why not larger displacement?
#1
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why not larger displacement?
Hey, I've been a lurker on this forum for a while now - even helped assemble a 13b-REW and plopped it into a friend's 2nd gen back in the summertime.
From what I understand, this is the non-flame technical forum area, so hopefully this stupid question isn't gonna get shot down.
One question that I can't seem to find answers to is... why are there no larger displacement rotaries? I mean, people add a third (like the 20b) or even a fourth rotor to get more displacement , but what if the entire rotor assembly was just enlarged?
Piston/reciprocating engines don't have the same standard piston size and cylinder bores. Having only one standard rotary size (654cc) for every (modern) rotary engine out there is like having only one piston size for every single piston engine out there. Want more power? Add cylinders/pistons!
There is no replacement for displacement, turbo or otherwise.
From what I understand, this is the non-flame technical forum area, so hopefully this stupid question isn't gonna get shot down.
One question that I can't seem to find answers to is... why are there no larger displacement rotaries? I mean, people add a third (like the 20b) or even a fourth rotor to get more displacement , but what if the entire rotor assembly was just enlarged?
Piston/reciprocating engines don't have the same standard piston size and cylinder bores. Having only one standard rotary size (654cc) for every (modern) rotary engine out there is like having only one piston size for every single piston engine out there. Want more power? Add cylinders/pistons!
There is no replacement for displacement, turbo or otherwise.
#2
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Mazda currently has the 16x (1.6L) engine in development, which is effectively a 3.2L. Increasing displacement is far more difficult than just boring out a cylinder and adding a large piston. The entire engine has to change shape; namely the housings, irons and rotors.
16X: http://www.mazda.com/mazdaspirit/rotary/16x/
16X: http://www.mazda.com/mazdaspirit/rotary/16x/
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the whole no replacement for displacement thing is a piston engine saying. The rotary make much more efficient use of the combustion cycle. Thats why the rotary was outlawed in many racing circuits with displacement requirement, because a under 4.0 piston engine just cant make the power a small displacement rotary can.
Sure if you up the displacement you will have more power, but when the motor as it is is capable of making plenty of power why change the design
Sure if you up the displacement you will have more power, but when the motor as it is is capable of making plenty of power why change the design
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Mazda currently has the 16x (1.6L) engine in development, which is effectively a 3.2L. Increasing displacement is far more difficult than just boring out a cylinder and adding a large piston. The entire engine has to change shape; namely the housings, irons and rotors.
16X: http://www.mazda.com/mazdaspirit/rotary/16x/
16X: http://www.mazda.com/mazdaspirit/rotary/16x/
the whole no replacement for displacement thing is a piston engine saying. The rotary make much more efficient use of the combustion cycle. Thats why the rotary was outlawed in many racing circuits with displacement requirement, because a under 4.0 piston engine just cant make the power a small displacement rotary can.
Sure if you up the displacement you will have more power, but when the motor as it is is capable of making plenty of power why change the design
Sure if you up the displacement you will have more power, but when the motor as it is is capable of making plenty of power why change the design
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you have to think from a production stand point though, a 1.3l rotary is a good size for a small car, like what was said before increase the displacement involves a complete redesign of the entire motor not just putting in a deeper crank and larger pistons, In a piston engine you can gain .3-.5L no problem the rotary just isnt that simple
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#8
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First, the shape of the combustion chamber on a rotary is particularly long when compared to a piston's. And the rotation of the rotor makes it longer yet. You have to consider speed of the flame-front during the combustion event. Complete combustion and efficient use of the force produced is different than that of a piston. Simply deepening the "bath-tub" on each rotor lowers the compression ratio and might even change how the force produced by the combustion event is directed. Widening or lengthening the combustion chambers would also effect exhaust and intake characteristics (and timing) in ways that make my small brain spin.
Second, there are no piston rods. The rotors are in direct contact with the e-shaft (crank). So the lobes of the e-shaft would also have to be widened relative to the wider rotors and bearings.
Even if you were able to simply widen the housings and rotors with something aftermarket, cooling might also become an issue. Without separate inlet and outlet ports for each housing (and rear iron), the coolant might be too hot by the time it reachs the combustion side of rear housing to do much good.
It's efficient in that there is no reciprocating mass and fewer moving parts. The nature of the rotary's exhaust pulses also lends itself well to turbocharging. But it's actually less efficient in other ways.
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Holy mind-boggling rotaries, batman.
The reason I asked is because I like building custom engines, and I was looking into the possibility of trying to do a 'different' rotary. I'm beginning to think that building any rotary itself is a miracle.
If you guys could do something unique, or interesting, to a rotary engine, what would it be?
The reason I asked is because I like building custom engines, and I was looking into the possibility of trying to do a 'different' rotary. I'm beginning to think that building any rotary itself is a miracle.
If you guys could do something unique, or interesting, to a rotary engine, what would it be?
#12
Are you experienced?
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Holy mind-boggling rotaries, batman.
The reason I asked is because I like building custom engines, and I was looking into the possibility of trying to do a 'different' rotary. I'm beginning to think that building any rotary itself is a miracle.
If you guys could do something unique, or interesting, to a rotary engine, what would it be?
The reason I asked is because I like building custom engines, and I was looking into the possibility of trying to do a 'different' rotary. I'm beginning to think that building any rotary itself is a miracle.
If you guys could do something unique, or interesting, to a rotary engine, what would it be?
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