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craig a
9th August 2017, 12:22 PM
Mazda claims to have designed a vehicle that will largely eliminate the need for spark plugs in petrol engines, increasing fuel efficiency by as much as 30%. The development also increases the existential threat facing diesel engines (https://www.theguardian.com/environment/2017/jun/05/air-pollution-fears-demand-diesel-cars-fall-fifth) because its fuel economy could match dieselís performance without high emissions of nitrogen oxides or sooty particulates

Mazda said it would sell cars from 2019 with a newly developed petrol compression ignition engine, a technology that automotive manufacturers, including deep-pocketed rivals such as Daimler AG and General Motors, have been chasing for decades. The engine ignites petrol through compression, removing the need for spark plugs and increasing fuel efficiency.

But Mazda said its Skyactiv-X engine would have spark plugs that would be used in certain situations such as at low temperatures.

Mazda boosts petrol engine efficiency in fresh blow to diesel | Business | The Guardian (https://www.theguardian.com/business/2017/aug/08/mazda-petrol-engine-breakthrough-puts-another-nail-in-the-coffin-of-diesel)

lyonsy
9th August 2017, 04:38 PM
well they were the only ones to perfect the rotary were the first to get Atkinson cycle to work on an otto cycle and now the first to make compression ignition work.
the good news is but they can use it to revive the rotary

PAT303
9th August 2017, 04:50 PM
What did that bloke say ''tell him he's dreamin''. Pat

PAT303
9th August 2017, 04:51 PM
well they were the only ones to perfect the rotary were the first to get Atkinson cycle to work on an otto cycle and now the first to make compression ignition work.
the good news is but they can use it to revive the rotary

What rotary did they perfect and what engine had Atkinson cycle?. Pat

lyonsy
9th August 2017, 05:03 PM
from the 13b on they have had the rotary sorted and reliable so long as you let them warm up and didn't do short commutes everywhere
kjzem 2.3L v6 that was fitted to the eunos 600 mazda 929's of the early to late 90's where the first manufacture to use variable valve timing to create a atikison cycle effect in a otto cycle engine.

PAT303
9th August 2017, 06:52 PM
Mazda simply held the inlet valves open passed bottom dead center to reduce pumping losses,that does not make it an Atkinson cycle engine.Rotaries are a design dead end,the reason no other manufacture bothered with them. Pat

DeeJay
9th August 2017, 07:00 PM
Mazda simply held the inlet valves open passed bottom dead center to reduce pumping losses,that does not make it an Atkinson cycle engine.Rotaries are a design dead end,the reason no other manufacture bothered with them. Pat
Pat,
Dead end or not, the comment was that Mazda perfected them ( as far as possible to perfect any engineering concept) . Warming them up was indeed the trick, certainly tested my patience back in the 70's..

ramblingboy42
9th August 2017, 07:12 PM
I was taught that compression ignition is by definition "dieseling"......some cars did this after a hot long run after the ignition was turned off...I think it was reasonably common in the "new" high compression Vanguards.

Wouldn't that make this "new" engine a diesel?

Mazda did the Miller cycle engine.....I had not heard of the Atkinson, has it been used successfully in a production vehicle?

101RRS
9th August 2017, 09:13 PM
I don't know what is so special about using petrol for a diesel function - turn the ignition off on my old Subaru and I could keep it running quite happily with a bit of throttle [bigsmile1].

It was NSU, not Mazda that brought the rotary to production - Mazda just refined the concept and took out some but not all of the flaws.

Garry

lyonsy
9th August 2017, 10:15 PM
Mazda simply held the inlet valves open passed bottom dead center to reduce pumping losses,that does not make it an Atkinson cycle engine.Rotaries are a design dead end,the reason no other manufacture bothered with them. Pat

yes which is creating an Atkinson type cycle on an otto cycle engine that yes does reduce pumping losses which improves engine efficiency and if you want a fuel miser na engine that's what you do, just ask Toyota with their 1.5L Prius engine, if you do it with boost it then becomes a miller cycle on an otto cycle engine

the nsu was flawed and rushed out to beat Mazda to the market with the engine essentially still in prototype stage while Mazda's 10a was more production ready but until the masses got hold of them that was when more flaws became know and then due to only mazda continuing to go with the rotary took until the 13b to get enough mechanics to know how to work on them (no google back then)

Atkinson cycle is similar to miller cycle but with out boost

as for design dead end most major car manufactures had production ready engine's ready to go and then the 73 oil crisis hit and due to their fuel usage they all pulled the pin apart from Mazda, so to achieve what they have with it for only one company doing all the r&d on it they have done remarkable well, it also gave Mazda something to set it apart from all other Japanese manufacture's.

with direct fuel injection Mazda should have an engine that is now more economical and able to meet new emission laws as well it should also mean they can run much higher compression ratio's for greater performance.
will it ever make low down torque like a big piston engine maybe if you made it have a larger elliptical crank (btw this is what Mercedes and gm had done) to allow more torgue or you build it as a very efficient high rpm air pump which is what they have been doing so far with their halo cars in the rx7 and rx8

as for whats special about it its the first time something as volatile as petrol has been able to controllable combusted with compression ignition

