally said:


> So they're using performance/race longtube headers, and deliberately inducing combustion through high compression called 'engine knock' when it happens otherwise. Where's the breakthrough?



It's not a huge breakthrough per say, they are making the design compatible with unleaded fuels, but nobody else has done so and brought it to large scale automotive production.

It's a fair bit different from knock, closer related to pre-ignition I suppose.


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## GreiverBlade (Aug 9, 2017)

Melvis said:


> we can thank them for the Rotary engine thats for sure.


actually not Mazda is to thanks for the Rotary ... but rather the Dr. Wankel
https://en.wikipedia.org/wiki/Felix_Wankel
controversial history nonetheless ... but like most "innovation/invention" you need a war to draw them out ... sadly.

and that engine wasn't used firsthand by Mazda
https://en.wikipedia.org/wiki/NSU_Ro_80
obviously not the 1st car that used it ... but my grandfather had one
the 1st one was that one
https://en.wikipedia.org/wiki/NSU_Spider

and motorcycle
https://en.wikipedia.org/wiki/Suzuki_RE5
ok i should have put Sachs motor or Norton or DKW instead of Suzuki 



FordGT90Concept said:


> Wankel engines are kind of crappy though (dirty and inefficient).


muh... crappy i wouldn't say ... they had quite some success and fan ... (if you did write "i find the Wankel Engine crappy" i wouldn't quote    ) dirty? well, which combustion motor isn't dirty... (even the new Mazda Skyactive is still a dirty engine, even if it is more efficient ) efficient? hum, technically no engine is really efficient , but true the Wankel design was too much fuel hungry ...

it had a nice sound nonetheless ...


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## Aquinus (Aug 10, 2017)

It's a gasoline/petrol version of a diesel engine with part-time spark plugs for when the engine is cold. Look out Carnot, here we come. 


GreiverBlade said:


> muh... crappy i wouldn't say ... they had quite some success and fan ... (if you did write "i find the Wankel Engine crappy" i wouldn't quote   ) dirty? well, which combustion motor isn't dirty... (even the new Mazda Skyactive is still a dirty engine, even if it is more efficient ) efficient? hum, technically no engine is really efficient , but true the Wankel design was too much fuel hungry ...


Carnot would be disappointed in the Wankel. Thermal efficiency with that engine is garbage and higher expansion ratios is what lets you approach the maximum possible power out of a heat engine. The wankle produces a lot of power because it revs high, it eat a lot of fuel because it has a poor expansion ratio in terms of the area at the beginning and end of the combustion stroke. The Prius gets good gas mileage because it leaves the intake valve open longer and pushes some air out but, has a high compression ratio if the valve wasn't left open longer. So you have the expansion ratio of basically 14.5:1 so, you get great gas mileage. The electric motor is just to make up for the under-powered engine that's super efficient.

Diesels are just efficient because you compress the hell out of it until it explodes. They're really heavy engines though.

Efficiency = Increase in volume at the end of the combustion stroke to bring the ignited charge to atmospheric pressure and temperature. Thank you, Carnot.


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## FR@NK (Aug 10, 2017)

niko084 said:


> have my doubts/concerns, primarily on reliability



Reliability will be the biggest issue as these engine will have even higher piston pressures then diesel engines. If they do make it strong enough then the power to weight ratio will be abit heavy.



niko084 said:


> I assume this will also require a high pressure fuel pump on the rail which adds more drawback.



The fuel is injected on the intake stroke so you wont need a high pressure fuel rail. Not to say they wont use one though.



GreiverBlade said:


> well, which combustion motor isn't dirty...



Injecting oil into the combustion chamber to help seal the "rings" makes it much more dirty compared to most engines.


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## neatfeatguy (Aug 10, 2017)

CrAsHnBuRnXp said:


> Love my Mazda. Hopefully when I trade in my 6, this new engine will be in it.



I love my 2005 Mazda 3 (especially the lava orange color), how she handles and the zip she has under the hood....but a few things that really pissed me off when about the 50k mile mark was hit. Makes me second guess going with Mazda, but perhaps I'm lucky with my car, she hasn't had too many issues. When I got my car the warranty was only for 36,000 miles. At least warranties today have much improved since I got my car back on 2005.

First issue around 50k: Purge solenoid valve fail/sticking. Only cost around $20-25 to fix, but still a pain.
Second issue around 60k: alternator failed
Third issue around 60k: gunk buildup in throttle body (regardless of regular oil changes and filter changes) - about every 15k since I have to clean it out
Fourth issue around 75k: thermostat failed
Fifth issue around 120k: front right wheel bearing failure. It wouldn't really have been much of an issue since it's a normal wear and tear thing, but you need to machine press the knuckle out and back into the new bearing. By the time you buy new parts and find a shop with a machine press, the cost for them to do the work only leaves you around $150 under the cost of having a place do everything it for you. So I had my local Mazda dealership fix it for me.

