Why rotary engines are better than piston engines!
12-05-2005, 04:29 PM
#26
Registered
Thread Starter
Join Date: Apr 2005
Location: Philly
Posts: 50
Likes: 0
Received 0 Likes
on
0 Posts
Rotary or Piston
Both rotary and piston (reciprocating) engines rely on the expansion pressure created by the fuel-air mixture. Due to the difference between the mechanisms in the way that the expansion is used, already proves which engine is more efficient. Rotary engines outperform piston engines in almost every aspect of design, but it doesn’t fit everyone’s needs. The rotary engine has far fewer parts than a piston driven engine. Rotary engines use only two rotors to generate and absorb their power, resulting in a motor that is much smaller, lighter in weight and an engine that can last under the most rigorous conditions. Rotary engines are also very cost effective; especially for the amount of horsepower they are capable of producing. In this essay I will be comparing reciprocating engines to the new 13b rotary RENISIS engine.
The rotary engine only has three moving parts; their synchronized motion allows for less wear and tear and a smoother ride, even at full throttle. The major difference between the two motors in this category is the rotary engine has far fewer moving parts. Since it uses its own inertia created, and has far fewer moving parts than the piston engine it results in less wear and tear in the motor. Compared to a reciprocating engine and how it violently changes its direction, and applies extra unneeded tension in the motor. Because of the rotary engines design it allows it to combust, compress and intake or exhaust all in one rotation of the rotor. That means it does three out of four steps simultaneously, instead of having the four processes carried out within each cylinder, resulting in a smoother ride with less vibration. One draw back of this revolutionary process is a lack of torque. The torque it does produce can be compared to a V6, which isn’t bad for the cost of most rotary engines and the fact that they drive as smooth as V8’s.
The rotary engine is more durable and reliable. The rotor turns at only one third the engine speed. Therefore when the engine is running at 9000 rpm the rotor is spinning at a lazy 3000 rpm. Because of that, the rotary engine can withstand driving under high load operation. That’s why this engine gained the win at the 1991 Le Mans 24-hour race, an event that tests cars to their performance and endurance limits. Since the rotors spin at only one third the engines speed it makes up for its lack of torque with being capable of having an extreme top speed, and a real boost of raw power in the higher rpm’s.
Since the rotary engine has so few parts it is very small and more affordable. Due to its engines size it can be fit right on the chassis of the car, resulting in great handling and excellent balance. As well as size it also dominates in weight to its competitor the inline six-cylinder reciprocating engine. This advantage is very attractive to automobile designers especially in light of the trends toward stricter requirements in crashworthiness, aerodynamics, weight distribution and space utility.
Although it is lightweight and cost efficient to make, it does have its drawbacks. This rotary engines design actually eats more gas, so in today’s society that can really be detrimental. The rotary engine also has higher exhaust gas emissions making it harder for its creators to legalize it. It can be argued that maintenance is a problem with rotary engines for the reason that in the winter owners must let his/her engine warm up for 5 min. If the engine shuts down in the cold a person risks flooding his/her engine, which can cost lots of money. Owners must also keep an eye on their oil levels, because the rotary engine tends to burn more oil than a conventional motor.
Besides keeping it in check the rotary engine is a fun life experience if you own one. Judging by the small size lightweight, simple structure, quieter with less vibration, as well as reliability and durability puts this engine at the top of the charts. Taking all this into consideration no wonder their new RENISIS engine won engine of the year in 2003. For the small price of maintaining a rotary engine it can last an incredible 200 thousand miles. Altogether the rotary engine is worth the money it costs, because with its amazing gains it puts you into racecar territory. Taking all this into consideration it is easy to see why the rotary engine outperforms the reciprocation piston engine.
Both rotary and piston (reciprocating) engines rely on the expansion pressure created by the fuel-air mixture. Due to the difference between the mechanisms in the way that the expansion is used, already proves which engine is more efficient. Rotary engines outperform piston engines in almost every aspect of design, but it doesn’t fit everyone’s needs. The rotary engine has far fewer parts than a piston driven engine. Rotary engines use only two rotors to generate and absorb their power, resulting in a motor that is much smaller, lighter in weight and an engine that can last under the most rigorous conditions. Rotary engines are also very cost effective; especially for the amount of horsepower they are capable of producing. In this essay I will be comparing reciprocating engines to the new 13b rotary RENISIS engine.
