As one project is wrapping up I am quickly becoming interested in yet another rotary project. I am not certain that many have experience but I am interested in opinions and arguements a-like regarding the topic. I am aware of the budget necessary to complete such a project and I can assure you I will make it happen one way or another, I wouldn't think of wasting anyone's time on a whim, so please, any constructive information would be greatly appreciated.



I have an opportunity to purchase a cloned 4 rotor if you will, essentially two 13B's bolted together, yes, the kind where the first and third would fire at the same time etc. I am also looking at a non-sequential approach with a turbo for each rotor, as much a plumbing nightmare as it may be, I want to entertain the idea for now.



I also want to stay with an RX platform chassis as well, it may need to me a mid-engine custom or moving the firewall around some to make room. It would be nice to keep it "street legal", and, I use that term so loosely, I am not really interested in a tube frame chassis with a body hung on it etc.



So there it is for now, let me have it, good, bad, or indifferent.

Sounds like you'd need a 1 ton pickup to fit all that in the engine bay.

Unfortunately, that's how it will sound too. It will sound like two 13Bs reving up together instead of an R26B. If you're ok with that, go for it. https://www.nopistons.com/forums/pub...IR#>/bigok.gif

[quote name='TYSON' date='Aug 21 2005, 11:34 AM']Sounds like you'd need a 1 ton pickup to fit all that in the engine bay.


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of course, it may not be able to get stuffed in any rx type e-bay, but that is the purpose of this discussion, it may not be able to accomodate 4 gt30 turbo's either, but again that is the idea, find out what will work and what won't before a bunch of time and money is wasted.

[quote name='Jeff20B' date='Aug 21 2005, 11:43 AM']Unfortunately, that's how it will sound too. It will sound like two 13Bs reving up together instead of an R26B. If you're ok with that, go for it. https://www.nopistons.com/forums/pub...IR#>/bigok.gif


[/quote]



What is the alternative, machining a different E-shaft? what effect would that have on the rest of the engine?

i might point out that the r26b is rated at 750bhp, i'll go out on a limb and say you dont really need turbos for this one https://www.nopistons.com/forums/pub...DIR#>/wink.png



which also makes it easier to fit/plumb

[quote name='j9fd3s' date='Aug 21 2005, 12:30 PM']i might point out that the r26b is rated at 750bhp, i'll go out on a limb and say you dont really need turbos for this one https://www.nopistons.com/forums/pub...DIR#>/wink.png



which also makes it easier to fit/plumb


[/quote]



Engine builders idea for the turbo per rotor, or wet dream.



I would imagine a bigger single wouldn't be out of reach either or two middle of the road snails would make the plumbing task easier.



To me, it really isn't about making gobs of tourqe and horsepower as the ultimate goal, it's really about putting a quality project together, in an rx platform, that isn't run of the mill. A challenge to put something unique together, if it makes gobs of power so be it, nothing more than a nice side effect, lol.

ive heard that the differences from the block length in comparison with that of a 20b is minimal..

anyone know how they achieved this.. side housing thickness perhaps... doubt they would slice it off the rotor and housing...

heres a pic of guru racing 4rotor pport...

10A rotor housings?

amp that 4 rotor you posted is done 'wrong' notice that the 2 center rotors recive less air flow than the outer ones do. if they were using the side ports (which dont apear to be blocked off) they would want a primary and a secondary runner per rotor. here only the end rotors have secondary ports. again, with the peri ports this isnt an issue. i guess thats why they didnt go to the trouble of using 20B center plates.



that is also the answer to your question amp. the 20B center plate with the one primary and one secondary port is much thicker than a 13B center plate. multiply that diffrence by the 2 center plates needed for a 4 rotor engine and you easily save a few inches in length by going peri port. this 4 rotor is prolly only 2 inches longer than a 3 rotor with the correct center plate. i guess the same thing could be said for doing a 3 rotor with peri ports or with using the jeff bruce modified 13B center plate. there 'short 20B's' as they're referred to are a few inches sahorter than real 20B motors. hitman has pics of his short 20B in his first gen on his web site. if i remember correctly he was one of the first 2 ppl to run a jeff bruce 'short 20B' motor (now sold through guru and others) about 5 years ago. pics and details should still be on his site

i just read my response and its a lil confusing. what i meant to say is yes they achived the shorter length by using modified 13B center plates instead of using the thicker 20B/26B center plates. the only way this is really a good solution is when building a peri port motor so that the port sizes in the plates does not come into effect. notice the center rotors would be getting fed by 2 x primary intake runners while the outer ones are fed by 1 x primary and 1 x secondary each if the motor was running off the side ports

heres a real 20B motor. notice the thickness of the frontmost center plate? a true 4 rotor engine would have 2 plates of this thickness.



