i was thinking could you take two, two rotor engines and put them together by welding the two eccentric shafts together and wind up with a four rotor?

 

That would be crazy. That would be so hard to make it run too.

 

yeah but if it was possibl it would be a fun project but probablly a tuning nightmare.

 

welding the ecc. shafts? that would be hard to balance and center correctly. maybe dual intakes would help with tuning?

 

For what it would cost to get it running correctly, you are better off just buying one from pineapple. Welding is a very bad idea. Besides balancing issues, it just wouldn't have the strength that it needs. Tuning would be fun though...... just imagine two intakes with dual webbers/mikunis.

 

pineapple?

 

It's been done read about here too. Might try a search.

 

It hasn't been done enough for a search to be easy! But I'm sure there's a little info somewhere. The reason there isn't a huge amount of info on 4-rotor engines is because of how insanely hard and custom it would be to pull one off successfully.

What about stationary gears to support the middle two rotors? and which plate would you use for the middle between the two engines? A standard intermediate iron wouldn't have any place to mount a stat gear, so you'd need something more like what the 20b has.

You can get a custom e-shaft machined, which would be a much better idea than welding, but you still have to figure out how the engines are going to bolt together to form one engine..

And what about oil supply and ignition? You have to remove the oil pump and distributor from the rear engine to be able to mount it to the back of the front one... Are you going to run it all from one oil pan and stock pump? And how are you going to do ignition with one dizzy? Not to mention coolant flow.

And we haven't even talked about mounting issues yet.

it's just WAY more of a custom job than you realize...

Jon

 

jon's right. search it and decide for yourself. it seems a good 13B would be a good building block for a fast 7. it would be cheaper, eaiser for parts and more fun without the frustration. search 787B and see if you can find anything on the four rotor in that. you might learn some neat facts that i wont spoil for you about that amazing le mans winning machine!

 

I could be wrong but there aren't many 4 rotor engines in 1st generation RX-7s. So you might get better response in a different sub forum. Anyway,

You can buy a kit, parts or engine here:
http://www.kiwi-re.com/wwd_showroom_cat10_2.php

or here
http://www.autotechmotorsports.com/r_and_d.htm

or here
http://www.pineappleracing.com

or here
http://www.downingatlanta.com

or maybe here
http://www.hurley-engineering.ltd.uk/hme13btt.aspx

A couple recent threads (took about 10 seconds to search and find them):

26b where to buy
https://www.rx7club.com/rotary-car-performance-77/26b-where-buy-587203/

Where can i get 4 rotor parts
https://www.rx7club.com/general-rotary-tech-support-11/where-can-i-get-4-rotor-parts-587199/

4 rotor 12A
https://www.rx7club.com/rx-7-audio-visual-lounge-143/4-rotor-12a-584947/

edit:
another one
ignition and balancing of 4 rotor
https://www.rx7club.com/rotary-car-performance-77/ignition-balancing-4-rotor-284665/

 

just sp a 13b and be happy.

 

because it wouldn't be unique enough duh

 

damn, i forgot everything gotta be jdm tight.

 

How much is teh cheapest 4 rotor eccentric shaft for a 12a based engine? ( to lazy to look it up)

 

Not sure about one for a 12A based engine, but the cheapest I've seen for a 13B based engine is about $5000. A proper 4 rotor engine would likely run you at least 20g's.

You might be able to have an e-shaft custom made from a piece of proper mild steel stock and heat treat it just right, but that would cost more than it would cost to build a reliable 250hp TII engine.

 

Iirc, all the 4 rotor e-shafts are 2 piece, for 2 reasons. 1. The center of the shaft needs a bearing support. 2. You can't assemble the engine if the 4 lobe shaft is solid.

This is just another pre-adolescent , (read noob), wet dream.

 

They're all 3 piece for the reasons trochoid stated above.

 

dont think anyone has mentioned this but uh, the 4 rotor engine each rotors ahaft is 90 degrees from the others ans opposed to 180 for the two rotors (i know this isnt worded right but you know what i mean?) 4-rotors fire 1-3-2-4 IIRC welding the e-shaft is never going to work, the E shaft has to be machined precisely.

 

^Good point, that makes it almost nessesary to get a propper kit, the $5000 dollar kit I saw had the e-shaft and irons I believe.

 

I would say that for the money it would take to build a four rotor yourself, and the parts it would take to get it put into a car and running, you could afford to build a 10 second FB using a 12A.

Actually, I would say that the amount of money it would take is pretty unfathomable. So much custom work, so much you'd have to deal with, and in the end, would it even be worth it? Sure you would have something different, but that's not always such a good thing.

 

Oh you bastard. I was thinking the exact same thing at work.

26b 4 rotor FTW!

 

Sadly,this is true.....
Unfortunately,on our sandwich based engines,its not a simple matter of stacking another slice of bread,a slice of meat,a slice of bread,ect,ect,ect....

If you fully understand how the rotary is balanced,timed,assembled and internally supported,then you wounldnt have even asked if you could home-make a 4 rotor.Those who have made custom 3 and 4 rotor engines,have machine shops,lots of time and money,and plenty of rotary experience.If you can afford a real 4-rotor engine,then turn off the computor and whip out the checkbook....it wont be cheap,but itll damn sure be fast and unique.

Welding two 12A or 13B Eshafts together would not yield you a true 4 rotor engine......itd just be two 2 rotor engines, inline.

 

Yes, but 2 - 2 rotor engines would still be pretty cool I think. How do they hook 2 or 3 V8 motors together on those tractors (the ones that do tractor pulls)?