The rotary engine only has three moving parts; their synchronized motion allows for less wear and tear and a smoother ride, even at full throttle. The major difference between the two motors in this category is the rotary engine has far fewer moving parts. Since it uses its own inertia created, and has far fewer moving parts than the piston engine it results in less wear and tear in the motor. Compared to a reciprocating engine and how it violently changes its direction, and applies extra unneeded tension in the motor. Because of the rotary engines design it allows it to combust, compress and intake or exhaust all in one rotation of the rotor. That means it does three out of four steps simultaneously, instead of having the four processes carried out within each cylinder, resulting in a smoother ride with less vibration. One draw back of this revolutionary process is a lack of torque. The torque it does produce can be compared to a V6, which isn’t bad for the cost of most rotary engines and the fact that they drive as smooth as V8’s.
The rotary engine is more durable and reliable. The rotor turns at only one third the engine speed. Therefore when the engine is running at 9000 rpm the rotor is spinning at a lazy 3000 rpm. Because of that, the rotary engine can withstand driving under high load operation. That’s why this engine gained the win at the 1991 Le Mans 24-hour race, an event that tests cars to their performance and endurance limits. Since the rotors spin at only one third the engines speed it makes up for its lack of torque with being capable of having an extreme top speed, and a real boost of raw power in the higher rpm’s.
Since the rotary engine has so few parts it is very small and more affordable. Due to its engines size it can be fit right on the chassis of the car, resulting in great handling and excellent balance. As well as size it also dominates in weight to its competitor the inline six-cylinder reciprocating engine. This advantage is very attractive to automobile designers especially in light of the trends toward stricter requirements in crashworthiness, aerodynamics, weight distribution and space utility.
Although it is lightweight and cost efficient to make, it does have its drawbacks. This rotary engines design actually eats more gas, so in today’s society that can really be detrimental. The rotary engine also has higher exhaust gas emissions making it harder for its creators to legalize it. It can be argued that maintenance is a problem with rotary engines for the reason that in the winter owners must let his/her engine warm up for 5 min. If the engine shuts down in the cold a person risks flooding his/her engine, which can cost lots of money. Owners must also keep an eye on their oil levels, because the rotary engine tends to burn more oil than a conventional motor.
Besides keeping it in check the rotary engine is a fun life experience if you own one. Judging by the small size lightweight, simple structure, quieter with less vibration, as well as reliability and durability puts this engine at the top of the charts. Taking all this into consideration no wonder their new RENISIS engine won engine of the year in 2003. For the small price of maintaining a rotary engine it can last an incredible 200 thousand miles. Altogether the rotary engine is worth the money it costs, because with its amazing gains it puts you into racecar territory. Taking all this into consideration it is easy to see why the rotary engine outperforms the reciprocation piston engine.
12-05-2005, 07:00 PM
#27
Bummed, but bring on OU!
Ahhhhhhhh!!!! paragraphs... 
see also:
http://www.rotaryengineillustrated.com/index.php
As far as weight goes, rotary engines are rather heavy. It's just that their compact nature allows that weight to be positioned beneficially in the vehicle.
see also:
http://www.rotaryengineillustrated.com/index.php
As far as weight goes, rotary engines are rather heavy. It's just that their compact nature allows that weight to be positioned beneficially in the vehicle.
12-05-2005, 07:16 PM
#28
The 8th Deadly Sin
Join Date: Jan 2005
Location: Root Creek
Posts: 300
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by kngfmsta
Rotary or Piston
Rotary engines use only two rotors to generate and absorb their power.
In this essay I will be comparing reciprocating engines to the new 13b rotary RENISIS engine.
Rotary engines use only two rotors to generate and absorb their power.
In this essay I will be comparing reciprocating engines to the new 13b rotary RENISIS engine.
And get your spelling right! It's RENESIS!!
Hahahahaha! Yes, I'm pedantic!! Anyway, good luck!
12-05-2005, 07:32 PM
#30
Registered User
Join Date: Jan 2004
Location: Chesapeake Virginia
Posts: 283
Likes: 0
Received 0 Likes
on
0 Posts
Drawbacks...
Lower MPG - less efficient than a piston engine in that respect (a 1.3L getting 21MPG? To the mass market public that isn't good)
Not much grunt off the line
Less acceptance by the mass population (translate that as lower mass market appeal). Niche market.
Less places you can get it worked on (try breaking down in some back-water burg sometime)
Always look at both sides of the argument...lots of positive postings but address the negative also.
Yes, I am sure I will get flamed for this posting...oh well.
<drives off in her '63 'vette and does not really care>
Lower MPG - less efficient than a piston engine in that respect (a 1.3L getting 21MPG? To the mass market public that isn't good)
Not much grunt off the line
Less acceptance by the mass population (translate that as lower mass market appeal). Niche market.
Less places you can get it worked on (try breaking down in some back-water burg sometime)
Always look at both sides of the argument...lots of positive postings but address the negative also.
