Restriction is what creates your pumping loss. They close the valves because the air will act like a spring and when you compress it you get some of that energy back (as you mentioned). Otherwise if the valves or ports can't be closed you would want the throttle to be as open as possible. Look at why diesels have much lower pumping loses than gasoline engines, and why they have to install a throttle in the exhaust to get any engine braking.


Also, if you leave the valves open you have a tendency to pull a lot of oil up past your rings and the absolute last place you want oil and fresh air to end up is in your cat, not just for emissions reasons but also for the fact it'll destroy your cat in a heart beat.


Lastly, cylinder deactivation systems are very rough running and require extra systems in place just to iron that out. If you shut off an entire bank it creates a very noticeable effect every time and snapping the throttle open isn't the quietist either. Add onto that the amount of vibration going through your engine mounts and you'll see why OEMs have starting moving towards active engine mounts just to smooth those beasts out. It gets to the point that it makes a lot more sense to just have a smaller engine and run a turbo on it to get your required power. Why deactivate to 4 cylinders when you can just have 4 to begin with and still make 360hp while passing emissions and getting good fuel economy?


Maybe when everybody has switched over to solenoids for valves the rotary engine will use them on their ports and maybe adopt a shutter like system that can open only part of the port at a time to control valve timing and not have an excessive amount of blow by trapped in the runners between events. Plus it'll allow cylinders to cut out in nicer orders to avoid the sudden change that deactivating a bank has (think of a soft rev limiter). The advantage a rotary would have with shutting off a rotor is that they are very smooth engines to begin with. A downside is that when anything goes wrong with combustion in the rotary you already have that same rotor going through a combustion event plus another intake event about to happen. Instead of just having that cylinder misfire and catching it during that cylinders intake stroke, you already have two misfires in a row before you can compensate.

 

With a 2 or 3 rotor using fly by wire ITBs you can shut 1 rotor off alternating between which one is firing.

My first hand experience is, while using msd on leading there is no noticeable loss in performance by disconnecting trailing which means the trailing plug hole is hurting preformance. I'm currently not using trailing in my rx7 which is safer under boost.

Before Mazda moves in to new tech they need to focus on there existing problems and the problems are simple. Apex seals have gotten smaller over the years, I don't think it takes hi paid engineers to realize it won't last as long. The coils used in the rx8 are terrible and causes the engines to self destruct.

Also I have switched to 4.1gears which helped the car in every way including average mpg of 21mpg. 19.5 with ac on recorded of several months with gas app.

 

I keep seeing all this garbage about 2 spark plugs being a problem...

Please read Rotary Engine by Kenichi Yamamoto. Page 51 4.7.4 "location and number of spark plugs"
1 plug will reduce HC and NOx emissions at the cost of higher fuel consumption to maintain the same level of power. It's not that either setup has any more or less power potential as you seem to imply that it should. More plugs make for less fuel and higher emissions. That's the only tradeoff that was found. The only potential power loss mentioned was at WOT when they tested the trailing plug hole farther in the trailing direction, and this was only caused by the blow back from the apex seal crossing the hole.

Apex seal size has nothing to do with anything other than taking more detonation abuse, however, a detonation on a rotary is a detonation on a rotary. In either case, 2mm or 3mm, you're motor is likely dead depending on the severity. In general, 2mm seals are better because they seal better, and they dissipate heat more quickly. A 3mm seal can warp with a large exhaust port due to the added heat retention. Mazda changed to a 2mm seal for a reason...

As for the ignition coils in the RX8, that had nothing to do with engineering. That was a marketing decision to cut costs on the car even against the best wishes of the engineers.

I'm not sure what's up with all the "internet engineers" that have popped up lately that think they have all the answers, and that Mazda never did their research. Also have to remember that they're making a motor that will "just work" in almost any condition, where enthusiasts are trying to make more power than what they're provided with.

Your "mods" are counter productive in a way... you use a 4.10 to increase fuel economy, then only fire 1 plug to decrease fuel economy while not even addressing the issue of the added blow back from the training plug hole (unless you welded up the hole and resurfaced the housing...). But then you probably should have also adjusted your leading plug location to account for the changed fuel burn characteristics to account for a single plug setup. It's just not an idea that I can get behind, sorry.

I'm not saying that it's wrong to chase more power or try new things, but it's always best to understand exactly what you're doing and why it's beneficial.

I can agree that it may be worthwhile to look into alternating the firing faces of the engine when not under load and cruising at speed on the highway, but I'm not qualified to accurately test something like that. Would be kind of difficult/expensive to set up and prove.

 

Lots of bad information there when it comes to the RX-8.

One line I'll address though:
What do you think "new tech" accomplishes? Trust me, Mazda isn't messing with the "Breakthrough" the guy on the video had. Look at thinner rotors, greater eccentricity, a new method for improving sealing to piston-like levels, all aluminum block, ...PLUS the newer SkyActive suite of technology like higher compression ratios, direct injection, better exhaust design, etc...