I'm at 125k on her now and normal wear and tear issues have cropped up to be fixed (broken rear strut mounts, replacement of rear struts - done around 110k). I need to replace rotors and breaks and if I have the cash I'll replace the front struts, too. Mechanically, under the hood, she's still in pretty good shape. Exterior, with the MN winters she started rusting on the rear wheel wells 3 years ago, regardless of all the washes and turtle waxes I put on her over the years. I suppose she's in pretty good shape for a 12 year old car. Gets me from A to B.

Only real issue I have when it comes to driving the car is driving in the winter. Even with quality snow-type tires, if there is more than 6 inches of snow on the ground, you're going nowhere if you have to come to a complete stop. I've gotten hung up in my driveway a couple of times when the snow was 6+ inches deep.  Since she's pretty low to the ground, compared to a lot of other cars on the road, the big chunks of hard, packed snow that fall off other vehicles that sit in the middle of the road, I have to drive around or they smash into the under body.....I watch every other car in front of me drive right over it like it's not there.

If I stick with Mazda I'd look at something a bit higher off the ground with similar room/handling, all wheel drive......I'd probably look to a CX-5 or CX-3. Outside of some unforeseen failure on my Mazda 3 hatchback, I figure I'll get another 3-4 years out of her before she's pretty much ran into the ground.


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## Aquinus (Aug 10, 2017)

neatfeatguy said:


> I love my 2005 Mazda 3 (especially the lava orange color), how she handles and the zip she has under the hood....but a few things that really pissed me off when about the 50k mile mark was hit. Makes me second guess going with Mazda, but perhaps I'm lucky with my car, she hasn't had too many issues. When I got my car the warranty was only for 36,000 miles. At least warranties today have much improved since I got my car back on 2005.
> 
> First issue around 50k: Purge solenoid valve fail/sticking. Only cost around $20-25 to fix, but still a pain.
> Second issue around 60k: alternator failed
> ...


I'm 2 1/2 years and 55k into my 2015 Subaru Impreza and the only thing that has broke is the power window switch for the drive side window. I considered the Mazda 3 but, I wanted the AWD for the winter. I have the manual transmission which has the 50:50 viscous coupled limited slip center diff which does wonders in the snow. Even with all-seasons, it handles decently in the snow. Like you, I'm no stranger to snow here in NH. The Saab was a nightmare with repairs and in the snow though. I will never go back to front-wheel drive.


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## Melvis (Aug 10, 2017)

FordGT90Concept said:


> I read an article in truck trend that compression ignition is possible with gasoline but the compression ratios to make it happen are ridiculous.  In short, the fuel economy improvements are offset by the weight of the engine to compensate for the high pressures (this is why diesel engines tend to be much heavier than gasoline engines).  Increasing fuel economy standards may lead to requiring the development of compression ignition gasoline engines (surprised Mazda is first).
> 
> 
> Wankel engines are kind of crappy though (dirty and inefficient).



Also they dont last very long, high wear rate and use three times as much petrol.



GreiverBlade said:


> actually not Mazda is to thanks for the Rotary ... but rather the Dr. Wankel
> https://en.wikipedia.org/wiki/Felix_Wankel
> controversial history nonetheless ... but like most "innovation/invention" you need a war to draw them out ... sadly.
> 
> ...



Yes I know of the NSU having the rotary engine also, but I mean Mazda made it work like it says in the article they fixed some issues with the original design and I guess the rest is history from there onwards. Mazda made the rotary 
successful


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## JC316 (Aug 10, 2017)

FordGT90Concept said:


> That's knocking (premature combustion), not compression ignition.  Compression ignition engines (largely diesel) use a high pressure fuel injector which forces fuel into the cylinder at maximum compression.  The energy from this causes the fuel-air mixture to ignite.



Detonation is technically compression ignition, just unintentional and not timed. It's also a great way to blow a hole in your piston.  It's also a great way to do this to a head gasket. With direct injection coming to gasoline engines, it was only a matter of time before a compression based ignition would happen. I'm just curious as to how much power they can extract with this technique.


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## GhostRyder (Aug 10, 2017)

I was reading up on this and though multiple users have beaten me to the punch in saying it, its a similar system to a Diesel engine.  I like the idea, but that high of compression is going to be a bit harder on the engines and require a design that can hold up under pressure otherwise you end up with the Chevy 350 Diesel.


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## FordGT90Concept (Aug 10, 2017)

Melvis said:


> Also they dont last very long, high wear rate and use three times as much petrol.


Advantage of being over-built to handle the pressures: compression ignition tends to last 10 times more miles than your usual gasoline engine.



JC316 said:


> Detonation is technically compression ignition, just unintentional and not timed. It's also a great way to blow a hole in your piston.  It's also a great way to do this to a head gasket. With direct injection coming to gasoline engines, it was only a matter of time before a compression based ignition would happen. I'm just curious as to how much power they can extract with this technique.


Mazda's article says that the main issue with compression ignition is that the torque curve suffers.  As @Aquinus said, it might be better suited for hybrids (electric motor supplements the gasoline engine when torque is inadequate).


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## Aquinus (Aug 10, 2017)

JC316 said:


> With direct injection coming to gasoline engines, it was only a matter of time before a compression based ignition would happen.