http://www.auto-illusions.com/rx7/images/DSC01018.JPG

heres a 26B with the 2 thick center plates. im not sure why the 26B motors had the extra thick center plates as they were all peri port motors, mabye the center bearings and stationary gears they used were very large



http://www.motorpride.com/ProjectRotary/26b1.jpg

Speed NYC, your right about the irons...but notice that the 4 rotor is Peripheral ported? lol

i did notice, did you read my post?

the peri ports are exactly what allowed them to make this motor so short.......

Oh ok....sorry. They must have had a e-shaft custom made for that application.

In the instance of a true, or bastardized 4 rotor motor installation in an rx-7 platform, in the sense of spitballing, a mid engine application would solve some of the fitment problems of the conventional engine bay, assuming it was to be a non p-port.



The difference from a true 26b or 2 13b's bolted together is irrelelvant at this point.



The budget I currently have will allow the completion of a bastardized 4 rotor in an rx chassis with a great amount of class, quality, and prowess while maintaining respect to all that is rotary...to complete the project with an actual 26b I would need some backing, from a couple different sources.



I haven't ruled that option out at all, we are just not that far down the road yet.

[quote name='R.P.M.' date='Aug 21 2005, 02:05 PM']Oh ok....sorry. They must have had a e-shaft custom made for that application.


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yes, jeff bruce makes custom 2, 3, and 4 rotor e shafts and modifies center plates for the building of these engines. you can orger the 3 and 4 rotor shafts in short or long config. guru and kiwi re sell kits made my jeff bruce

and his precision engineering company



hers a quote from hitmans site:





Custom made 3-rotor based on RX4/5 13B components, Custom made Crankshaft, 12A RX7 centreplates with one modified to take a stationary gear, RX-5 end-plates and rotor housings. Custom parts made by Jeff Bruce.

heres a link to the engine specs

http://www.hitman.hm/engine.htm



heres a link to the car buildup. again notice that this 'short 20B' was built over 6 years ago.



http://www.hitman.hm/rx7.htm



jeff bruce's contact info is on that page too, im sure its changed since then, but you can buy the stuff from guru or kiwi now

I had seen those shots and heard the name before but couldn't remember any of the specifics, thanks for the tip!



It will be interesting to track the man down and see if we can put something together.

To make a 'short' three rotor would be price competitive with a big turbo upgrade if you have to buy all the turbo bits anyway (intercooler, etc)





We called down under late one night https://www.nopistons.com/forums/pub...1047683785.gif





BTW, the think 20b centre plate is 50mm thicker than a normal one.

Go for the 26b and then when you can, get a new e-shaft machined to make it "true." Hell, go as crazy as you and your wallet want to/allow.

[quote name='j9fd3s' date='Aug 21 2005, 11:30 AM']i might point out that the r26b is rated at 750bhp, i'll go out on a limb and say you dont really need turbos for this one https://www.nopistons.com/forums/pub...DIR#>/wink.png


[/quote]

But two non-turbo 13Bs would be less than or around 400hp at the flywheel. Not really worth the effort or added weight without turbos.

[quote name='SilverSeven' date='Aug 21 2005, 08:47 PM']But two non-turbo 13Bs would be less than or around 400hp at the flywheel. Not really worth the effort or added weight without turbos.


[/quote]





Please tell me you got this number some other way than just taking bhp numbers of a 13b and multiplying by TWO



https://www.nopistons.com/forums/pub...1047683664.gif

[quote name='SilverSeven' date='Aug 21 2005, 05:47 PM']But two non-turbo 13Bs would be less than or around 400hp at the flywheel. Not really worth the effort or added weight without turbos.


[/quote]





[quote name='ColinRX7' date='Aug 21 2005, 09:26 PM']Please tell me you got this number some other way than just taking bhp numbers of a 13b and multiplying by TWO



https://www.nopistons.com/forums/pub...1047683664.gif


[/quote]



Seriously, it makes no difference at this point, the only time it will make the slightest bit of difference is when it comes time to attach a transmission and readend or transaxel so those components work correctly and efficiently from whatever power the engine makes.



