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

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

#251

Post by wredue »

runlaszlorun wrote: post #233
class3shock wrote: post #228

Earlier quoted context omitted.

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 s…

>20-30%

Your total guess is orders of magnitude off.

Most software today is in the ballpark of 10,000x slower than it should be.

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

#252

Post by Narishma »

wredue wrote: post #251
runlaszlorun wrote: post #233

Earlier quoted context omitted.

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 s…

>20-30% Your total guess is orders of magnitude off. Most software today is in the ballpark of 10,000x slower than it should be.

That's not what they're saying. They're talking about things that couldn't be done due to performance issues but are now possible thanks to improved hardware.

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

#253

Post by grecy »

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…

> even the fastest chargers take 5-10x as long as filling up with petrol (2-3 mins vs 20-30)

I just drove to the airport in a bit of a rush. Drove straight up to pump, tapped credit card, authorized for $100 and opened cap at same time. Stuffed the pump in and held it at max flow. 45l of gas later (small car), cap back on, pump away and moving again.

I don’t think it would be possible to be faster.

Total time stopped: 7 minutes.

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

#254

Post by wredue »

Narishma wrote: post #252
wredue wrote: post #251

Earlier quoted context omitted.

>20-30% Your total guess is orders of magnitude off. Most software today is in the ballpark of 10,000x slower than it should be.

That's not what they're saying. They're talking about things that couldn't be done due to performance issues but are now possible thanks to improved hardware.

Software developers rarely question the hardware they are developing on/for. Unless you were developing in the pentium and earlier era, it has almost definitely not been true for you that “the hardware is not capable of running this idea” (ignore certain obvious high performance sectors).

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

#255

Post by lelanthran »

markhahn wrote: post #239
twobitshifter wrote: post #237

Earlier quoted context omitted.

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.

Unsprung weight does not have a linear impact.

Increasing the unsprung weight by 10% causes a 100% deterioration in handling and ride quality.

You're suggesting increasing the unsprung weight by about 400%.

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

#256

Post by Ntrails »

Narishma wrote: post #252
wredue wrote: post #251

Earlier quoted context omitted.

>20-30% Your total guess is orders of magnitude off. Most software today is in the ballpark of 10,000x slower than it should be.

That's not what they're saying. They're talking about things that couldn't be done due to performance issues but are now possible thanks to improved hardware.

10 years ago we designed a system to approximate a chunk of maths we did not have time to do every second, too slow.

If you started from scratch you'd never even consider doing anything other than the original obvious "correct" maths. Approximation be damned.

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

#257

Post by lagadu »

Prcmaker wrote: post #128
porphyra wrote: post #36

Earlier quoted context omitted.

Sports cars, in general, are much loved but seldom bought.

I'm literally waiting for it, have been for quite a while. Small cars have numerous benefits over just being sporty. An electric, or even a hybrid 86/BRZ or miata would be great, but can't be compared to the mini or fiat, and while tesla might be fast, it's huge. Even with a price increase these could be more affordable than a lot of sports cars. The 86/BRZ has been a huge seller too.

The MG Cyberster is coming out pretty soon, also the electric Cayman, though it's a completely different price bracket.

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

#258

Post by Grazester »

cookiengineer wrote: post #199
ryukoposting wrote: post #141

Earlier quoted context omitted.

It has nothing to do with sentimentality. Wankels have tremendous power-to-weight and power-to-size ratios. Their main problem is reliability. The generally accepted solution to improve rotary engine reliability (oil injection) results in poor emissions. The wide, flat-ish combustion chamber doesn't help the emissions problem, either. The Wankel is at its most efficient and its most reliable when operating at a const…

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…

Where are you seeing all these magically rotaries? Yeah the guys in NZ and maybe some Americans(Rob Dahm) have some high horsepower rotaries but let's not pretend it's the norm and that they are more reliable than an equivalent piston engine.

Built Nissan VR38DETT V6 produces 2000hp. A full billet block will produce 3000hp+. Nissan GT-R guys(T1, ETS,AMS) Let's not even get into the big block V8's because these things will run all day at that hp and be a whole lot more reliable than anything mentioned here.

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

#259

Post by rootusrootus »

markhahn wrote: post #239
twobitshifter wrote: post #237

Earlier quoted context omitted.

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.

> once mentioned them to a car engineer .... now that I think of it again, is a bit silly

No offense, but this right here is peak HN.

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

#260

Post by TylerE »

seabrookmx wrote: post #209
hatsunearu wrote: post #207

Earlier quoted context omitted.

No, rotary engines are terrible. For one, the equivalent of variable valve timing doesn't exist/cannot exist for rotary engines, unless Mazda creates a miracle. VVT and VVL lets you do some insane things in terms of efficiency and good engine behavior, so the rotary falls behind a lot. The rotor is pretty much unable to be cooled too.

I'm not saying rotaries are great, but two stroke piston engines can have variable port timing (typically called a "power valve"). I don't see why the same method couldn't be applied to a rotary.

The same reason we don’t use two strokes anymore? They’re environmental disasters and wildly inefficient.
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