ericgrau

iTrader: (1)

There have been similar threads on this. I'm asking something related, but I think different.

Mazda is trying to get the rotary engine to run on 4 rotor faces (2 per rotor) for mpg, similar to a V6 running on 4 cylinders. It avoids the problems from running on a single rotor, such as no lubrication to the unused rotor. Problem is air is still going to the unused rotor faces. So the exhaust mixture becomes very lean, and the catalytic converter won't work properly. I believe this would lead to a lot of NOx. Or worse: not enough fuel to heat up all that air going to the cat, which means the cat won't work at all.

But let's say you don't have a cat. Would it be possible to tune the engine to skip a couple rotor faces, using a Haltech perhaps? Has anyone tried this?

ddub

Where did you get this information exactly? And that would make it kind of odd in my opinion.

locketine

That trick doesn't change fuel economy that much for v8's, which would probably benefit the most. They gain maybe 5% to their mpg, which isn't much when you're getting numbers very similar to ours. The unused rotor in a single rotor configuration would still be lubricated... lubricant is injected based on rotation, not fuel usage.

I guess it would still be interesting to try though. The best method would simply be to fire every other face so all the rotor faces get an equal amount of work. ofcourse running an engine on the verge of detonation would net you the best mpg regardless of engine configuration. Manufacturers don't do this so they don't have to deal with engines going PING!

NOPR

hmm.... that could be tricky. its a neat idea, but im not sure if the haltech could be tricked to fire like that. it would have to be fire, fire, wait, fire, fire, wait, etc. and the same thing with the fuel injection. the only way i can see to do this would require reprogramming the ECU's most basic settings, which means sending it back to the homeland if its an e6k, or reprogramming it yourself if its an E8. even still, it would be tricky and im not sure how you could do it. making in an on off switch or an automatic thing that happens during cruise though... i doubt that thats possible. maybe someone smarter/more experienced can chime in.

NOPR

the fuel is a key part of the lubricating because the oil on slightly drips in, and is dispersed throughout by mixing with the fuel. thats just what i remember from last time this came up, perhaps someone can elaborate.

i dont think it would be on the verge of detonation. the o2 sensor in the exhaust would read lean, but each combustion would still be 'tuned'. the one rotor face that isnt firing... well, it isnt firing, so i dont see how it could detonate or pre-ignite. you do have a point about firing every other face, i didnt even think about that. firing like i described earlier would only hit the same two faces over and over, but would that be enough to lubricate the rotor?

unW7WZ

Just a thought, but lets say, you only had one rotor. Like divide 1300cc by 2. 650 cc engine with one rotor. I know its not the same, but Mazda did a plethora of tests on the wankel engine in the '60s. With one rotor, the engine has to fight an imbalance at rpms lower than 1200. When Mazda tested this, they found that with one rotor the torque fluctuated erratically. This lead to the design of the 2 rotor engine. They tested all the way up to 4 rotors (the 787b engine is a good example of 4 rotors). There are good examples of 1 rotor wankel engines in motorcycles ( the RE-5 from suzuki is a good example of this. Unfortunately, they are rare as hell). My assertion is that as balanced as it could be, it would still be slightly off, causing much vibration. Just a thought, and I'm probably waaay off base. Sorry for the tangent. All I was trying to convey is why Mazda dropped the only engine they dont build ( single rotor engines. I know you argue that this is why they would use a 2 rotor system, but if you have ever felt an EXTREMELY low idling 2 rotor engine running-- im talkin 300-400 rpms-- its torque map would be all over the place, thus a massive vibration. ) one rotor systems is because the vibration at lower rpms ( drop a rotor and I would be sure at 1500 rpms vibrations would win out) is soley due to the fact that a balance must be reached with the rotation of the e-shaft. 6 sides, fired accordingly= lower rpm balance. 4 faces, fired accordingly, would be slightly imbalanced, and necessary accomidations that would need to be made to balance it would destroy the 6 face balance. Not saying it isnt possible, just saying, unfeasible. I can't imagine a world with a rotary VTEC engine.


