I have been debating for some time about what rebuild I will embarke on. I have an 83 12a with 20k on a rebuild and I have an 84 13b ( out of the SE ) that I have no idea what the condition of the motor is. My goal is to rebuild one of the two and supercharge it, but I do not know which one. I am leaning toward the 13b for the difference in torque, but as I said I do not know the condition of the housings, rotors,etc. Considering the condition the tranny was in when I rebuilt it I can only assume that she has been neglected/abused. What would be more cost effective and what would you guys do if you had the choice? Thanks in advance for your opinions.
Jim

 

Im no god and not a fan of 6port. but here's my $0.02. Assuming that the 6port is in good shape, I would use 12-A plates to make it a 4port. So the best thing to do is take the 6port motor apart and see if the rotor housings are re-useable.

 

i would stick with the 12a but that is me im a little bias... the 13b se motor is from my understanding the bastard of the 13b's(i could be very wrong) but its not a very good plat forum to start with....

also the 12a is a rebuild so it shoudlint cost as much to rebuild as most the parts should still be good

 

I was already leaning toward the 12a for the reason mentioned, it is a rebuild so I know the motor is good. Just a few things to replace to insure it could handle supercharging. I was not sure if the 13b from the SE was a 6 port or not. I would prefer if I was going to rebuild a 13b that it was 4 port.

 

OK, to get a good answer we need to know your intended use for the car, the HP goal, is it going to drag, autocross, daily drive, Targa Newfoundland, what reliability, what budget, noise, local emmisions, etc, etc, etc.

Sorry to be a butthead but more is needed to give you any realistic answer.

 

Definitely not a butthead question. That info would produce more concise answers.

 

Thanks Scott, oh and I got the shipment yesterday, thank you again....

 

I have no budget in mind, but would like to minimize any expense if possible without sacrificing longevity. My intention is to supercharge it and keep it more of a daily driver with some autocrossing. I would like to keep the exhaust noise similiar to the setup I have now. Racing beat streetport system. I have no goal as far as HP except to get the most I can without taking away streetability. I know a lot of guys are going turbo but my thinking is SC for the low end power. I think rotarys have enough high end with the higher revs we can obtain. Emissions is not an issue here in MI, simply will be none. Hope this helps narraw it down a little. This is in the beginning stages ( thinking ) and I am just looking for some feedback guys, thanks.

 

Most people go with 13BT as it is relatively cheap, and easily makes 300 hp with few mods, it is reliable and quiet.

SC hasn't had similar HP numbers in almost every case, it is unique, expensive, the engine wasn't built for SC either.

There are a few SC 12a members in here ie: KimsFB, they do seem very happy with the results at a significant price though.

 

Supercharging is cool, but it limits your options and its expensive. for the cost vs. performance route, I would go turbo. aftermarket turbos are fairly universal and suffer from a huge aftermarket support.

 

Well if I go turbo I am going to need the help of all of you. I have NO knowledge when it comes to turbo anything. I would rather keep the expense down and if the rotary takes to turboing I would rather go that route. Now the question is 12a or 13b. Remember, I have a good 12a outback but the 13b is seriously in question. Almost positive I will need a new rotor and housing. And yes, I will read the threads before I post a repeated question.

 

The s/c is cool, sounds neat and gives great torque and throttle response (I run the Camden on a 6 port 13b in a 85 SE). The s/c would be great for autocross or drifting and is nice on the street. If you get a used set up for a good deal, than go ahead. If you're thinking new, give your head a shake. While I do like mine, and it does live up to it's advertised promise, it doesn't fullfill my dreams and desires. You would be wise to just do a 13bTII swap with a factory ecu to begin with and plan on a standalone and intercooler later. A mildly ported TII will pull hard and you have the potential to add a standalone, intercooler and bigger turbo later for bigger jumps and can eventually hit 300+ hp easily. For the same money as a TII swap, the s/c 12a or 13b has a potential for a documented max of 211hp, that's it! Not to say it doesn't drive well, we're talking bang for the buck here. Only upgrades afterward are water/meth injection for a leap of maybe 30hp, then a mild nitrous shock for a max of 75hp. Throw that water/meth on a stock TII with a ported wastegate and you're at about 250hp. Just my opinion, been there , done that! I'd do turbo if I were to do it all again, at least you're not capped at 211.

 

Building the 13B will take the the stock TII turbo and exhaust mani, sourcing the intake makes it harder, unless a TII intake can be modded to fit, then go efi, or a wrap around blowthrough

The 12A has plenty of intake oprions for both carb and efi, there will be some minor mods to make the TII turbo and mani to fit.

If the 12A is in great shape, it can be turboed without the cost of a rebuild and may be cheapest option with most of the cost going to intake, exhaust and fuel systems.

 

Turbo the 12a and you'll be screaming!!! Check out some of Directfreak's videos...

 

Well I think you convinced me Trochoid. The 12a has only 20k on a rebuild and the 13b is....well. Ugly. So if I understand correctly, a stock 12a as far as the apex seals and the guts of the motor can handle turbo as is, or should I tear down and do some reinforcing. I believe I read in an earlier post that the 12a has 3mm apex seals. Is this correct? I suppose I better plan a few hours at the library studying the threads to avoid the phone charges out here in the sticks.

 

Thanks for the firsthand knowledge. I really do not like the idea of being stuck at 211hp for the cost associated with it. For you to say you would go turbo if you did it over is enough for me.

 

Longevity determining factors will include: Quality of rebuild, amount of boost run, tuning and peak rpms. These are tha main ones. All pre-86 rotarys have 3mm seals, except a few very early ones that have 6mm ones, which are not in the scope of FB's.

Research will be your best tool, takes lots of notes if you are searching off-site. Have fun.

 

Thanks ^^^ and don't be surprised if I get stuck to get a few turbo illiterate questions from me. And one more question, should I do some stage of porting such as street or bridge?

 

Set a hp goal first. If you want to port, you will be tearing the engine down. If all the hard parts are still good, you might get away with a gasket kit. If the apex seals show much wear, replace them.