Mazda design petrol engines without spark plugs which increase fuel efficiency by 30%

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

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Originally Posted by DeeJay

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..

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

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.

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

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Originally Posted by PAT303

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

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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

https://www.youtube.com/watch?v=WBkfOUaEcWM