PAT303
9th August 2017, 10:35 PM
yes which is creating an Atkinson type cycle on an otto cycle engine that yes does reduce pumping losses which improves engine efficiency and if you want a fuel miser na engine that's what you do, just ask Toyota with their 1.5L Prius engine, if you do it with boost it then becomes a miller cycle on an otto cycle engine

Both of those engines got their ''efficiency'' from decreasing the volume of air compressed in each cylinder,instead of compressing the air they blew it out of the inlet valves.That all sounds good but in effect,what you have is a 2.0ltre engine with the stroke of a 1.6,so your efficiency comes not from any fantastic development but instead from a smaller internal capacity.Again that sounds good but you have the weight of the car and a 2.0ltre engine,but the power and more importantly the torque of a 1.6ltre so in real life the driver spends most of their lives with their foot to the floor trying to get the thing to go,which blows the efficiency line out the window.Toyota got around the lack of power by adding an electric motor,friends of mine in Kalgoorlie had a Prius that averaged 5 ltres per 100 driving to Perth and back,about the same as a normal small sedan,so again your cutting your nose off in spite of your face. Pat

PAT303
9th August 2017, 10:39 PM
Pat,
Dead end or not, the comment was that Mazda perfected them ( as far as possible to perfect any engineering concept) . Warming them up was indeed the trick, certainly tested my patience back in the 70's..

They only perfected the 4 rotor 787B,the car engines like the 13B are thirsty short lived torque less dead ends. Pat

Svengali0
10th August 2017, 05:05 AM
I've had two NSU Ro80 cars in the past. The later engine fitted (single plug) was smoother and more torque than the 12a retrofitted to one of my cars..and turned out to be more reliable as well. So NSU engineers (my grandfather, an engineer worked at the Neckarsulm factory after the war but before Felix Wankel appeared) largely solved most of the gross issues with rotary (except fuel & emissions & oil use) just before VAG AG took over and ended NSU in1977. To my mind, our Japanese colleagues demonstrate excellence in refining and problem solving some else's designs. Their forte as it were. Btw variable valve arrangements were examined by two manufacturers before the war. I'm unable recall which ones but believe one was Italian.

PAT303
10th August 2017, 09:03 AM
The decision to go to the 4 rotor design in the 787 was to increase the overall power,it was also fitted with variable length inlet trumpets to increase or decrease the inlet air speed to better throttle response.Another innovation was adding a second set of plugs,as the major failing of the wankel design is the compression ratio decreases as the rotor rotates,the second set of plugs fired to keep the flame front moving at the desired burn speed.The rotary has too much seal length and complexity to ever be considered as anything but a curiosity. Pat

lyonsy
10th August 2017, 10:14 PM
Both of those engines got their ''efficiency'' from decreasing the volume of air compressed in each cylinder,instead of compressing the air they blew it out of the inlet valves.That all sounds good but in effect,what you have is a 2.0ltre engine with the stroke of a 1.6,so your efficiency comes not from any fantastic development but instead from a smaller internal capacity.Again that sounds good but you have the weight of the car and a 2.0ltre engine,but the power and more importantly the torque of a 1.6ltre so in real life the driver spends most of their lives with their foot to the floor trying to get the thing to go,which blows the efficiency line out the window.Toyota got around the lack of power by adding an electric motor,friends of mine in Kalgoorlie had a Prius that averaged 5 ltres per 100 driving to Perth and back,about the same as a normal small sedan,so again your cutting your nose off in spite of your face. Pat

the engines only use this geometry when the ecu works out they are up to speed and cruising so as to get better fuel economy and better emissions.
a Prius is not designed as a highway cruiser and at highway speeds the electric motor will actually be a hindrance on fuel economy then a benifit along with all associated weight due to the hybrid system, so to be doing 5L is reasonably good, you would prob find removing all the hybrid gear on the highway would reduce fuel into the 4's.

the 26b was a development of the 13b but made for all out performance with reliability (how they won the race was reliability not out right pace)
the twin plug thing they have been using on just about every rotary i can think of ots why they had twin dizzy's
the nsu was rushed out into market before it was ready to ensure they beat Mazda (and prob also showed mazda few issues that they had a chance to correct a bit before they released the cosmo) to be the first manufacture to build a rotary powered car.
as for lack of torque thats cause the rotary's that have been developed have been for sports (yes in the 70's mazda did fit them to everything including kingswoods) not big lazy cruising so they have in effect the same style power to a short stroke large bore piston engine where they have little down power but scream like a banshee, if they decided they wanted to make something make power down lower they would need a narrower rotor but a larger eccentric crank so they get a larger mechanical advantage, but that wouldn't be as fun to drive in a sports car
a similar engine to the rotary are the honda vtec engine's where they are useless under 6000 but scream too 8000 maybe more where the rotary will go an extra 1500-2000rpm

but yes Japan is as a culture takes something and refines it and makes it work properly this can be seen in their workforce people don't aim to start their own business they intended to work for an established business, and this has been found with most cultures that have low immigration rates as immigrants are around 75% more likely to start their own business in a new country then a citizen of that country is,
so with a immigration rate of around 2% or less new fresh idea's and innovative technology are not their strong suit how ever they are increadable good at making stuff no one else can make work actually work and reliably

lyonsy
10th August 2017, 10:16 PM
https://www.youtube.com/watch?v=WBkfOUaEcWM