Below is a link to MAzdaFC.com.

You will see the drawring of the adaptor I thought up. I think it would work. Check it out.

http://mazdafc.com/modules.php?name=...pic&t=183#3634

Justin

 

Yeah basically the same as the RENESIS 3(?) stage intake manifold...
Primaries only, then secondaries, then the 5th and 6th ports...

 

So pretty much it's just a riser?to lengthen the runners?

It might work as a thermal barrier as well if made out of some material like plastic so the UIM doesn't get heat soaked as easily.

 

Yeah with butterfly valves in the secondary runners to close them off at low RPMS.

 

I like the idea. I might have to try it out on a spare manifold to see if it will work.

 

Exactly. I got the idea from talking to people on the Rx8 Forum. They told me about the ports in the rx8.

No. It rasies the intake yes but thes only cause there has to be some meat for the Port Butterfly Rods. Basically the Secondary ports have throttle plates that close during low RPM but open at higher RPM.

Correct

Justin

 

Acutally probably not, but keep us updated with the results.

 

You Saying it probubly wont work?

How Come? im always looking for more ideas

Justin

 

I think on a stock port engine you might not see much, if any, gains. But I think you opened up the motor and changed the porting a bit you might see some better gains.
Anyone have any info on the timming of the rx-8 intake ports?
The stock primary ports on our engines just seem way to small to me to make any power over 1,500rpm! they're tiny! but hey I could be wrong, i usually am

 

Mazda spent quite a lot of time and money developing the FC intake manfold, especially on the S5. I doubt there is anything you can do to improve it. Indeed, modifications to the S5 manifold often result in power loss.

Also, the Renesis uses a completely different lower manifold, and the port size and shape isn't even close. For all intents and purposes, it is a completely different engine.

Also, unless you can provide dyno pulls that proves keeping the secondary throttle plates closed generates more torque, I don't believe you.

 

And the renesis doesn't exactly produce a good deal of low end torque anyway.

 

Considering it's top end HP (250hp?) and the fact its a very small displacement engine it has remarkably good low end (from what i've read.. havnt been in one yet..)

 

there is only so much you could ever expect from 1.3 n/a liters.....

 

Well for my first test when i had this idea i dissconnected the secondary throttle plates on the TB so it was only running on the primary. It had power till 2000 rpm. I brought it up to 4000 just for ***** and giggles and the engine did not like that at all. lol

Justin

 

This Post is an Edited Version of the Above post. This stupid Forum runs to damn slow and I wasnt going to wait for 5 minutes for the stupid thing to finish

---

I cant make you belive me but I feel a power difference when only the primary ports are open. Its not anything to jump up and down for. but there was an increase.

Mazda did alot of developing on the FC intake. and you wonder why they are now keeping the secondary ports closed and low rpms on the Rx8. Basically for the same reason I am keeping them closed. Even tho the rx8 has a different intake system. Its based on the same design

But like I said before i have no dyno proof and wont have any till I make it.

Justin

 

The Renesis is a completely different engine. You can't even campare the intakes. Take a look at some of the technical drawings of the port size, shape, location and the intake/injection system and you will see what I mean.

 

True the ports and all that are completely different, but it's still the same concept. I do agree that porting the motor would yeild better results with a new manifold design since the primaries are small. But I'd love to see some results of this study...I'm sure they're be positive.