Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

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

nippon.com

Post reply on HN
Print view View original

211–220 of 295 posts

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

#211

Post by virtue3 »

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…

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 benefit from being on a fixed power band. It's why they work so dang well on large ships.

Where as rotary engines(rx-7's at least) need a rebuild every 80-100k miles. So I think without really knowing what you're doing mechanically or having access to a mechanic that can repair those kinds of engines you aren't going to be super reliable with a rotary.

Green hydrogen approaches via rotary engines does seem quite interesting. I think if the reliability of the rotary could be improved that could have some serious merit. Or at least making small enough generators that you can easily ship them out to be replaced/repaired could have serious merit.

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

#212

Post by ggreer »

giobox wrote: post #180
ggreer wrote: post #155

Earlier quoted context omitted.

I agree with the adage, but brute force seems to win in this specific case. Even though it's the lightest model made, my Miata only gets 0.82g on the skidpad.[1] The Model 3 Performance gets 0.96g thanks to its wide tires, which are needed to transfer all its power to the asphalt.[2] This difference isn't just due to the 1990 Miata's older suspension and tire technology. Even the latest Miatas only get 0.90g of later…

> I agree with the adage, but brute force seems to win in this specific case. Even though it's the lightest model made, my Miata only gets 0.82g on the skidpad The current ND2 (2019+) Miata regularly pulls ~0.95 stock in magazine tests, almost identical to your model 3 Performance number. > https://www.motortrend.com/reviews/2019-mazda-mx-5-miata-clu... You can exceed 0.95 and get ~1 on an ND Miata with slightly wide…

Yes and you can modify the Model 3 to increase cornering ability, but like in the case of the Miata it means increased tire wear, worse comfort, and worse mileage. Not to mention money.

My point was simply that even if you know vehicle A is twice as heavy as vehicle B, you don’t know for sure which one is faster in the turns.

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

#213

Post by seabrookmx »

rootusrootus wrote: post #4

Almost feel bad for GM, the article did not mention the Volt when talking about series hybrids. But I guess it is a Japan-focused news source.

As mentioned elsewhere in this thread, the Volt is not actually a series hybrid despite being marketed as such. There is a planetary gear set (ala. Toyota hybrids) connecting the engine to the wheels at most speeds.

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

#214

Post by speedgoose »

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 because I live around Oslo in Norway, a place where it’s the age of electric cars.

I think ICE for cars has a very limited future in the age of electric cars. I see it reserved for specific applications where the energy density is a must, and some car enthusiasts activities.

Hybrids are some kind of temporary solutions for places where the EV infrastructure aren’t good enough yet. Once the infrastructure is good enough, some people will still buy ICE for a little while as they are unsure, but most switch to full electric eventually. At least that what happened around Oslo and happens now in the country side of Norway.

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

#215

Post by trevyn »

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…

Is this intended to be an anecdote about life in Oslo, or are you suggesting that you expect the world outside of Scandinavia will somehow become more like Scandinavia over time?

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

#216

Post by connicpu »

m463 wrote: post #188

It's worth mentioning that serial hybrids, like the BMW i3 rx, might not be able to drive on the freeway on the output of their generator. That's why it's a "range extender" - at some point you have to pull over and charge. EDIT: this is a big secret that none of the marketing materials (want to) make clear. I'm uncertain the output of the wankel, but maybe with its power-to-weight it might get closer to being able t…

I don't know where you get this idea, my Chevy Volt is perfectly capable of reaching 70mph+ while holding the battery level steady (in the Hold mode)

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

#217

Post by speedgoose »

trevyn wrote: post #215
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…

Is this intended to be an anecdote about life in Oslo, or are you suggesting that you expect the world outside of Scandinavia will somehow become more like Scandinavia over time?

Yes, with the right political decisions most countries could switch to electric vehicles. EVs also are nicer to drive and cheaper over the vehicle lifetime. It’s just a matter of time in my opinion.

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

#218

Post by rgmerk »

Merad wrote: post #200
_yb2s wrote: post #104

Earlier quoted context omitted.

Thank you, I've wondered for years why we didn't have tiny gas turbine engines...

They definitely exist for small RC aircraft, but they're very expensive.

And chew through fuel at truly extraordinary rates.

This one, for example, weighs 450 grams, but can consume its own mass in fuel every three minutes!

https://www.kingtechturbinesaustralia.com.au/product-page/k4...

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

#219

Post by fransje26 »

willis936 wrote: post #189
Retric wrote: post #178

Earlier quoted context omitted.

That rate isn’t a deal killer for a plug in hybrid. The engine might see ~1/4th the ware per mile spending the vast majority of its time off. Meanwhile hybrids really want a small and lightweight engine because of all the extra equipment.

Right but then why not use a more efficient and reliable engine? The motors will last hundreds of thousands of miles. The power circuitry should have a similar run if kept cool. Why have an ICE that's more likely to fail with lower thermal efficiency? The engine used in Toyota's most popular cars runs in Atkinson most of the time with a 40% thermal efficiency. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC7425626/

> The motors will last hundreds of thousands of miles.

They might, but with the current average build quality of the car industry, the rest of the car will die well before that..

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

#220

Post by m463 »

connicpu wrote: post #216
m463 wrote: post #188

It's worth mentioning that serial hybrids, like the BMW i3 rx, might not be able to drive on the freeway on the output of their generator. That's why it's a "range extender" - at some point you have to pull over and charge. EDIT: this is a big secret that none of the marketing materials (want to) make clear. I'm uncertain the output of the wankel, but maybe with its power-to-weight it might get closer to being able t…

I don't know where you get this idea, my Chevy Volt is perfectly capable of reaching 70mph+ while holding the battery level steady (in the Hold mode)

The volt is not a serial hybrid. The motor is physically connected to the wheels (in an interesting way btw), so it can drive on gasoline alone.
Post reply on HN