My 13B NA Build Thread
 

Hi everyone,

I'm Dan, from Argentina. Down here RX-7's are very rare cars... and people who know how to work on them are even stranger to come by -- so me and a friend decided to work and rebuild my car.

This is my piece of shit FC, I love it.

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I decided to go the NA route.

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The car itself is a '91 FC... but not your average FC... it's a "Middle East/NZ" spec... or something weird like that.

It has a S5 body, S4 engine with S5 size/shape intake ports, Distributor, Thermal Reactor exhaust, ABS + 4pot brakes, rear seats, open diff, and a unique 6-PI actuation system.

Check the bay out

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So, the plans for this first stage are the following:

• Large Streetport Intake porting (Pineapple Racing template)
• Large Streetport Exhaust porting (Pineapple Racing EP2A template)
• Send the ABS to hell
• Send the AC to hell
• OMP delete
• Emissions + Air Pump removal
• Cruise Control delete
• Pulsation Damper mod
• Complete Engine Rebuild

So it starts...

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Old 3-piece Apex Seals

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Intake porting~

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Until I get a proper header (I plan to build a custom one), I got ahold of a US spec S4 exhaust manifold to replace the hideous and incredibly heavy Thermal Reactor.

Check them out.

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Now blocking off several thingies...

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... and doing some Throttle Body mods

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Got the plates lapped, they look really nice!

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And decided to send the exhaust inserts to hell! :egrin:

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Removing even more stuff out of the car...

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Several cleaned/to clean parts...

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Ported housings, check the size of those exhaust ports!

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A close-up of my engine's super VTEC. Instead of the rotating sleeves operated by exhaust backpressure, this LIM has these nice valves. The aux ports themselves (inside the front and rear plate) have a nice curvature as well!

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The ducts for the rear rotor were full of carbon deposits... all thanks to some EGR thing.

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Nice dual-sheave alternator pulley

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Another pic of the S4 exhaust mani... there's some beveling work to be done there, since the exhaust ports are massive now...

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Porting the TB a bit...

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The "stuff we don't need anymore" corner... there's over 100kg in parts in there

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Getting ready for the rebuild

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Setting up a notebook to record the whole process

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Build time!

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Cool Man!

That's a very weird engine setup that came stock!

With the basic engine assembled, time to celebrate with asado and beer!

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Work continues...

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Now with the oil pan

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Beautiful

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Getting the engine in...

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Sending part of the exhaust to hell

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Getting more stuff in

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Wow that thermal reactor thing is a trip. Never seen one of those before.
Lookin good man. I may have missed it, but what are your plans for the exhaust? Just wondering why you didn't use headers, especially since the engine's ported. Noise constraints maybe?

edit: Oops I just read the part where you said the stock mani was a temporary thing. My bad!

Such a cute little engine, hehe

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... my friend Luis battling against the wiring

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So that's as far as we've gone at the moment... we're waiting for some MSD Blaster 2 coils to arrive so we can work on the DLIDFIS setup and fire her up!

I'll obviously keep posting stuff as we continue to work! :)

Ive never seen housings like that. I wonder how those valves work? Nice work.

Here's some detail on how the dynamic intake works for this particular model

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Nice job so far. Gotta love the Euro style FC LIM and the thermal reactor.

One thing I would recommend is to put the BAC back on. That's now the ECU regulates the idle speed.

Wow, crazy stock setup. The butterfly valves on the lower intake manifold seem so rare.

+1 on keeping the BAC, you will hate yourself for removing it later.

Thats a crazy l.i.m. Would be perfect for to start a 6pi turbo and still keep the 6pi working. I had a video from old top gear in early 86 showing the new FC and it was a s4 motor with a dizzy.

Just out of curiosity what is the ECU code? Maybe its my imagination but the center iron doesnt appear to be the same series as the front and rear irons.

I'll see how it runs BAC-less, and if it becomes unbearable the BAC will go in again.


ECU code is N368.

The center iron hasn't been swapped or anything weird -- it's what came with the car, stock.

holy fuck I've never seen that gigantic thermal reactor before!! I thought the cast ones were big. good God!

I must be magic, haven't had a bac in yrs and have never had idle issues after i set it.

^If you want the stock 750-800 RPM idle, you need it. Otherwise, yes, just turn the idle (throttle stop) screw and go with a 1100-1200RPM idle.

Why thermal reactor? Does this thing generate heat for your car or is it some sort of catalytic converter/exhaust manifold all in one thing?

So odd that your car comes with a distributor.

