converting the Renisis into a 3 rotor

[TYPE RX-7]

well im currently doing research on making a custom rotory work.. i have experience in doing this so im not new to it... i like the fact of the extra prots it has so what i am planning to do is to duplicate it into a 3 rotor ... im not sure how im gonna have the rotors remade yet either ceramic filled with titaium plating.. or duno still looking it up on what exactly im going to do .. im just in the research and develop phase... the power potential is there greatly... and what i am wanting to do is to turbo it... the only fall back i can see in doing a 3 rotor is the crankshaft which in all 3 rotors or more... strain the crank (should i make outa titaium?) and the heat issue.. i will be needing a big cooling system... next comes the tranny... should i use the RX-8 or find something custom to do.. well this process will take a long time. but any info that can help email it to me at [email protected] any additional info from any other tech out there will be greatly apprecated... i been working with RX-7's from 1st to 3rd gen..played with a RX-8, rebuilt several 3 rotors...worked on 2 RX-3's.. only thing i havent done is add rotors... which i know is highly expensive to do especially on the Renesis... i used to work for a mazda dealership i still have connections to get parts engines and so on so suppiles will be a lil cheaper for me... damn my spelling and my laziness

[Steel]

durrr... it would cost an ASSLOAD of money just to have those extra parts designed and milled. Assload as in..like.. lots.

But assuming you have the assloadforementioned amount of money, you should see if it would be a good design parameter to keep the rotors at a 120 degree spread.

and those side exhaust ports are a pain in the ass, iirc, each endplate has a more freely flowing exhaust port..uh diameter i guess. Therefore if using the same parts, the middle rotor would have a harder time than the 1 and 3 rotor to exhaust.

soo, you're looking at 2 X completley custom designed midplates, completley custom eccentric shaft no matter what, if you want a turbo it just makes matters more expensive.. heavy intake modification, custom header. Oy my wallet hurts just thinking about it.

And so far, the RX-8 has been dynoing an (you guessed it) ASSLOAD lower than the 247hp/215hp targets. I'm talking 180hp to 205?hp.

*edit* oh yeah, and you prolly wouldn't want to use titanium, unless it's a really expensive alloy. Titanium and its alloys has a pretty low modulus of elasticity.. which means it bends pretty easy. Goes back, but still takes less to elastically deform it. It also has a tendancy to gall easily, and with all the sliding going on in there, prolly not a good idea. There are steels out there that would do a much better job. That's why auto manufacturers are still using it. The biggest advantage titanium and its alloys have over steel's is weight.

[rotary911porsche]

Why not just get a 20B? The cost would be lower. Parts are readily available.
A four rotor may actually be easier. (Two rotors firing at the same time would be easier than trying to reconfigure the crankshaft.)
Follow this link http://members.tripod.com/~grannys/4rotor.html
for a writeup on a four rotor conversion.

[dayna240sx]

i need to raise the BS flag on this guy,

If he really had 1/2 the experience he claimed he wouldn't be asking such basic rotary questions...

for example he claims he has re-built a 3 rotor, yet is not bright enough to think about using a multi-piece e-shaft for his project/.

More over why increase displacment of the renesis, how about you tune what is there first...

and if you really want to machine and modify everything to increase displacment you would be better off widening the rotors (maybe weld two rotors together) lengthen the stat-gear bearing, and bearing surface on a custom e-shaft... make a 2.6 litre 2 rotor.

custom tension bolts., the water seals on the renesis on on the rotor housings (again) so you could easily mate 2 rotor housings.

Oh but you've worked on so many rotaries you prolly already knew all this.

[Steel]

Originally Posted by dayna240sx

i need to raise the BS flag on this guy,

If he really had 1/2 the experience he claimed he wouldn't be asking such basic rotary questions...

for example he claims he has re-built a 3 rotor, yet is not bright enough to think about using a multi-piece e-shaft for his project/.

