http://blog.caranddriver.com/mazda-n...-rotary-lives/

not sure if i shouldve put this into the gen auto sub-forum...but its a little piece of the puzzle for the new rotary! one piece at a time, and its slowly coming together.

 

Nothing really new there. More "confirmation" is always handy though.


('Confirmation' in quotes because it's more solid than most rumors, but still no direct quotes, meaning the journalist could be misinterpreting some of the information)

 

"reduced rotating mass"

Not a good thing in the torque department. Hmm...

 

Why? Isn't torque the leverage? It would seem to me that the lighter the rotor (and other spinning parts) is, the more effective the combustion against the rotor.

I mean, a lightweight flywheel doesn't cause any torque penalties? Makes you feel the torque better.


If drivetrain loss is in horsepower, and horsepower is torque X RPM, drivetrain loss is actually in torque, just getting compounded by RPM. So lighter should be a benefit to torque production. Or do I have that all backwards?

 

Other than the part about combustion, ya I think you have it. Lighter mass means it will spin up faster.

From the article:
We've heard this over and over from Mazda spokesmen all the way up to the Chairman. Believe it.

 

Hopefully when the said Hybrid they thinking electric motor assist will take care of the low torque.

 

everybody is getting rid of the 6 cylinders. even BMW are putting a 4 cylinder turbo engine in their 328i's.

 

I'm thinking it will be more like a locomotive. A rotary engine driving a generator connected to batteries. These driving either a electric motor connected to the differential. Or, electric motors on the hubs. That would reduce friction loss and make it easy to make a four wheel drive car. The ride may suffer due to increase of un-sprung weight.

 

the sky active mazda 3 engine has a 30%( thats THIRTY %) reduced internal friction. Now think about this for a minute. How did they do that and not sacrifice reliability?
Antifriction Coatings will be a thing in the future--the very near future. Check out the Microblue site. I have been promoting that for the past 8 months or so? This is one way of reducing friction.
The electric water pump will be a thing that is soon offered in all IC cars--mark my words. The parasitic drain of the mechanical pump will no longer be tolerated. Think about it...in a world in which manufacturers crave 1-2 mpg more out of their engines ( hence part of the reason of going back to the 4 cyl version) if they can get rid of the water pump parasitic drain and reduce friction like microblue can--then there is more mpg, cooler running, increased hp/tq and increased reliability. Its coming--mark my words today.
The on demand alternator is coming along with a different way of charging the battery also.

 

^ using exhaust energy for electrical power.... In theory, high exhaust flow rates could provide voltage/current enough to power even a small power boosting in-line electric motor...

 

well what about Mazda's new e-loop and i-brake (i forget what is called) technologies? couldnt the eletric motor assist actually assist these? or are those systems fully dependable on the actually cars battery/ecu power?

 

sadly, most people are afraid of ANY kind of change, and they're driving the market, not us small potatoes.

and the biggest change people afraid of is : "Cost"

Lighter rotating assembly does not mean you will lose torque, Torque is really based on a leverage effect, 13B has a really short stroke so it needs a turbo to have reasonable torque. Mazda already did their best on the 13B-MSP, consider it has a "side exhaust" port and it still have higher output than the last NA Rotary Engine.

but lighter rotating assembly usually means thinner/weaker assembly, and the only solution is again, "Cost"

For example, instead of Cast Iron, use Aluminum rotors, instead of Heat-treated tip Apex Cast Iron seals, use Ceramic, etc etc. but all of the above WILL drive the cost UP. Mazda already tried Aluminum Rotors back in 80s, yep, 30 something yrs ago. it ran 1230812038 times better than Cast Iron rotors any day, but they know no one will buy a car that cost 5 times as their target back then. So they're stuck with Cast Iron Rotors.

Only thing we can do is wait.

 

Immediately avaliable torque is generated from the conversion of motion to energy. Moving mass=additional immediate torque.