Yes, I am sure I will get flamed for this posting...oh well.
<drives off in her '63 'vette and does not really care>
12-06-2005, 12:52 PM
#32
Registered User
Join Date: Jun 2005
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
as a street motor, the rotary isnt really a "better" alternative to a piston. as a race motor though, its strengths begin to shine. here are a few things off the top of my head:
the good:
race:
1. can rev very high depending on the design of the particular motor giving you longer power band then MOST piston engines.
2. relatively high output/displacement (although piston technology has surpassed the rotary at the max)
3. 3 moving parts so less rebuilds
4. although heavy (weighs MUCH more per displacement then most "sport/race" oriented motors), the weight is very centralized and compact.
5. compact size allows you to keep a low center of gravity especially when using a dry sump system
6. in race series that only have displacement restrictions for the motor, the rotary allows you to kind of cheat the system. (this used to be the case, at the pinnacle of piston technology, the rotary has been matched.)
7. it displaces 2-3 times the volume of air compared to a piston motor of equivalent size thus less turbo lag with the same turbo.
8. more bang for the buck when compared to a piston motor that has equivalent size/performance although squeezing power out after the fact does get expensive.
street:
1. uniqueness (sound, feel and the fact that you have something so different from everyone else)
2. smoothness of the motor
3. sporty feel
4. if its an N/A the motors last forever
im sure i missed a few things but you get the idea. all in all, the rotary has been surpassed by the piston "but" when you factor in the cost of the motor, your getting prime performance for relatively low price.
denward
the good:
race:
1. can rev very high depending on the design of the particular motor giving you longer power band then MOST piston engines.
2. relatively high output/displacement (although piston technology has surpassed the rotary at the max)
3. 3 moving parts so less rebuilds
4. although heavy (weighs MUCH more per displacement then most "sport/race" oriented motors), the weight is very centralized and compact.
5. compact size allows you to keep a low center of gravity especially when using a dry sump system
6. in race series that only have displacement restrictions for the motor, the rotary allows you to kind of cheat the system. (this used to be the case, at the pinnacle of piston technology, the rotary has been matched.)
7. it displaces 2-3 times the volume of air compared to a piston motor of equivalent size thus less turbo lag with the same turbo.
8. more bang for the buck when compared to a piston motor that has equivalent size/performance although squeezing power out after the fact does get expensive.
street:
1. uniqueness (sound, feel and the fact that you have something so different from everyone else)
2. smoothness of the motor
3. sporty feel
4. if its an N/A the motors last forever
im sure i missed a few things but you get the idea. all in all, the rotary has been surpassed by the piston "but" when you factor in the cost of the motor, your getting prime performance for relatively low price.
denward
12-06-2005, 05:15 PM
#37
Registered
Join Date: Dec 2004
Location: Los Angeles, CA
Posts: 1,505
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by StewC625
All joking aside, the primary benefits are:
- High HP/displacement ratio (238 to 1.3 L? Wow! That's racing engine territory in a piston car)
- Exceptionally compact packaging, again, compared to power generated (if memory serves, the core of the engine (basically the block and end plates stripped of accessories and intake/exhaust manifolds, etc.) occupies about 3 cubic feet or less. This allows optimum placement in the chassis for best weight distribution, lower cowl and hood profiles for better aerodynamics, etc.
- Exceptionally light weight compared to power generated - another insane figure that borders on racing territory.
- 3 moving parts in the engine compared to dozens and more in a piston engine (and more and more with increasing cylinder counts into V-8, -10 and -12 configurations).
- And that spinning Dorito thing ...
Seriously one of the best engine designs ever - too bad no one besides Mazda put serious effort into totally perfecting it - I agree, had it gotten the same R&D as the piston engine, we might all be driving around going Hmmmmmm instead of Boing Boing.
- High HP/displacement ratio (238 to 1.3 L? Wow! That's racing engine territory in a piston car)
- Exceptionally compact packaging, again, compared to power generated (if memory serves, the core of the engine (basically the block and end plates stripped of accessories and intake/exhaust manifolds, etc.) occupies about 3 cubic feet or less. This allows optimum placement in the chassis for best weight distribution, lower cowl and hood profiles for better aerodynamics, etc.
- Exceptionally light weight compared to power generated - another insane figure that borders on racing territory.
- 3 moving parts in the engine compared to dozens and more in a piston engine (and more and more with increasing cylinder counts into V-8, -10 and -12 configurations).
- And that spinning Dorito thing ...
