vipeRX7

A lot of people have said on this website that it would be very difficult to add a 3rd rotor to the renesis. I'm assumed that the reason is that the two rotors would have to share a rotor housing wall (is that what it's called?) and that the intake and exhaust ports are on the non-shared walls. However, for each rotor there are two exhaust ports, and it doesn't make sense (to me) why they would have two exhaust ports on the same (namely the outside) housing wall (plus the pictures of the Renesis only show one exhaust port on a housing wall). So for each rotor, there must be an exhaust port on both housing walls ... but that would mean that exhaust would leak from one chamber to another since one of the walls is shared. So does this mean that the two rotors do NOT share a housing wall? If this is true, then it means that it wouldn't be any harder to add a 3rd rotor than it was to add the second (which imho is better than using forced induction because it would be a lot easier to add aftermarket FI on Mazda's factory 3 rotor than it would to add a 3rd rotor to Mazda's factory FI), so one pitfall of 3 rotors is no longer relevant :D. Also, if each rotor has 2 exhaust ports, could the aftermarket people add a second intake port for each rotor to allow for increased power? :D Or would it be difficult (on the high power version) because of the variable intake timing (isn't that how the high power version gets the additional boost?) ? Sorry if thats confusing, I'll give clarification if requested. Just some thoughts, what do you all think?

Jeff20B

Well, the intermediate housing allows the exhaust ports to mix within the port itself before it even enters the manifold. I assume that's ok with a two rotor engine for scavenging. However, a three rotor engine's rotors are phased 120º apart and may be problematic with this type of exhaust port.

Here's something Mazda could try: why not add a seperater plate in the intermediate housing's port to keep the exhaust pulses seperate for a little longer; like untill they reach the manifold for instance. It could be made from the same material as the diffusers in 'FC NA exhaust ports (Renesis exhaust is supposed to be cooler, right? Then no problem with heat). Also, the other wider 20B-only intermediate housing which holds a stationary gear is already 80mm wide and should be easier to house two seperate exhaust ports; one large and one small (much like intake ports on a 20B).

Man, I'd love a three rotor Renesis!

NegatiZE

Hey, why not just make it 4 rotor and forget about the problems???

Farsyde

didnt the japanese version of the rx-7 have 3 rotors? It seems the only mod needed (for any number of rotors for that matter) is to just have separate exhaust pipes for each rotor (possibly combining rotors that fire alternately). I vote for a 10 rotor 1000hp engine!!!

vipeRX7

I wish! The only production 3-rotor car I know of was a turbocharged luxury coupe sold as the Eunos (a luxury brand of Mazda) Cosmo. At one point in time, it was the fastest domestic car in Japan. Though it was rated at 280 hp, it really had ~320. Unfortunately it was never sold in the US due to emissions and bad fuel economy (but a few were imported). As far as 3-rotor RX-7s go, the only ones in the US were modified 2-rotor RX-7s created by Peter Farrell Supercars and Pettit Racing (there may be others). But a 3 rotor renesis ... just imagine ...

Jeff20B

You don't need 10 rotors to make 1000HP anymore. A 20B can hit 1K if souped sufficiently up. Some 13Bs can hit 700, too. But for reliability, a 4 rotor making 1000HP is safer (only 250HP per rotor).

I very muchly want a three rotor Renesis!

wakeech

PLEASE stop making new 3 rotor motor threads...

there are tons of reasons why it's not going to happen in the near future, so for all you guys who're incapable of searching on your own...

read this, and this,and ESPECIALLY this...

and that's just for starters.
do some catch up reading, use the search, and please stop re-rehashing the same old stuff... if new, unanswered questions pop up in your head, write them down as you continue to read, and please PLEASE ask them... :D