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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

#81

Post by darby_eight »

callalex wrote: post #78
mattmaroon wrote: post #15

I have never understood why the Volt Series Hybrid idea never took off. It is more efficient to turn gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels. Is it perhaps that the cost involved is just too much more than a plugin hybrid to make the small extra fuel savings worth it?

“It is more efficient to turn gas into electricity” I don’t think that’s correct. It may be true for highly variable/low loads where the pumping losses in the pistons dominates. However the majority of fuel consumption in a car happens at traveling speed (highway miles). That is the area that needs to be optimized for. My 2015 Honda Accord Hybrid takes this approach. At below-freeway speeds the gas motor runs in seri…

> However the majority of fuel consumption in a car happens at traveling speed (highway miles).

Unless of course you drive primarily in stop-and-go traffic, e.g. delivery drivers, taxis, commuter cars, etc. Quite often you won't exceed 50 kph. For whatever reason, I've never seen (or have and forgotten) a car marketed towards this market—probably for exactly the reason that plug-in hybrids perform better in this scenario.

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

#82

Post by Tade0 »

mattmaroon wrote: post #15

I have never understood why the Volt Series Hybrid idea never took off. It is more efficient to turn gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels. Is it perhaps that the cost involved is just too much more than a plugin hybrid to make the small extra fuel savings worth it?

Both the Chevy Volt and Toyota's hybrids rely on a planetary gear set to blend power between the gasoline engine and electric motors.

Here are the differences explained in more detail:

http://roperld.com/science/ChevyVolt.htm

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

#83

Post by bob1029 »

user_7832 wrote: post #73
coryrc wrote: post #28

Earlier quoted context omitted.

Then you may as well use a gas turbine, which is pretty much better in every way that matters for generating purposes.

Apparently they really don't scale well. I found this reddit post explaining it better: > Gas turbines scale extremely poorly. They rely on small clearance between the rotating blades and the housings for efficiency. The smaller the turbine, the greater the relative clearance and the more energy is lost. Gas turbines, at least with established technology, make very little sense below 300ish HP. As a real life compari…

300 HP = ~220 kW

I believe a Tesla can charge its battery pack at approximately this rate.

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

#84

Post by illegalsmile »

jmspring wrote: post #9
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.

The funning thing is, people I know who have a Volt love their cars. Haven't tried one myself. My family has a couple of paid of Toyota gas vehicles that are 8+ years old and will probably live longer than we will.

My friend has a few volts from 2013-2018 (that he loves) and I usually borrow one for trips to see family and friends 12-16 hours away rather than drive my truck. I think they're great vehicles. ~40mpg at 80-90mph on the highway is really good though it does take premium for that 40+ mpg and it has a smallish tank so you have to stop a little more often. Once you reach your destination all driving is done on electric and charges overnight on a regular outlet/level 1. Their maintenance is surprisingly low for what seems like a complex system.

Crazy to me that Chevy has abandoned their PHEV platform considering others, like Toyota, are in such high demand. Speaking of which I spent a week with a Rav4 Prime and found that equally as impressive range-wise as a volt.

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

#85

Post by eep_social »

sethhochberg wrote: post #16
jpgvm wrote: post #3

Earlier quoted context omitted.

Wankels can be made extremely compact so that might have something to do with it, i.e it has both very high power to weight and power to volume specs. I honestly don't know if that is the reason though, perhaps someone more knowledgeable of the specifics of range extenders might chime in but I imagine that is an important factor.

They have a pretty narrow power band (produce efficient max power at a small range of RPMs) which always somewhat limited their use for normal ICE cars, but is a pretty workable constraint for an electrical generator. So you have compact size, good power to weight ratio, and power limitations that don't really matter for range extender purposes. Lots of potential. I can't find the article right now, but I'd swear I r…

Maybe you’re thinking of the Edison kits? They seem to be putting a genset into the truck bed to do EV conversions: https://news.ycombinator.com/item?id=38893567

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

#86

Post by philwelch »

coryrc wrote: post #56
WalterBright wrote: post #38

Earlier quoted context omitted.

Gas turbine cars have been built, but they tend to set anyone on fire if they walk behind the car. https://bandimere.com/previewing-the-brakes-plus-jet-car-nat...

You're probably being silly, but for anyone else, gas turbines as used for generators don't have jet exhausts on them, i.e. https://www.youtube.com/watch?v=yR5oVn-Fvvg

So what do they do with the exhaust?

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

#87

Post by narag »

ggreer wrote: post #60
skellera wrote: post #8

Earlier quoted context omitted.

I don’t understand why Mazda doesn’t just make a drift-tuned electric car. You could do amazing stuff with software focused on that driving style. A true electric successor to the RX-7 would capture so much attention.

Several reasons. First, like most of the Japanese manufacturers, Mazda bet against electric vehicles. They focused R&D on improving engine efficiency and getting their engines to run on hydrogen. If Mazda wants to make electric vehicles now, they have to play catch-up, or license key technologies from other manufacturers. Second, batteries are heavy. For sedans and mid-size crossovers, this isn't much of a problem. E…

It seems Mazda is going ahead with an electric Miata, they just don't know how electric it will be:

https://www.motortrend.com/news/2026-mazda-mx-5-miata-electr...

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

#88

Post by busterarm »

ksec wrote: post #66
skellera wrote: post #8

Earlier quoted context omitted.

I don’t understand why Mazda doesn’t just make a drift-tuned electric car. You could do amazing stuff with software focused on that driving style. A true electric successor to the RX-7 would capture so much attention.

>A true electric successor to the RX-7 would capture so much attention. Not entirely sure that would be the case even with a Red Sun label on it.

As someone who owns a white turbo fc, sans stickers, I would be interested.

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

#89

Post by davewritescode »

jeremymims wrote: post #27
mattmaroon wrote: post #15

I have never understood why the Volt Series Hybrid idea never took off. It is more efficient to turn gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels. Is it perhaps that the cost involved is just too much more than a plugin hybrid to make the small extra fuel savings worth it?

This was how the BMW i3 worked. It was a rather novel design that included an optional small electric scooter motor in the rear that had a 2.5 gallon gas tank. When the battery was low, it would be charged by running the small generator. This was clearly a wonderful idea but it was hamstrung by a silly California rule requiring the gas range to be less than the electric range to qualify for rebates. With a 6 gallon t…

That and the fact that in the US the car is tuned to only turn on the range extender when the battery is nearly dead and it can’t always keep up.

Thankfully it’s trivial to change.

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

#90

Post by busterarm »

SebFender wrote: post #68

I have so many bad memories from this engine. I finally brought them to court to win. But all this to say Mazda has been out of the game so long living on dreams with this engine.

Mine went 110k miles without ever blowing up and then I decided to rebuild it.

It's got as much longevity as other cars from the era if you pay attention to oil/omp and (over)boost (if you have a turbo). Everyone puts in at least a downpipe and then neglects all of the other mods (wastegate mod, better fuel bump, bigger injectors, wideband o2 sensor and new fuel map, better intercooler, etc) that you'll be forced to do along the way or suffer from boost creep and an eventual grenaded engine.

It's all of the other things under the hood that I've had to replace from all that heat though. Three alternators. A wiring harness that caught fire...

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