AFAIK Mazda had the reliability aspect of the rotary under control with the NA FB and FC engines.
So, hopefully, with a well thought out engine that is not rushed through development we should see quite an improvement in the reliability department.

 

I wonder if Mazda will finally implement a large capacity oil reservoir for either engine oil or 2cycle this time around for the oil metering system? Something large enough to last in between oil changes. They could also put a dedicated low metering oil level indicator in the dash as a warning. I think this will be more user friendly and better for the engine not having the sump oil levels drop between oil changes and they could run synthetics in the sump. Make it so Mazda.

 

It is odd that they delivered a number of cars to market engines that consume oil normatively but have never thought to add some kind of monitoring/warning system to tell the driver to top up.

 

you need to read between the lines, but with the Rx8 they had a working sideport engine in 1995, and it was only when Ford made them take it out of the 2400lbs Rx-01 and into the 3000lbs Rx8 that it suddenly didn't meet its performance and economy targets, so they had a last minute crunch to get it to do so, and then they didn't get time to make it reliable enough.

keep in mind Mazda is small, and when Ford took over they basically got rid of the R&D department, so the rotary engine group in 2002 was one guy.

i know the above scenario sounds really obvious and dumb, but Ford took over Mazda in 1996, and Ford, basically is a history of insanity.*

with the FD, they had two problems. the first being that when the car came out, there were like 5 people in the world who knew how it worked, and second the bean counters pinched a few too many pennies.

there is a boost solenoid, its the white one. the hose sees boost, and pops off. when it pops off you get no second turbo. there were many many many cars that got multiple sets of turbos because this hose popped off. the previous Cosmo has a clamp on this hose, but the FD doesn't.

as a proof the warranty history of a 93 car can be a couple of pages, but a 95 car is usually really short, so the FD can be reliable, it just wasn't sussed out


*the Edsel has the transmission control push buttons in the center of the steering wheel. so when someone cuts you off, and to go to honk the horn, you put the trans in reverse when you're moving which blows it up. one would think that they would have noticed this in testing, but they didn't. Ford lost $250,000,000 in 1960 money on the Edsel.

 

I think that's a possibility. With the 2014 research on the rotary oil consumption and newer seal materials (requiring less oil), the overall oil consumption may drop to the point where a reasonably sized oil tank may be enough to go between oil changes.
Wasn't the Rx-8 initially touted as using 1 quart of oil every 10000 miles? If Mazda could really achieve that figure with the new engine, an oil injection tank could be used, and a fairly small one at that.

And users are now becoming accustomed to having to fill up other tanks in their cars other than the fuel tank, at least with the latest diesel engines. PSA has been using their version of the DPF that requires the use of a liquid catalyst to promote filter regeneration. And more recently manufacturers have been adding AdBlue injection systems which, again, require an additional tank that must be filled up.
So the prospect of forcing users to filling up two separate fluids should not be such a no-no anymore for manufacturers.

Such an oil injection system would have several advantages: using 2-stroke oil that is designed to burn cleanly will certainly help with emissions when compared to burning 4-stroke oil. And the fact that it would be clean oil that is injected will help lubricate the engine better, a good thing for reliability (and maybe for fuel consumption?). There would be less chance of clogged oil lines due to deposits, further helping reliability. Finally, 2-stroke oil is (usually) cheaper

 

Think the Rx8 uses quite a bit more oil than 1gt per 10,000 miles. Also if they keep lowering the engine, it just makes it harder to add capacity to the sump with it being shallower. Shallow sumps don't do so well with oil slush. I really do want the dedicated oil metering sump this time around.

 

Yeah, I know. I was just saying that AFAIK such a figure was initially mentioned before the Rx-8 came out, only to be proven wrong by quite a bit.
If this time Mazda could make it happen for real, it could very well be the end of the rotary's reputation for burning oil.

Dry sump

 

Really the big oil loss in the rotary hasn't been from the little bit they inject to lubricate the apex seals.

It has been that the side housings warp once warm (worse with side exhaust ports) and the oil control rings stay flat and don't seal- so you get a bunch of oil up along the side of the rotor that gets flung past the side seals especially when diluted with fuel from the intake port (partially open/close port blows onto rotor side).

