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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

#41

Post by mikestew »

HPsquared wrote: post #22
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.

The unique sound is a key selling point for rotary enthusiasts. Kind of raspy, almost like a 2-stroke.

Kind of raspy, almost like a 2-stroke.

That's not what the TV commercials from the 70s told me:

"Piston engine goes 'boing, boing, boing, boing'"

"But the Mazda goes 'hmmmmmmm'"

(Oh, of course there's a YouTube video: https://www.youtube.com/watch?v=oHzeGEHWMjo)

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

#42

Post by fodkodrasz »

coryrc wrote: post #28
sethhochberg wrote: post #16

Earlier quoted context omitted.

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…

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

Except for consumption, waste heat generated, size.

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

#43

Post by idontwantthis »

ch_sm wrote: post #20
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 gasoline into electricity and then drive the car with that than to directly connect the engine to the wheels I thought so too, but my research suggested that the efficiency is pretty much the same if not worse and power delivery is worse. Do you have some links? I‘d like to be wrong on this one.

I thought the idea is that the battery acts as a buffer and the engine is always either off or at constant rpms in its ideal power band.

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

#44

Post by ryandvm »

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?

Stellantis (Dodge) has an upcoming version of the RAM 1500 that does this. It's an electric truck with a 145 mile range on electric battery; once that is expended the gas engine kicks on to run a 130 kilowatt generator.

https://www.cnbc.com/2023/11/07/new-ram-pickup-ev-has-gas-po...

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

#45

Post by dragosmocrii »

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?

have a look at the new Mitsubishi outlander EV, it kinda works like the volt

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

#46

Post by jdblair »

shanusmagnus wrote: post #32

What was the purpose of using the rotary engine in the first place, for ICE cars? From the comments it seems it's maybe lighter for a given power output. Is that it, other than just the novelty of it?

Lighter and mechanically simpler were the selling points. Poor fuel efficiency and trouble with the seals were the downsides.

My uncle had an RX-7 back in the 80s when I was a kid. I remember when it was idling I could see the exhaust puffing, in pulses. It only had a single combustion chamber after all.

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

#47

Post by dragontamer »

A good article.

It barely addresses the elephant in the room however: The Toyota Prius and its Atkinson engine.

The Atkinson engine is 99% the same as a regular engine (aka: Otto cycle), except the timing is different. Instead of closing the valves when the piston+cylinder is full of gasoline+air mix... the Atkinson engine waits a bit and "leaks" some gasoline+air back out before closing the intake valve, effectively burning only 70% of the fuel, but getting maybe 85%+ of the power of a regular Otto-cycle engine. Its a simple and cheap tweak to a traditional engine that grossly improves efficiency (but at huge costs to low-end torque).

Basically, any regular ol' carmaker who is mass producing Otto cycle / regular ICE engines can easily tune their piston timing to be an Atkinson engine instead. I believe Toyota even has computerized controls today that switches between efficient Atkinson (lower-power but higher efficiency) modes and powerful Otto cycle (higher power but lower efficiency) modes, though this control isn't really used too often in practice.

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This article makes a good point that Mazda has a culture of this... rotary engine. It does compare it (somewhat unfairly) to the Atkinson engine though (inside the Prius and RAV4), I don't think anyone expects any traditional engine (Otto or Rotary) to keep up with Atkinson Engine efficiency.

Its a good try however. But it does raise the question of what benefits can this rotary engine give over other engine types.

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

#48

Post by kjkjadksj »

porphyra wrote: post #36
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.

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

You’d think its a different time now that the kids who grew up lusting over these cars now have money for one, enough money to create a new car market where even a pickup truck can be almost six figures optioned out

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

#49

Post by gimmeThaBeet »

Tagbert wrote: post #30
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?

The Volt worked best as an EV with an ICE range extender. As an EV, the 40-52 mile range was sufficient for 90+% of daily driving. Adding more range would have little true benefit. It was a series hybrid, but it was mediocre as a hybrid due to the added battery weight. Nissan has the E-power hybrid that is the pure series hybrid that you describe. AFAIK it is not as efficient as a regular, parallel hybrid. The advant…

I got my honda partially because it has the closest thing to nissan's e-power (in many ways the same, but with a couple twists).

At low speeds (Now this probably isn't really accurate, but architecturally I think I like it because the only thing keeping it from being a BEV is the battery size (only a couple kWh); the electric motor is strong enough to be usable on its own.

I think Toyota has increased the power on the normal prius, and definitely on the prime, but it used to be as part of the power split system, the electric drive motor wasn't sized to be enough on its own.

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

#50

Post by dragontamer »

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…

> 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?

You've got it backwards.

The Prius's Atkinson engine makes low-end torque *worse*, and then relies upon the EV Motor to drive the car at low speeds (0mph to 10mph) before the ICE kicks back in.

If ICE is operating, its at higher RPMs where the generator can still be useful (low RPMs like 500 are too low for the Atkinson engine to be effective in any way, the computer instead increases the RPM to maybe 2000, and uses all the power to drive a generator instead)

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So you see, the name of the game is efficiency at all costs, with EV-motors assisting whatever compromise you built into the motor. In the case of Toyota, its absolutely undrivable crap for low-end torque ICE, but a powerful enough 60hp to 100hp electric-motor that can handle the low-speeds and stop-and-go traffic, smoothing out any problems.

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IE: The engineers build a highly compromised ICE engine (the Atkinson engine) that has a far narrower band of usable RPMs than a normal vehicle. Then they smooth out those problems with electric motors.

It sounds like Mazda is doing the same trick here with their Rotary engine, but the Rotary engine doesn't have the crazy-good efficiency curves that the Toyota Atkinson engine has. Efficiency isn't the "only" name of the game however, but Mazda now needs to find out a good way to market this engine / highlight its strengths.

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