Is there any way to improve the performance on the current intake mainfold? I know it employs the use of the S-DAIS system, but how can you tune it to get better airflow on an N/A setting? Also, when designing a turbo kit, is it possible to keep the existing manifold when using low boost, or do I have to fabricate my own? I assume a custom intake manifold would be necessary for high boost apps. Would it be necessary to disable S-DAIS for high-boost? Also, when boosting, is it necessary to add a MAP sensor? The RX-8 doesn't have one, because the MAF does the airflow monitoring. wakeech explained in the S-DAIS thread that for the high-power RENESIS, we must find a way to include the tertiary power port. How does one design an intake manifold that can do this? Electronic valving seems like a good solution, but it is very costly and complicated. I was looking for the easiest solution. Perhaps keeping the third power port open at all times may suffice? But, I deem it as unecessary at low speeds. Any suggestions?

 

It would be pretty hard to improve on Mazda's design for the NA Renesis, as it uses Helmholtz resonance tuning to give good power across the rev range of the engine. Some intakes may make more HP at a certain point, but give up HP elsewhere. Point being, for the NA renesis, I'd leave the stock airbox alone at this point.
My big worry with using the existing manifold would be that the plastic portion might not hold the pressures. But maybe a low enough boost wouldn't bother it. We won't know until someone tries it.
I wouldn't think so.
This one's beyond my knowledge to answer. Perhaps Rotarygod can speak to it?

 

IT IS DEFINETLY POSSIBLE TO "RE-TUNE" the s-dais for more power in NA form or more power in certain rpm ranges. that's exactly what they did for the Mazdaspeed rx-8s in japan. they changed the shape/size of the airbox (i don't know exactly only know that it WAS changed)and i believe 1 runner to improve the power in the lower rpm ranges. one of the things that might be necessary with FI is to open the shorter more direct path sooner along with the VFAD. a map may be necessary so that a piggy back could somehow trick the PCM into opening these paths based on pressure instead of rpm.

 

Thank you for the advice guys . I wonder if for forced induction, it would be necessary to eliminate the VFAD in place of a traditional intake tube. I am not sure about the MAZDASPEED RX-8's S-DAIS modifications. So, I suppose the idea would be to somehow improve on the current S-DAIS system rather than designing a new mainfold, which is quite costly. Do you think the RENESIS should have employed electronically-controlled valves instead of vacuum-regulation? I think electronics would have made it much more simple to tune the S-DAIS. Now that I have some information about this subject, I think the current manifold will be fine for high boost. It is only a matter of adjusting it for high-boost support. I think in N/A form, the introduction of a MAP would not be necessary, though it is possible.

 

No worries the plastic intake runners, on the MP3 are good up until 10psi according to MP3 Guy. And even then they don't burst or anything like that, instead the tubes expand and contract like a artery. At 4psi which seems to be the max with the current compression, it wouldn't be a problem.

 

i know this was discussed before but lets get this clear for this thread. i thought that the valves in question were electronically activated. but i also remember a post that suggested SOME were vacuum. is it one or the other or both?

 

The only thing that is directly electronically run are the auxillary ports. Their sleeves rotate by way of an electric motor. The rest of the devices are done through vacuum. The part that confuses everyone is that inline on the vacuum lines there is a solenoid. This solenoid when closed blocks any vacuum from getting to the actuators. These solenoids however are electronically activated so that at a certain rpm they receive a signal that tells them open and let the vacuum pass. This is what opens the actuators. When people say they are electronic or vacuum, they are both right. There are vacuum actuators that are operated by electronic solenoids.

 

thanks rg. i thought i remembered it was a combo. thanks for the clarification

 

rotarygod, do you think there is any way to make the S-DAIS completely electronic? Thank you for clarifying that. I probably should've referred to that Mazda training video before I made any assumptions :o.

Also, are there better materials for this particular manifold that would allow better flow? What would happen if you ported the manifold, in an N/A or forced induction application?

 

If you replace the vacuum actuators with electric motors or electric actuators I don't see why it couldn't be done that way. Finding some that are tough enough to live through hard use is going to be the difficult part.

