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Another interesting article about how the rotary is superior to the piston
01-21-08 | 12:45 AM
#1
Thread Starter
Banned. I got OWNED!!!
Joined: Nov 2007
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From: Torrance
Another interesting article about how the rotary is superior to the piston
Heres the link to the full version. I just copied the main part.
http://www.answers.com/topic/wankel-engine
While a four-stroke piston engine makes one combustion stroke per cylinder for every two rotations of the crankshaft (that is, one half power stroke per crankshaft rotation per cylinder), each combustion chamber in the Wankel generates one combustion stroke per each driveshaft rotation, i.e. one power stroke per rotor orbital revolution and three power strokes per rotor rotation. Thus, power output of a Wankel engine is generally higher than that of a four-stroke piston engine of similar engine displacement in a similar state of tune and higher than that of a four-stroke piston engine of similar physical dimensions and weight. Wankel engines also generally have a much higher redline than a reciprocating engine of similar size since the strokes are completed with a rotary motion as opposed to a reciprocating engine which must use connecting rods and a crankshaft to convert reciprocating motion into rotary motion.
National agencies that tax automobiles according to displacement and regulatory bodies in automobile racing variously consider the Wankel engine to be equivalent to a four-stroke engine of 1.5 to 2 times the displacement; some racing regulatory agencies ban it altogether.[4] After Mazda won the 24 hours of Le Mans in 1991 with their 787B car powered by a 4-rotor Wankel engine, the FIA (Federation Internationale de l'Automobile) decided to ban rotary-engine cars from racing in that league.
Advantages
Wankel engines have several major advantages over reciprocating piston designs, in addition to having higher output for similar displacement and physical size.
Wankel engines are considerably simpler and contain far fewer moving parts. For instance, because valving is accomplished by simple ports cut into the walls of the rotor housing, they have no valves or complex valve trains; in addition, since the rotor is geared directly to the output shaft, there is no need for connecting rods, a conventional crankshaft, crankshaft balance weights, etc. The elimination of these parts not only makes a Wankel engine much lighter (typically half that of a conventional engine of equivalent power), but it also completely eliminates the reciprocating mass of a piston engine with its internal strain and inherent vibration due to repeated acceleration and deceleration, producing not only a smoother flow of power but also the ability to produce more power by running at higher rpm.
In addition to the enhanced reliability by virtue of the complete removal of this reciprocating stress on internal parts, the engine is constructed with an iron rotor within a housing made of aluminium, which has greater thermal expansion. This ensures that even a severely overheated Wankel engine cannot seize, as would likely occur in an overheated piston engine. This is a substantial safety benefit in aircraft use since no valves can burn out.
A further advantage of the Wankel engine for use in aircraft is the fact that a Wankel engine can have a smaller frontal area than a piston engine of equivalent power.
The simplicity of design and smaller size of the Wankel engine also allows for savings in construction costs, compared to piston engines of comparable power output.
Due to a 50% longer stroke duration compared to a four stroke engine, there is more time to complete the combustion. This leads to greater suitability for direct injection.
As another advantage, the shape of the Wankel combustion chamber and the turbulence induced by the moving rotor prevent localized hot spots from forming, thereby allowing the use of fuel of very low octane number or very low ignition power requirement without preignition or detonation, a particular advantage for hydrogen cars. Mazda has recently placed a hydrogen-burning rotary engine in one version of its RX-8 sports car and Mazda 5.
http://www.answers.com/topic/wankel-engine
While a four-stroke piston engine makes one combustion stroke per cylinder for every two rotations of the crankshaft (that is, one half power stroke per crankshaft rotation per cylinder), each combustion chamber in the Wankel generates one combustion stroke per each driveshaft rotation, i.e. one power stroke per rotor orbital revolution and three power strokes per rotor rotation. Thus, power output of a Wankel engine is generally higher than that of a four-stroke piston engine of similar engine displacement in a similar state of tune and higher than that of a four-stroke piston engine of similar physical dimensions and weight. Wankel engines also generally have a much higher redline than a reciprocating engine of similar size since the strokes are completed with a rotary motion as opposed to a reciprocating engine which must use connecting rods and a crankshaft to convert reciprocating motion into rotary motion.
National agencies that tax automobiles according to displacement and regulatory bodies in automobile racing variously consider the Wankel engine to be equivalent to a four-stroke engine of 1.5 to 2 times the displacement; some racing regulatory agencies ban it altogether.[4] After Mazda won the 24 hours of Le Mans in 1991 with their 787B car powered by a 4-rotor Wankel engine, the FIA (Federation Internationale de l'Automobile) decided to ban rotary-engine cars from racing in that league.
Advantages
Wankel engines have several major advantages over reciprocating piston designs, in addition to having higher output for similar displacement and physical size.
