Mazda - Compression Ignition Petrol Engine

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kryptonjohn

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Topic # 223014 8-Sep-2017 09:18

Mazda working on a compression ignition petrol engine car - and claim it could have full lifecycle (well to wheel) equivalent or better emissions that EV.

Interesting...

https://www.stuff.co.nz/motoring/road-tests/96441241/mazdas-new-skyactivx-petrol-plans-to-put-the-pressure-on-electric-vehicles

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Reply # 1860694 8-Sep-2017 09:26

But it is only competitive against a Coal Thermal Grid,

In places where you have major renewables (or presumably nuclear) EVs still beat it

"The cleanest thermal power generation method is Liquid Natural Gas and according to Mazda's sums it's the only one that beats SkyActiv petrol: 100g/km."

Its a nice idea, but by the time it gets to market (prob 5 years) I think its going to be a solution looking for a problem, as coal is already a declining source of Grid power, with gas taking over, + a big push into renewables,

kryptonjohn

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Reply # 1860702 8-Sep-2017 09:41

Note also that it has more power in addition to more efficiency so depending on the downsides that they will have to iron out, and the fact that ICE engines are going to be around for a while no matter what happens with EV it's still got a lot of potential.

Cody64

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Reply # 1860823 8-Sep-2017 12:40

'but by the time it gets to market (prob 5 years)'

that's what I thought but apparently will be in new model 3 at the end of 2018.

TwoSeven

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Reply # 1860861 8-Sep-2017 12:58

kryptonjohn:
Note also that it has more power in addition to more efficiency so depending on the downsides that they will have to iron out, and the fact that ICE engines are going to be around for a while no matter what happens with EV it's still got a lot of potential.

I am not sure there would be more power since I think fuel as an upper limit per unit used. However, I think that from the perspective of increased compression when the unit is within its operating range, there would be an associated increase in torque.

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Reply # 1860878 8-Sep-2017 13:26

wellygary:

But it is only competitive against a Coal Thermal Grid,

In places where you have major renewables (or presumably nuclear) EVs still beat it

"The cleanest thermal power generation method is Liquid Natural Gas and according to Mazda's sums it's the only one that beats SkyActiv petrol: 100g/km."

Its a nice idea, but by the time it gets to market (prob 5 years) I think its going to be a solution looking for a problem, as coal is already a declining source of Grid power, with gas taking over, + a big push into renewables,

What is the green (or ungreen) value of other items?

Say - g/km of the most efficient passenger airplane assuming it goes at full capacity.

And g/km of food, iphones, pencils, clothing, furniture, etc when imported?

I live quite a boring life and don't buy things and cannot afford to travel too often.

Sidestep

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Reply # 1860945 8-Sep-2017 14:38

TwoSeven:
I am not sure there would be more power since I think fuel as an upper limit per unit used. However, I think that from the perspective of increased compression when the unit is within its operating range, there would be an associated increase in torque.

Obviously limited by the amount of energy available per unit of fuel, but fuel is generally burned very inefficiently in Internal Combustion Engines, and if that energy is more efficiently translated into pushing the pistons, more power – torque/hp - per unit of fuel, and better economy- as in miles per given unit of fuel, will result.

Flame front propagation has always been an issue with sparked engines – and good thermal efficiency hard to achieve with gasoline/air a relatively slow burning mix – which is why multiple spark plugs were theoretically better, and spark advance (before Top Dead Centre) relative to rpm was so important.

As someone who used to mess around with engines I find this step towards theoretical perfect combustion very cool.

Chasing straight HP we used to build engines with as much compression and advance as we dared, running right on the ragged edge of detonation – and have spectacular failures.
And any time other than running at WOT they became extremely inefficient.
High compression and fixed cams with tons of lift and overlap meant hard starting, loping, backfiring and overheating was expected from a performance engine in street use.

At first glance what they're managing here with their supercharged, Variable valve timed, 16:1, extremely lean burn engine, is bring a (direct injected) lean fuel/air mix up to the verge of compression-ignition and then taking control of combustion with a small High Pressure injection of fuel to start the compression ignition process.
Keeping this running efficiently under all conditions is going to require plenty of computer power, (sensor fed) awareness of every variable, high quality fuel, and immediate control of every aspect of the engine's mechanical cycle.

Edit:grammar

Linuxluver

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Reply # 1860957 8-Sep-2017 15:01

Sidestep:

TwoSeven:
I am not sure there would be more power since I think fuel as an upper limit per unit used. However, I think that from the perspective of increased compression when the unit is within its operating range, there would be an associated increase in torque.

Obviously limited by the amount of energy available per unit of fuel, but fuel is generally burned very inefficiently in Internal Combustion Engines, and if that energy is more efficiently translated into pushing the pistons, more power – torque/hp - per unit of fuel, and better economy- as in miles per given unit of fuel, will result.

At the end of the day, energy efficiency isn't really relevant.

Burning petrol releases carbon at 2.2kg / Litre.