More over why increase displacment of the renesis, how about you tune what is there first...

and if you really want to machine and modify everything to increase displacment you would be better off widening the rotors (maybe weld two rotors together) lengthen the stat-gear bearing, and bearing surface on a custom e-shaft... make a 2.6 litre 2 rotor.

custom tension bolts., the water seals on the renesis on on the rotor housings (again) so you could easily mate 2 rotor housings.

Oh but you've worked on so many rotaries you prolly already knew all this.

hehe.... owned

[BlackLabel6542]

i emailed granny's for info on their design to see if i could replicate it but they told me that they sold the design to another company cant remember the company right now

[Entreri33]

Ill double the BS flag

However doubling the width of the rotors would I believe actually decress the efficency of the renisis and its side exhaust ports. I personally dont believe that wider rotors is the answer for more displacement. I know I am in the minority here when I say that more narrower rotors woudl be more efficent and powerful. I have nothing readily availble to back my conclusion other than a gut feeling from piston engines. ie a 5.0 v8 doesnt make the torque and HP of a 5.0 V12.

Also Mazda has claimed that they havent solved the ehaust issues of a renisis 3 rotor yet so my question is how does he think he will be able to do it if a team of engeneers hasnt been able to for the past several years? And if they have can we see a 3rotor RX7 instead of a turbo renisis???

[dayna240sx]

Originally Posted by Entreri33

Ill double the BS flag

However doubling the width of the rotors would I believe actually decress the efficency of the renisis and its side exhaust ports. I personally dont believe that wider rotors is the answer for more displacement. I know I am in the minority here when I say that more narrower rotors woudl be more efficent and powerful. I have nothing readily availble to back my conclusion other than a gut feeling from piston engines. ie a 5.0 v8 doesnt make the torque and HP of a 5.0 V12.

Also Mazda has claimed that they havent solved the ehaust issues of a renisis 3 rotor yet so my question is how does he think he will be able to do it if a team of engeneers hasnt been able to for the past several years? And if they have can we see a 3rotor RX7 instead of a turbo renisis???

A few points here, In a rotary, with the same DISPLACEMENT... the rotary with the most rotors (eg, a 4 rotor 1.3 litre using 40mm width rotors, vs a 2 rotor 13B using the traditional 80mm rotors) will make more PEAK hp, and have a smoother power band... although, the 13B 2 rotor will have more (low end) torque. You have to attribute rotor width to the "stroke" on a piston engine) For example a 383 (stroked 350) would have more torque than the base 350.

This being said, you are correct by assuming that more narrower rotors would be better... but the key to doing this would be to offset the rotors more.. for example, the 20B has the front and rear rotors doing the same thing... while the centre rotor is 180 degrees off, (essentially the rear 2 rotors are a 13B, and the front most rotor is timed with the rear most rotor) i would wager the 20B would see ATLEAST a 10-15% increase in torque and HP by replaceing the e-shaft so each rotor is 120 degrees offset. a 4 rotor would be 90 degrees, where as the R26B had the 1st and 3rd on the same timing, while the 2nd and 4th were on the same timing as well... imagine how much better they could have done with the lemans program with another 10-15% more power.... they could have gotten even better fuel mileage.. smoother power, and all for the cost of a different CAS.

I have always thought it would be cool to have like a 6 rotor with 30-40mm width rotors that are 1/2-2/3 the standard diameter.. would rev like crazy...

Mazda's problem with the wider rotors and also the 3-rotor Renesis is due to the fact that they are trying to not make new parts..

IF their side housings were wider, and the exhuast port was re-shaped to flow through the exhaust ports at a higher velocity a lot of their problems would be solved..

IF you hear of the company with the 2(13B)=4-rotor plans, LET ME KNOW!!!
I would love to try this... maybe but one in a FOX body Mustang with a T-5 adaptor, and eat some V8 ass in their own chassis!!!

[Entreri33]

There was a guy on the rx7club.com forum making 3 piece eshafts to build your own 26b. I cant find the tread but it was out there.