Rx-8 Intake manifold in S5 N/A, possible?
 

i was poking aroud online and noticed the intake manifold gaskets for the s5 n/a and the 6 port Rx-8 are strikingly similar. so how could i adapt one, i believe it'll bolt up, but im not sure on the peculularitys of the swap
the rx-8 looks to have a bigger much less restrictive intake than the s5 n/a. so this could prduce a nice power jump I would think

The RX-8 intake is designed for a radically different motor.

For example the aux ports on a RX-8 don't even start to open until around the same RPM as the VDI opens on the S5 non turbos, and the VDI on the Reni is even higher still.

What does this mean too you? Well the reni is designed to be running at 3000 rpm at 60 MPH, and the intake runners are tuned for a much higher run out than S5 manifold.

See intake runners are tuned for the motor. With the reni's much lighter rotors and side port design, the RPMs and intake velocity wouldn't match what the S5 motor would be needing.

There is a lot more than just size to consider when looking at intake manifolds

hmm interesting

How are the RX-8's aux ports actuated? vacuum? Air pump? Solenoid? Stepper motor? Couldn't the timing of the port openings be adapted to the S5 engine? The S5 ECU sends outputs to solenoid air valves to open/close ports/vdi, couldn't the same be used to control the RX-8's manifold?

The aux ports on the Renesis are actuated electrically with a motor. They are very different and there is no way to retrofit the Renesis system to a 13B system.

I have a Renesis end housing and a 13B 6 port housing lying around. I'll try to get side by side pics. I also have both intake gaskets where you can really see how far off they are.

linear actuator and gear drive. Just like the throttle body (drive by wire system).

Sure, but again, the runner length is tuned for different RPMs. The location of the VDI actuator and valve are set for 7000 RPM, not 5200 RPM, so the sonic wave from the engine would be tuned to the wrong spot for a S5 motor.

So I suppose if you could change the port design and timing on the engine and use lighter rotors, with the champer on them, maybe then the sonic waves from the port closing could use the Reni manifold... Some one would have to try it to see though, because on paper, it makes no sense what so ever. Plus, as I recall the reni manifold matches up to the S4/S5 13B like the REW top manifold does to the REBT manifold

And if you equated bigger manifolds or runners to making more power, then using the S4 manifolds on a S5 would give you more power since they are also bigger than the S5 ones. Right?

The intermediate ports line up but the outer ports aren't even in the neighborhood. The Renesis outer ports don't turn as sharp. They come in from much farther out. You wouldn't even want to try to adapt it. The Renesis aux port sleeves are much alrger in diameter. They attach to the lower manifold and have no rods in the airstream. This is a good thing. It's just not anywhere near feasible. I'll take pictures and post them later.

Here's a picture of the 13B and Renesis end housings next to each other. You can see that the Renesis secondary runners are larger. It doesn't look like much but there is a significant area increase. These are opposing housings so notice how much farther out the secondaries are on the Renesis than the 13B. The aux port is also much higher and larger than the 13B runners. They use much larger diameter sleeves that are gear actuated on the outside. There is just no way to make this match up. At least not in a way that would be worth the effort. It would be easier to make a new manifold. The primaries do line up perfectly though but that's not enough to make it easy. I'll try to get a shot of the intake gaskets tomorrow. You'll really see how far off they are then.

It looks kind of funny to see the exhaust port on the iron. Not used to it yet :D

^ Ditto! So tiny and...well....square :) I like my PP ports. I hear PP exhaust ports are better anyways and I would think its because you can get more exhaust out quicker and easier?

with considerably more overlap too (which wastes both fuel and efficiency).

Fixed :)

I've talked to some RX-8 guys who've blown their engines for various reasons and apparently they are far more prone to internal carnage because any shrapnel created during a failure has no easy way out of the engine and ends up along for the ride for God knows how many cycles.

Just a little food for thought. I like the comparison shots too BTW Rotarygod, nice.

^ hahahahahaha.

I know but im talking power performance? The side ports may help low end a little right? PP ports better for mid to high end?

Yeah, the side ports give it a better low end. The zero port overlap also lets the Renesis have larger ports without hurting emissions so much. That plus the raised redline gives it much higher power than the stock 13B. The Renesis started out as a project to make a low emissions rotary, IIRC. But yeah, a heavily ported PP will easily beat a heavily ported Renesis.