Edit: Havent heard of very many v6s running on 4. Then again Im behind times. I thought only v8s could accoplish this. 2 pistons on each side balances it out. For instance northstar, or whatever Dodge calls theirs, and Ford's power on demand. I don;t really listen, IMO if you buy a V8, you should be getting a V8, not a half-time V8/4cyl motor. Just an opinion.

Also, under load, the o2 sensor doesnt read, (is that right? not sure,. but I thought it only made a diff at idle. Maybe I'm thinking of something else. For real, does it read at higher than idle?. Anyway) and ev en then, the engine wouldnt be balanced. The closest I would think this could work is if it alternated firing: for instance, each rotor fires 4 times, thus hopefully counteracting the balance to some extent. Still, a redesign of the entire engine would be necessary. The rotors would have to be a sizeable difference, or something so they spin slower or faster i n relation to each other. Balance is everything, and fighting imbalance makes the whole plight redundant. I hope someone can shed some light on my blabberings. This is a forum, and anyone with ideas should chirp in, and prove the other people wrong. All I have said is strictly my thoughts, and not fact.

ericgrau

iTrader: (1)

VTEC is something different. It makes the valves open earlier at higher rpms for maximum power, while operating normally at lower rpms for best chamber sealing for mpg & power. The RX-7's 5th & 6th ports do the same thing, letting in intake air earlier at higher rpms.

That's a good point that asian cars don't seem to turn off cylinders too often, just american cars. Maybe it's just a gimmick that doesn't help much.

neverknowsbest

the "turning off cylinders" is the big domestic car companies attempt at making their bigger v8powered popular models continue to sell when gas prices are giong up, by attempting to increase gas mileage.. while i dont have any actual figures on this i believe it helps slightly.. u dont see too many import cars doing this because they usually get better gas mileage to begin with, and they are the standard, while the american companies are trying to compete with them.. they dont need to turn off cylinders...

anyway the new cadillac sixteen... even tho i think it may still only be a concept has a v16 producing around 1000bhp i do belive. and under low ropms its only using 4 cylinders, and then when u step on it a bit more its using 8 then at WOT its using all 16 and giving you all 1000hp... or at least thats what i remember reading.. its just a way to compete with cars that get higher gas mileage.

neverknowsbest

and its been a while since ive looked at this but.

http://auto.howstuffworks.com/quasiturbine.htm

its about a new engine design, that seems like an improvement of the rotary, using 4sides instead of 3, anyway read the article and let me know waht u think.. sounds interesting..

neverknowsbest

and imo if mazda made a 4 rotor car that turned off 2 of the rotors much in the same way that the northstar v8s turn off half of their cylinders. and use 2 for fuel economy, and then use all 4 under more demanding loads it would be interesting? plausible? what do u think?

Enthu

iTrader: (1)

I posted about that awhile ago. No one paid attention . Seems liek a good improvement, though it adds some complexity. I woudl think the developers of this would be trying to get Mazda interested since they are the only mass-production rotary company there is.

neverknowsbest

yea, another thought i had just earlier, a friend of mine just bought a new sports bike, and i know that there has been a rotary motor cycle, but why not a 13b on a sports bike? i would think it would be awesome.. apart from the fuel consumption haha.

lupin

iTrader: (3)

how about putting the renesis 13b in the 91 miata body style(gutted interior except for small carpet, no ps or ac). I wonder if that would get better mpg?
I would prolly give up my rx7 for that -_-.

naa, I'd have to take out loans.

R_PROWESS

iTrader: (3)

I don't see how you could do it. the every other side of the rotor concept I mean. every time the face doesnt fire. its still compressing. making the face that does fire work even harder. and so on. it would take much more fuel to over power the compression. at a normal idle you probly would use even more gas let alone powering you down the highway. I dont think it's posible. the only way i can think of is to be able do disconect the 2 rotors at the esentric shaft and have one sit still while the other does the work (maybe even alternate every time its activated), some sort of quick disconect internal electric clutch, not likely.

R_PROWESS

iTrader: (3)

on the other hand i did have this idea... to release the pressure that the free spining rotor would still create, have a large valve between the two spark plugs that only opens when activated. eliminating the rezistance for the rotor that is doing the work... just my idea