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Anyone here an expert on this topic. I figured with all this RX-8 talk we should educate the members here on rotary engines (including myself). How are they different/similar? Why did they stay with the rotary for the new generation RX-7? etc etc.

Thanks,
Joel

 
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are you talking about the differences between the rx-7 and rx-8 engine?

first of all, there are a few unique things about rotory engines....

1. no pistons, camshafts rods, VALVES
2. the combustion chambers move

the rotory engine basically is a 2 rotor, 1.3L
it works like piston engines but without valves. the rotors spin over the intake and exhaust ports and open and close the intake, and exhaust, timing is critical for this to work properly


the main revision on the rx-8 is the overlapping

the previous rotory engines used to have a problem called overlapping, basically its when the rotor spins, sometimes the exhaust will mix with the intake gases, this happens when the engine is revving really high

the new renesis (rx-8) also has a higher compression ratio and can achieve the same, if not more, HP than the previous rotories, this is accomplished by a higher redline, which is a good sign of NA tuning... now previous generations were geared towards achieving high HP thru turbos, now this causes a lot of wear and tear on the engines, and as any mechanic will tell you, rotories are really expensive to work on...

the renesis for the most part is a tuned naturally aspriated engine.... and they havent changed the displacement so its still a 1.3L engine... but produces an amazing 250HP which is insane for a 1.3L engine

 
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go on www.howstuffworks.com, they have an article on rotary engines

 
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Also, if I remember correctly, those little 1.3 liter engines guzzle gas like a V8!!!

 
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Yeah, it does use a lot of gas. 1 of the reasons why it wasnt produced in all cars. Especially that 3rd Gen RX-7... I think it had about the same gas milleage as a TT SUpra.

 
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thats another difference for the renesis... it actually recycles the unused fuel....

 
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The whole concept of the rotary engine is great because it is so simple compared with piston engines. Its like a combination of a turbine and a piston engine. Doesn't have valves so it doesn't need a cam shaft and the neat thing is its always spinning in the same direction, unlike piston engines where pistns are constanotly changing direction which isn't very effecient. Its also very compact if you compare it to an equivalent piston engine. That 1.3L 2 rotor engine can be roughly equated to a 6-cylinder piston engine as it has the same number of fires per revolution. The reason the displacement seems so low is because its like 3 pistons sharing one combusition chamber. One rotar spins in place of 3 pistions in seperate chambers which when you add them up make a much bigger number than 1.3L. Its low on torque, and that's why it revs so high so it can make 250hp. That also makes it less practical for street use, but I'm sure there is a way to tune a rotary to make more low-end torque.. There's no way to do anything like vtec with a rotary unless the rotars themselves change shape or the intake/exhaust ports move around or maybe the whole chamber changes shape which is pretty impossible I think, but I dunno anything. Anyway, 250hp from 1.3L is pretty kick ***... I want one.