Streetable is also a goal to keep in mind, an emissionless groundpounder, and it will take the good graces of the local hot rod council to grant an SP license plate to make it happen.



To put the 13b's into perspective, the engine that I am lined up to buy is nearly 3000 dollars cheaper than a full blown p-port race motor, having an e-shaft made to make the firing order act and sound more like the real thing, not to mention the other benefits, will eat most of that savings up, if I go that route, but essentially I will only have to invest as much as someone whom is buying a full race p-port engine.

[quote name='TYSON' date='Aug 21 2005, 10:34 AM']Sounds like you'd need a 1 ton pickup to fit all that in the engine bay.


[/quote]





I submit that a four rotor would easily fit in a first generation RX-7 with the stock transmission placement. One would likely need to scallop the crossmember, and definitely relocate the radiator to the hatch, but it would be doable.



Shift the transmission back several inches and you could probably use a front mount radiator, if you made new mountings that pushed it as far forwards as possible. The issues of relocating the transmission are moot, since a new crossmember, driveshaft, and potentially a shifter hole will be needed for a sufficiently strong trans.



The second generation cars don't seem to have as much underhood room, but that may simply be an optical illusion due to the hood opening in a different direction. Rear mount radiators seem to be easier for these, however.

i'm a bit of a newb but if you are going to get a custom 4 rotor e-shaft up, would it be possible to make VERY thin intermediate plates, like 10mm thick, that way you would decrease the amount the rotors travel in the middle of the engine by making it shorter, but also reduce weight/length making it easier to fit.

I think the importance of the stationary gears and corresponding bearings become even more important when adding rotors, increasing the length of the shaft will, in turn, increase the possibility of flex in the shaft. The smart money says the plates should remain at the maximum thickness.



The "center plate" in a cloned 4 rotor is also an important issue it seems. Mating a rear and front plate from a 13B, while using an adapter piece intermediately, makes some strange restrictions to the coolant passages, as well as the cosmetic appearance from the outside.



I am leaning towards having a custom center plate machined, in addition to the E-shaft, allowing for proper; coolant flow, dowel pin placements, stationary gears, bearings etc.



Keep in mind, even if it were possible to walk in and order a 26B, the price tag would be in excess of 70,000 dollars. Having some machining work done to improve the overall aspects and performance of the cloned motor offsets the budget some, but still leaves the finish build cost way under that of an actual 4 rotor.



The challenges involved in installing the engine in an RX chassis will be nothing in comparison to getting a clone built!

This is pretty much what the shaft will look like...



http://89rag.nopistons.com/gallery/a...t/pg03_17b.gif

variable length, multi-step intake trumpets, I only wish!

[quote name='89 Rag' date='Aug 27 2005, 08:39 AM']variable length, multi-step intake trumpets, I only wish!


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they used headlight retractor motors and cables dude, the harware isnt fancy. in fact the 787b is a neat car to play "spot the stock parts" game on, theres a suprising amount of stuff thats off of normal mazda cars

[quote name='j9fd3s' date='Aug 27 2005, 11:50 AM']they used headlight retractor motors and cables dude, the harware isnt fancy. in fact the 787b is a neat car to play "spot the stock parts" game on, theres a suprising amount of stuff thats off of normal mazda cars


[/quote]



Interesting, I haven't had the pleasure to see it in person.



it's a room issue too, all that in the conventional engine compartment would be rediculous.

[quote name='89 Rag' date='Aug 27 2005, 02:48 PM']Interesting, I haven't had the pleasure to see it in person.



it's a room issue too, all that in the conventional engine compartment would be rediculous.


[/quote]



well hopefully they have it at ss8 this year. the setup is compact in height, but one side is radiators, and the other is airbox. or in other words the engine bay isnt fc shaped.



http://www.scuderiaciriani.com/rx7/787B/



http://www.scuderiaciriani.com/rx7/787B/787_19.jpg



http://www.scuderiaciriani.com/rx7/787B/787_21.jpg

The 787B will not be at SS8 this year.

with a 4 rotor running the engines 2 rotors firing at the same time, you wouldn't need to have any counter weights would you?

i think the 26b is the ****, i would love to have one,here is a pic of a 26b its still got the factory gearbox and driveline,it has 590hp and does a 10.561/4 mile and it is still road driven

no pic...

No pic, double postin' when you should be granny postin' like you should be.