Node

iTrader: (1)

Was wondering if anyone had input on a n/a manifold for torque.

This will be on a stock s4 6port w/ megasquirt.

Stick w/ stock manifold? I plan to keep 6ports working.
Was thining about maybe some 4x 40mm crotch rocket ITB's, or some dual TWMs

But I want lots of torque and midrange, do I just look for the longest intake runners?
How does the placement of the throttlebody itself matter, should i have them near the motor, or at the top.....

Thanks,
Ben Martin

GUITARJUNKIE28

very generally speaking, long runners with a big plenum.

Kyrasis6

And try to keep everything as straight as possable, bends create turbulance which decreases air flow and velocity. If you can increase flow and keep the diameter of the runners and intake the same or smaller then velocity will increase and so will torque.

t-von

iTrader: (8)

Just copy the manifold runner length and design from the auto Rx8. That engine has the most torque of any NA 13b. Rotary god will tell you the same.

diabolical1

iTrader: (3)

find Kahren's setup ...

GUITARJUNKIE28

that wasn't built for low-end torque.

TT_Rex_7

For a rotary, keep the runners long. You CAN'T make the runners to long, I promise!

If at all possible, try adding a small taper to the runners. Make the runners match the ports on the engine, and have them get larger in size as it goes towards the plenum. Maybe 1-2 degrees. Although adding a taper makes the runners seem shorter, it'll keep velocity up, so IMO, it's more than worth it! Just don't get to crazy with the taper! If you keep it within 1-2 degrees, you should be just fine.

As for the plenum, make it 2-3 times larger than the total volume of your runners. Going over 3 times the total volume of the runners won't make much of a difference, if any at all. On Auto Illusions intake manifold, we are making the plenum volume 2 times the total volume of his runners.

-Alex

crispeed

Most of the Torque gain on the rx-8 set up is due to the way the intake works. Basicaly the motor runs on two ports at low rpms and switches over to a four port and then to a six port as rpm increases. Also the intake length is basicaly cut in half at high rpms with one valve and another valve opens at even higher rpm so that all the ports share one common plenum to gain the most at that rpm range.
It offers the best of all ranges kinda like variable cam/valve timing on a piston motor.
It would be very good to apply the same principle to a ported motor for the street. Stock primaries, street ported secondaries and peripheral ports at high rpm just for example.

Node

iTrader: (1)

.....Idea
I'm not going to do this, but someone should fit a RX-8 mani to a 6port peripheral exhaust!
will be the newest GTUs craze. I can see it now.....
But I don't want that.
I want something custom that just makes people stare and go whoa, cool. Hopefully it'll be a noticeable upgrade

You place the plenum after the TB, correct. can it work properly before the tb plates?

TT_Rex_7

I'm unsure of which "direction" your speaking of, but it goes TB-Plenum-Runners-Motor.

Although this idea would depend on your budget, but have you thought of ITB's?

-Alex

t-von

iTrader: (8)

Well actually RG measured the runner lengths of a 4 port auto Renesis and a 6 port version. He claimed the 4 port had runners longer than the 6 port manifold. What your talking about is the 6 port with VDI. The extra runner length is why the 4 port had more bottom to mid range than the 6 port engine. Now odviously the 4 port couldn't match the aux ports when they finally opened.


I'm still waiting for someone to engineer a semi PP with a switch valve to open the 5th and 6th ports. I have my own ideas . I just need access to the correct machinery.

TT_Rex_7

I think I might have a few of those "correct machines."

-Alex

Node

iTrader: (1)

I thought of TWMs first, as a EFI sidedraft weber type deal. But the TWMs are too expensive.
I then looked at crotch rocket ITBs on ebay, fuel rail, TPS and decent sizes

I think I've came to a conclusing.
Stock 3 barrel throttlebody to keep price to a minimum.
Not sure on if it will keep the 6port LIM, or ditch that.
If keeping 6port lower intake, then run the 4 runners straight up, combine the two primaries into one, and attach it to stock throttlebody w/ a cone filter on top, and then a "turkeypan" and some sort of shaker/ram air scoop or cowl induction setup.

If not keeping the stock LIM, then go almost straight out from the port to get rid of the hard 90 that it makes and just make teh intake manifold go towards the passenger side and make a large gradual curve to where the TB is situated

Right now I'm grasping at muscle car ideas and whatnot. Simple and effective!

On the old firechicken shaker ram air scoops, they had the solenoid activated flapper door covering the ram air holes, it would stay closed until you floor it, like nitrous.
very cool idea, would keep the elements out also!

-Ben Martin

rotarygod

iTrader: (1)

The 4 port Renesis intake runners are definitely longer than the 6 port runners by several inches. It's hard to tell just by looking at them mounted to an engine in the car. You really need to see them side by side. The 6 port intake is more than just the same manifold with 2 extra ports added to it. The 4 port also has more conservative intake timing. All of this adds up to the 4 port being capable of more power than the 6 port right up to about 7000 rpm. Too bad the auto tranny sucks back so much of the power.

