projekt

here

projekt

ok, i'm on dial up, it sucks. pity me

Sanspistons

Hmmm; back to the "future of rotaries" topic...

I think that the stratified charge "diesel" rotary may be the only hope for the future; even with it's low rpm drawbacks in makes emissions on the order of diesels not gasoline engines. And maybe supercharging will make up for the rpm deficit.

As far as the trailing volume problem; has anybody tried multiple sparkplugs SIDE BY SIDE in this area? Maybe a non-existant combustion chamber (no dish at all) with say six spark plugs in two rows? As somebody said, their's so much info out there it's hard to find answers...

On a lighter (?!) note; even diesels are being legislated out of existance by the over-zealous CARB and it's me-too cronies. I say when the engine put's out LESS emissions than it takes in it's an air purifier!! Don't think these people will stop until only electric cars (powered by those hideous coal plants!) are left. Let's hope not.

Sanspistons for a cleaner, faster ride!

projekt

no one cares anymore?!

Hamza734

Stratified charge direct injection is definetly the way to go. Do some digging and you'll find there's a good NASA research paper on it from the late 70's... Also, higher compression ratios are the wave of the future. I remember something from Yamamoto book about
the maximum theoretical (as defined by the rotor and housing dimensions) CR for a 13B was something like 30 to 1 (!?). Obviously it can't be that high, but I think 12 or 13 to one is doable.

peejay

A decently engineered combustion chamber will have "automatic" stratified charge... IE if you get the swirl right and the spark plug is decently placed (or engineer the swirl to be around the spark plug) then the mixture is nice and easy to light near the plug and gets leaner and leaner the further away you go. Then you don't need to dump in so much fuel, so BSFC goes way down...

projekt

that and turbo diesels already run compression that high or higher. and the rotary CANT make the same torque as a piston engine because of the angle of force and the rotary's internal gearing

Hamza734

Absolutely true. But by stratified charge, I meant continual operation at lambda values greater then 1 (i.e. an AFR of GREATER then 14.7 to 1). The latest Bosch EFI can do this. Does wonders for fuel economy...

The NASA paper talks about a stratified "economy" mode for rotaries...I'll try track down the number.

-H-

Hamza734

Internal gearing

Typical CR for a modern diesel is around 20 to 1. That's where there efficience comes from. I think the trick is that Diesel is considerably less volatile then gasoline. However, I think the energy content of gasoline is actually higher.

Steel

aobut the oversquare/undersquare argument. If you want real high revving, look at modern i4 motorycle engines, or F1 engines! they are ridiculously oversquare.

projekt

the CR is insanely high because on the compression stroke there is no gas in the cylinder. only a moment before tdc is the fuel injected and the CR gets to it's peak and combustion occurs.

diesel has more potential energy, it's less refined from the original grude.

the rotary has an internal gearing of 3:1 this reduces the torque output (the way a tranny multiplies it, but in reverse)

daveo

1. Redsign it from scratch.

2. Make all moving parts out of ceramic material, or find a way to coat them, for ecample bearings, apex seals, housings...

3. Use hydrogen/alchaol for fuel.

4. Use NO oil, it wont need it

5. no spark plus as such, make the "plugs" part of the rotor and housing, place a strip of metal across the face of the rotor(in the recess), and across the face of the housing.Just gotta find damnd good metal... or make it a diesil, it will have enough compression...

6. Use the PP design from the renesis, with no port overlap(no boinger can do that)

(yes u can use cermics like this, allready tested in boingers)

Now the problems of low compression, burning oil, having a recess that the apex as to go past(that lowers compression)

The redline will be serioiusly hi

neptuneRX

well, after spending about... 1hour reading all of what everyone posted. I have a two prong reason for believing that RE will be around for a long time. Here it goes:

