My friend and I are looking very deeply into assembling a 4 rotor from two 13bs, we have worked out the accentric shaft adapter as well as rearplate/ adapter/ frontplate setup in the center of the motor. The hard parts are worked out, but after some more thought, the idea of opposing the shafts 90 degrees instead of the original 180 degrees came up. Does anyone have any ideas on the ignition of this beast if opposed 90 degrees as well as 180 degrees. Were actually considering running a DSM coilpack and ecu for rotors 3 and 4 with a stock 12a distributor up front with the points matched to fire leading and trailing spark at same time. This works in theory at least. Any other ideas? The motor will be carbed so no worry of coupling the ignition with fuel injection.



Also, how have the 90 degree opposed 4 rotors been balanced in the past?

Why don't you just go crank trigger...? ...it should find the proper degrease per every spark. Or try sakuras PC.. (http://www.pistonvsrotor.com/index/derecha.html#).....or microtech..

Kilo racing from orlando florida recently ran 10.02 in a 85 rx7 (2150LBS) perifial using microtech..oh and on GAS...NO turbo or juice



Although i like your style of using a 12A ditributer to fire leading and trailing spark.

I am a fan of PC less power.."Rafaelito 13B, 12A Distributer, Twin Webber downdrafts, & Turbo = 7.6 @ 180MPH"



As far as balancing goes there is a far greater issue that should be corrected before you have to balance the engine and that is crank shaft stress, distortion & flex. Some of my friends that use 3 rotor engines in puerto rico have seen the actual shaft twist and flex under high boost or stress.



One of their solutions is to have a billet 1peace shaft made of 4130 that would be superior to the 2 piece OEM shaft. (i think you can get it here but i am not sure http://www.pistonvsrotor.com/negroracing/c...ogo/index.html)



So if it is a problem with 3 rotor engines then it will most likely be an issue with a

homemade 4 rotor engine.



I also like your carbureted idea..There are two or three cars in puerto rico that are attacking the aspirated league with 3 rotor perifials on on juice ..such as a Datsun 1200 called chimiquie ..and a few more on the way. With 2rotor cars already in the mid 8's, They will with out a doubt touch the 7's......

For the fastest rotary cars int he world check out www.pistonvsrotor.com.



Regards

Jonathan

Well, I responded to this elsewhere, but I'm going to bring up the shaft flex thing first.



The problem with the 3-rotors and the reason the shafts start flexing like that is because the rotors are 120 degrees apart from each other, and the stationary gears aren't evenly spaced... There's a bearing, rotor, rotor, bearing rotor, bearing... or maybe I have that backwards, but it doesn't matter. The point is that there's two rotors with no bearing between them.



So what, you ask... the 13B does that too. Yeah, but it's different. They're opposite each other so the forces (more or less) counteract each other. The 20B will have them 120 degrees apart... so it's unbalanced! Yes, the whole thing balances out, but that section doesn't... and the forces build up pretty quickly.



Only real way to get around that is to add another bearing.



I... uh... really really have to wonder exactly *HOW* a 1-piece 3-rotor eccentric shaft would work. It seems to me that it would sort of make it impossible to get one of the bearings on which... kinda makes it impossible to put the engine together. https://www.nopistons.com/forums/pub..._DIR#>/dry.png Making a stronger e-shaft is just a bandaid fix for this problem anyway; there's limits to how much poor design you can overcome with better materials.

I would think the best way is a 4 peice for the 3 rotor.

a.

ll

ll

ll==============

ll

ll

b.

__

l l_

l___l





Part a. is a plain shaft with a cam or keyway on it



Part b. is a combination piece that supports 1 rotor and 1 bearing



so you can use 4 bearings for a 3 rotor



The shaft will have a stop on it to keep all the pieces from floating and it allows you to set endplay for the engine.



Or at least thats how I would build one in my world.



https://www.nopistons.com/forums/pub...IR#>/bigok.gif

For your 4 rotor engine built from two 13Bs, you could run them 180º apart I suppose. The ignition would be extremely easy to figure out. All leading plugs could fire at the exact same time. Don't believe me? Then you've got more thinking ahead of you. An FB distributor could be used on each engine to cover leading and trailing.