The Renesis manifold is nice because the bends in the airstream are very gradual and there isn't anything really protruding into the airstream. This is a big contrast to previous rotary manifolds. Each of them had something big wrong with it. Not sating the Renesis is a perfect manifold. It is just much better than anything Mazda has ever previously used. Crispeed explained well why the Renesis manifold makes good power.

The Renesis manifold could not be integrated onto a 13B. The intake ports on the Renesis end plates are farther out. The air doesn't have to turn nearly as sharp to get into the engine. The primary ports line up perfectly with the 2nd gen primaries. It's the outers that have big issues. It is far enough of that you wouldn't want to use an adapter plate. It would require some cutting and welding to make it work.

If you want to make a good manifold, keep it simple. Make a couple of different length systems or just one that has several easily replaceable parts. Set it up so the plenum can be removed easily and swapped for a different sized one. Set it up so you can remove intake runners and bolt longer or shorter ones on. It's OK if they turn. You're experimenting. Figure out which setup(s) you like and then fab up the final manifold. If you want to get really crazy, cut of a VDI system from an S5 manifold and try to integrate it on. Use your imagination. If you can't cut and weld aluminum, use steel. It's heavier but easy to get and weld and it's only temporary until you get one worked out the way you want it.

I used ot use a custom built manifold but have just settled on an S5 n/a manifold on my car. The 6 port system and VDI still work and I'm happy with it. It is possible to get more top end out of it but I just like the overall powerband. It's pretty flat.

GUITARJUNKIE28

speaking of which, where are my flanges?
imma have some fun with my fd!

j200pruf

iTrader: (4)

If one were to make a system like this using butterflys in the runners would they need to be as close to the port opening as possible (IE 6 port sleeves)?

I know that the E-Spec 6 ports just had a butterfly where the manifold bolts to the engine. But my idea was to use the secondary computer controlled butterflys on the Suzuki GSXR TB's. But I want to say that some one told me that those wouldn't work because they would be too far away from the port.

GUITARJUNKIE28

i've got a question fred might be able to answer...

*i'm not planning on this--just curious)

what would happen if you had your intake going to the plenum, then the throttle bodies (itb's) after it? would the plenum still have a similar effect, or would the whole intake system add to the effective volume of the plenum? just curious.

rotarygod

iTrader: (1)

At full throttle it doesn't matter where the plenum is in relation to the throttlebody. At part throttle it'll change things a bit. If the plenum is after the throttlebody in a traditional manner, all of your intake tuning at part throttle is shared in the entire system as it is at full throttle. With the plenum before the throttlebody, when you are at part throttle any returning pulses will largely reflect off of the throttleplates and go back down the intake runner. The more the throttle plates are open, the larger the effect the reflection from the plenum will be and the less from the reflections off of the throttle plates. I still haven't figured out how to calculate this effect accurately yet though. Typically you can get some better low end with the plenum before the throttle plates as you will get better velocity through each runner at part throttle due to the effect of each plate. This too varies with throttle location in regards to distance from the intake ports. There is alot to think about.

Try it. See how it works.

GUITARJUNKIE28

i might try it with the first gen then...it's a beater.

let's go to pick n' pull to look for tb's

Sammymatik

Wouldn't all the trial and error research be very difficult to achieve the desired results?

rotarygod

iTrader: (1)

Trial and error is what helps you learn. You can know all the theory in the world but without actually seeing firsthand how it all comes together, you won't get very far. It's definitely not easy but if it was everyone would do it. Once you understand how it all works and why, it isn't as hard to get your desired results or at least know what it will take to get them. Experimenting is also fun. I've tried so many different combinations of intakes and exhausts and have always come back to the same couple of preferred setups. I've enjoyed learning though so I wouldn't say I wasted any time out of it. It's all about learning.

GUITARJUNKIE28

so would the intake tube add to the total plenum volume, or would it get to a point where it would have less of an effect?

rotarygod

iTrader: (1)

No it doesn't. The plenum is only the large airspace where all of the runners collect. The intake tube is just that, an intake tube. It ends at the plenum. If you had this intake tube slowly increase in size to match the plenum size, then you'd just have a larger plenum. Of course it wouldn't be an intake tube anymore either. Look at a diesel engine sometime. They still have intake plenums but diesels have no throttlebodies. They only alter fuel flow. It's always getting full air. The plenum still does it's job.

On nonturbos, the length and diameter of the intake tube can have significant tuning effects. On turbo cars it's just an air channel.

GUITARJUNKIE28

coolness.

i don't see myself doing this anytime in the very near future...i'm way too busy, but i might poke around with that for ***** n' giggles later on.

i'll probably have a new LIM for my fd in the next few months, though. that one will be fun.