Proper topic title, this time OLD THREAD: https://www.rx7club.com/1st-generation-specific-1979-1985-18/will-these-fd-rotorhousings-fit-my-12a-motor-696169/

Last year i had an epifany(sp) Going through threads i discovered Robert Rotaryshaggers red beautiful FB blowthrough Turbo monster, this inspired me to test my skills with a 12A.
I had a 12A core engine laying around that i decided to tear apart, came out really nice, but the housings were flaking really bad.
I started sourcing 12A housings, turns out they are hard to find and new ones would cost me my first born, here in Europe. Sucks.

What to do:
I got ahold of a fellow forum member in Belgium, bought two used REW housings with some chrome flaking.

Threw them in the the CNC mill and went to town


5 mm off each side.


Cut some water seal grooves in them and had a few beers.


Fitting Side seals.


Securing bearings with M4 setscrews.


Random assembly picture.


ABCON assembly goo and Hylomar Smurf Snot is your friend


Mild Streetport.


Very shortblock.


Frontcover internals.


Oil Debubblificationplate (yeay I invent words)


I highlighted the 13B letters, just for the sake of total confusion, only the true rotard will notice.


Turbo manifold fabrication. Later i wll get a better turbo/manifold.


As above.



Bored at Work, why not put it to good use instead of posting random **** on the forum.:

Port scribing tool


Seal box




Just for fun, I hooked up the compression tester today. It showed 45psi.
Now that might seem low, but this was just me turning the flywheel by hand. Ha ha. I need to build a test stand.

 

did you cnc ground the housings down and if so how much?

 

Yep, I removed exactly 5mm on each side of the housings. Did it in a few steps and the last cut was super thin, so as to get a really flat smooth finish.
Four sides ate one cutter, I'm willing to believe, it aint just regular aluminium.

Well I'd be lying if I took credit for the CNC part, I had a friend do it for me. Numbers and computers hate me.

 

Very Nice.

Did you fabricate the turbo hat and boost prep the carb yourself?

 

Yes I made the plenum in stainless, the carb is turbo prepped from the factory.
Bought the manifold from Pierce Manifolds, looks okay on the outside but the ports needed to be matched to the irons. Im not impressed by the accuracy of their mould

 

Nice to see it assembled, You posted the CNC pics a while back? right?

 

Exactly, Hades
But I figured I would do it over again with a, not so n00b'ish, thread title.
The old one scared people away haha

 

Dude, did you make that seal box?
That is just SICK if you did! :p

Everything is so clean and methodical, I don't see how this could be anything other than perfect in it's assembly.

Did you fabricate the manifold yourself?

 

...too late.

 

Looking nice.

 

Would you be interested in making another turbo hat for a price?

Need 1 for my mikuni... pm me a price if interested.

 

your plates did you lap them and have them nitrided?

 

looking good.. BUT, a long,long time ago i made a few carb hats with the charge pipe off set and for some reason the barrel that had the charge pipe directly in front of it was leaner than the other barrel( egt guage probes in front and rear exhaust header).. thats why all the carb hast i meke now are centered
so here is a tip for ya, jet the rear a few steps richer than the front

oh, and dont use a turbo other that a stock s4 or s5 with an oer carb, the needle valve can't flow enough fuel for anything bigger ... i found that out the hard way..

oh and whoever told you the OER carbs were turbo prepped from the factory lied to ya! they arn't

 

Rx7learner.
Nah sorry, but im sure someone else is willing to make some money off you

Blwfly.
I lapped them myself, didnt bother to have them re-nitrided

Robert.
Thanks for the advice, I appreciate it.
It says somewhere in the manual that came with the carb that they are boost prepped.
Ohh well I believe in You, more than I believe in a piece of paper.
So what do I need to do to boostprep it ?
It allready has a plastic float, rubber sealed shaft bearings and it sees turbo pressure in the floatbowl somehow I guess.

Thanks
Kim

 

all of the above is correct but you also need to seal the nuts on the bottom of the carb(the ones that hold the venturies and aux. venturies in place) or gas shoots out around the coarse threads when there is any boost applied to the carb.. also check your needle valve and get back to me on the size.. it needs to be at least a 1.7 ..i also ues a larger fuel inlet or drill out the banjo to get better fuel flow. im just wonderig why you didnt buy this stuff from me!! you wouldnt have to worry about this stuff!

 

Thanks Robert, I'll check the NV tomorrow.
Banjo is gone in favor of a 6-AN set-up.
When I asked in Your thread, in the Vendor forum, I had allready bought the carburetor.
It wont happen again, Master

 

Robert is the man w/ these types of set ups!

 

Needle Valve is 1.8
I teflon taped the setscrews for the venturis.

My plan is to break it in without the turbo for about 2000km's (1200miles)

Oil hook up will be 4-AN or 6-AN in and 10-AN out

Tight fit



And a picture of my retirement plan LOL

 

Is that exhaust mani gonna hold up?

 

It has a support brace between the two pipes.
Its hard to tell from the pictures, but check the one where its in the vice.

 

wow are those stamps lol collectors item there

 

ok good..
next, you will need to drill and tap your intake manifold (1/8 pipe) one on the front rotor and one on the rear rotor.. tap the manifold on the motor side since there isnt alot of room on the outside= run into turbo.. next,install fittings, use silicone hose and Y them together before going to the fpr and boost guage to insure a strong boost/ vac. signal..

 

I see a jerrycan.

 

Please marry me
J/K - Thanks you're the best.

Does it make a significant difference whether I tap the primary or secondary runners.
I was thinking about using PolyURethane hose and snap connectors that we also happen to use at work on the pick n' place robots. It's pretty strong ****.

 

Some pictures Pre rebuild.

Carb and boostbox in its early stage.


Fresh welds. And by welds I mean I ran it together with the TIG


An hour in the microbiological cleaner and then I wirewheeled the **** out of the gunky rotors


Made an oil recess in the stationary gears, made them with the last dull lathe-bit available in the shop - hence the bad finish


Milled a few more windows in the bearings


Guess what


Man I love my job.