Pre-ignition is what will kill your cylinder, piston, or head-gasket. Even when timed, compression ignition ignites with a lot of power and it doesn't make for an even combustion. Even diesels are like this as you can literally hear the ignition which almost sounds just like knocking... oh wait, it is.  The difference is with spark ignition, there is a well defined front to the flame as it expands and engines are designed to take advantage of that. If fuel is combusting in an abnormal pattern, pressure and temperature rises much faster than during controlled combustion. The result is extreme stress to the piston and rods. In order to handle that, you need stronger internals which are heavier. More reciprocating mass means lower max RPM which will end up being just like diesel with a limited power band but, more torque per full cycle.


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## JC316 (Aug 10, 2017)

FordGT90Concept said:


> Advantage of being over-built to handle the pressures: compression ignition tends to last 10 times more miles than your usual gasoline engine.
> 
> 
> Mazda's article says that the main issue with compression ignition is that the torque curve suffers.  As @Aquinus said, it might be better suited for hybrids (electric motor supplements the gasoline engine when torque is inadequate).



Diesels suffer from a poor RPM range, they make great power, just not for very long. That's why a lot of your semis have so damned many gears, the usable RPM range is too narrow. The modern diesel solved a lot of the power problems by moon boosting with a turbo. You get a compression based gasoline engine with a 10 speed auto and a turbo, it could be quite powerful.



Aquinus said:


> Pre-ignition is what will kill your cylinder, piston, or head-gasket. Even when timed, compression ignition ignites with a lot of power and it doesn't make for an even combustion. Even diesels are like this as you can literally hear the ignition which almost sounds just like knocking... oh wait, it is.  The difference is with spark ignition, there is a well defined front to the flame as it expands and engines are designed to take advantage of that. If fuel is combusting in an abnormal pattern, pressure and temperature rises much faster than during controlled combustion. The result is extreme stress to the piston and rods. In order to handle that, you need stronger internals which are heavier. More reciprocating mass means lower max RPM which will end up being just like diesel with a limited power band but, more torque per full cycle.



Yep. The disadvantage to the spark plug is that it doesn't burn all of the fuel, not by a long shot. Unburnt fuel is wasted power and more emissions. It's why we have gone to so many catalytic converters and EGR systems.


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## Aquinus (Aug 10, 2017)

JC316 said:


> Yep. The disadvantage to the spark plug is that it doesn't burn all of the fuel, not by a long shot. Unburnt fuel is wasted power and more emissions. It's why we have gone to so many catalytic converters and EGR systems.


That's because it runs hot. Gasoline/petrol engines are typically tuned to run rich because running stoichiometric is going to have very high temperatures and the extra fuel absorbs some of that heat by changing phase (liquid to gas.) This is how water/methanol injection works, the mixture is used to lower the temperature of the charge by absorbing said heat and that heat is what causes pre-ignition. The flame also travels faster when you run rich versus running lean so, typically less fuel means that you want to advance the timing more but, too advanced of a timing with too lean of a mixture can also cause knocking.

Personally, I think that a pseudo-Atkinson style engine like the Prius has is the way to go. You lose power density to gain efficiency and in some cases, that's an acceptable trade-off. You gain the advantage of having a higher expansion ratio but, you effectively have a smaller engine for the actual displacement of the engine since you're pushing some of the charge back out and into the intake manifold. I think that mixed with a turbo-charger would probably yield the best benefits with modern technology that we already have.


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## fullinfusion (Aug 10, 2017)

CAPSLOCKSTUCK said:


> Its fuel economy potentially matches that of a diesel engine without high emissions of nitrogen oxides or sooty particulates.
> 
> Mazda's engine employs spark plugs under certain conditions, such as at low temperatures, to overcome technical hurdles that have hampered commercialization of the technology.
> 
> ...


I wonder if THIS engine wont have the problems the current engines have during winter months, over fueling and washing down the cylinder walls past the rings and into the oil; pan.


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## Brusfantomet (Aug 12, 2017)

GoldenX said:


> Here in Argentina we still use common engines modified to run on natural compressed gas (with a huge canister on the back), it's way cheaper, very popular with taxis.


yes, that is petrol engines (Otto cycle), running on a different but equally volatile fuel as petrol. The Dual fuel engine i was describing is a diesel engine (Diesel cycle).
The new Mazda engine is a mix of the two cycle styles.


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## GoldenX (Aug 12, 2017)

We also use diesel engines with CNG.


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## CAPSLOCKSTUCK (Oct 25, 2017)

Mazda reveals new Skyactiv-X engine

Mazda will showcase the Skyactiv-X technology at the Tokyo Motor Show this week. When it launches the engine in 2019, the automaker says it will deliver as much as 30 percent fuel efficiency over its Skyactiv-G engine, already one of the most fuel efficient gasoline engines on the market.







https://www.youtube.com/watch?time_continue=1&v=9G1eOU2Eguw


https://www.cnbc.com/2017/10/25/with-new-technology-mazda-gives-spark-to-gasoline-engine.html


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