Okay, I DID do a search but couldn't turn anything up. After tearing down my N/A motor, I am not too fond of the 3 piece intake manifold that comes stock on the 13B's. I'm sure that Mazda thought it was the best thing to use when they designed those motors, but I think they suck. I also don't understand why I can't find any aftermarket intake manifolds for these motors. I tried E-Bay, Google, and Yahoo and still found nothing.

Now I don't know if anyone makes aftermarket i.m.'s but I have been thinking about making my own for my new Tii motor. I am pretty efficient at Tig welding and was planning on making a one piece aluminum one. But my question is really this. Is it feasable to make my own and would it work, given that it had all the same vacuum hose connectors and such?

While I have your attention, I also planned on making my own fuel rails seeing as though I cant find any aftermarket ones either.

Im not starting this thread looking for anyone to do any searching for me, but to see if someone had made their own intakes and fuel rails. Or if someone had the same dilemma as me and found a place that sells them.

I know this is a long thread but I appreciate yall looking at it for me.

 

if you make em and they work i will buy em buildin a na i dont want 400hp but mabe a fun 220

 

Mazda went into a lot of R&D to come up with that design.
You think they would just randomly produce a casted aluminum intake manifold that complex if they could get away with something cheaper and simpler?

The problem is that you need to balance out low RPM power with high RPM power.
Sure, short runners make for big power, cause you can get the intake charge faster into the engine.
The problem with short runners is that they lack intake velocity at lower RPM's.
This is one if the fundamental problems of intake design on almost any gasoline combustion engine.
Recently, the use of multi-stage intakes which use different length runners were used as a compromise design to get the best of both worlds.
This is the concept behind the S5 "VDI".

One of the BIG problems with trying to redesign the Mazda stock intake manifolds is the fact that it uses the multi-throttle plate TB.
By keeping the primary and secondary ports separated, you can keep the high intake velocity to the primaries without the problem is dilution from adding the secondary ports.

Are you sure you used to be a mechanic???


-Ted

 

What ever, Ted.

Anyway, all the plumbing I have seen for a custom intake has been a large diameter main pipe, with several (usually four) smaller pipes coming off and going to the head.

Im not talking about redesigning it completely. Im saying using a piece of aluminum pipe in the same diameter as the inside of the TB. Running it in basically the same shape of the stock intake manifold, then splitting it off into the four smaller inlet pipes that actually dump into the motor. That way its actually getting a higher flow of air into the intake. Plus it would clean up the look of the upper side of the motor alot more then it is now.

 

Ted's got good explinations. The girl in his avatar looks hot from far away, but most import models are like that

 

Look. Im not saying that Ted is wrong. Im just saying that tried and tested designs for higher airflow shouldn't be ignored.

Im pretty sure that the Mazda people did a lot of development but bascially all the intake manifold on the 13B is, is four pipes that run from the TB to the motor. There isnt a whole lot of design in the manifold. But if you look at it from a simplistic approach, what is the manifold doing? Going from 1 pipe to 4 right? Thats basically what I am going to try as well. Its not like its a new thing either. Edlebrock, HKS, and every other company making intakes have used the same principle. Use one pipe for as long as you can. So if I use a 3 1/2 ID piece of aluminum pipe and follow the same design of bends and such Im basically doing the same thing they are. Only this way I will save about 10 pounds and may (note I said may) increase the airflow.

I have the pipes laying around so what am I loosing? I only have something to gain. That is IF it actually works.

 

I say do it up. I would like to see one. Your talking about utilizing the stock throttle body?

 

Yeah. A ported and polished, but "stock" throttle body.

 

So your doing this on a 4 port or 5 port engine? Are you fabricating the complete manifold , or jsut the top , or loewr piece?

 

5 ports, huh ?

 

i am makeing a custom intake mani for my s4 n/a but mine is going to be turned around faceing the same way a turbo mani faces , due to the fact of better intercooler pipeing flow, but it does use the stock throttle body

 

 

The intake manifold is actually very well designed, the length of the pipes and the design of the chamber (ie upper manifold) is very specific, it is designed that when the rotor sweeps past the port and close it, that the resulting shock wave is sent back up, is reflected by the upper manifold and comes back down just as the port is opening so it can cram more air in then otherwise possible,

that said i do think that it can be improved and ported quite a bit.

s4 intake manifold and throttle body that is ported can support a bridge ported motor to some pretty crazy numbers. Though if you were going all out and didn't care about it being street-able and you wanted to do individual throttle bodies coming rite out of a plenum go for it, though if you already are going all out why not make them slider throttle bodies to now that would be cool

 

haha, i've never seen that smiley/gif/whatever you want to call it...