The Renesis intake manifold is a wonderful intake. It will be hard to improve upon it without sacrificing somewhere else. I don't see any benefit from porting it out. I would use a different upper manifold for forced induction use though. There is a two part logic behind this. The first is that I just don't trust composits under heavy boost. For lower boost applications it should be fine.

The second reason is for performance. Most people want to use shorter runners but I tend to think backwards from everyone else. For turbo use or when a supercharger bypass valve is open, the engine is basically running naturally aspirated. Since this is primarily only going to be at lower rpm's I would rather design a longer intake manifold that tunes the intake to a lower rpm range. This will give much better off boost response and actually help turbo spool up when you do get back on the gas. It's neat how that works. When under boost intake tuning takes on a whole different form. The turbo/supercharger is going to force air into the engine whether the intake runners are long or short. I would rather design a system that gives me great low end power when off boost. The turbo will make up for the intake length. It's the best of both worlds. Then again I also believe in higher compression ratios with forced induction for much of the same reasons.

For boosted applications I would tend to design an intake manifold out of aluminum. You could add a plenum chamber but a simple merge collector would suffice. Aluminum will hold more heat than the composite manifold will so there is a disadvantage. The good news is that you can go and get it ceramic coated. The other option would be to make it out of stainless steel. This is a heavy option though. Stainless has good heat retention properties and will not heat up like aluminum will. Top it off by ceramic coating it too. It would be fine in this application. Just don't ceramic coat stainless in exhaust applications as it holds too much heat in at that point and will probably break the welds.

In summary, make it out of metal, ceramic coat it, and if being used for forced induction purposes make the runners collect farther from the engine and closer to the throttle plate.

 

Where exactly are you getting 4PSI being the max? Inquiring minds want to know...

 

umm.. wouldnt that mean that the s-dias stuff wouldnt function under
WOT when there is zero vacume? You sure they dont use airpump air or something else?

 

Interesting. Thank you rotarygod for the information . Thank you everyone for the support .

 

rotarygod does make a point about using longer intake runners. Not only are they sufficient for low-speed and mid-range torque, they also provide a broad, flat torque curve at low speeds; the turbocharger keeps the top end strong. Also, is the intake manifold on the RENESIS symmetrical? If not, what would be the effect of a symmetrical manifold? I hear that Mazda rotary engines employ non-symmetrical manifold designs, but I'm not sure.

What about the position of the fuel injectors? Will the angle with respect to the horizontal suffice under a high-boost application? I hear injectors are not to exceed 20 degrees with the horizontal (Corky Bell).

With the extra boost supplied by the turbocharger, is it necessary to include a MAP, assuming there would be a positive change in pressure in the intake manifold?

 

More then one person has blown more then one motor trying to run 5psi+. One guy blew 8 motors.

 

When was this? It sounds kind of weird for the engine to fail with only 5+ psi. Heck, even a person's stomach can handle 6 psi before rupture .

 

Info was bestowed in me as per KD Rotary. I forget the guys name who blew 8 motors, nor would i really like to embarrass him by saying it seeing as he does own a business.

***nods to the post below***

 

killing 8 engines is called being a moron of an engine tuner.

 

i hate when people say "blew a motor" or "blew a tranny" it doesn't tell you anything about what happened.

 

If that is the case, perhaps using a different material for the intake manifold may be in order.

 

They hinted that the side seals gave out for most of the blows.

 

polak my wrath was not directed at you sorry if you felt it was. thanks for the info. the side seals have been a concern since they travel over the ports. think this was really a pressure issue or a tuning issue?

 

Side seals? Uh oh . I have heard that side seals are the last to go. Is there any truth to this?

 

Back to the intake manifold, would using longer runners affect low-speed power? The goal for any tuner, especially in making a sound street car, would be to increase the average power, not maximizing it at x-rpm. I think this is why S-DAIS is employed, since changing the length of the runners assures a healthy powerband and a flat torque curve.

 

using longer runners would increase low rpm power