What does it mean for an RX8 to be rotory powered?

[StageLeft]

Am I really the only one who figured out Segalore was being sarcastic?! Come on people, I think you all were up too late last night

 

Boy do I see a lot of speculation, erronious facts and just plain falsehoods in this thread.

Fact ;

The rotary engine was developed in Germany by Dr.Wankel

Fact :
Oil seals are not the cause of oil burning in earlier rotaries, the Apex seals and cast iron side seals were at fault

Fact ;
Air was pumped into the exhaust, not gasoline to clean up it's emissions

Fact ;
Oil is mixed with fuel to lube the Apex seals and cast iron side seals

Fact ;
The rotary is not fuel efficiant, it is horsepower to weight efficiant (as was mentioned before, the large combustion chamber and exposed surfaces reduces it's thermal efficiancy)

Fact '
The rotary has a much lower coeffeciant of internal friction compared to piston engines

Fact ;
There never was nor never will be a fuel system that transforms a internal combustion engine into a thermally and fuel efficiant device
The modern internal combustion engine cannot produce "200 MPG" because 85% of the heat generated by combustion is not used, it goes out the tailpipe and cooling system.

There are many good books on the subject, I suggest putting down your mouse, shutting off your PC and spending some quality time at the library.

 

[SagaLore]

Originally posted by: ElFenix

Originally posted by: SagaLore

Ummm no, it is not anything you've read or heard. My physics teacher was not telling me an urban legend.

:Q

note: there is not enough energy in a gallon of gasoline to get a car to move 200 miles

Considering that gasoline automobiles are only 10-15% fuel efficient, I would have to disagree.

 

[SagaLore]

Originally posted by: Eli

Originally posted by: SagaLore

Originally posted by: Skoorb
In regards to better or worse I'd say that it's pretty clear that, overall, it's an inferior engine. There has been many years to research and "perfect" (within reason) the rotary engine and mazda remains the only manufacturer to put one in their consumer vehicle. In fact until the new RX8 they weren't even using rotaries for a while (since RX7 had stopped production for a while). There is obviously some novelty marketing going on with the rotary engine. A person can buy an Rx8 and know that nobody else is buying a new car with a rotary, so that's definitely an attractition. Yes, it's lighter than a conventional, but hardly any cars use them, whether you're talking about a commuter car, a race car, or a drag car. They just aren't as good, although they are not CRAP and they do still work decently and can be made at a fairly competitive price, as mazda has done with the RX8. Objectively I still think that the 350z would be a better bang for buck, but the rotary is different which makes it fairly neat.

LIAR! :|

It's just underdeveloped, that is all. The piston engine has been by far longer researched and built, way back since steam engines. The engine market still has a quite a lot of propoganda built into it - my old high school science teacher had a brother that patented a new fuel system that gave engines (back in the day) 200 miles to the gallon, but an engine company bought it off him and then shelved it permanently.

coughcoughhackbullsh!tcoughhackburp

Damn cough.


Anyway, You would understand why this is not possible(with todays engine technology) if you understood the fact that energy is neither created nor destroyed; it merely changes forms. Gasoline only contains a certain ammount of energy. Coincidentally, it takes a fininte, known, calculable ammount of energy to propel an object.. in this case a car, at XX miles per hour.

I suppose if you made an engine that was more thermally efficient, you could significantly improve on todays MPG numbers.. but a simple fuel delivery modification isn't going to do it.

Sorry.

Well it was more than just fuel delivery. It was a modification to the entire engine.

 

[SagaLore]

Originally posted by: Roger
Boy do I see a lot of speculation, erronious facts and just plain falsehoods in this thread.

Fact ;

The rotary engine was developed in Germany by Dr.Wankel

Fact :
Oil seals are not the cause of oil burning in earlier rotaries, the Apex seals and cast iron side seals were at fault

Fact ;
Air was pumped into the exhaust, not gasoline to clean up it's emissions

Oh okay. It's been awhile since I looked into this subject.

Fact ;
Oil is mixed with fuel to lube the Apex seals and cast iron side seals

Fact ;
The rotary is not fuel efficiant, it is horsepower to weight efficiant (as was mentioned before, the large combustion chamber and exposed surfaces reduces it's thermal efficiancy)

Fact '
The rotary has a much lower coeffeciant of internal friction compared to piston engines

Fact ;
There never was nor never will be a fuel system that transforms a internal combustion engine into a thermally and fuel efficiant device
The modern internal combustion engine cannot produce "200 MPG" because 85% of the heat generated by combustion is not used, it goes out the tailpipe and cooling system.