Not burning petrol releases no carbon.

If car is getting 100km / Litre (crazy number - to illustrate the point) it's still releasing carbon into the atmosphere....along with whatever else.

So maybe more carbon is released making the cars? Doesn't stack up.....because an EV typically so many fewer parts in it.....so there is less emissions overhead in the manufacture because there was a lot less to manufacture (and transport).

Mazda is trying to do the best it can with its technology. Good on them for trying.

But we needed to stop releasing CO2 10 years ago......and we've instead been steadily ramping it up. It's worse than ever....and the consequences of the CO2 released in the past is already working through the climate system in now very obvious ways. The feedback loop is decades long. It's not linear either.

The changes we're seeing now are the low, flat part of a curve we don't really want to explore the limits of.

In many ways, it's already too late....and people don't yet realise that. Now it's just about how bad it will get. We're not looking good there at all.

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kryptonjohn

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Reply # 1860964 8-Sep-2017 15:19

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Sidestep:

At first glance what they're managing here with their supercharged, Variable valve timed, 16:1, extremely lean burn engine, is bring a (direct injected) lean fuel/air mix up to the verge of compression-ignition and then taking control of combustion with a small High Pressure injection of fuel to start the compression ignition process.
Keeping this running efficiently under all conditions is going to require plenty of computer power, (sensor fed) awareness of every variable, high quality fuel, and immediate control of every aspect of the engine's mechanical cycle.

Note Mazda's engine is a hybrid - it has spark plugs but uses them variably as required. Some more details in this article:

https://www.wired.com/story/mazda-injection-compression-skyactivx-engine/

Coil

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Reply # 1860965 8-Sep-2017 15:21

So what I gather is the theory behind this is that in the meantime while we get our crap together, In the life cycle of this car it will emit less pollution than it would in a life cycle of an electric car at present day.
If thats the case then its a good thing, If we find a new energy source or way to store energy in the next 10 years then this car will be doing us a favor in the meantime.

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kryptonjohn

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Reply # 1860966 8-Sep-2017 15:22

Linuxluver:

At the end of the day, energy efficiency isn't really relevant.

Burning petrol releases carbon at 2.2kg / Litre.

Not burning petrol releases no carbon.

It's never so black and white in the real world so efficiency is relevant. Reducing carbon is still better than nothing and as efficiency goes up carbon emitted goes down. ICE isn't going to just disappear any time soon.

dickytim

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Reply # 1860988 8-Sep-2017 15:40

Coil:

So what I gather is the theory behind this is that in the meantime while we get our crap together, In the life cycle of this car it will emit less pollution than it would in a life cycle of an electric car at present day.
If thats the case then its a good thing, If we find a new energy source or way to store energy in the next 10 years then this car will be doing us a favor in the meantime.

Don't mention this to the EV zealots, they don't want to hear about how much CO2 or other negative side effects the production of their cars causes in production or do a fair evaluation.

They seem to be in a little bit of denial.

I'll definitely be keen on a CX-5 with this technology in it... so long as the sums stack up.

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Reply # 1861112 8-Sep-2017 23:31

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I wonder how many EV owners use wood burner. How much CO2 does a wood burner release? What about the BBQ?

alasta

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Reply # 1861137 9-Sep-2017 07:21

I am quite excited about this development. It sounds mechanically complex so I'm not sure if it would be wise to be an early adopter, but to be fair the Skyactiv transmission is also very complex and I'm not aware of anyone experiencing any early failures. The Japanese seem to be quite good at getting things right first time.

Here is an interesting article with some more detail.

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Reply # 1861149 9-Sep-2017 08:20

Linuxluver: At the end of the day, energy efficiency isn't really relevant.

Burning petrol releases carbon at 2.2kg / Litre.

Not burning petrol releases no carbon.

If car is getting 100km / Litre (crazy number - to illustrate the point) it's still releasing carbon into the atmosphere....along with whatever else.

So maybe more carbon is released making the cars? Doesn't stack up.....because an EV typically so many fewer parts in it.....so there is less emissions overhead in the manufacture because there was a lot less to manufacture (and transport).

Mazda is trying to do the best it can with its technology. Good on them for trying.

Ignoring actual production costs and the massive environmental destruction from lithium mining, Mazda are saying the production of electricity is largely fossil fuel based and this is the driver behind their efficiency figures. By only focusing on the burn cycle onwards in their car however, they seem to be (conveniently?) ignoring the costs behind producing and delivering petrol itself to arrive at these figures.

surfisup1000

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Reply # 1861157 9-Sep-2017 09:01

kryptonjohn:

Note also that it has more power in addition to more efficiency so depending on the downsides that they will have to iron out, and the fact that ICE engines are going to be around for a while no matter what happens with EV it's still got a lot of potential.

ICE will die out very quickly as soon as an EV becomes available with decent range with a price similar to ICE. Currently, you can get either decent range or decent price, but not together :)

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