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post #76 of 306 (permalink) Old 11-23-09, 23:31 Thread Starter
 
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post #77 of 306 (permalink) Old 11-24-09, 21:50
 
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Just in case we have n00bs wondering how a Rotary works!!


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post #78 of 306 (permalink) Old 11-24-09, 22:24
 
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Just in case we have n00bs wondering how a Rotary works!!

what the hell is rotary.. is it a type of snow blower?

seeing my other hobby is trains.. heres a rotary for ya.


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post #79 of 306 (permalink) Old 11-25-09, 9:13
 
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One of tha causes for tha rotary's poor emissions and mileage is illustrated by that animation. Like a piston engine with a radical cam the fresh intake charge is exposed to the exhaust port for a time and that allows good cool air and un burned fuel to escape the chamber.

This is mostly a low RPM issue (also like the radical camed piston engine) and it has been addressed pretty well in the renisis version, but I'm wondering if anyone else thinks the rotary would benifit from direct injection?

If the fuel is not injected until the trailing seal has passed the exhaust port the contamination becomes a non issue, less fuel needs to be injected for a given A/F ratio and emissions go down as well.

I have also thought about strictly timed sequential port injection, but my thought is that even at low RPM where the problem is most prevelant the time between the exhaust being closed off and the intake being closed off would be very small. (you could actualy start injecting some time before hand but not much) That would require primary injectors of a much larger than normal size to flow enough fuel in a fraction of the time a normal set would have.

The injectors would still have to be precise and thats something thats not easily done as injectors get drastically larger.

At higher RPM the issue becomes less prevelant so at some point the injectors could return to a more normal duty cycle. Infact as RPM climbs and the time between the exh port being closed and the int port remaining open gets smaller and smaller it would quickly become impossible to inject enough fuel in the available window.

Thoughts? Opinion? Ideas?

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post #80 of 306 (permalink) Old 11-25-09, 12:52
 
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I'll get back to that later ls six, I just want to mention that I've been thinking about a new rotary concept which would involve a sort of Cam and Piston IN the rotor.

It would basically be a completely round engine, not the peanut shape that the current one has. Keeping the 3 chamber system, the deeper part of the rotor face would be like a piston. After passing over the intake port and being fully sealed by the "apex" seal, the "cam" would push the "piston" to compress the air/fuel mixture and allow it to combust. I know it's vague and hard to picture now, but I'll draw it up tonight and scan it to show you guys what I mean. I obviously don't have any training as an engineer, but this idea I have would be worth discussing IMO.

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post #81 of 306 (permalink) Old 11-25-09, 15:09
 
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I get the idea but I'm having a hard time working out the mechanics of it, I had an idea once that had one rotor compressing the air fuel charge once before it passed another port to the second rotor for some more compression and ignition.

Kinda thought the same thing for a piston motor but in that case a screw type cpmpressor is much more efficient than any piston type compressor.

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post #82 of 306 (permalink) Old 11-25-09, 15:40 Thread Starter
 
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Wouldn't that start to break down the simplicity of the rotary design? I mean it would most likely bring in a host of new headaches for reliability and longevity.

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post #83 of 306 (permalink) Old 11-25-09, 15:49

 
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Quote:
Originally Posted by ls six View Post

I have also thought about strictly timed sequential port injection, but my thought is that even at low RPM where the problem is most prevelant the time between the exhaust being closed off and the intake being closed off would be very small. (you could actualy start injecting some time before hand but not much) That would require primary injectors of a much larger than normal size to flow enough fuel in a fraction of the time a normal set would have.
Its been done, about 10 years ago a shop here locally did a sequential port fuel injected PP 13B to show how well the particular brand of after market ECU they were using could work. should be no problem on a j-port/bridgeport/extend port motor if it'll work on a PP
PP motors have a ridiculous amount of overlap, and normally with carbs you cant get them to idle under 2000rpm let alone produce any torque.
This sequntial port injected version idled at around 900 and was producing torque at 2000rpm and went on to make 400hp at 9000Rpm on the engine dyno.
The article was in one of my old car magazines, I probably still have it, but I dunno where, prolly in a box somewhere in the garage.

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post #84 of 306 (permalink) Old 11-25-09, 18:32 Thread Starter
 
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Thats bad ass, direct injection FTW. I wonder if Mazda has thought about doing this on the new Renesis engines. They do it on the new MS3 & 6.

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post #85 of 306 (permalink) Old 11-25-09, 18:57
 
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Wouldn't that start to break down the simplicity of the rotary design? I mean it would most likely bring in a host of new headaches for reliability and longevity.
What I'm thinking doesn't really add too much more. It adds a lobe to the crank/eccentric shaft, similar to a cam in shape. It also add a moving "deep" point in the rotor as opposed to a fixed one. and Maybe 2-4 springs per rotor face(on the 'inside of the rotor, which would mean creating a 2-piece rotor). But my design eliminates the peanut shape which creates a shaking motion and places strain and wear on the current Rotary at Idle. My round design also eliminates the "knocking" of the Apex Seals to the housing, which would logically increase longevity. Anyways, I'm leaving work now, I'll draw it up when I get home.

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post #86 of 306 (permalink) Old 11-25-09, 20:53
 
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Alright, so here is a rough sketch of what I'm thinking. It;s obviously not completely thought out, no one can design an engine in such little time and NO research, but this is my idea...

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post #87 of 306 (permalink) Old 11-25-09, 21:06
 
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Chief, could you dig up that article or point me in the right direction to get the info? I figured someone must have had the same idea, I wonder if the RX8 uses the concept to any degree? Even retarding the injection by a few degrees would have an effect.

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post #88 of 306 (permalink) Old 11-25-09, 21:33 Thread Starter
 
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Damn Joey that still looks like it has the chance for epic fail. Think if one of those pistons and the springs and shit fell out into the housing! But I see what you are saying and it makes some sense to me now. So the piston gets pushed up by the cam lobe once it has the intake charge and compresses it even more to get full compression before ignition and then drops back off. I am assuming that the cam lobe is stationary?
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post #89 of 306 (permalink) Old 11-25-09, 22:08
 
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Yes the cam lobe stays in place and doesn't move. I was thinking about a way to get rid of the rumble or shake that rotaries have so that it could perform better at lower revolutions, this is what came ti mind. Getting rid of port overlap, keeping compression, and getting rid of the slight lateral movement that the rotor has moving up and down in the housing.

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post #90 of 306 (permalink) Old 11-26-09, 12:30
 
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Then you would need 2 lobes to make it a 4 stroke engine, the one lobe in the pic compresses the mixture on one side then allows for the power stroke to occour on the downward face of the lobe.

But theres no action to expel the exhaust then draw in an new charge.

Also where dose the output occour? If the housing and cam are stationary then you would need some way of connecting the rotor to the drivetrain.

96 MX-6 full exhaust A/C delete spoiler delete probe wheels and a turbo in the worx. 01 626 brake's98 626 sway bar Altima rear sway bar links.http://www.cardomain.com/ride/2934576

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