One word: Ceramics.
[/quote]There are many good books on the subject, I suggest putting down your mouse, shutting off your PC and spending some quality time at the library.[/quote]

I must make a correction - the KKM is the current wankels, the DKM was Wanke's preferable design. I got them switched.

 

Ceramic coated rotors and combustion chambers are not going to give a "wonder engine" that get's 200 MPG, ceramic coating does improve thermal efficiancy but only by 2.5% at best, you are still dumping a huge amount of heat out the exhaust and cooling system period.
On top of this you have to drive a oil pump, water pump, not to mention all the frictional losses inherent in any internal combustion engine.
Please base your statements on facts, not heresay or rumors, I don't care if your teacher told you that the moon was made out of cheese, facts are facts and here are some interesting ones ;

Fact ;
It is impossible to increase the thermal efficiancy of a modern gasoline burning internal combustion engine by anymore than 5%.
Why ?
How do you propose to reclaim all the lost heat that escapes in the current design of internal combustion engines ?
Yes, Isuzu has manufactured in the past a diesal engine that had no cooling system nor oil system, it was manufactured out of ceramic parts, it had a thermal efficaincy of 22%, unfortunately it cannot withstand it's operational temps for long periods of time, as I recall, it lasted for 25 hours before self destructing.
Our current materials that are available are not up to the task, now remember that this engine only achieved 22% thermal efficiancy, there was still a very large loss of heat out the exhaust, as it stands, there is no way that the current design of engines can come anywhere close to the thermal efficiancies needed to come close to 200 MPG.
What is needed is a new engine design that extracts all the heat from combustion before exhausting the waste products of combustion.

Now do you understand that your teacher is full of bull ?

Fact ;
Frictional losses account for 15% of energy lost (Pistons, cam(s), crankshaft bearings, rod bearings, piston pin etc. all have reletively high amounts of friction), this example is a "modern engine" with the best lubricants available.

Fact ;
No matter how well you design a combustion chamber, there will always be unburnt hydrocarbons thus leading to more ineffeciancy.

Fact ;
Only 20 % of the heat generated actually goes to expanding the gasses which propel the piston down it's bore, the rest is radiant and thermal heat being disapated, this fact alone prevents high efficaincy.

 

[Slammy1]

My gues would be a hybrid powered car (gas and electricity). You could get 200 MPH with todays tech that way. This is still going?

 

[wasssup]

how reliable are those old RX-7's by now? (the early 90's FC's, non-turbo)? sounds like a nice cheap way to get into the rotary club, but i dunno how those engines stood the test of time..

 

[Eli]

Originally posted by: wasssup
how reliable are those old RX-7's by now? (the early 90's FC's, non-turbo)? sounds like a nice cheap way to get into the rotary club, but i dunno how those engines stood the test of time..

They are reliable as long as you take good care of them.

 

[Eli]

Originally posted by: SagaLore

Originally posted by: Eli

Originally posted by: SagaLore

Originally posted by: Skoorb
In regards to better or worse I'd say that it's pretty clear that, overall, it's an inferior engine. There has been many years to research and "perfect" (within reason) the rotary engine and mazda remains the only manufacturer to put one in their consumer vehicle. In fact until the new RX8 they weren't even using rotaries for a while (since RX7 had stopped production for a while). There is obviously some novelty marketing going on with the rotary engine. A person can buy an Rx8 and know that nobody else is buying a new car with a rotary, so that's definitely an attractition. Yes, it's lighter than a conventional, but hardly any cars use them, whether you're talking about a commuter car, a race car, or a drag car. They just aren't as good, although they are not CRAP and they do still work decently and can be made at a fairly competitive price, as mazda has done with the RX8. Objectively I still think that the 350z would be a better bang for buck, but the rotary is different which makes it fairly neat.

LIAR! :|

It's just underdeveloped, that is all. The piston engine has been by far longer researched and built, way back since steam engines. The engine market still has a quite a lot of propoganda built into it - my old high school science teacher had a brother that patented a new fuel system that gave engines (back in the day) 200 miles to the gallon, but an engine company bought it off him and then shelved it permanently.

coughcoughhackbullsh!tcoughhackburp

Damn cough.


Anyway, You would understand why this is not possible(with todays engine technology) if you understood the fact that energy is neither created nor destroyed; it merely changes forms. Gasoline only contains a certain ammount of energy. Coincidentally, it takes a fininte, known, calculable ammount of energy to propel an object.. in this case a car, at XX miles per hour.

