Mazda’s rotary engine in the age of the electric car • Hacker News Board

Re: Mazda’s rotary engine in the age of the electric car

#231

Post by newsclues » Sat, Mar 30, 2024, 12:51 PM UTC

class3shock wrote: post #228

npunt wrote: post #204

I've always seen rotary engines as one of the best examples of a particular approach to design that solves something very elegantly but relies too much on one critical component where all the pressure of the design is applied. In the case of a rotary engine, it's the apex seals. They're a great warning for designers/architects/engineers to not get too enamored with the elegance of a system if parts of it are not yet…

I would just add that sometimes ideas exceed the technology of their time. So revisiting a design that had deficiencies (weak points, high production costs, bad emissions, etc.) with new tools, materials, etc. can lead to breakthroughs. Not that that's what is happening here, just why some ideas that previously didn't work seem to circle back around.

It’s hard to tell if you can improve technology until it’s good enough (jet engines) or if it’s a futile dead end.

Kelly Johnson of Skunkworks had a keen mind for differentiating between them.

Re: Mazda’s rotary engine in the age of the electric car

#232

Post by ryukoposting » Sat, Mar 30, 2024, 12:54 PM UTC

virtue3 wrote: post #211

cookiengineer wrote: post #199

Earlier quoted context omitted.

Technically, the Wankel rotary engine design allows much higher power output than an I-4 or even a V-6 engine design due to no strains on the rods, and much less strains on the piston(s) as those literally blow up all the time in I4 engine designs in similar power output ranges. I've seen many very reliable 3 or 4 rotary wankel swaps in RX7 FD3S that output far beyond anything imaginable any V8/V12 could produce. 200…

While I also share in your love of Wankel engines I think you are grossly skipping over their unreliability (mostly around the seals). There's an extremely good reason "rural" applications are reliant on diesels. It's not uncommon for a diesel engine to hit 300k+ miles and still operate reliably. And not to mention simply. They are relatively easier to maintain than a standard gasoline engine. Diesels also greatly be…

My guess is this: Mazda believes its battery-only range is enough for most driving situations. If they're right, the rotary engine's more limited lifespan would be a moot point since it will still last the vehicle's entire lifetime. One can only hope.

The maintenance thing is concerning, though. Nobody knows how to work on these things. As an RX-7 or RX-8 owner, you're either doing most of your engine work by yourself, or you're driving very long distances to go to a specialty shop. We can pray that it's reliable enough for this to not be a problem, but if these engines start failing, it's going to be a huge mess.

Side note - the geometry of a Wankel rotary engine makes a diesel version impossible - you can't get enough compression. Diesel rotaries do exist though. An American company called Liquid Piston is making them for the Army. The intent is to use them in diesel generators, since the resulting generator is much smaller and lighter than more traditional diesel generators.

Re: Mazda’s rotary engine in the age of the electric car

#233

Post by runlaszlorun » Sat, Mar 30, 2024, 1:37 PM UTC

class3shock wrote: post #228

npunt wrote: post #204

I've always seen rotary engines as one of the best examples of a particular approach to design that solves something very elegantly but relies too much on one critical component where all the pressure of the design is applied. In the case of a rotary engine, it's the apex seals. They're a great warning for designers/architects/engineers to not get too enamored with the elegance of a system if parts of it are not yet…

I would just add that sometimes ideas exceed the technology of their time. So revisiting a design that had deficiencies (weak points, high production costs, bad emissions, etc.) with new tools, materials, etc. can lead to breakthroughs. Not that that's what is happening here, just why some ideas that previously didn't work seem to circle back around.

I feel like software is the poster child for this. My hunch is that a lot of techniques have been dropped for performance penalties that may be on the order of 20-30% (totally guessing here) when Moore’s Law often has covered that gap in mere months.

I read a comment on HN a while back that you can look like a genius in software by going back about 10 years and finding something forgotten. The whole web development shift from server-side to client-side and now drifting back to server-side as if it’s something new seem to validate this. Though in this case it just seems like the extension of the decades long back and forth of going from mainframe with super minimal client, to PC only, to networked, to client/server, to server-side web, etc, etc.

Re: Mazda’s rotary engine in the age of the electric car

#234

Post by cobalt60 » Sat, Mar 30, 2024, 1:40 PM UTC

class3shock wrote: post #228

npunt wrote: post #204

I've always seen rotary engines as one of the best examples of a particular approach to design that solves something very elegantly but relies too much on one critical component where all the pressure of the design is applied. In the case of a rotary engine, it's the apex seals. They're a great warning for designers/architects/engineers to not get too enamored with the elegance of a system if parts of it are not yet…

I would just add that sometimes ideas exceed the technology of their time. So revisiting a design that had deficiencies (weak points, high production costs, bad emissions, etc.) with new tools, materials, etc. can lead to breakthroughs. Not that that's what is happening here, just why some ideas that previously didn't work seem to circle back around.

Adding to the list of deficiencies, Apex seals!!

Re: Mazda’s rotary engine in the age of the electric car

#235

Post by jessekv » Sat, Mar 30, 2024, 1:40 PM UTC

Cthulhu_ wrote: post #143

labcomputer wrote: post #118

Earlier quoted context omitted.