Wankel engines are considerably simpler and contain far fewer moving parts. For instance, because valving is accomplished by simple ports cut into the walls of the rotor housing, they have no valves or complex valve trains; in addition, since the rotor is geared directly to the output shaft, there is no need for connecting rods, a conventional crankshaft, crankshaft balance weights, etc. The elimination of these parts not only makes a Wankel engine much lighter (typically half that of a conventional engine of equivalent power), but it also completely eliminates the reciprocating mass of a piston engine with its internal strain and inherent vibration due to repeated acceleration and deceleration, producing not only a smoother flow of power but also the ability to produce more power by running at higher rpm.
In addition to the enhanced reliability by virtue of the complete removal of this reciprocating stress on internal parts, the engine is constructed with an iron rotor within a housing made of aluminium, which has greater thermal expansion. This ensures that even a severely overheated Wankel engine cannot seize, as would likely occur in an overheated piston engine. This is a substantial safety benefit in aircraft use since no valves can burn out.
A further advantage of the Wankel engine for use in aircraft is the fact that a Wankel engine can have a smaller frontal area than a piston engine of equivalent power.
The simplicity of design and smaller size of the Wankel engine also allows for savings in construction costs, compared to piston engines of comparable power output.
Due to a 50% longer stroke duration compared to a four stroke engine, there is more time to complete the combustion. This leads to greater suitability for direct injection.
As another advantage, the shape of the Wankel combustion chamber and the turbulence induced by the moving rotor prevent localized hot spots from forming, thereby allowing the use of fuel of very low octane number or very low ignition power requirement without preignition or detonation, a particular advantage for hydrogen cars. Mazda has recently placed a hydrogen-burning rotary engine in one version of its RX-8 sports car and Mazda 5.
01-21-08 | 09:42 AM
#3
No it's not Turbo'd
Joined: Jun 2002
Posts: 2,511
Likes: 2
From: Los Angeles, Ca
Whom are you trying to kid ?
We all know what the benefits are supposed to be, and we're also VERY familiar with the shortcomings of this engine design.
My old boss had a saying, for every way, that one method is far superior, it has at least one way it's not.
That being said I hope nobody in an FD or T2 reads the fuel bit and thinks he/she can save herself a buck !?
We all know what the benefits are supposed to be, and we're also VERY familiar with the shortcomings of this engine design.
My old boss had a saying, for every way, that one method is far superior, it has at least one way it's not.
That being said I hope nobody in an FD or T2 reads the fuel bit and thinks he/she can save herself a buck !?
01-21-08 | 01:47 PM
#6
Whom are you trying to kid ?
We all know what the benefits are supposed to be, and we're also VERY familiar with the shortcomings of this engine design.
My old boss had a saying, for every way, that one method is far superior, it has at least one way it's not.
That being said I hope nobody in an FD or T2 reads the fuel bit and thinks he/she can save herself a buck !?
We all know what the benefits are supposed to be, and we're also VERY familiar with the shortcomings of this engine design.
My old boss had a saying, for every way, that one method is far superior, it has at least one way it's not.
That being said I hope nobody in an FD or T2 reads the fuel bit and thinks he/she can save herself a buck !?
01-21-08 | 01:52 PM
#7
sounds like an old article, only a large turbine strapped to the side of a conventional rotary can outproduce most typical aluminum block naturally aspirated V8s that weigh in only slightly heavier than a cast iron/aluminum block rotary engine. until the rotary becomes all aluminum it is quickly falling out of place as a high horsepower to weight ratio engine.
it does have many benefits in durability when overheated, if you don't need to start it again after you shut it off that is which is why it is preferred for aircraft. the coolant seal grooves cut into the iron housings was a major mistake made by mazda when transitioning to the second series 13B in '86 and has become one of the main shortcomings of the engine since.
as for reduced hotspots in the combustion chamber, that is true but you have to keep in mind the rotary engine internal temps are quite a bit higher internally when forced induction is added and they quickly become more prone to detonation than piston engines do at much lower operating compression levels.
it is a unique engine and why we love them but don't try to kid yourself. they are like a delicate flower and if they don't get water everyday they die.
it does have many benefits in durability when overheated, if you don't need to start it again after you shut it off that is which is why it is preferred for aircraft. the coolant seal grooves cut into the iron housings was a major mistake made by mazda when transitioning to the second series 13B in '86 and has become one of the main shortcomings of the engine since.
as for reduced hotspots in the combustion chamber, that is true but you have to keep in mind the rotary engine internal temps are quite a bit higher internally when forced induction is added and they quickly become more prone to detonation than piston engines do at much lower operating compression levels.
it is a unique engine and why we love them but don't try to kid yourself. they are like a delicate flower and if they don't get water everyday they die.
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01-21-08 | 08:19 PM
#13
Banned. I got OWNED!!!
Joined: Dec 2006
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Likes: 1
yeah, they didn't want to spend the millions Mazda did. It took 5000 motors before Mazda was happy with their design. GM, Ford, BMW, and Mercedes Benz couldn't/wouldn't do it. They stuck with what they knew while Mazda looked for a way to differentiate itself from the other japanese manufacturers.