I suppose if you made an engine that was more thermally efficient, you could significantly improve on todays MPG numbers.. but a simple fuel delivery modification isn't going to do it.

Sorry.

Well it was more than just fuel delivery. It was a modification to the entire engine.

C'mon now. There are teams of highly capable engineers working to design and build engines for thousands of manufacturers around the world.

If you think anybody has the power to squelch engine design technology, I do believe you are a fool.

The only way you're going to significantly increase the thermal efficiency of an engine is to make it out of material that can operate at temperatures of 6-7-800 degrees. Along with this, we need a lubricant that is also stable at these temperatures.

We do not have such technology. Our current metals and alloys dislike being over 500F. Even the CHT of air-cooled engines should never go above 500F.. so I would assume that the CHT of an auto engine would be lower. This temperature is also the breakdown point for our best synthetic oils.

If you don't see why it is not possible yet.. oh well.

 

[StageLeft]

Originally posted by: wasssup
how reliable are those old RX-7's by now? (the early 90's FC's, non-turbo)? sounds like a nice cheap way to get into the rotary club, but i dunno how those engines stood the test of time..

Well let's just say I hope you have a ready savings account to cover repairs

My gues would be a hybrid powered car (gas and electricity). You could get 200 MPH with todays tech that way. This is still going?

There was a "car" I think that somebody got at least 200 mpg with that I was watching on tv. Of course this "car" was really just a seat on wheels and it was run around a track at low speed. Really just a science experiment to see how little gas per mile driven one could get. Current hybrids will need to be 4X as efficient to get 200 mpg.

 

[Demon-Xanth]

Part of the HP/L deal that is often NOT mentioned, is that the Rotary engine is in two or three stages of the combustion cycle at the same time. This is why sanctioning bodies will multiply thier displacement by 2 or 3 to put them in the appropriate class.

How they can be in more than one stage:
With the rotor having a point half way between the intake and exhaust ports, it is on the equivilent of the exaust stroke, intake stroke, and the compression stroke at the same time. In 1/6 of the rotation, it will be halfway between the intake and exhaust strokes and will be going through the compression and combustion strokes. The 3 sided rotor is the equivilent of three pistons, but the size is only counted by measuring one of them.

 

[Amused]

I heard if you use a Wankel Engine too much, you'll go blind!

 

[Eli]

Originally posted by: Amused
I heard if you use a Wankel Engine too much, you'll go blind!

:Q

 

[Zenmervolt]

Originally posted by: Eli

Originally posted by: FreshPrince
Ok, got done reading that article...looks like it's less efficient than conventional piston engine. Why did Mazda go with this engine?

I think you've got that backwards.

It is much more efficient than a piston engine. Read how a conventional 4-cycle auto engine works, then read about 2-cycle engines, then read the rotary articles again.

It is not more efficient in terms of power for fuel burned. It is only more efficient in terms of power per unit of displacement.

ZV

 

[SagaLore]

Originally posted by: Roger
Ceramic coated rotors and combustion chambers are not going to give a "wonder engine" that get's 200 MPG, ceramic coating does improve thermal efficiancy but only by 2.5% at best, you are still dumping a huge amount of heat out the exhaust and cooling system period.

As long as you can keep the heat from self-destructing the engine, you can do away with the cooling system and put the heat to more use. Ceramics are the key to prevent the alloys from melting.

Fact ;
It is impossible to increase the thermal efficiancy of a modern gasoline burning internal combustion engine by anymore than 5%.
Why ?

It's also impossible to fly to the moon. Oh wait...

How do you propose to reclaim all the lost heat that escapes in the current design of internal combustion engines ?

Extended expansion stroke. Also water injection.. er... nevermind, been down that path before.

Fact ;
Only 20 % of the heat generated actually goes to expanding the gasses which propel the piston down it's bore, the rest is radiant and thermal heat being disapated, this fact alone prevents high efficaincy.

I agree. So what is your point? They're not permanent obstacles...

 

[Demon-Xanth]

The world's most efficient internall combustion engine is a diesel that pulls in about 50% efficency, it's available in 6, 10, and 14 cylinder configurations. As an added bonus, there's ladder rungs in the engine block!

Edit: LINK!