As for the OP, not all of the nipples on the intake manifold just go straight through to give vacuum. Some of them are just a source for fresh air (fuel and oil injector air bleeds), and you'll want to look at the locations of the stock ones and try to replicate them (on the plenum or perpendicular to the runner for static pressure, parallel or angled to the runner, or on the outside of a curve for a mix of static and dynamic pressure etc). Also, will you have a flange for the BAC valve etc? Lets see some calculations for plenum volume and runner length at a variety of RPM's and loads. How about consideration given to a variable length intake system? I have a couple ideas in mind for my next project that should be pretty innovative.

For other custom ones, look at some of the fabbed ones for carb conversions. I think RB sells some.

 

(I'm not trying to be rude here, I just don't have a lot of time to type right now but couldn't ignore this topic. Don't take anything I say as an insult even though it might be a little rough)

ReTED is right on the money...

It's obvious that you don't know anything about manifold design. That's fine...not everyone is expected to know these things. We'll look at the S4 manifold because I think you have an S4.

First and foremost, the Mazda manifold is FAR MORE then 4 pipes that go into the engine. We need to look at things from a holistic standpoint. The manifold, engine and throttle body cannot stand alone.

As I'm sure you are aware, 2nd gen NA 13Bs are a 6 port design. There are three distinct sets of intake ports, controlled via valves.

There is also a progressive 3 blade throttle body.

The lower single blade operates at low throttles and controls the primary ports (in the middle iron). The secondary and aux ports are closed. This means great driveability at light throttle (less then 15% or so) because air velocity is very high due to the longish thin runners and port shape. This keeps torque high as more chamber filling takes place even though the engine speed and airflow are low.

As you step on the throttle, the secondary throttles start to open as well. This allows air to the secondary ports (outer irons, bottom set of ports). The engine needs more air as RPM and load increase so these ports provide it. Mazda has used a design like this for MANY years, back in the carb days where the secondary carb barrels were vacuum operated. Anyway, the secondary ports are larger, flow more air and have more aggressive timing in that they open earlier and close later. Better for higher RPM operation. The set of runners is also known as the "DEI" runners. Imagine the secondary intake runners as a horseshoe with a throttle body in the upper part of the hoop allowing air into the runners. Each secondary throttle blade feeds one runner, but the runners are also joined. This means that both rotors are on a common runner. And it's a long one....

As engine speed increases, velocity in the runner increases. When one rotor closes an intake port, the air charge slams into the side of that rotor and then reverses direction, flying around the horseshoe. The shockwave comes back on the other rotor with an open port and forces air into the chamber. Mazda and various SAE papers say that this effect generates at peak 2 PSI of positive pressure. That's pretty damn impressive.

But wait, there's more! There are two more intake ports, known as the aux ports (or 5th and 6th). The aux ports are above the secondary ports on the end irons, and have VERY late closing (about equivalent to that of a peripheral port). Because of the sheer amount of port volume that the secondary and aux add up to, the aux ports must be closed at low RPM to maintain charge velocity. Open them up and the port timing is way too late, and velocity goes to hell. Hence the major torque loss when people wire open their aux ports.

At around 3500-3800 RPM, the engine is spinning fast enough and sucking enough air that the aux ports come into play. Barrel valves open them up and allow air through the aux ports. Because of the high engine speed and air velocity now present, these late closing ports continue to fill the chamber even after the rotor starts moving towards compression and the secondary ports are long closed. More chamber filling means more air/fuel mixture, which means more power of course. Think of the aux ports as variable valve timing for the rotary, though the secondary ports are almost the same thing due to the two stage throttle body.

The S5 NA manifold is a lot more complicated. Someone else can explain that one.

What does this mean? It means that Mazda has put considerable design effort into these manifolds and they clearly do the job. The S4 NA engine produces 146 HP, which is 10 more then the old 13B EGI engine found in the GSL-SE 1st gen. The S5 of course produces 160HP, largely due to the VDI manifold. The torque curves of both engines are pretty damn good, all things considered.

What looks to you like just a few pipes has been carefully designed and selected to match the engine.

Can it be improved? Of course. Look at the Renesis. It goes even further with more valves on the secondary ports, and another set of injectors with a sophisticated ECU to manage it all based on load and driving conditions.

No, that's not it at all. As well as providing the optimum flow for the engine (runner diameter and plenum size), you need to manage things like the shockwave created when a rotor closes. Design the wrong size plenum and this can cause horrible flow at certain RPM ranges.