Seriously one of the best engine designs ever - too bad no one besides Mazda put serious effort into totally perfecting it - I agree, had it gotten the same R&D as the piston engine, we might all be driving around going Hmmmmmm instead of Boing Boing.
and to the thread starter
the rotary engines doesnt have any advantages over the piston engine, you're going to have a tough essay to write.
Last edited by StealthFox; 12-06-2005 at 05:26 PM.
12-06-2005, 05:45 PM
#38
Registered User
Join Date: Jun 2005
Posts: 464
Likes: 0
Received 0 Likes
on
0 Posts
hahahaha.... as harsh as it sounds, stealth is right. until rotaries stop using iron housings and solve the "lack of compression issue" the piston motor at the max still does most things better.
denward
denward
12-07-2005, 05:07 AM
#41
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by StealthFox
are you kidding the rotary engine is not light weight for its size at all in fact it is heavy for its size almost as heavy as some small block V8 engines! a t56/lt1 transmission/engine combonation is lighter than a 2 rotor engine and transmission combonation and produces more power.
But I've never done it myself and that's based only on what I've read, so I might be wrong. Can you fill us in with the exact details? How much do the 13B, 13B-MSP, and LT1 weigh?
12-07-2005, 11:34 AM
#42
Registered
Join Date: Dec 2003
Location: Orlando, FL
Posts: 1,223
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Deslock
Yeah, the rotary engine is dense. But I thought that if you swapped a t56/lt1 (along with the necessary parts) into an RX7, you were looking at a 100+ pound weight increase. In order to keep the weight distribution close to 50:50, don't some people add 50 pounds into the spare tire well?
12-07-2005, 08:51 PM
#43
Registered User
Join Date: Aug 2005
Posts: 77
Likes: 0
Received 0 Likes
on
0 Posts
Here is another fact that most people forget:
The rotary is specially easy to adapt to other types of fuel like the hydrogen because it minimized blow back. If we ever see the world switching over to hydrogen, I will expect electric fuel cells car to rule the low horse power world, but more and more rotary design will be adopted for high horse power appications.
The rotary is specially easy to adapt to other types of fuel like the hydrogen because it minimized blow back. If we ever see the world switching over to hydrogen, I will expect electric fuel cells car to rule the low horse power world, but more and more rotary design will be adopted for high horse power appications.
12-07-2005, 09:00 PM
#44
Registered
Join Date: Dec 2004
Location: Los Angeles, CA
Posts: 1,505
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by MazdaManiac
Uh, no.
The lower rotational inertia and fewer moving parts are reason enough.
The lower rotational inertia and fewer moving parts are reason enough.
and tell me how fewer moving parts make an engine superior? let me count how many ways it affects performance of the engine in any way...hmm...lets see...NONE.
Last edited by StealthFox; 12-07-2005 at 09:02 PM.
12-07-2005, 09:01 PM
#45
Registered
Join Date: Dec 2004
Location: Los Angeles, CA
Posts: 1,505
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by beachdog
Even if the weight of the v8/trans and the rotary/trans were identical, you would still have to add weight to the rear to keep a 50/50 distribution. The v8 is taller and would have to be located further forward to fit in front of the firewall. Identical center of mass but located further forward would increase the wieght of the front end.
12-07-2005, 09:42 PM
#46
stop flooding ur engines
stealthfox, ur officially a rotary moron. i have a rotary engine in my bedroom and i can lift it up by myself. i am 5'10 and weigh 150 lbs. there is not one v8 in the world i can even move off the ground. ur an idiot.
the transmission of an rx8 weighs as much, if not more than the rx8s entire engine.
a 1.3l engine with 238 hp is 183 hp per liter. thats virtually 3 horsepower per cubic inch. in order for a 5.7l v8 to make 3 hp per cubic inch it would have to make over 1000 horsepower. i bid goodluck to chevy trying to match that. o, by the way, make it a low emission vehicle and that gets 18 mpg city, with 10:1 compression and 91 octane.
"no advantages over a piston engine"?
3 moving parts compared to the thousands in an OHV v8 means more reliability. less parts that move are less parts to break. valve adjustment? timing belt replacement? warped head? thrown rods? spun bearings? blown head gasket? floated valves under high rpm? cracked piston? ever hear of these?????
not in a rotary
a 100 lb engine thats 2 feet long and 1 foot high will give better 50/50 than a 500 lb v8 thats 2-3 feet high. dont get me started on valvetrain noise or how they r just generally not smooth at all.
no wonder u got a v8 in ur 7. u didnt kno what u had, or u blew it up bc ur that retarded. thank the wankel god u dont have a rotary anymore. felix turned over in his grave when u decided to get a 7.
