Howdy folks, I posted these in my build thread but thought I would share with my NA people as well. I'm working on an NA build using 50MM ITBs and wanting to run a Haltech PS1000. I've come a long way but have much further to go. There is almost no information on NA 13b builds so I called Borla who bought TWM inductions and they made me this ITB kit TPS included for the deal of the century as far as I'm concerned. My engine has a large street port right now but I'm leaning towards a bridge.

 

yesss! I have been tempted in this TB setup before too. I'm curious to see how you like it.

 

What's interesting to me is that I think the runner length is close to the same as mine and I am running 4x46 mm Hayabusa bodies and mine runs great. I do run 2 different runner ID's with smaller runners on the street ported primaries and larger runners on the Bridge ported outers. I just want to see how the throttle response and power curves will be as mine has decent bottom end and pulls strongly from about 4,000 to well over 9,000 rpm. Could you do a rough measurement from the manifold to keg mounting face to the outer body face? At the outer end of my stacks I am close to 14". Most of the street guys wrap the runners over the keg and have runner lengths close to 20".

Regards,

Eric

 

which gold film is that??

 

Are those Banzai mounts?

 

Pulling a tape so very rough, 11.75"-12". Is your car a track only car or can you street drive it also? what are you doing for engine management?

Just some cheap stuff I got off amazon. I am not sure how it will hold up to engine bay temps so its kind of an experimental thing for now. If it peels I'm going to get the real gold heat shielding.

Hmini Racing through bolt design.

 

I am running a Megasquirt and the car is a full on race car so it doesn't need to be good on the street or at low end. Right now it chugs under low load at low engine speeds as the engine braps, but beyond that it's as tractable as a street car.

Eric

 

Sorry to revive the old thread but I am suuuper interested in going full ITB setup on my 90' GTU 6 port...

Since Borla bought out TWM Induction, they have since released their own ITB's obviously.

After some reading I've found quite a cheap ITB setup on Borla but I do not know if it fully equates to the TWM Kit because it looks a little different than the one you had in your pic.

The Borla 2900 Series is what I'm after. It looks a little different because its a split ITB setup and I was wondering if I could just buy the 50mm LH ITB with TPS and drop it on a Weber IDA intake manifold...

I'm very green in this subject so please enlighten me.

Here's a link to the ITB - https://www.borlainduction.com/2900-series.html

and some pics



*EDIT* - After re-reading OP, I realized you had it custom built by borla... How much did that end up costing if you don't mind me asking?

 

the one you've picked will fit a DCOE intake, which is the side draft style. you could actually get an RB upper intake, and then use this. intake length is probably long enough where you get lots of midrange.

just really quickly, the DCOE and IDA have different footprints (feetprince?). in Italian, the DCOE is a double throat, something, Horizontal (side draft) with a Choke. the IDA is a downdraft, two throat with no choke.
(D is doppio, double. O is Orizontale, Horizontal. I is inverted)

so short story long, if you want to run an IDA manifold you need a TB with an IDA foot print

 

Is there any performance difference between a 45 and 50mm ida style itb?

 

bwrx7- The Kit costs 425 but I think they gave me a really good deal because that was the first quote I got and being the stand up individuals they seemed to be they honored it. I think they were saying it should have been around 500 or so. The guy I dealt with the most was Dale Schaller.

I originally was going to use a DCOE style wrap around manifold but I am shooting for 220 RWP and I read that the factory LIM was very inefficient for flow or something. Also I read somewhere the shorter the better for peak HP. So I decided on the IDA style.

I have been working with Build 2 Apex and the dude that I've been talking with there, Nader Sharif, says they are working on their own ITB kit. so you may want to give them a call and see whats cookin with that.

 

Jeezus- I'm not sure. I'm guessing it depends on your port job. This is the first ITB car I've ever attempted to build, or really have been around, so I'm still very green as to performance. Plus I'm still massing parts so my shitbox doesn't run.

 

any progress with your project in the past 5 months?

 

I really wish they offered the porsche kit at 1/2 I would like to run a throttle body for each iron essentially. but no, you have to buy both banks...

 

Is there a manifold that will run the Porsche style TB?

If one will have to be made, might as well get the 3 of the single SU style.

 

Not too much of an update on my build. I got the Engine in the car, and the interior is currently pulled out for the rewire of the Haltech. I have been racing in an endurance series so that has taken all of my extra car money for the summer. I hoping to get the car started by Xmas. I still need the individual coils, the injectors, and dual wideband o2. Plus a few sensors and odds and ends. I'm also not sure if i want to spend a bunch of cash on gauges or just buy a racepack, I'm leaning Racepack although I don't want to lose the factory look of the gauges but I think it would be cheaper overall. Here is the link to my build thread for better updates if you want to check it out from time to time. https://www.rx7club.com/build-thread...k-ups-1074841/



How the interior Currently sits



The engine bay with some factory stuff to be removed and missing some aftermarket items. but basically how its going to look.



Orange FC is our endurance car. Its all mostly stock with a exhaust and roll cage. Pictured at Portland International Raceway 7.23.17

 

Need a gurney flap on that hood heat extractor! What rear wing and supports are you using? Did you need to add any internal support to keep the rear body panel from buckling due to the downforce?

I've also thought about trying to build a 3 ITB setup but that certainly complicates the manifold design. I'll probably end up keeping it simple with 4 though and see how it runs on my full bridge. Get that thing up and running before winter sets in!

 

no, it would have to be made, but I like your SU idea! didn't think of that...

 

I have this same 50mm twm setup on my car. My Stock port gslse 13b puts 190rwhp out. Seems like itbs can be had alot cheaper now than when i got mine 10+ years back. Drivability was good with an e6x. I just switched to an ms3pro and an ignition setup like the rx8. Curious to see if i net any gains.

 

190whp on stock ports? That seems awfully high, do you have the dyno sheet I could look at?

I'm on the fence between a wrap-around or a down-draft. Trying to find information on optimal runner length for certain RPM bands. I'm not building a high RPM screamer, but I don't want to leave power on the table because I chose the wrong intake runner style.

 

Doing this lazymode... old Mazda paper has 18" from port surface to trumpet entrance (this is for peripheral port but should basically apply) providing resonance at 7k RPM, 16" at 8k RPM, 14" at 8.5k. Assuming the R26B was basically the same port configuration and matching the torque peaks to the other paper, its minimum runner length was 14" - if that's right, according to its paper, it was running 15" runner length at 8k rpm, 17" at 7.5k, 19" at 7k, and 21" at 6k RPM and below.

A whole lot of rules of thumb, assumptions and fudge factors in that list there, but it's a place to start.

 

That actually meshes perfectly with the "old Mazda paper" if you accept that they may have set the software up to control to those lengths at those speeds with the expectation that the engine would accelerate more quickly than the trumpets could be controlled.

Hardware lag is a real problem that needs to be tuned around..

 

i'm sure there is some, but the trumpets actually move really fast. fun fact they use 2 miata headlight motors with a pulley and cable system to operate the trumpets.

one fun thing about the 787B is how many stock Mazda parts are on it

 

Well, that paper was dated from 1990; 900032, so I mean, one has to figure it's related. Scanned it from university SAE transactions years ago but not sure if I'd get sued if I shared it. It's mostly about tweaks to 1d simulation to account for peripheral ports, but shares findings that correlate between simulation and test engines.

Some day I should sit down with some books and try to code stuff (... and pretend that there's a market in developing hardcore simulation tools for rotary stuff in this day and age)

 

Hey idk if it was mentioned already but what' the lower intake manifold? I am also trying to go with itb on a stock port s5