Just got 3D designing software, so just playing around with it trying to get better, decided to try to design a intake manifold for the stock rx7 TB.

But i can't take credit for coming up with the idea. That was Sgt.Stinkfist.

Anyway, just started so it isn't much yet, but should get it done before new years
Port measurements are from a S4 T2 Lim.

 

Wow! That looks just like my intake for my 4 ITB setup. Just extend the runners about 4 inches, angle them upwards about 40 degrees, flare them out some so that they are all equidistant, add the ITB's, put on the bells so that the whole intake, ITB and bell setup clears 11 inches and BINGO. Thats what I did and it works quite well.

I used the different runner ID's from the ported center and outer irons to determine the runner ID. It provides a flexible setup, immediate throttle response and looks monster cool. Though the 4 ITB's at full draw tend to be louder than the exhaust from the drivers seat, LOL.

I will watch this and see what happens.

Eric

 

Nice!

 

have you guys checked out that setup Kahren built a while back? this was the concept. i think he called it stock ITBs or something to that effect. if you haven't seen it, it's worth a look.

 

Was this what you meant? Never seen it before, but what i have in mind is much shorter.

 

no, that's not what i was talking about. although, if that's one of his creations, i don't recall seeing it.

i just spent about 15 minutes or so searching for it, and the best i can do is: https://www.rx7club.com/time-slips-d...ld-e6k-358038/ .

i think that might be the right thread, but the photos are all gone. basically, it was a custom manifold and the OEM throttle body was mounted vertically (not completely vertical. it actually tilted away from the engine a little) on it. i think he dynoed like 185+ with the STOCK ports and later ran just under 200 with a revision of the setup - i honestly don't remember if it was ported at that point or not.

i absolutely do have a photo or two of it, but i would have to search through a whole bunch of backup discs because it would have been on my desktop from years ago. it's not on my current laptop. if you want me to get it, just let me know. it may take a while, but i can get it.

 

Wouldn't hurt but doesn't realy matter either, i was thinking that it might be an idea to tilt it slightly, i will probably draw up a couple of different designs
I'm still learning to use the programme, so progress is slow.

 

https://www.rx7club.com/2nd-generati...-s5-na-834592/

Here is the for sale thread from Kahren's intake manifold.

 

That is more or less excactly what i had in mind. Good to know it actually works too! Might even try to build this when i'm done with the design.

 

Drew up something similar to the Kharen intake, not happy with it yet tho. But it should work the same, will need to measure in the engine bay, to see if it would fit.
Flange is for an FD TB, so it would be easy to just put on an FD tb elbow and a filter.




Btw does anybody have a measurement from the intake flange on the engine to the strut tower?

 

I like this.

 

i think it was a stock port. its a long time ago, but i remember he was looking at the stock throttle body, and comparing that to say a 2x48mm throttle body (weber, etc) and thinking that the stock throttle was actually bigger (3x45mm? FD is 1x45 and 2x50?).

so he decided that the restriction was the intake manifolds, and the new one made ~200rwhp on a stock block, and the ported engine made ~190, although limited by fuel (he had a vise grip on the return line)

since then we've found that Mazda has posted VE graphs of different runner diameters, and after they chose that, they have graphs of VE vs lengths. if you keep the stock diameter, the improvements over stock are that you can KEEP the stock diameter consistent the whole way, you get to make it much straighter than stock. the length however should work the same, although you get the freedom to pick the one you want.

the S4 is 500mm, the S5 you'll have to look, but i wanna say 700mm and 300mm?

 

I think a custom manifold from the 6-port lower to the stock or even FD throttle body might offer some real gains. Ditch the VDI but keep the 5th/6th ports operational.

What do you guys think?

 

Haven't realy made any progress, but i did draw a more or less accurate version of an N326 BAC, to use when designing the manifold.

 

nice! lol

as an aside i helped a friend put one of these manifolds on 84-92 13B Six Port Side Draft Intake Manifold...

we were expecting a really flat curve with a high peak, but it turns out to be really strong in the 3-5k range.

i didn't think to measure it, but carb with airhorns + the manifold is still probably ~12"

 

I hadn't seen that one of Kahren's. I really like that design you got there! How do you plan on mounting the BAC? On the middle runners? I just went without on my itb setup.

 

It goes on the primary runners stock, + it would be much more work to fit them to the sec runners.

 

Started on drawing the FD TB aswell..



Could anyone be bothered to measure from the intake flange on the engine to the strut towers, and from the top of the intake flange to the hood, just need to make shure how much space is available. I'm at college and my FC is 600miles away, so i can't do it myself...

 

FC I'm assuming? I'll measure mine when I get home tonight if no one else posts the info by then.

 

Yup, FC.

 

I measured around 310 mm to the strut tower and no more than 280 mm to the underside of the hood from the centerline of the intake runner. I have a 6 port, so the top of the flange might be a bit higher. Hopefully that gives you an idea.

 

I built one a few years ago. I'll take some pictures and post them if you would like to see.

 

Thanks, that helps alot


Sen2two: Couldn't hurt.

 

Might abandon this for a while until i get better with inventor, tricky to get everything looking realistic. But i might try to draw some designs with 4 tb's since that is what i want to build for my engine. And it's simpler to draw in inventor.

 

if you're are going to be welding aluminum.. might as well go semi PP. its the bee's knees... i'm betting there is 400 N/a horsepower lurking in a rotary(1300cc) ready to be squeezed out.