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Discussion Starter #1
Can anyone tell me how many times a rotary fires per one revolution of the engine?
 

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Twice. A rotary has effectively 3 combustion chambers per cylinder, and on any given cycle 2 of them fire... or so I understand it. I can ask my brother if ya like... he's pretty well versed with them.
 

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Discussion Starter #3
Bob, somehow I knew you'd be the one to answer :D . Thanks. My buddy wanted to know, he has some theory or other about these things and needed to know.
 

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LOL..thats probably because I'm the only one who sits here bored at all hours of the night with nothing better to do than check this board about every half hour...

God I am tired of working nights.
 

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Discussion Starter #5
these things are confusing..........his theory has something to do with the displacement......I don't really get it, but this pic is cool 8)
 

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What is it? Maybe I can explain it a bit better for ya.

Rotories are pretty unique engines..and comparing one to a regular motor is like comparing an apple to a moose.

www.howstuffworks.com has a pretty good write up on them.
 

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In all fareness, you're not the only one stuck in front of a computer at odds hours of the night due to a job. Of course, my job is helping co-eds with computer problems... :) ... but it pretty dead most of the time. Of course, since I know nothing about rotaries, I'm shutting up now
 

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I wouldn't be complaining if I was up all night with co-eds. Instead, I'm stuck with a buncha Marines.... :?

Trade? :D
 

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Discussion Starter #9
Heh, I'm "stuck" at my computer all night too.......I can't sleep sometimes and being a bored college student have nothing else to do.

Well it goes something like this:
something about how many times the engine fires per rotation per rotor, or something like that, makes them an 8.0 liter engine, not a 1.3, and that means it's really inefficient. I don't know if his math worked right or not.
 

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I can safely say that your friend is completely talking out his ass.

The displacement of a rotary is said to be 1.3 liters, tho if you look at it more conventionally, the largest they can be called is 2.6 and that is argueable.

Check out the website I listed above and read up on it... and you'll see exactly why he is talking out his ass... If ANYTHING a rotary is more efficent (if you look at it from a physics perspective... less energy drained by keeping something moving in a circle than it there is use by pushing sometihng up, stopping it, pulling it down, etc....)than a regular motor.. just alot less durable (wankle soup anyone? :) )
 

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Discussion Starter #11
That's what he was trying to get across. The whole 8 liter thing was just something I threw out, lol. Basically, you summed up what he was trying to get at.
 

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ok so my theory is all based on how many times the engine fires. so if it fires 1 time per rotor per revolution then at 650 cc per lobe, then it displaces 1.3L (ie how mazda rates them)
then based on the fact that it takes 4 stroke motors 2 rev to complete teh cycle for full displacement.. then its a 2.6L motor... like you said. this i all agree one.....
my my question is how many times does it fire in reality... according to a text book i have on the wankle motor (not mazda's exact version) it fires 3 time per rotor per revolution, once for each face of the rotor. teh direct quote from the book reads "One revolution from the rotor produces three power strokes, one for each face of the rotor."
so if it fires 3 time per rotor per revolution then 6 fires per motor per revolution, and 12 fires per two revs of the motor. so 12 x 650cc is 7.8L

My question then is how many times does the mazda motor fire?

when it comes to a matter of efficiency there are sveral way to look at it. one is size vs displacement. the rotary motor is super efficient. 7.8L in a package that small is increadable.
or
7.8 l to make 140 hp (13b motor non efi) and no torque to speak if i find it very inefficient.....
 

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you know i found the answer on the how stuff works.... cool sight

" the output shaft spins three revolutions for each revolution of the rotor"

so it is a 2.6L motor then :)

there goes my theory.... but hey kept me busy for a while.... i love finding out new stuff.... i have way to much free time
 

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Glad I could point ya in the right direction :)

That site has alot of cool stuff. Read their explaination of the Manual trans... its even better than the wankle..
 

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Your math is great and all. But I'm currently driving one of the Rotary POS's. Mine is the early 12A 1.1 liter, and I'll tell you now... It acts like a 1.1 liter. It has less power (and no torque) than my old Ford Courier with a 1.3 liter I4 in it with 280K miles.

This is a great comparision as Ford and Mazda cooperate alot on various progects and the courier does have a motor in it that is stamped Mazda.
 

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My Bro's 84 originally had that 12A... he was gonna build that before he got the 13B.. but, as Norbie to aptly put it, "You can polish a turd, but then ya just have a polished turd."

My advice, if your keeping the torquless wonder... swap in a 13B :wink:
 

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well that was my point is that it is acutally a larger motor and very weak a the same time.... ie a bad inefficient motor. but simple said if you compare it to a a reg 4 stoke that takes 2 revolutions to complete the cycle then the mazda is twice as big and half as strong based on hp per liter
 

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Ah yes, rotor to piston competition some very valid points are made so far.

My opinion on this is that rotary engines should be in cars only if plain on racing it.
Normal everyday driving on a rotary is frustrating sometimes due to no torque, BUT if you want to have a car you need to go fast and throw around corners, it’s really hard to beat a rotary. Simple to get 10k rpm’s, an engine that I personally can pick up without the need for an engine hoist (weighs about the same as a pony keg), and the engine design itself helps lower the center of gravity (half of it is below output shaft), and due to how short the engine is, allows the placement for the engine/transmission to be placed to get a perfect 50/50 distribution
 
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