Im really intrested in ITBs and im wondering what i whould have to get for ITBS to be possible on my s5 6port

 

Hmm... ITB's on a six port... not sure. I'm using REW mid and end plates for a four port intake setup with Hayabusa throttle bodies, actually I'm in the midst of fabricating the setup. A friend on the forum is doing much the same but I think he used four port irons also:

https://www.rx7club.com/canadian-forum-42/itbs-ftw-648413/

 

yup its possible but you will be missing out on the low end torque of a correctly desgined intake manifold. no reason it should be any different for a 6 port. just might be a little harder to make the outside runners.

 

his low end will be decided by the length of his intake manifold runners. Just find out the port timing and adjust the length of the runners accordingly.

 

what i probably should of said was im iterested in a set up what would i need like down to everything. UIM LIM TBs whats up lol

 

Do this:
REW Irons, Oil Pressure regulator
RX8 Stationaries, E-Shaft, Rotors
TII Housings
Mazda, Ianetti or NRS Apex seals
Custom UIM; four runners of optimal length as mentioned above
Suitable ITB setup i.e. Hayabusa, TWM, etc.
Haltech or Motec with a SK tune or two

Then go spin to 10,000...

 

Are ITBs streetable? Last I heard of someone useing them, they had part throttle and low rpm drive-ability issues.

Thanks for the input.

 

then they were probably ill-informed, got greedy and used throttle bodies that were too big. ITBs can be streetable if sized correctly - the whole design (runner length, TB diameter, etc.)

 

An easier set-up would be use 6PI end housings with a standart s4 or s5 (depending on what series end housings your using) LIM and just make a DCOE style manifold to bolt that to the ITB's.

 

HAHAH NOW THIS IS WHAT I WAS LOOKIGN FOR!

Lol i love your set up

 

yeah but then you lose out on the high end power, if you design the runner lengths for lower rpms, which is the whole reason for the ITBs

 

i'm running itb's on my 6-port...

they are supplied by a company called TWM.

parts used on my car (71' datsun 510)

TWM 50mm throttle body
TWM fuel rail
TWM air horn
racing beat 2 piece intake manifold (i think they don't make these anymore, but they do make a newer one that in hindsight i probably should have used)
TWM throttle posistion sensor
TWM plug/pin for TPS
fuel pressure regulator
high pressure fuel pump
fuel pressure gauge
haltech e6k
haltech wiring harness
ls1 ignition coils
1 bar map sensor fuel injectors

and a few assorted other random parts.

my only complaint is the itb's are kinda "weird" when going from a closed throttle to a slightly open throttle.

it seems to me that they don't want to open...so i have to push a little harder on the throttle. then the butterflies open a little farther than i had planned....basically because i have to push on the throttle harder than i had planned.

so i get a little unintentional wheel spin when leave stoplights....sometimes.

i've never driven a itb equiped car so i'm not sure if this is just the nature of the beast with itb's.

or....the other possibility is the throttle return spring is too stiff....which is basically what it feels like to me.

 

www.fuji-racing.com


They have an ITB kit using a weber lower intake manifold for the S5 6port. Its just under $1600 for everything you would need to get the car running short of a standalone. $2750 for everything plus a microtech.

give jimmy at fuji a call. very cool guy who will be completely straight forward with you.

BC

 

Compared the the stock NA manifolds you wont be losing much, if anything. You will gain almost everywhere. By adjusting the runner length you can decide where you want to put the meat of the powerband. the guys above have been doing miata ITBs for a couple years now and have found power everywhere in the powerband. If you size it wrong or get the lengths all wrong then you won't get the most out of the setup, but if you do it right you can find power nearly everywhere.


BC

 

That is what I was getting at in my previous post. From what I've seen and heard it seems hard to get a good part throttle response with ITBs. Is there a way around this?

