Hey Pele, I went to that website you posted. If what they say is right I can get tons of power. This is my plan...I'm replacing my 12A with a 13B right now. The engines is already out of my car. I'm going to do things as planned and do the swap and rip the 12A apart when I'm done and practice on it, later on if all goes well, I'll do it to the 13B. Another question, that website was talking about 13B's that come stock at 135HP making almost 200-250 HP! Can anyone substantiate this? This porting sounds great...

Thanks guys,
Jesse

 

Bridgeporting make the idle really rough and you have to set it above well over 1000 RPM to get it to hold an idle. Not very streetable. Plus you'll have to upgrade your exhaust and intake heavily to keep up with that porting.

The numbers they quote assume there is a free flowing exhaust system and a good intake system with high flow carb or injection.

Crappy carb or restrictive exhaust will drop your numbers.

If you want a good kick, but keep a semi stock exhaust and carb, and keep it on the street, a street port seems like the best bet. Guys, wanna back me up?

 

But for race purposes, bridgeporting would be the way to go? I'm getting my car in good enough condition to sell so I can build up my rally car. When I do port my engine it will be with the intent of racing it. When you talk about good intake, do you mean high flow filter and/or what else, will my 3" pipe and K&N cone work? I've already got a high flow cat and exhaust, and I'll probably come up with some headers before I do the bridgeport.

I'm an avid "do-it-yourselfer" and will probably buy an air compressor within the next week, what kind of grinders will I need? I'm kinda new to metal working(Wish I hadn't slept in shop class now Fortunately I have my junk 12A to operate on before I ruin a perfectly good engine.

One last thing, where do I get these templates you people speak of? This is going to suck when a ruin a few engine blocks but maybe 3 or 4 ruined engines down the line I'll get it right.

Thanks again guys,
Jesse

 

Templates can be had from Racing Beat or MazdaTrix.

For an all out racing engine, the best would be a prepherial port - thats what Mazda uses in their race engines (at least they used to).
After that a J-Bridge, then Bridge, then Street, then no ports.

 

For anything bigger than a street-port you'll need a different carbie. A lot of people use the 48mm IDA Weber which is considered to be the ultimate performance carb for rotaries. Both for its performance and tuneability. If you decide to run a street-port then the stock carb can be modified to flow more air and tuned to suit. As for the exhaust, if you really want to get the most out of a bridge-port you need a very free-flowing system. You'll need long-primary headers and good stainless-steel straight through mufflers.

 

But my engine isn't carburated, it's a 13B FI from an '84 GSL-SE? What mods should I make?

Jesse

 

Free flowing exhaust, probably the Racing Beat Road Race setup or something custom.

Good intake, Ported and polished manifolds, bigger injectors (Dunno where you're gonna find em though. The GSL-SE has the biggest injectors on any RX-7 and probbly all production cars.) Or ditch the EGI system on a carburetor. Probably a huge Holley or Weber.

If you keep the injectors, upgrade your fuel pump and ECU.

That should keep you from leaning out and blowing up the engine.

 

I've heard that you really can't gain near as much of an advantage with the 13B from the GSL-SE because it is a 6-port design to begine with and the ability to increase port size is pretty limited before you start cutting into critical areas of the block. A lot more of an advantage is gained from the 4-port design of the 13b..

Anyone???

 

I've heard you can get really good results by street-porting the 6-port plates but obviously you can't bridge-port it. But, I believe you can use the 12A plates with the GSL-SE rotors and rotor-housings to make a nice 4-port 13B which would give you heaps of porting potential. Then again you could just build up a 12A. I've driven a bridge-ported 12A and they scream. As for the fuel injection, just scrap it and put a Weber on.

 

If you are looking to port the motor, might as well make it really worth while by going at least a bridgeport.

I'm running an Extended Bridgport 51mm Weber and its completely streetable, although yes a little on the louder side. Probably about 240hp at the flywheel.

If you keep the injection (or maybe go aftermarket EFI with extra injectors) it will make it even more smoother and streetable as well

Damo

 

First off I wouldn't even bother with a 12A...that's the first mistake I made. After the Paul Yaw carb, RB exhaust, and Street port motor you'll probably be makin 160-180 horse within a very narrow power band. Instead you could go and procure a rebuilt 89-91 NA 13B with the variable DEI plenum and make 160 horse stock, with a much broader powerband--basic mods 180hp+.

I must say I bought into the whole 12A hype that makes a Yaw carb and a RB exhaust sound a lot more powerful than they end up being. If you really want to go fast I'd wait for the Renesis to come out and see if you can't purchse a new one from Mazda. Also, if this option becomes too difficult, you might be able to just purchase the most valuable part of a Renesis: the side housings. There's no tellin just how interchangable the housings might be with earlier 13Bs; maybe a budget motor could use just the side housings and old 13B parts for everything else. Of course, this is probably just wishful thinking.

 

I love the 12 a and i have seen heaps of power wann get extreme. Build up a 12a and drop a monster super charger and carb and hold on.

 

If you look at the renesis rotary design, it becomes obvious why it is so much more powerful AND CLEAN at the same time. The question is money. Would it be cheaper to wait for someone to wrap their rx8 and get the engine OR would it be cheaper to have a 12A housing and casings modified to exit its exhaust charge just like it breathes in its intake charge. Getting rid of any periphereal exhaust shenanigans is the key. Why couldn't someone make a new casting for the 12A or 13B with these changes? It would still be cheaper than picking up a new renesis rotary. Anybody out there with the necessary capital or contacts?

 

i have a streetport now its alright there is very noticable differece compared to stock engine. they need a little bit more revs to get of the line. But now im going for a bridge port.
I getting a med size port on the pimaries and a large on the secondaries and also a H/D clutch and a getting a 3 row core fitted to my old radiator. Should be fun!!!!!!!!!!!!