Hey everyone, I want to start by asking you not to flame me for saying im going to build a 4 rotor. I assume you get people with low posts claiming they are going to build one all the time and I understand that 99.9999% of the time it doesnt happen because they find out its harder than just bolting two engines together. I am not one of those people. Ive done some research and most importantly I have the facilities and resources to do it. Im currently going to school at Minnesota State University Mankato and majoring in Automotive Engineering Technology. We have lathes, mills, 3d printers, forging equipment, welding equipment, and everything else one would need to build an engine from scratch and then even dynos to test it when your done. We have even had students that build 5 sports cars (one for each student) as a project. Im going to need a senior project and a 4 rotor is something ive have rolling around in my head for quite some time. It would be a double 13b based engine with modified stock eccentric shafts.



At the moment im just feeling the project out and trying to figure out all the details so that there wont be any surprises if I decide to go for it.



So ive got some questions:



Which engine (year, etc) would be best and still affordable?



Does anyone have resources that might be able to help me figure out some of the details of the project? (A build article?)



What are the pros and cons about having the rotors indexed the same (2 fire at once) vs. separate firing order?



I have more questions but for now I need to head off to class



Thanks in advance for the help.

 

I've been wanting to do this for a while, and I'm almost ready to.. I need to be able to cast things, make sure round surfaces have a good surface finish (like I can see myself in it) and make sure things are perfectly flat before I am ready.



Basically a 26b uses a 13b crankshaft / eccentric shaft with a bearing on the end with a taper after that. The taper is as long as one housing, and has a keyway cut into it. There is two other eccentric shafts that are as long as one housing with a taper that is the reverse of the taper on the long shaft. These slide on eather end of the long shaft. The end of these is the same diameter as the inside of the bearing located in the outer two center plates. These are standard center plates with bearings pressed in the middle. The center center plate is normal in the 26b, however the race version 26g has a split bearing that's pressed into it.



I have a picture somewhere that illustrates this better than me talking about it.



The rest of the engine is stockish parts. See other posts for porting, polishing, side draft carbs, etc...



The intake and exhaust manifolds are custom, but if you get that far, the rest is trivial.



you will need two engines, and an extra middle plate to get enough to make it.

 

There is a kit from NZ or AUS that will save you time. There is a thread w/ all the info you need. I believe jeff20b is the thread starter.

 

https://www.nopistons.com/forums/ind...howtopic=60432







Top of this section

 

He's right, that's an info-wealthy thread.



Check it out, it's stickied for a reason.

 

Ok thanks alot. I will check it out.

 

Thanks for the suggestion but...

I dont want to use a kit because:



1. More expensive



2. wont work for an engineering project



3. Not enough thinking required



4. Not as much fun



5. WAY less bragging rights! ha ha

 

Brad i feel exactly the same as you with the idea of a 4 rotor. How bad *** would it be to roll up to some punk with that thing under the hood. Being an engineering student at the university of akron i have been thinking about and researching 4 rotors for quite a bit of time and i have found that making one is much much more complicated than i once thought... I would like to hear what you have so far and any ideas that you are currently thinking about.



The one problem that i have run into is the making of a eccentric shaft that can Reliably support every day use. Many people have claimed that simply splining together two shafts with a bolt down the middle can handle the stresses. But i have found that people who have done this only end up with ruined engines once the splines break. Granted in you only want it to run for a little while this would be the easiest way to go. If i were you i would try to find as much info as you can about mazdas r26b engine and their eccentric shaft.



But definitely keep me updated on your progress, I am very interested in making one of these egines!

 

If you think Jeff Bruce's kit from NZ is more expensive than you making your own I want some of what you are smoking. There is a reason these motors aren't just sitting at your local parts store. There are a handful of them that have ever been finished outside of Mazda. I understand that you are in school to be a Automotive engineer, but its just not that simple.



Good luck. With what you have stated I already know how this thread will end.

 

Your name sure contradicts your personality.



Although his kits is MUCH more affordable than most its still over $2,600 for the eccentric. I know its isnt as simple as bolting together some plates bud....thats the whole point. Its been done before and it can be done again. Im not just some kid who thinks I can wip it up in my garage. I have a whole machine shop at my disposal. Not to mention I dont even know if im going to do this as a project and even if I did it wouldnt be for another year. All im doing is gathering information and ideas.



But actually I would like to thank you.

Because its people like you who allow me to accel in life...if everyone had ambition and drive it wouldnt be such a great quality.