________
Paxil Side Effect
the transmission of an rx8 weighs as much, if not more than the rx8s entire engine.
a 1.3l engine with 238 hp is 183 hp per liter. thats virtually 3 horsepower per cubic inch. in order for a 5.7l v8 to make 3 hp per cubic inch it would have to make over 1000 horsepower. i bid goodluck to chevy trying to match that. o, by the way, make it a low emission vehicle and that gets 18 mpg city, with 10:1 compression and 91 octane.
"no advantages over a piston engine"?
3 moving parts compared to the thousands in an OHV v8 means more reliability. less parts that move are less parts to break. valve adjustment? timing belt replacement? warped head? thrown rods? spun bearings? blown head gasket? floated valves under high rpm? cracked piston? ever hear of these?????
not in a rotary
a 100 lb engine thats 2 feet long and 1 foot high will give better 50/50 than a 500 lb v8 thats 2-3 feet high. dont get me started on valvetrain noise or how they r just generally not smooth at all.
no wonder u got a v8 in ur 7. u didnt kno what u had, or u blew it up bc ur that retarded. thank the wankel god u dont have a rotary anymore. felix turned over in his grave when u decided to get a 7.
________
Paxil Side Effect
Last edited by RoXanneBlack8; 04-30-2011 at 08:37 PM.
12-08-2005, 12:06 AM
#47
Originally Posted by StealthFox
>.> you can lower your rotational intertia mass up your buttcrack all you want while my v8 rx7 pummels you into a bloody lumpy pulp
Inertia is everything. Why do the V8 guys waste so much money on lightened pullies, lightweight pistons, etc? To lower rotational intertia for a faster revving reciprocating assembly. The rotary motor doesn't need that because nothing is spun that isn't producing power.
Originally Posted by StealthFox
and tell me how fewer moving parts make an engine superior? let me count how many ways it affects performance of the engine in any way...hmm...lets see...NONE.
12-08-2005, 01:08 AM
#48
Registered
Join Date: Dec 2003
Location: Orlando, FL
Posts: 1,223
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by StealthFox
wrong the engine fits in in a way that DOES in fact keep the weight distribution
12-08-2005, 01:23 AM
#49
Registered
Join Date: Sep 2005
Location: OC
Posts: 627
Likes: 0
Received 0 Likes
on
0 Posts
More information on thermodynamics:
The flaw in rotary engines is thermodynamic, because the four strokes
always take place in the same but separate four locations of the
chamber, so that intake (freezing), compression, combustion (5000F),
exhaust, are a steady state thermal load. Finding materials and
lubricants that can wipe past these extreme temperatures is beyond
today's technology, both from an expansion and friction aspect, and
probably will remain so. To make rotary internal combustion engines
work, lower compression and rich mixtures are used, making them non
economical both in fuel and duration.
Reciprocating piston engines perform all four strokes in the same
place so that both piston AND cylinder see an oscillating operating
temperature in which a boundary layer and expansion cooling make the
apparent temperature so low that cast aluminum and cast iron can
contained them, less expensive materials and higher thermodynamic
performance. It is not without reason that the Wankel did not
succeed. Its flaws were known more than 80 years ago but the unusual
configuration had many wondering whether a rotary engine might be
possible after all.
The flaw in rotary engines is thermodynamic, because the four strokes
always take place in the same but separate four locations of the
chamber, so that intake (freezing), compression, combustion (5000F),
exhaust, are a steady state thermal load. Finding materials and
lubricants that can wipe past these extreme temperatures is beyond
today's technology, both from an expansion and friction aspect, and
probably will remain so. To make rotary internal combustion engines
work, lower compression and rich mixtures are used, making them non
economical both in fuel and duration.
Reciprocating piston engines perform all four strokes in the same
place so that both piston AND cylinder see an oscillating operating
temperature in which a boundary layer and expansion cooling make the
apparent temperature so low that cast aluminum and cast iron can
contained them, less expensive materials and higher thermodynamic
performance. It is not without reason that the Wankel did not
succeed. Its flaws were known more than 80 years ago but the unusual
configuration had many wondering whether a rotary engine might be
possible after all.
12-08-2005, 02:21 PM
#50
WWFSMD?
Join Date: Jul 2003
Location: Massachusetts, USA
Posts: 597
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by StealthFox
are you kidding the rotary engine is not light weight for its size at all in fact it is heavy for its size almost as heavy as some small block V8 engines! a t56/lt1 transmission/engine combonation is lighter than a 2 rotor engine and transmission combonation and produces more power.
Originally Posted by Deslock
Can you fill us in with the exact details? How much do the 13B, 13B-MSP, and LT1 weigh?