 

I've driven a ill tuned weber on a stock s4 6port in a repu, powerband was just fine and it sounds way better than the stock manifolds.
that was w/ shitty jetting and far from perfect timing on a junkyard motor. heavy flywheel, but still it was just fine. RX-7s are light and dont need **** for lowend.

dont be a vagina. theyre not that bad unless you've F'ed something up.
anyways, w/ a lightweight flywheel and rotary, how often are you gonna be under 3krpm?

ITBs rock my world. Sound great

 

One thing that would concern me with an ITB setup as linked is that the secondary ports are so much smaller and have shorter duration than the primaries, yet suck through the same size TB. I'd think that having the middle two be smaller, or have the middle two share a single TB would be better and would probably help low end power a bit (higer velocity) and shouldn't hurt power if they're sized right, as the current ones look way oversized.

The easiest way is with a weber sidedraft or downdraft manifold with a weber flanged TB. The ECU, throttle linkage, vaccum source for the brake booster and so on will have to be figured out by you though. There's no easy bolt on, all in one kit.

 

www.fuji-racing.com


Yes, there is. everything, including ECU if you want to pay for it.


BC

 

That's a TB, air horns, TPS and fuel rail, it has none of the following: manifold, injectors, wiring, vaccum source for brake booster, throttle cable hookup (unless by chance the stock cable is long enough, but I don't think so). There's no ECU either, so no, it's not a complete kit. It's a few parts bundled together, but far from a complete kit.

 

You should email Jimmy at Fuji racing. As of a few weeks ago it was a complete kit including manifold, vacuum block, and cable bracket on top of what is available there. Perhaps he has changed the kit in the past few weeks, as the price is about $1k cheaper now than it was then. However you can get a vacuum block from him, manifold is a weber side draft manifold that you can easily get from RB, but I am sure your could get it through him as well. Point being that if you wanted a full kit you could go through Fuji. He was even offering a Microtechs as of a few weeks ago.


Why he isnt anymore? I dont know. Call him and ask, or send an email.


BC

 

Grassroots Motorsports built a 13b with the help of Petit Racing for a 1st Gen car as a project for the magazine. There is a good discussion of what they used and how they went about it for the build. If memory serves me correctly, that engine made over 200RWHP with a street port. One of these days I am going to rebuild that engine and put it in one of the tubs sitting around here. It should be an interesting car.

 

Do you recall what issue that was in? As I finish mine up I will update within this thread perhaps.

 

The whole build ran in the Nov/Dec '93 through Sept/Oct '94 issues. The specific engine build was in the May/June '94 and July/Aug '94 issues. When the car came to my area, I was willing to go in on it for the sole purpose of getting the remaining 13b parts, the ITB's and the Haltec. The car still exists in one piece with logbook and all with an IT legal 12a in it.

 

Just noted this thread and wanted to pitch in some inlight a bit, now I haven't finished building the car yet but I acquired the Fuji Racing ITBS. Its actually the 47mm one. Now I didn't purchase the whole kit but most of the majob stuff. I bought a second racing beat 2 piece intake (I would of rather liked the 1 piece but couldn't find one at the time) For more details on the actual ITBs and the price that i've paid for them is here:

https://www.rx7club.com/1st-generation-specific-1979-1985-18/fuji-racing-itbs-finally-d-683967/

It also has pictures of everything basically. The fuel rail that Jimmy is currently selling isn't the best one but does its job ( I took it in to a local machine shop and changed the inlet and outlet sizes on there to fit a 1/4" NPT - Dash 6 AN fitting. As soon as I get the car up and running I will be hitting the dyno with it. I have a Holley dyno that I will be mostly comparing it to, to see differences and i'm expecting alot.

Jimmy from fuji racing will be hooking me up with various length air horns to see what I like best, and he has also supplied me with one of his spacers to see how I like that also.

I'm in a huge mess between figuring this stuff out, and also i'm swapping everything to another shell that is getting painted right now, with a changing to rack and pinion, changing interior color, setting up the caputer to work with MS, so ya busy all around on this car. Here's a few shots of it sitting though.