 

[Eli]

Originally posted by: SagaLore

Originally posted by: Roger
Ceramic coated rotors and combustion chambers are not going to give a "wonder engine" that get's 200 MPG, ceramic coating does improve thermal efficiancy but only by 2.5% at best, you are still dumping a huge amount of heat out the exhaust and cooling system period.

As long as you can keep the heat from self-destructing the engine, you can do away with the cooling system and put the heat to more use. Ceramics are the key to prevent the alloys from melting.

Fact ;
It is impossible to increase the thermal efficiancy of a modern gasoline burning internal combustion engine by anymore than 5%.
Why ?

It's also impossible to fly to the moon. Oh wait...

How do you propose to reclaim all the lost heat that escapes in the current design of internal combustion engines ?

Extended expansion stroke. Also water injection.. er... nevermind, been down that path before.

Fact ;
Only 20 % of the heat generated actually goes to expanding the gasses which propel the piston down it's bore, the rest is radiant and thermal heat being disapated, this fact alone prevents high efficaincy.

I agree. So what is your point? They're not permanent obstacles...

His point is that the technology doesen't exist today, and didn't exist in the 60s and 70s, to overcome these obstacles. Therefor, your 200MPG cite is discredited.

Originally posted by: Demon-Xanth
The world's most efficient internall combustion engine is a diesel that pulls in about 50% efficency, it's available in 6, 10, and 14 cylinder configurations. As an added bonus, there's ladder rungs in the engine block!

Yep.. I was going to mention this to Roger. I'd say "ladder rungs in the engine block" is a little of an understatement. The engine is simply unbelievable.

How do they go about making the giant components of such a thing?? Are there engine lathes that big? :Q

 

I agree. So what is your point? They're not permanent obstacles...

My point is you are full of sh!t, yes they are permanent obstacles in a piston engine, no matter what you do or what you manufacture it out of, there is no way in hell you are going to increase the piston engines thermal efficiancy past 50%, it just can't be done because of it's inherent ineffeciant thermal qualities.

 

[SagaLore]

Originally posted by: Eli
His point is that the technology doesen't exist today, and didn't exist in the 60s and 70s, to overcome these obstacles. Therefor, your 200MPG cite is discredited.

Well 200mpg might be a bit of an overexageration.

 

[apoppin]

Originally posted by: BadgerFan
Rotaries aren't in many cars for the same reason we don't use large chainsaw engines. While they are compact and powerful, they tend to be fuel in-efficient, noisy, and are heavy polluters. They also burn lots of oil. Now before any of you nazis jump on me I realize this is over simplified, but for a layman, I think it is a good answer.

That's the really OLD rotaries.

My 1976 RX5 (Cosmo) has a 13B rotary engine - 1.3 L and produces almost 300hp without turbocharging.

The only problem was with needing much smog controls. They are NOT noisy with headers or a muffler and mild polluters with emission controls and FAST . . . excellent gas mileage FOR a "muscle car".

And your's is OVERsimplified and a bad answer.

 

[SagaLore]

Originally posted by: Roger

I agree. So what is your point? They're not permanent obstacles...

My point is you are full of sh!t, yes they are permanent obstacles in a piston engine, no matter what you do or what you manufacture it out of, there is no way in hell you are going to increase the piston engines thermal efficiancy past 50%, it just can't be done because of it's inherent ineffeciant thermal qualities.

You are bitter. :lips:

 

My 1976 RX5 (Cosmo) has a 13B rotary engine - 1.3 L and produces almost 300hp without turbocharging.

Really ?

Care to rephrase that statement ?

 

You are bitter.

You are not too bright.

 

[Eli]

Originally posted by: SagaLore

Originally posted by: Eli
His point is that the technology doesen't exist today, and didn't exist in the 60s and 70s, to overcome these obstacles. Therefor, your 200MPG cite is discredited.

Well 200mpg might be a bit of an overexageration.

It's more than just that. Like I said, there are teams of highly skilled engineers working to design our engines. They are made for thousands of companies world wide; from small to large. You have to be a fool and a conspiracy theory nut to believe that innovation has been stifled. The oil companies are no saint, but it simply wouldn't be possible for them to "buy out a patent" and shelve it. You can't keep stuff like that secret for long, someone else is going to discover it.

Engine technology and knowledge has improved greatly from the 60s and 70s... we are still learning what happens inside the combustion chamber. It may be 150 years old, but it is actually quite complex on an energy level.

<--- wants to go to school and become an (I.C.E. specific..) Engineer.

Then I'll design my own engine, and put it in my Civic. :Q lol....