1) from a business stand point alone, why would mazda spend any more time and money on the RE (RX8) if they didn't intend on producing the engine anymore? They didn't bring back the RE because of the daily email and letters I send them. Or because there are crazy people like you and me that choice to pour money and hours into our cars. Mazda needs to making money, anyway they can. Selling RX8s isn't a hugh money making venture for them. Infact, I'm willing to go as far as to say, that they actually loose some money on the RE. However, having said that, I think Mazda, as well as all the other motor companies understand that oil isn't going to be around forever, and even at that, oil prices arent going down. They are going up. If consumers can afford to drive daily the sales of cars is going to fall. To counter this, GM, Ford, Toyota, Honda, and everyone else is venturing into Hydrogen powered cars, and/or electric assisted cars. Again from a business stand point, Hydrogen is grossly abundent, once the techology is cheaper it will a be a cheap process to fuel Hydrogen cars. Now many will argue that the techology is too expensive to make Hydrogen a resourceful source of fuel, but if you look at market trends in electronics, prices have fallen. The top of the line Personal Computer in 1995 for home purposes might run someone between 4-5k. Today, a top of the line PC might run high 2k. Same is true with TVs, DVDs, etc. As techology progresses it becomes cheaper. And eventually Hydrogen will get to that point.

2) From a mechanical standpoint, I don't think there is a problem with the RE design. Some of you are saying it has alot of efficiency problems. Remember the RE has maybe 30moving parts from intake to power stroke, as where the modern piston engine has atleast 60 that I can think of, and maybe more... alot of the energy deviried from burning the gas is lost in mechanical motions. The only reason piston engines are more fuel efficient is because of the large R&D dollars poured into it. To make this a bit shorter, I think mazda is betting on the RE to be the leading engine in Hydrogen fuels, and if they can get as much R&D in on it before Hydrogen becomes readly avalibably they might be able to sell it on being the most Hydrogen fuel efficient engine. But frankly in my opinion, you can't teach old dogs new tricks. RE and Piston engines even turbine Jet engines were the era of Fossile fuels. A new age is coming.... thus new engines, new concepts, new problems. The RE isn't gonna be gone in a few years. But eventually, sooner then later both the piston and RE will be a thing of the past

andrew lohaus

everyone misses the point on hydrogen.

IT DOES NOT REDUCE OUR DEPENDANCE ON FOSSIL FUEL.

currently hydrogen is refined from crude oil. yep crude oil. so in a way it is realy no different than gasoline, just cleaner. and when you factor in the energy required to refine it from crude, it is no more effecient.

the only way hydrogen can become the fuel of the future is if it is derived from water through electrolosis, the electricity for which coming from renewable resources.

dont buy the lie that hydrogen alone will solve all our problems. ever notice why no one talks about a hydrogen/oxygen powerplant??? thats because they know its ineffeciant and only a good means of STORING energy. not a direct source in and of itself.

peejay

So did I. if the mixture is only 12:1 or so near the spark plug, and leans out as you get further away, total air/fuel ratio will be much leaner than stoich.

Picture swirling a cup of tea with tea leaves in it. The tea leaves go to the center of the cup. Same principle.

BTW - Whoever said rotarys have internal gearing isn't the world's deepest thinker. That's like saying piston engines have a 2:1 gear ratio on the camshaft for reduced parasitic drag.

peejay

And the benefit would be?



Hydrogen is a dead end since it is so difficult to store. Alcohol is a nightmare fuel unless you live in a bland climate so you don't get to discover alcohol's "entertaining" properties in cold weather, or if you don't care about the *nasty* byproducts it generates when burned in an engine (turns the oil into a corrosive), or if you don't mind that the poor BTU content means fuel economy is terrible compared to gasoline. And then, of course, are the political problems: Oil spilled floats on water. Alcohol spilled mixes with water. Ethanol is a no-no because the BATF is very leery about large quantities of ethanol flowing around. I assume that you like the idea of alcohol because it's "renewable" - well, methanol is typically generated from natural gas right now. It'd be even more expensive were it generated from biomatter.



Why not? Your little zero friction, zero heat expansion ceramic fantasy?