So, you either need a lot of mass (think flywheel) to convert to work at the axel,

-OR-

You need a low-mass engine spinning at ungodly RPMs to make up the equivalent energy. This is what NYCGPS is talking about.

The Wankel actually has more in common with a jet turbine than a reciprocating piston engine. Piston engines always have a lot of moving mass that translates into immediate torque, even at mid RPMs. Jets (rotary cousins) generate more energy at high rpms, through increased fuel use and fast cycle rates, just like Wankels.

A rotary needs to spin-up to much higher RPMs to make up for the lack of mass. Read: Using a lot of fuel!

The only way to generate additonal torque, in the absence of any mechanical flywheel storage, is through more fuel usage and faster RPMs.

Lightweight flywheels allow the engine to spin-up faster. That's the way they increase power and torque. They don't have a massive crank-shaft, camshaft, and other attendant mechanical parts to store potential energy (torque) in the form of conservation of motion.

That said, it's what makes the Wankel magic. I'm not complaining, just pointing out a fundamental difference. More moving mass=more immediately available torque. The Wankel lacks superfluous moving mass, unlike a conventional piston engine.

I've had a few cocktails, but I'm on solid ground here. And know that I prefer the Wankel seven days from Friday.

 

I'm game


So, from that theory, if we stuck a Renesis in a 4,000lb Camaro, it would generate more torque, because the drivetrain has quite a bit more mass?

 

No. The drivetrain has much less mass because there's a Wankel driving it, not a v-6 or V-8. And the car itself weighs more, so there is more mass to be moved with a smaller amount of initial torque.

The Wankel has to spin a LOT faster to make up for the missing mass of the original piston engine.

 

Look guys, I'm only talking from experience and college physics classes.

Face it, the Renesis isn't known for brutish torque.

I'm not happy about it, either, but I love the Wankel for what it does best.

YMMV, and I'm not going to debate it to death. Go ahead and think otherwise.

 

Then what is the difference between a spinning driveshaft and a spinning rotor and a pumping piston? If the gears are 'locked', then moving any one piece has a direct motion in the other pieces. So the mass of a piston or the mass of a driveshaft would have the same impact. Different rates of impact, due to the gearing, but still the theory rule behind it. Right?


I fail to see the difference you are distinguishing.

(just to make sure I'm not read wrong, I've got no hostility, just friendly debate. I think you are wrong, but I'm willing to walk through your perspective... I also don't disagree with you on the overall merit of the rotary, or the actual final impact. I just don't understand your perspective, and I am trying to validate it in my head.)

 

Mass has the safe effect on max/peak torque as it does on top speed...none.

 

just think of a torque wrench ... same person(same power) using 2 different length of torque wrench, one is 6 inches and the other is 5 feet.

the E-shaft on Rotary engine is just ... short, and that's what kills it. well, good and bad.

 

We get that, it's not what's under debate at all.

What's under debate is the difference between if that wrench was made of solid cast iron or lightweight aluminum, and if it has any difference in the amount of torque being generated.

I don't believe that the mass of the object does have an impact on the torque itself, other than how freely it revs (like a lightweight flywheel vs heavier OEM)

 

Mass simply effects how fast you reach peak torque not what your peak torque is.

 

oh ok, well are-ax-eight got the answer.

anything thats lighter and stronger is always better and will help the engine to acclerate faster, too bad it always comes with the "more expensive" effectwith them.

 

I honestly think that at this point, Mazda could make a lighter rotor out of aluminum if it was all about weight, for very little cost difference over the current rotors. i think that there is more to it than just the raw manufacturing of a lighter rotor.

Do you have any papers on Mazda's use of aluminum rotors? That would be an interesting read...

 

http://www.autoblog.com/2012/04/18/m...ans-for-skyac/

 

Reading the comments make me laugh.. it's funny how many people have no clue of anything rotary engine related, yet still insist on commenting.