this same subject came up in my thread on the rx7 forums. im not on these forums alot so none of you know me, but i am a machinist and i DO have the capability of making a 3 rotor renesis intermediate plate if it is possible. i thought i would just like to share with you renesis people what had popped up on the other forums. maybe i can find some help with coming up with a real design for the plate, or a reason why it WONT work, or if its already been done...

when i first saw this thread, the title kinda suggests that 3 rotor 13B's (20B's) are something new, when they really arent. just search the rx7forums for 3 rotor or 20B and you will get tons and tons of info on how to do it. now to my understanding, a TRUE 20B renesis is something new...

 

i will rob a bank to get a renesis 20b 3 rotor in the next rx8.

 

if someone can confirm or deny if this theory will work, i will have one designed and made, and ill sell it to you. i just need to know if its going to be a major waste of my time or not.

 

we need a Fantasy forum ...

 

You will need a 2-piece e-shaft to assemble the 3-rotor, and of course custom intake and exhaust manifolds, ECU, an extra ignition coil, and 3 additional fuel injectors (if you keep the EFI like the stock setup).

 

those are things needed for every 3 rotor, no big deal.

the only thing that concerns me for the renesis 3 rotor besides the intermediate plate is the jet air thing, and controlling the 3 additional intake ports through the electronic throttle body.

im truely just looking for someone who knows a GREAT deal about the renesis, and if the sketch of the intermediate plate will work in theory. The intermediate plate is the only true issue at the moment since its the only part that does not exist at all, and has never been made. oil pan, motor mounts, ecu, etc... all of that minor stuff needs to be changed with a conventional 20B anyway, so those are not a concern to me at all. the majority of the design theory is the same except the intermediate plate and the new 3 port per rotor intake.

 

Retaining the S-DIAS system could be tricky.

 

you wouldnt. enitirely new intake manifold as you said. no sdais.

 

Stop playing with my emotions driveslikejehu.....

 

I imagine something like the 20b manifold could be made to work, but otherwise you are fabbing up something. His goal was a 3-rotor Renesis, and IMHO, one of the things that defines the Renesis (besides the all side port config) is the S-DIAS system. SDIAS is responsible for several points in the power curve where the engine can achieve over 100% VE. Obviously not necessary, but it would certainly be beneficial if the 3 rotor is to stay NA. A 20b manifold (which was for an FI application anyway) would probably not be ideal for a 3 rotor NA renesis.

 

agree totally. gettingthe lengths right is just some fancy math that some on this board can do. the barrels etc could be had from mazda using renesis parts. some aftermarket comps (motec etc) can operate solenoids/ports. so really its possible. just not something i would expect from the aftermarket. but doable- if you're already speccing the intake manifold why not?

 

Is it me...or is the list of parts needed not very costly in my opinion? I know little about aftermarket stuff but I just don't see the 15K price needed for such a build. If you use most of your current Renesis the cost of maknig it 3-rotor should be minimal.

Honestly, if driveslikeajehu is able to build a kit he could sell to the common joe nutbolt so he/she could build their own 3-rotor that would be great.

I know it's been asked before, but let's come up with a list parts and give a fair price for each part (labor to build and the material needed). Like that we all would have a better idea of what it takes.

Once you build the first custom parts and made molds of them (or used a fabrication computer/machine) it shouldn't be too tough to just keep building the parts needed and sell them like they sell Turbo kits.

If this was possible...I'd go 3-rotor instead of turbo one day.

 

Most people probably wouldn't go through the trouble. But I agree, its completely possible. But its just another piece of the puzzle. My point was that there is a LOT more to think about when considering building a 20b out of parts.