Very old idea. Doesn't work too well, since you can't adequately control timing. Most recently, SAAB was playing with it, and touting the horrible spark gap as a "benefit". I guess the 9-5 is chock full of "road hugging weight" as well...



Lots of boingers have no overlap. In fact, almost all newer boingers have no overlap. That's why they idle so glass-smooth. They have to idle glass smooth because emissions is so incredibly tight right now that oftentimes the cars have to be cleaner than the ambient air. Unfortunately, without any overlap, you can't run long-duration camshafts without opening the exhaust too early or closing the intake too late, killing your midrange power from bleeding off vital cylinder pressure at the beginning of compression/end of power cycle. With a hefty amount of overlap, you can have long duration cams, and still close the intake port at a decent time and open the exhaust port at a decent time. The downside is that very low speed and low load running suffers. That's why more and more engines have variable cam timing - they can run nice long duration cams for good flow, spread them out at idle so it idles smooth, then when you put your boot in it, it can tighten up the separation angle so that the intake closes and the exhaust opens at a decent enough time.

And the RX-8 engine does not have peripheral ports. That is the whole point - it has side ports for exhaust as well as intake. And that's why it sucks, from a performance standpoint.



I assume you're referring to not needing any oil. I've never heard of ceramic engines being developed for runnign without oil, just running without coolant. The idea being that the ceramics can handle the higher temps better than iron or aluminum, so the engine can run REAL hot so there is less energy lost to the cooling system, because there wouldn't *be* a cooling system.

Somehow, you only heard about them for a few months, and you never heard about any kind of durability testing...



Those are minor problems compared with the major issues at hand, namely awful combustion efficiency and awful heat-loss issues (internal surface/volume).

And that is a good thing why?

projekt

that would be me and thanks for being an idiot. the reason i stated the internal gearing was in reference to rotaries lacking torque. i'm aware that it's a necessity as i've argued many times before. please read and think before you post.

andrew lohaus

how many times does it have to be covered that if you want more tourqe JUST STICK A SHORTER FINAL DRIVE ON THE DAMNED THING!!

peejay

Rotaries lack torque because of poor thermodynamics. See hot loud exhaust and the requirement for super big cooling systems. That is combustion heat being thrown away via the exhaust system and radiator, instead of being used to propel the car.

Most of the "lack of torque" complain is lack of *low end* torque... which is mainly a function of poor sealing at low speeds (esp. with 1 piece seals) and port timing that would be deemed "outrageous" as a boinger's cam timing, even after figuring that 270 degrees of e-shaft timing = 180 degrees of crank timing and adjusting accordingly (rotary TDC to BDC is 270 degrees, boinger TDC to BDC is 180 degrees)

The internal gearing has zero, zilch, nada, nothing to do with engine output, it's merely there to keep the rotors timed in the housing.

"please read and think before you post" indeed.

Hamza734

As usual Peejay's right

Nearly half of the the energy of a rotary is shot out the exhaust. This is one reason why turbo's are such a great compliment to rotaries. The cooler the exhaust, the more thermodynamically efficient an engine. This has been the driving force in turbine development in the last forty years.

As for the torque issue, port timing aside, there is one major reason for our cars being low on torque: the 13B is effectively a short-stroke engine. To generate more torque, you need a larger lever arm. (tau) = F x R

peejay

Well... I don't believe in the "longer stroke = more torque".

Torque is force on a lever, right? So you can increase torque bu either making the lever longer, or making more force. A larger diameter piston has more surface area and thus has more downward force, so would generate more torque. For the most part, displacement is displacement. (Unless you're looking to get that final Nth degree of efficiency out of the engine in which case certain dimensions become important)

andrew lohaus

no. it wont give you more engine tourque, but a shorter final drive will give you more WHEEL torque. and thats about as good as its gona get for us.

peejay

Until you upshift.

projekt

then why do transmissions multiply torque? this same gearing setup would lead me to believe that the gearing of the rotors effects the torque output as well.

neptuneRX

fuel engines are finished once someone makes a high out put battery that can be quickly recharged, and last days on end.