By the way, the 26B and R26B rotors are phased 90º. It's what gives the engine that nice pneumatic drill sound. All you've gotta do to get your engines to sound that way is to rotate one E shaft 90º from the other. Let the individual distributors do their jobs correctly, and it (the entire engine) will have no problems running.



The firing order of a 90º engine would look something like this. L1 and L2 front engine, L3 and L4 rear engine:



L1 0

L3 90

L2 180

L4 270



Any questions?

On second thought, you were thinking of not having a front cover on the rear engine, weren't you? That's probably a bad idea because I don't think a single oil pump in the front engine only would be enough to give adequate volume and presure to both engines. Then again, what do I know?

Well... I'm going to throw this in because it's really oddball but sorta related.



It just occured to me that with a peripheral port engine, the end / intermediate housings don't have to be nearly as thick as they are. The only thing you have to fit is the stationary gear.



I know, nice idea in theory. Well, I think I figured out how to simplify the design of the intermediate plates enough to be (relatively) easy to machine. Only caveat is that this is done by changing the oil passages... and thus requires a dry sump. Oh well, no biggie. https://www.nopistons.com/forums/pub...#>/biggrin.png



The eccentric shaft is always the sticking point in these sorts of things. I *think* I figured out a way to do it and have all the oil passages with, again, relateively simple machining. 5 piece but oh well... lets me put a bearing in the center intermediate housing too.



As long as we're making side / intermediate housings from scratch, why not have a different transmission bolt pattern? This isn't *necessecary* but would certainly make things easier for some people.



In case people didn't catch the reason for making the intermediate plates thinner, using scientific wild-assed guess calculations I figure that you could get a 4-rotor out of 13B parts into the same space you can fit a 20B into.

We have the ignition worked out for the 180 degree apart motor. You are right, it is easy. The 90 degree opposed motor is a little tricky. The current idea is to use a crank position sensor from a DSM and modify the ecu to fire correctly. As for balancing a 4 rotor turned 90 degrees apart. I have seen granny's speed shop do a 4 rotor and did not neet external balancing as they balance themselves, however with a 90 degree opposed motor, I dont believe this is the case? In our plan, we really dont include using two distributors. The iron part of the front case of the rear "motor" bolts closely to the rearmost iron plate of the front "motor", with a thin aluminum adapter in between the two. Using two distributors would be easy. Agreed. Packaging is somewhat difficult though. As for oiling, we plan to overdrive the oil pump and run an exterior line to the rearmost section of the motor to feed it. It has been done before and worked for an entire racing season, so....

Here in New Zealand, we can buy a kit for building a 4 rotor from two 13Bs. Shaft and bearing/gear modification to the centre plates are available off the shelf from Precision Engineering.

There are already a couple of PP variants running competitively here.



Gary

It's been done about a dozen different ways. If you just want very simple, very easy ignition. Try this.



On the front pulley, add a 1/2" thick aluminum disc with a single iron reluctor

(I use an iron 10 penny nail) and mount two Chrysler pick up coils 180 degrees apart on the front case.



Each coil triggers one MSD to fire both Leading and Trailing coils for one housing on the front half. (I used the GM double ended coils from an Oldsmobile (I think) so you would need 4 of those coils, or 4 of many styles of double wire motorcycle coils).



Same on the rear half, but a single reluctor mounted on the flywheel, two pick up coils (this is the magentic biased pick up, inside the distributor of 70s and 80s Chrysler products) mounted on the rear cast iron 180 degrees apart to run both housings on the rear half. Starting the engine with full advance already in place is no problem at all.



Some sort of industrial coupling between the two shafts to absorb some of the shaft flex, and it will hold up just fine. If you make the junction rigid, you will go nuts trying to keep the rear crank in it.



Anyway. No distributors at all. Very clean looking installation. If you cannot afford 4 MSDs, use the Chrysler amplifier. About $20.00 each.



Only a 5 HP top mount geared starter will turn the pig up, but they are available as rebuilt.



Mount the whole mess on a 1 inch thick aluminum plate with the oil pan screws. Leave it 3 inches wider than the gasket flange for stiffness and cut out the area that is inside the normal oil pan. Mount it in rubber. Dont let chassis twist damage the engine. And that chassis will be twisting, be assured.



If you need a picture of that reluctor wheel, I will dig it out and make some.



Lynn E. Hanover