Yes the problems are simple, but not the solutions. And returning to RX-7 technology is a move in the wrong direction. It wasn't a solution at all.


And btw, I was making 24mpg on the stock gears just fine. I've hit 27mpg hypermilling it.

 

the shorter 2mm renesis seals did what they needed to do, and they still did better than the 3 piece seals that mazda used from 1986 through 2002.

 

how about this? Why Ceramic Engines?

 

Yes, ceramic components have been considered to be the ideal scenario for performance and emissions for a long time for the rotary. The problem is around production. Ceramic components are very easy and simple to make, as long as the shapes are simple basic shapes. Shapes such as the housings, end plates, and rotors would require extensive tooling to create, and tooling ceramic is EXPENSIVE. Mainly because it is so hard that it just eats through bits, including diamond. Ceramic is ~3 times harder than stainless steel.

There are other factors, but the tooling required is the main problem.

 

I've been thinking about other options. Instead of the same old 2 rotor, what about a "miniature" 4 rotor with a 180-180-180-180 rotor offset so two rotors are firing at the same time. I'm not an engineer. Just stating what makes sense in my own mind. But the 180 offset should help with torque and overall power while the smaller high compression rotors and housing should help with fuel economy.

Again this is just my own speculation. What do the experts think?

 

Seen a video awhile back about Ernie brink breakthrough on the rotary engine. I can only imagine the money involved for testing, at the very least someone taking the risk on one of their own engines. Has no1 tried some of his theories? I've tried looking up the guy only to find that it seems he has dropped off the face of the earth? Why has no1 encouraged/sponsored this guy or why has he not shown to the world that this works? it doesn't/is impossible? Call me gullible, but the thought behind it could take this engine to a whole new level. Found this discussion on rx7 forum Purported Improvements to the Rotary - RX7Club.com


Just a thought. Would love all the insight on this as possible! Everyone who could tell me (and the world) more need reply, please!

 

Yeah, it's been discussed thoroughly.
Google "RX8Club Rotary Breakthrough."
I among many have brought it up after seeing it.
You won't be the last.

 

I apologize. I was searching for threads with the guys name in name, thinking it would appear at least once in the discussion. I read through the other thread last night. It had crossed my mind but obviously didn't give it to much thought, why this guy went onto the show with a hack-job of a rotor and had no results or proof that it could work. That's when givin the thought that it was a marketing ploy. Again the idea behind it is great. Sad it couldn't be implemented into play. Now we know (or at least assume) why Ernie dropped off the map. Too bad. At least it gives us hope for the next revolution of rotary technology.

 

all engines are air pumps pumping air why would you let your rotary engine waste air and fuel past a plug hole inside your engine all that air and fuel wasted never got fire in the combustion chamber to make power for you on the track down side no more flames out tail pipe

 

apex seals are at 3000rpm the e shaft is at 9000rpm my number 1 847 421 3592 ernie brink

 

laser ingtion is on the way soon no bigger than 1.5mm and almost the width of the rotor housing awesome

 

Apex seals are 3000RPM and Eshaft is 9000RPM? What are you talking about?

 

I'd like to know more about the 'rotor housing awesome'. Is there a DIY?

 

Merged with existing thread.

 

a rotor is 3000rpm the tach is at 9000rpm apexs are on the rotor

 

Ernie, I have no idea what you are trying to prove.

Your theories don't seem to be addressing known problems, and are addressing something that Mazda has already played around with a lot.

 

your engine is a air pump when a apexs seal meets a plug hole at 3000rpm it leaks air and fuel inside your air pump engine right out the tail pipe never burned for you power on the track this happens all through the rpms 3 to 1 ratio

 

call me 1 847 421 3592 ernie brink rotarys will spin on

 

Have you addressed the fact that the 13b dimensions have a rotor that is too wide for the flame front to get to the tips?

Have you addressed the thermal expansion rate differences?

Have you addressed the carbon buildup problem?


You are tinkering with something that has a neglible impact while ignoring the major issues.

 

I would be a bit surprised if this is actually Ernie Brink. This guy is barely forming sentences and Ernie seems well spoken in interview..

 

That doesn't really signify much. I have trouble talking in person...

I'm not sure who else would have sought out references to him.

 

He is undoubtably correct about using a small slit for a spark plug opening, this is definitely causing loss of compression at low rpms where emisssions are tested and mpg is effected. Carbon build up would be my first consern and fuel fawling plugs, because there is no place for it to vent once its trapped. I would imagine a small channel made below the opening would allow a bit of blow by that could prevent this from happening. Worst case senario you have to pull a plug and clean it as part of regular maintenance, which isn't good for the automakers but would be better for us tuners.

As for the combustion chamber offset I would like to see the results on that. I am going to be one of the first to try the spark plug mod its brilliant and probably has been over looked or rejected do to carbon build up. Looks to me like someone gave up instead of trying to improve this design.