The n/a manifolds are by no means perfect and can be improved upon but the T-II manifolds aren't all that people think they are. I definitely don't consider them better. How many bends each one makes in relation to each other is irrelevant. Air is funny stuff. It doesn't always do what you think it will based on the way something looks and many times doesn't.

 

The simple answer was that I could not find 1.25" weld els that were thin enough. The ones I could find were very thick SCH40 cast steel and thus unsuitable. The transition isn't actually too bad inside. I ground it smooth and the POR-15 filled it in nicely.

Bends do not necessarily equal restriction. Many times bends are simply used to increase runner length while taking up a minimum of physical space. The TII lower intake also has a VERY tight radius at the bottom where it meets the engine. The NA is MUCH smoother and since the runners are the same size (at least S4 NA vs. S4 TII) I don't see any advantage to the TII lower.

The NA upper is not great for wildly ported engines. The TII intake is better since it's less complicated.

I'm not sure what you are trying to do. Is this on a TII engine? If so, then just use your existing intakes. If you want to spend some time you can grind off all the emissions fittings from the thing, and then carefully separate the runners by cutting between them. I've seen this done and it looks great. Apparently takes weeks though. Frankly if it's about looks I think the FD upper looks stupid, especially on a non-REW engine.

If this is for a 6 port, keep the 6 port lower and either make an adapter to fit the TII upper or make your own upper.

 

aaron can I ask why you didn't go the way or the plenum then a ida throttle body set up then the lim, its just what a lot of aussies's run and wondering which performs better.

im at the stage when in looking at both but done know why one would be better then the other, or what different characteristics one would have over the other.

I guess with a ida set-up it would flow more as you can have 2x 50 dia. throttle bodies ? (only just though.)

just wondering your thinking.

cheers

 

Aaron's single 75mm TB is quite a bit bigger than a 2x50mm TB.

 

sorry thought it was a 70.

but still what about the justification between having the plenum b4 or after the TB ? just want to know aarons thought on having it after the TB when so many ppl down here have it before.

 

Unless you have multiple throttles the plenum always goes after the TB. It's a bit hard to do it any other way. All those people you're referring to have IDA-style TB's with multiple throttles.

 

Yeh they do, cheers

 

The main reason is cost. $600 US is quite a bit of money and while the ITBs are cool, in my mind it's not worth it on a street car unless you have a specific reason to use them. Neither a big single nor two ITBs maintain the stock staged design and ITBs would have been more of a pain to plumb and set up. Also I would then have to work in aluminium and since I don't have a TIG in my basement (yet) that would be more of a pain.

Flow is not really an issue. A 75 MM throttle body moves a HUGE amount of air, as does the stock Mazda throttle body. Unless you're shooting for more then 600HP, throttle body size is not an issue.

Unless you have ITBs that force you to place them after the plenum, the plenum is always after the throttle body so it can provide the necessary "surge space" when the engine demands more air. It's not relevant in this example but if you were tuning the intake the throttle plates would also disrupt the air pulses and cause turbulence.

When dealing with intake's it's very beneficial to look at how the big manufacturers do it since a single person generally does not have the resources to simulate and test hundreds of designs. Most OEM intakes have a plenum of some type and it is most always after the throttle body.

This is the one time I wish I had attended higher education then highschool and taken a fluid dynamics course.

 

Admit it Aaron. You want to come to Tennessee and give some love to my car .

 

If you don't mind me asking, what do you do for a living while only having a highschool education?? could have fooled me

 

I work at a computer company. 99% of our business is networking, on site service, web hosting and application development. The other 1% can range anywhere from robotics to industrial control and monitoring to building mobile satellite Internet trailers. Without going too far off topic, one of the greatest myths in Canada/USA is that you cannot succeed unless you have a University/College diploma...

 

I'm well aware of that myth, and it may just be a myth but it is alot easier to succed/be recognised witha degree. But back on topic. Beautiful car man, can't wait till she's all back together and tuned. I'm sure she'll be a wicked ride.
Dom

 

I was just looking at some threads about custom intakes and figured I'd add the links here:

About how the dynamic chamber works, runner lengths, modifying stock S4 intake, etc.
https://www.rx7club.com/forum/showthread.php?t=405896

How to figure out intake runner length (lots of good math and info)
https://www.rx7club.com/forum/showthread.php?t=199788

Open plenum intakes (carb discussion)
https://www.rx7club.com/forum/showthread.php?t=223100

Modifying secondary injector locations on NA intake (good pictures)
https://www.rx7club.com/forum/showthread.php?t=123035

Calculating intake runner length and plenum volume
https://www.rx7club.com/forum/showthread.php?t=94362

Some random discussion
https://www.rx7club.com/forum/showthread.php?t=153420

 

That one that I did where I cut open the dynamic chamber, moved the injectors, and used a Mustang tb turned into one big flame fest from people who actually need to see everything in order to believe it. It's ironic how the biggest whiners in that thread were also the ones that always make claims but never show any proof. That setup did run with the stock ecu although very far from optimal and with alot of rigging to make work. When I used a Haltec later it worked much better. The throttle response was very touchy and there was a loss of low end power. Top end was great. I have since gone back to the standard S5 intake manifold because I have a few things to play with. I have a bunch of different manifolds that I swap out from time to time just to see how they work. I always seem to like one characteristic of each of them but am never satisfied with them as a whole. That's what compromise is all about.

 

Total agreement here. It's the nature of people for those who have no talent or chance of accomplishing to criticize those who do.

That's about what I am expecting from my intake. Hopefully there is sufficient adjustment in the two "accellerator pumps" in the Microtech to tune out this twitchyness at low throttle and during transitions.

 

where do you base your design off of for your intake? do you do calculations with fluids to determine them? and how's it going so far? get any hp gains with it, better than the stock one?

 

rotarygod has posted a great topic in the past regarding calculating plenum volume and runner size. Should be an easy search under his name with "calculating runner size" as the keywords.

I just used an old book from the library.

 

pretty sweet

 

I was away from the treads for a while, and checking your treads"Boy you got this down pat",congratulation...........

 

Holy thread resurrection!

Just to add something useful, I think I'll be making some mods to that intake. It has performed very well but I need somewhere to mount a BAC valve. Not having ECU idle control is a major annoyance. I'll likely just weld a flange to the bottom of the front "box".

Additionally I will be making an entirely new manifold at some point to take advantage of what I've learned by making and tuning this one.

 

Will you be adding back the air pump as well?

 

I won't be reinstalling the air pump. It's not needed in my setup and even if I wanted it, there is no room.

 

Hey Aaron can we get a final installed picture of your set up? My buddy and I are looking to make this set up for my car. If you got more secs on it could you pm it to me?

 

http://www.youtube.com/watch?v=H1Mry...eature=related

 

4+ year thread ressurrection. damn....