I know this is a stupid idea, but figure I would though it out there. Just wondering,, can the old 13B Rotor housing fit wth the renesis midplate (the two rotors share the same exhaust and intake housing, that's why they can't make a 3 rotor renesis. (or so I've been told). I am thinking that is where the big difference in the engines lie. Yes, I know you would have to fill the Peripheral exhaust port, but hey, they fill the intake ports for peripheral intakes. Anyways, This is just a question to think about, not serious about it.

P.S. This is a part is serious though, can you use the 13b rotors from 89-91 RX-7's on a 13REW, Reason being, they weigh the same as the 13REW rotors, but have a 9.7CR, so if you milled them down to 9.0 spec, would they not be a bit lighter then the 13REW's,, Thanks for the neuron fires.

 

I know you can swap FD rotors into FC engines, so I'm pretty sure that you would be able to swap FC rotors into FD motors. I'm not sure that milling the rotor faces would be a good idea because the rotors are hollow inside. If you take too much material off of them you will reduce the thickness of them, and that can be very dangerous if you run boost. Also you would have to make sure that you have each rotor individually balanced, and I believe you would have to get a new counter balance for the motor as well. Overall I don't think it would be worth it. The S5 rotors have a compression ratio of 9:1 and the S4 8.5:1. Are you talking about milling down the FD rotors? You can get your rotors professionally light weighted which I would advise if you are looking to reduce rotating mass in the engine.

- Steiner

 

Intresting idea, but the question everyone is going to ask is "WHY!!!!!" If you have to worry about emissions, just do a full renesis swap, if you don't have to worry about emissions there is absolutly no reason to get rid of the PP.

 

it would be funny to put renisis rotor housings into an older 13b, zero emissions vehicle!

 

The older 13Bs had the water orings in on the iron housings. The renesis has them on the alum housings. Something to think about, or not think about.

 

Actually the older 13b's had the seals in the rotor housings..
The 'new' style 13b's had them in the side plates...
The 'newer' style 13b's have them in the rotor housings....

or in year terms

seals in sideplates 1986 - 2002(?)
seals in rotor housings < 1986; >2002(?)

 

Well, I went to mazdatrix website, and I found:

Model C.R Weight (grams)
13B N/T 89-92 9.7 4328 9.54
13B Turbo 89-92 9.0 4328 9.54
13B T/T 93-95 9.0 4328 9.54


The 89-91 NT rotors weigh the same, how about instead of mililng down into the rotor,, is it possible mill it out,, widening the hole,, or better yet,, just replicate the relief from the 93-95TT rotors..

As for the Renesis/13B hyrbid,, Thought of a few advantages.

1. Better Emissions - (save the world...lol)
2. Faster Spooling - Ports are bigger and no overlap (intake
air from turbo not shunt out the exhaust ports)
3. Better fuel economy
4. Turn the boost dial down/off, put in regular gas, and still have some
power (good for long trips, crappy weather, and just wanta save $$$)

 

the renesis won't spool a turbo faster. the side exhaust layout is pretty restrictive.

 

Well, not sure if it will spool faster, but if not it should be close to the same. There are some turbo kits on the RX-8 page getting around 240-280 whp with just 7lbs of boost. I would imagine that the torque curve of a turboed Renesis or a 13b with MSP (basically the same thing) would be much smoother and not as "peaky" as the Standard FD engine, with the added benefit of mileage and emissions

 

pop onto the major horsepower upgrades section on rx8club.
i've got a porting thread in there and there's probably a dozen FI threads too.

the results aren't as impressive as you might think.