"The rotary is like a 25 year old man full of promise. The piston engine is an old man waiting to die." kenichi yamamoto, founder of the Rotary program at Mazda.
"The rotary is like a 25 year old man full of promise. The piston engine is an old man waiting to die." kenichi yamamoto, founder of the Rotary program at Mazda.
Last edited by phoenix7; 01-21-08 at 08:34 PM.
01-21-08 | 11:52 PM
#17
Banned. I got OWNED!!!
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Likes: 1
01-22-08 | 04:17 AM
#20
Banned. I got OWNED!!!
Joined: Dec 2006
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Depends on what you like.
http://video.google.com/videoplay?do...8pushrodmullet
The Rotary is the black sheep in the automotive industry. Everyone wants it to fail.
I mean, i don't get the arguments.
I rented a 4 banger economy chevy for christmas vacation. Took it on a 10 hour trip and it got the same MPG as the 7 at 80mph. I have the pics to prove it too. It handled like ***, accelerated bad and just sucked when compared to the 7.
So if the piston engine is better why does an ECONOMY CAR with less than 50K miles get the same mileage as an NA with bolt-ons and piggy-back?
Let's not even get into the V8 deal. I don't think a V8 will get 25MPG let alone if they have a lead foot.
Torque? LOVE IT, feels good, the pickup going uphill is sweet. I just prefer the rotary. It does What I need it to do when I need it. ~2500lbs,
350hp. Don't really need more.
DOn't get me wrong, the achievements that have been made since the invention of the piston engine in the 1800s are amazing. Variable timing to improve mileage and increased performance (like the NA's 5th and 6th ports, OMG we got vtec too!), better materials, etc., etc.
I just don't like the piston engine that much.
I can appreciate a nice Chevy, with a nice lopey idle, open exhaust. I can appreciate a decent mustang, and the Supra and BMW I6s. I just don't think it does what I like any better than my 13B or the 13BT.
http://video.google.com/videoplay?do...8pushrodmullet
The Rotary is the black sheep in the automotive industry. Everyone wants it to fail.
I mean, i don't get the arguments.
I rented a 4 banger economy chevy for christmas vacation. Took it on a 10 hour trip and it got the same MPG as the 7 at 80mph. I have the pics to prove it too. It handled like ***, accelerated bad and just sucked when compared to the 7.
So if the piston engine is better why does an ECONOMY CAR with less than 50K miles get the same mileage as an NA with bolt-ons and piggy-back?
Let's not even get into the V8 deal. I don't think a V8 will get 25MPG let alone if they have a lead foot.
Torque? LOVE IT, feels good, the pickup going uphill is sweet. I just prefer the rotary. It does What I need it to do when I need it. ~2500lbs,
350hp. Don't really need more.
DOn't get me wrong, the achievements that have been made since the invention of the piston engine in the 1800s are amazing. Variable timing to improve mileage and increased performance (like the NA's 5th and 6th ports, OMG we got vtec too!), better materials, etc., etc.
I just don't like the piston engine that much.
I can appreciate a nice Chevy, with a nice lopey idle, open exhaust. I can appreciate a decent mustang, and the Supra and BMW I6s. I just don't think it does what I like any better than my 13B or the 13BT.
Last edited by phoenix7; 01-22-08 at 04:32 AM.
01-22-08 | 04:45 AM
#21
Banned. I got OWNED!!!
Joined: Dec 2006
Posts: 26
Likes: 1
The Rotary's only failure: Demanding so much attention and care. You can only make a machine work so long without proper care. The 100+ years of development have made an idiot proof motor (almost 
).
I know for a fact that a piston engine can last 3 years of constant driving from the Bay area to LA (8 hour trip each way) with nothing but gas. No oil change, no fluid change, no ANYTHING. JUST GAS.
because if that was the rotary it would not have lasted that long.
Is it the motor's fault? Is it a "BAD DESIGN" or an "Inferior design" when compared to the piston? I don't think so.
). I know for a fact that a piston engine can last 3 years of constant driving from the Bay area to LA (8 hour trip each way) with nothing but gas. No oil change, no fluid change, no ANYTHING. JUST GAS.
because if that was the rotary it would not have lasted that long. Is it the motor's fault? Is it a "BAD DESIGN" or an "Inferior design" when compared to the piston? I don't think so.
01-22-08 | 06:31 AM
#23
Whom are you trying to kid ?
We all know what the benefits are supposed to be, and we're also VERY familiar with the shortcomings of this engine design.
My old boss had a saying, for every way, that one method is far superior, it has at least one way it's not.
That being said I hope nobody in an FD or T2 reads the fuel bit and thinks he/she can save herself a buck !?
We all know what the benefits are supposed to be, and we're also VERY familiar with the shortcomings of this engine design.
My old boss had a saying, for every way, that one method is far superior, it has at least one way it's not.
That being said I hope nobody in an FD or T2 reads the fuel bit and thinks he/she can save herself a buck !?
01-22-08 | 08:04 AM
#24
here !