what is the best way to build a non- turbo race engine for my fc. I am only shooting for 13,s all motor and 12,s on spray. Will do bridge porting and street porting but not p-porting. No matter what combo I use 89-91 rotors (9.7 compression) will be used. I have not decieded on fi or carb yet. Should I stay with the 6-port system or go with the turbo 4- port system?

 

First a few questions. Will it be a race only car ? Are you going to remove interior and seats ?How long do you want the engine to last?

I would suggest a 0.31" bridge port (8 mm ) which is the limit you can do,before having to machine into the rotorhousing`s o-ring groove.

You can use 6 port housings,but the motor wont last to long,before water starts seeping into the combustion chambers.

If its race only,then i would go for j-bridge or Monster port.

What does your car way aprox ?

 

This is my interpretation of the ultimate n/a street engine:

'89-'91 High compression rotors balanced and lightened
4 port housings
Streetport primaries
Bridgeport secondaries that do not cut into the water jacket.
My machined constant area exhaust sleeves with a big port
Guru Racing eccentric shaft with center bearing for high rpm use. It weighs less too!
12A intermediate housing with the water o-ring grooves machined to interchange with later engines.
Long primary exhaust with properly designed merge collector.
Custom built intake manifold with runner lengths that correspond to each ports timing in regards to length and desired rpm. The manifold would use a valve that would open up the bridgeport runners only after a certain rpm to maintain good low end power and mileage yet still have great top end. Single plate throttlebody.
Guru Racing dogbox transmission designed to shift at 9500 rpm.
10000 rpm max redline. The center bearing makes this possible!
Hardened parts, better bearings, etc...
Aluminum flywheel.
Haltech


I think that would do it easily but the budget is quite high.

 

what iron housings do I change on my engine to change to a 4-port design? What about turbo housings? Pre-86 13b housings? Where can I find a picture of a small bridge port?

 

You will have to change your front and rear housings to make a 4 port .Pre `86 housings will work good.
You can make the bridge size to about 1/4 ".that would work good,and the engine will last long,if you dont rev the hell out of it,with the proper oil mods.

Here is a pic of a small bridge port(about the size i quoted) Its someones signature on this site.

Walter,how much money do you want to spend ? I you can give me a estimate.i can work of that

 

Not to threadjack walter, but given 3k$ and knowing that the car(na FC) would be daily driven/track car what would you get for the engine.

 

So I can use 12a front and rear irons with no problem. Will my 88 front cover fit. I didn't understand what the last question was about though. I would like to keep it reasonable like 2000.00$. Yes I think Im giong to go with that style bridge, Thanx! BTW where can I get a high pressure pressure unit. I am going to run pre-mix. Also what is the best carb to use webber or holly and can I run a 75 shot of nitrous with a carb if I wanted.

 

Some carbs have built in bungs (I think that's what they're called) specifically FOR NOS...

Blake

 

Care to elaborate on this any Karism?

 

Liquid Anarchy : I dont have any photos taken of my engine builder`s race engine at this stage. He doesnt have the problem,but it will start to leak after a while.Its only the law of fisics

Please refer to the pic .I edited this to his porting style,so that you can see how "race only " this is,and why it wont last to long.

The two ports are joined as one ,sleeves removed with a extra port cut,right to the outer water passage.The yellow bit is the water passage block off ,and the extra big black block,is a extra port that is made

Its really,really rough. Idles at 4500 rpm . Makes maximum hp at 11500 rpm. Extensive oil,rotor and clearance mods are required

 

Here is the second pic,this time from the intake manifold side.

This will be very expensive to maintain,seeing that its max hp application ,in a class that peripheral port has been banned long ago.

Walter : I` dont think that your `88 housings will work.The number of bolts in the housing differs,and you will have to find housings thats bolt holes line up,and have the same quantity. I cant really help you with this,seeing that there was so many different housings.

I can make a list of things that you will require for a succesfull ported engine

karis

 

iS IT POSSIBLE TO USE T2 IRONS ON FRONT AND REAR AND STILL RUN A SMZLL BRIDGE PORT. I AM VERY CONFUSED ON THE HOUSINGS DILEMMA, I DON'T KNOW WHICH ONES TO USE TO CONVERT TO 4-PORT?????

 

He'll need front, middle, and rear side plates as well as the rotor housings that match from either pre '85, or post '86. As you know, that's when Mazda moved the water seals from the rotor housings to the side plates. They're not interchangeble.

'74 to '85 12A side plates would work. Just stay away from GSL-SE side plates in the pre'85 group and you'll be fine.

T2 rotors will have lower compression, but they can still be used naturally aspirated. You might lose like 5hp.


This is what Jeff20B answered ,he has done this before. Hope this helps ?

Karis

 

i WAS LOOKING AT MY OLD FACTORY MANUAL FOR MY 83 RX7 AND IT SAYS(AND SHOWS) THAT THE WATER SEALS ARE IN HE ROTOR HOUSINGS NOT IN THE IRONS LIKE 86-95 13BS SO HOW IS IT POSSIBLE FOR ME TO USE 12A HOUSINGS WITH OUT MACHINING THE O-RING GROOVES IN THE HOUSINGS. MAYBE I CONFUSED BUT PLEASE HELP ME OUT. P.S. CAN I DO A SMALL BRIDGE PORT ON A 6-PORT HOUSING?

 

The earlier 13B housings looked exactly like yours,they didnt have a o-ring groove in the plates.
I would suggest that you sourced some old 13B rotor housings

 

Edit : Pre `85 13 B housings will do the job perfectley!

 

where would I possibly find pre-85 13b housings(irons or rotor housings)

 

I dont think it would difficult to find. You stay in USA right ?
There are loads of parts that go around. You could ask some guys on the forum,iam sure they will be able to help you.

I`am a bit to far to assist you with parts.

Also have a look on e-bay for some.

Karis