 

at our machine shop, we can make ANYTHING. he have CNC Mills, lathes, fully computerized bandsaws and presses, every type of welding you can think of... probably over 20 different machines (some I dont even know what they do), and people who know how to use them. so fabrication and machining... simply isnt an issue.

the only problem we would run into, is that we dont have anyone thats very experienced with the renesis (hence the reason for this post), although we do have some people and resources for very experienced 13B-rew builders, as well as a 20B builder, and my rx7 to tinker with if need be.

today im going to give some detail pictures to the boss (who does almost all of the CAD and g code work) of all kinds of plates for the renesis as well as the conventional 20B center bearing plate, to see if we can come up with a workable intermediate plate for the renesis with the nessesary intakes and side exhaust ports. of course we will need some different plates in hand to measure exactly, but he will at least be able to tell me if we can do it in our shop. IMO, if we can do that, we can solve the intake issue.

most of the cost comes from parts that a normal person cant make themselves (motor mounts, manifolds, modify the subframe, etc) but for a very experienced shop that can do all the fab work on hand, no its not going cost 15k, probably ALOT less than that. it IS going to cost us alot of time though, especially with the design and CAD aspect, but also with things that we dont need to waste our time with (even though we probably COULD machine them here if we had drawings) like the e-shaft, rotors, housings, etc etc. some things are just better to be bought.

as for making kits... if we actually do this and make a fully functional 20B renesis, without modifying the car itself as much as possible, im sure we will sell kits to whoever wants them, but i doubt we will market them. we have different plans for the design once its completed.

SO anyone with ideas or problems that nobody has mentioned before... feel free to share. oh yeah... we will eventally need an 8 to stick this in... so if you see a totalled or junked one let me know, we will fix it up.

 

drivelikeajehu there are several knowledgeable people here (RotaryGOD, MazdaManiac, etc etc) that could give you alot more information than I can. Heck...there are people here or maybe even vendors that could also help this project out...take some of the work on themselves to help speed things up.

Go here, this 8 might be useful for something before our poor friend ends up putting it in the grave. https://www.rx8club.com/lounge-4/first-last-time-drag-track-83269/

Go here:

http://www.rotaryengineillustrated.com/renesis.php

For some pictures and information that might be helpful.

I really can't help much but I sure would love to see you build a 3-rotor Renesis. Like I said, I'm the 3-rotor Renesis dreamers club president...lol.

 

As said earlier, if you want this to have a chance to sell, I think making it retain the Drive by Wire and a modified S-DAIS system is important...

 

As soon as I reinstall photoshop, I will generate a 3-rotor renesis picture from the previous picture + drivelikejehu's sketch. If for no other reason than to give wannahave a new desktop and to stop his endless slobbering.

Hey, while we're daydreaming, maybe we could replace the cast iron parts with aluminum. That way you end up with a 3-rotor renesis that weighs the same (or less?) than a stock renesis. Oh yeah, and market this to the airplane guys, apparently there is growing interest in rotaries there.

 

lol

 

racing beat makes aluminum plates, but i THINK (dont quote me on this) they are mainly used for racing applications, as aluminum does not hold up to longterm wear as well as steel or cast iron. i dont know where that came from but i swear ive heard or read that somewhere. someone correct me if im wrong.

i definately want to see this photoshop! my sketch is kinda crude i know, it was one of those frantic things so i didnt forget my idea. i get lost in my mind sometimes. thats why all you guys are here to help me out!

ive gotten great responses so far keep em coming! even you guys who think this is a huge waste of time and money and it will never work, i wanna hear what you have to say!

 

What about a 4 port per rotor renesis, 2 rotor renesis is 3 ports per rotor

2 end plates would be stock, and the 2 middle plates you'd fab up and have 4 circular intake holes in it and 1 exhaust port, since you are machineing so many parts, you might as well create a new 3-rotor-renesis with 12 ports that can rev even higher!, instead of using what mazda have, why not improve on its design, dont know if more port # is better tho
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Its definatly going to be longer tho, thats the biggest disadvantage i see
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One thing about the intake manifold will be the VDI system. This is a big part of the Renesis intake system. You aren't going to be able to do it with 3 rotors. There will have to be no VDI. This valve effectively changes the intake length. This would be extremely difficult to pull off with 3 rotors. VDI has never been applied to a 3 rotor successfully before. With a large amount of work you could make the auxiliary ports work but I just don't see VDI happening.

 

Why do all the rotors have 4 ports?

 

Sorry, check out my previous thread end of page 3, its just an idea i thought up, instead of 3 ports per rotor, perhaps 4 would be better? and 2 identical intermediate plates would make things simpler? maybe?
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