Thermal reactor was Mazda's "early" solution to the "ultra high" HC problem

reason is that rotory's combustion are relatively long and narrow. lots of unburn(partial burned) fuel = high HC and high carbon monoxide

Thermal reactor is just a heavy duty chamber with fresh air injection so it allows the unburnt gas to "finish" burning.

I seen one of those in person recently, it weights like maybe 100 lbs or some crap. Think of it, its pure steel.

so u can buy template for porting your own engine, ive watched arron cake port before but if theres a template id feel much more confident doing ti my self, also does porting the intake throttle body help much and is it very difficult? and did i read wrong since you said you were using a s5 uim? and if you are what is required to do the installation

putting down under 200hp for a non turbo I doubt porting the TB would be worth the trouble, but done correctly it can increase its max flow rate and reduce the resistance. there ought to be some comparisons documented using a flow bench.

That thing is a unusual car...like a mix of all the left over parts from SA22(thermal reactor) through s5. I do however like that LIM, would be a nice way to have 6pi working with a turbo, just were to find one.

I'm using the stock UIM at the moment. I believe it's a S4 one.


Exactly... it's like they had a lot of stuff lying around and had to assemble some more FC's.

The brake master cylinder is out of a S5 T2, for example.

It also has a 12v AFM instead of the usual 5v.

Oh, and that unique N368 ECU no one knows anything about.

Regarding the LIM, I might get rid of it in the future... I plan on running ITB's.

itbs?

Individual
Throttle
Bodies

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I was wondering, what should I do with these passages when building a header?

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Should the flange just block them off? Or maybe I should modify the flange so that the gases that pass through those ducts get routed into the exhaust tubes?

block dem bitches! can you get exhaust sleeves that don't have the EGR port? I'd do that if it's not crazy expensive.

Hehe, I plan on not running exhaust inserts at all :)

Just like you see it there in the pictures... nooo inserts!

yeah I just noticed that with the fully assembled block... why are you doing that???

If you check some of the first pictures I posted, you'll notice that my engine originally had the classic "NA inserts" in the exhaust ports -- these have those undesirable baffles that are a pain in the ass to grind so I decided to do a little research on running the engine without the inserts altogether.

I found that very few people had actually tried this, but the few that did were actually very happy with the results. Regarding engine temperatures, they should only go up by 1~2ºC.

Wouldnt worry about it, look at his center iron...no EGR port.

you have quite a neat little project going. it's kind of trippy looking at everything from the fact that a '91 model came with so much older technology to watching you build the engine from back to front. :) everything seems to be coming into place.

Hehehe :lol:

I was waiting for someone to notice that detail!

Hmm ran tb mod/ported tb full emission removal and idle was solid 750ish after warm up.

how do the itbs work and can they just go on any na with exhuast and intake mods? and what is the exact benefits of them?

In a warm climate that would work.

I've gone through the trouble to put mine back. Helps a ton when it's cold out. I've had to start my car when it was 25 degrees out. That won't happen with a TB mod and no BAC, unless you want to sit there with your foot on the gas and pray the car won't flood if you fail to keep it from stalling.

^Lived in north dakota for most my life where winters are @ -30f asa norm. This was when my 7 was a daily. Today its a different story. Mushiki...Tweakit ITBs=awesome town.

I wouldn't run without the exhaust sleeves. Get a set of turbo sleeves perhaps?

Dibs on the LIM when you don't want it anymore. :suspect::lol2:

this is my fault . . .


maybe also ....

Noticed in one picture the new engine sitting horizontally without the front crank bolt installed... I sincerely hope your thrust bearings aren't crushed.

The coldest temperatures you'll experience down here in Winter are about 32ºF


Hehe, they look pretty good ;)


Why not?


They aren't, I promise.

subscribed... interesting that so much of the engine is different than what I'm used to since it's a Euro-spec.

You'll need a standalone EMS to run ITB's.

okay thanks they look fucking badass

you suck! and you'll continue to suck until i get back to Florida :D

(by the way, i've always been in love with your country)
supposedly, there are issues with flow. i say "supposedly" only because i didn't do the testing and i don't have the numbers, not because i don't believe it - because i do. in most cases, the turbo sleeves help to get back what you would lose by running no sleeve at all.

^its a velocity thing, makes for a peak engine. Ina np or pport race engine where u gonna see 7k+, no sleeve will jet some more per. Ona streetported motor like this ur prob only hurting the powerband.

Sorry for the typos, autospell ona phone and can't edit.

I understand that it "might" hurt the powerband down low and/or make it more peaky... we'll see -- like I mentioned before, there isn't really much data or experience on running the engine with no inserts... and the only information I managed to gather was actually favorable.