Mazda has fixed this issue with their new oil study and have done such a good job that they had to add oil injectors for the side seals now!

My RX-8 auto with ~60k miles now uses very very little oil in normal driving.

When I flog it along at 47mph in 1st gear all day (auto-x or mountain roads) it can use a quart in an hour or so. The low oil light lets me know when to add a quart or more.

Leakage past the rotor...

 

In contrast my turbo rotaries usually make oil. Its magic.

Okay- no, it is fuel dilution of the oil.

The new turbo 16X with revised oil sealing/injection will probably be back to oil producing instead of oil consuming unless they have all the injectors direct injection and none at the port or upstream.

 

lol, the new engine would do better though. the better side housings should help with the fuel dilution too. perhaps they will have some fancy PCV system too, the newer piston cars have some pretty involved setups there

 

Yep. And I suspect that the switch from cast iron to aluminium for the side plates may have helped quite a bit. The thermal conductivity of aluminium is much higher than that of cast iron, so it's less likely to have localized hot spots with aluminium side plates which may cause warping.

Wait, The S2 Rx-8 already had 3 oil injectors per rotor. Do you mean that Mazda will add even more oil injectors?

The recent patents so far only show port fuel injection. Absolutely nothing regarding direct injection. We know that direct injection can help big time with emissions and fuel economy, so it's practically certain that Mazda will employ it. Or at least a mixed setup with both direct and indirect injection.

One thing though: the "rotated" engine layout basically prevents putting fuel injectors where they were on the 16X. Given that the intake side of the engine is already cluttered with the oil injectors (as seen in the patents), that only leaves a few places where the direct fuel injectors can be placed. Basically next to the spark plugs.
That is unless Mazda is happy putting fuel injectors inside the oil pan.

 

Quote:
Originally Posted by BLUE TII View Post
Mazda has fixed this issue with their new oil study and have done such a good job that they had to add oil injectors for the side seals now!


Wait, The S2 Rx-8 already had 3 oil injectors per rotor. Do you mean that Mazda will add even more oil injectors?

The new oil studies were done 2014- so, yes; different ideas than the S2 RX-8.

more injectors? Probably not, but in different areas.

 

picked up the magazine today. i dont read japanese but the pictures and stuff are cool. if anyone wants a copy feel free to pm me. i'll have some available until thursday. only the first 20 pages are RX related but the rest of the magazine goes on about other cars and things like that.

 

Before anyone freaks out about the mustang-looking RX-7, those are an "artist's" rendering. If it ends up looking like that, I'll be pissed, but I'm sure it won't.

The system is exactly what I was talking about wanting for this car. Mild hybrids like this are the future. So many benefits and no draw backs. (Well, except replacing a belt is easier than figuring out what wire isn't working, and OEM can really **** up the ECU software that controls these electrical systems...)

Mazda already has their i-ELOOP.

Replacing the starter motor and alternator with a 15-25hp electric motor isn't much of a weight increase at all.

Replacing pullies and belts reduces parasitic loss.

A fully 48v system is lighter than a 12v system or hybrid 12v/48v one.

And, of course, you have the stored electricity to spool up the turbo quickly at any RPM.

It ends up adding more than the 15-25 hp of the engine, because on WoT, instead of an alternator, water pump, oil pump, and other systems draining 15+ hp from the engine, they're draining none and you're adding the electric power for a 30-50hp increase. (assuming there is stored electricity in the cap/batteries to power those)

So not only do you get a 10-30% increase in fuel economy, you get a 10-15% increase in power. And really, more like a 50% increase in power off idle.
The weight should be the same as an equivalent 12v ICE system, or at most 75lb or so which is well worth the power increases.

A typical 12v ICE system is just so inefficient, archaic, and bad for a street car.

This is correct, and I hear there are further improvements coming in the seal designs on the new engine.

Sump pan?
The new RX better have a freaking dry sump like pretty much every super sportscar has these days.