You can certainly make more power by designing your own intake, but it will be power in a single RPM range. Broadly speaking, short runners with large diameters make great power up top, but suck down low due to lack of velocity. Longer thinner runners make good power down low, but choke the engine up top due to lack of flow. As you can see with the Mazda intake, they have solved both these problems.

If you are talking about the typical V8 aftermarket manifolds, they suck. Fixed runner length and diameter limit them to making power at only a narrow RPM range.

Feel free to give it a try. It's a lot of work. Here's the topic covering my custom intake manifold:

https://www.rx7club.com/forum/showthread.php?t=498432

 

I love the fact that you guys can do anything and its cool. But let someone else suggest doing the same thing, and instantly they become ignorant.

But all ignorance aside, Im not the one who made an intake out of steel. The whole point of making a custom intake is for better airflow and reduced weight. Aaron, I dont see how you reduced the weight by using the materials you did. And, btw, your welds sucked. Just making a statement.

But dude, your being a little moronic. I mean I say that an intake is 1 pipe going to four. You call me wrong, then post a link to your intake, thats exactly the same as what you just told me was wrong.

And honestly, fab isnt a lot of work. I dont know how long it took you to build that manifold, but fabrication of it should have taken no more then a couple of hours. Even with fitting and adjusting and measuring.

But fact of the matter is Aaron, your whole post trying to make me sound dumb, sure it works. Right up until the point where you link your intake build. Then you just become a hypocritical ******* and look stupid for trying to tell me not to do it.

 

ahh but his manifold is designed for turbo were the gains from his manifold with the boost are superior were as when you remain na the stock manifold does a dang good job through a large area of the rpm range.

 

Yeah, I do remember saying in my first post that I was going to build an intake for my Tii motor that I just ordered. So, um.... yeah.

 

Don't say I didn't warn you...

Full version...
https://www.rx7club.com/announcement.php?f=17&a=92

Oh, and...
This is not about us squashing you into doing something "cool".
I think it's more like...why don't you try and see if you can produce something that performs better than the stock system.
Talk is cheap - anyone can talk about making something.
Talking the talk and walking the walk is a whole 'nother matter...


-Ted

 

Why don't you just get the tweakit.net itb kit?

 

First off Ted, I never bashed Aaron. I just said that it was hypocritical for him to tell me that my design wont work, when he did the same thing. Only his was a worse design, imo, because he used steel instead of aluminum to save weight. If he wants to ban me fine, but it just reinforces the hypocritical thing I was saying.

And the second my new motor comes in, yeah I plan to tear apart the intake on it and start from there. Unless of course the N/A and Tii intakes have the same dimensions on them. In which case, I will start on it this week.

But monkey, I couldn't find any aftermarket intake kits. I originally asked about them as well as building my own, but no one came forward with any kits. So I will give the suggested kit a look and see how looks.

 

ok First off, mike, Aaron did state that he in no way meant to be rude, HOWEVER, you go along and and call him childish names, are we not adults here? this is a forum, and this is just one of the many discussions.

That said, here is my 2 cents. Go for it...Aaron did make his own, why couldn't you? However, there is flow you always have to think about. Aaron is a smart guy, i'm sure he tested flow at least once.

All in all, i say go for it...you have nothing to worry about, but I would hate to see it run with it and something happen to the motor. Take measurements, and take your time, lastly, have fun with it.

good luck
chris

 

Im not sure, but I think he was using flux core for that manifold? If you look at his most recent thread about TINA, his welds are better.

If you want to mess around with building a manifold, go for it. If you really want to play around with it, make it bolt together for now. That way you could try out a few different size plenums and mabey different length runners.

Do you have a standalone? It would make it easier to get it to run right, then you could ditch the stock TB too.

 

When you start to use words like "moronic" and "*******", it sure looks like a "bash" to me.


-Ted

 

No, you become ignorant when you post **** like "I'd like a 200mm throttle body" in a thread and follow it up with " the Mazda intake manifold sucks because I think so"

You didn't read the whole thing did you...

He didn't tell you its wrong. He explained why the Mazda manifold is so complex. You just took it the way you did.

I'll start the stop watch. Its 12:43 here now. Report back with a finished and mounted manifold by 3:00. I'll be graceful and give you till 4:00 ..........please.........

Actually you're doing a pretty good job of that yourself.

There's plenty of custom intakes floating around, delslow built one, Aaroncake, Rotarygod. Many many. Sure, you can build one - they are trying to prepare you with ideas to think about when designing it since you OBVIOUSLY had no idea. If you had an idea - you wouldn't think the stock intake is stupid.

/thread