> it was hamstrung by a silly California rule requiring the gas range to be less than the electric range to qualify for rebates. The problem is that BMW wanted to get the same amount of credits as a pure-BEV. California anticipated that a car with 300 miles of gas range might spend much of it's life being driven on gas if there was no penalty for doing so... and in fact that is exactly what happened with many Europea…

> and in fact that is exactly what happened with many European plug-in hybrids sold as company cars. The counter force to that is that lease car drivers have to meet certain fuel efficiency goals, so, adopt an efficient driving style and plug in the plug-in hybrid instead of ragging it around; I'm not sure what the consequences were though, probably more taxes. Either way, enough of a push for my colleagues with plug…

I'm curious which country it is that has these fuel efficiency goals.

Re: Mazda’s rotary engine in the age of the electric car

#236

Post by SoftTalker » Sat, Mar 30, 2024, 2:32 PM UTC

01HNNWZ0MV43FF wrote: post #97

kyleee wrote: post #70

Earlier quoted context omitted.

Of course Jay Leno has one; not sure if he’s featured it on his youtube channel (I don’t recall seeing it). Awesome

Yep I've seen it on his YouTube. The "EcoJet" https://www.youtube.com/watch?v=10q9_pB6unU He said that they had to put really big brakes on it. I guess for some reason you can't just have a clutch. Personally if I was going for eco I'd want something more clever than "bigger brakes" but maybe building something like a Hybrid Synergy Drive is harder than building a turbine.

> He said that they had to put really big brakes on it.

There's no compression braking (engine braking) with a turbine engine.

Re: Mazda’s rotary engine in the age of the electric car

#237

Post by twobitshifter » Sat, Mar 30, 2024, 2:57 PM UTC

npunt wrote: post #204

I've always seen rotary engines as one of the best examples of a particular approach to design that solves something very elegantly but relies too much on one critical component where all the pressure of the design is applied. In the case of a rotary engine, it's the apex seals. They're a great warning for designers/architects/engineers to not get too enamored with the elegance of a system if parts of it are not yet…

In hub motors might be another automotive example of this. They were used by Ferdinand Porsche and invented in 1896. Ever since engineers keep trying them out as a simple elegant solution. Eventually they will break through I think, but there’s the same allure in the simplicity of it all.

Re: Mazda’s rotary engine in the age of the electric car

#238

Post by speedgoose » Sat, Mar 30, 2024, 3:08 PM UTC

deergomoo wrote: post #230

speedgoose wrote: post #214

I used to own the first gen electric i3 with its tiny range. I didn’t wish to have the hybrid ICE version to drive further, but I did wish for more electric range and more fast chargers along the road. Nowadays, I have a cheaper car with a lot more range, almost 4 times more in real life conditions, and plenty of fast chargers everywhere. I don’t see why I would bother with an ICE. It makes no sense for me. It’s beca…

I am a big proponent of EVs, but I personally think hybrids will have a really long tail, especially as the technology improves: we could feasibly end up with a situation where much city driving in a hybrid is zero-emission EV-mode. Two reasons: First, in relation to your point > Once the infrastructure is good enough I live in the UK and I think this is gonna take a long, long time here. Not only will we need to bui…

If you think about cost, long term it’s cheaper to skip the ICE and have a slightly better electric power train with a bigger battery capacity. That’s what Carlos Tavares said to the French government many years ago. Hybrids have two systems and that’s expensive and complex.

Installing electric power plugs everywhere isn’t that challenging. I’m sure UK can manage it if the local government decides to do it seriously.

By the way, 35k€ for a brand new car that is cheap to run isn’t a bad deal. New cars are expensive. Maybe you can wait a decade or two before switching with a cheap used EV that has enough range.

Re: Mazda’s rotary engine in the age of the electric car

#239

Post by markhahn » Sat, Mar 30, 2024, 3:16 PM UTC

twobitshifter wrote: post #237

npunt wrote: post #204

I've always seen rotary engines as one of the best examples of a particular approach to design that solves something very elegantly but relies too much on one critical component where all the pressure of the design is applied. In the case of a rotary engine, it's the apex seals. They're a great warning for designers/architects/engineers to not get too enamored with the elegance of a system if parts of it are not yet…

In hub motors might be another automotive example of this. They were used by Ferdinand Porsche and invented in 1896. Ever since engineers keep trying them out as a simple elegant solution. Eventually they will break through I think, but there’s the same allure in the simplicity of it all.

I admire the idea of hubmotors as well, but once mentioned them to a car engineer, who basically said "think about unsprung weight".

Which, now that I think of it again, is a bit silly because most EV mass is battery, not motor.

Re: Mazda’s rotary engine in the age of the electric car

#240

Post by markhahn » Sat, Mar 30, 2024, 3:20 PM UTC

486sx33 wrote: post #2

Does it produce more low end torque verses a traditional gasoline combustion engine? If not then why is it better suited for electrical generation? Is it more efficient with less load? The article mostly makes it sound like Mazda just loves the wankle and wants to find any possibly way to bring it back - even though it has “high” emissions… so coupling it with a hybrid electric motor makes it happen.. That can’t be t…

sorry, why would low-end torque be important?