 

This list could go on forever (excessive heat, no technical knowledge from mechanics, knock tolerance, etc). I know the rotary is a passion project for someone important at Mazda (since it certainly doesn't make sense profit-wise), but going down the list weaknesses and trying to address each one is like trying to plug a leaking dam with your fingers. And even if they did manage to engineer solutions to mitigate all the weaknesses, Mazda wouldn't be able to leverage the money, time, effort, and resources spent because no other cars in their lineup even use a rotary. Mazda is literally going to lose money on every RX to do what - so they can use an inferior engine?

The solution to all their engineering problems already exist, it's called the piston engine. Not only does it address all their engineering problems, but it makes financial sense too. Any advances they engineer for the new RX engine can be leveraged throughout their model lineup. Every dollar invested in R&D will be reaped manifold.

Personally, I'd like to see a state of the art high compression turbo 4 cyl. making ~400hp in an ultra lightweight RX. It'd essentially be the most exciting car you could possible drive, and that includes the exotics.

 

It would then cease to be an rx and become an mx. you just described an mx-5 Rf mazdaspeed edition.

 

I agree the rotary has a lot of disadvantages compared to the best piston engines (which Mazda doesn't make either btw).

I also am frustrated that Mazda has refused to exploit the rotaries actual advantages (compact dimensions and low weight) to their fullest.

Current crash standards and consumer demand for big cars does not suit the rotary.
Meanwhile, Mazda has done an amazing job getting the Roadster/Miata/MX-5 back to its lightweight roots.

A 350lb 400hp 16X rotary in a 2,400lb hard top ND chassis for $40k-50K would be an exotic car killer and the rotaries advantages in that chassis could mitigate its ho-hum gas mileage (if Mazda can improve it to ho-hum standards from abysmal).

Even a turbo 4cyl engine would be taller and ~100lbs heavier- which would affect such a car.

Again, doesn't look like the direction Mazda is going with the rotary, so I have to grudgingly agree with you.

I am very glad Mazda is making a new rotary car, but will it be relevant? I guess we will see.

With the all new modern tooling and if Mazda revises some processes rotary engine production could at least be quite cheap/fast compared to past rotaries using the old late '60s tooling/processes/assembly.

 

Mazda working on "fundamental and structure issues of rotary engine", no electrified RX model

2016 LA Motor Show: Mazda rotary engine to return in 2019

- So, Mazda 2 EV in 2019, likely with the RE range extender option.
- As for the Rx, it will come back, but no timeframe given (as usual ).
- “completely new technology” for the new generation SkyActiv rotary engine, with the ignition system one area of focus. HCCI?
- No decision had yet been made on whether to employ turbocharging. Maybe Mazda is unsure whether to embrace the high-revving nature of the rotary with an NA engine or whether to go for the "safer" option of using a turbo. One hopes that both approaches are being developed in parallel for now.
- No hybrid for the new rotary, at least initially. Maybe at a later time when regulations become more restrictive and if battery technology improves enough

One quote says "Turbochargers is one of the possibilities for our smaller rotary engines". Does it mean that there are also larger rotary engines?

 

Longer and taller, yeah, heavier, maybe not...

I've been saying for a while, somebody should make a compact, short-wheelbase, lightweight 50/50 sports car with a very low hood/cowl with a compact V4.

 

That frumpy RX-9 ain't going to cut it with its RX-8ish revisited body lines. They should just stop now if that's what they plan on rolling out.

 

Someone must have leaked your idea to Toyota and Subaru then, although that is a boxer. They still managed to make it front heavy though :/
V4 would sound better. - especially if they can make it rev to 11.

 

Boxer doesn't really work all that well in an FR car. To clear the steering the flat-4 engine is actually positioned quite forward in the car. A V4 could have been positioned further aft on the same wheelbase.



I'd be happy with 8k 2.5 liter or 9k 2.0 liter, but of course 11k would be fine!

 

i think a really narrow angle v4 would be pretty optimal. you have 2 cylinder head so emissions are feasible, but its shorter than a normal engine, but without the width of a regular V engine.

plus you can maybe still use 2 cams, instead of 4, etc, so it may be a bit lighter.

kind of like a 1930's Lancia

 

A VR4 engine? Like half a VW W8?

 

Or 2/3 of their VR6