rotorface85

i have a stock port 12a that was rebuilt less than 30,000 miles ago. i have a gt35r turbocharger and bae cast manifold. i plan on running around 400whp out of this engine.
My question is:
can i take the engine apart and put in new solid corner seals and springs and change the o rings and gaskets without replacing the bearings and the apex seals or do you think that i should change everything even though i bought it from an old lady who babied it... im assuming that the immediate responce will be to get a complete rebuild kit but if the apex's are still in good shape why bother? i have a spare set of 12a plates that i plan on street porting and polishing them to achieve my goals. also i am running a 45dcoe carb and manifold. locked in distributor and planning on studding the block to make it a little more stable.. i have been reading build threads for the past month at work( work is slow) im not trying to be a cheap *** because all my parts are brand new and i payed top dollar for quality. im just trying to get an honest opinion from someone who possibly has done this before.

seanrot

iTrader: (2)

Depends on the condition of the parts inside. If they are still within spec reuse them. If not then well replace them. Personally with all you have to do to get the turbo system running I would build the system on the engine and run it till it fails the rebuild a purpose built engine. If your gonna open it port it too... I mean your already there.
I have a street port 12a with 14000 miles on it. I'm shooting for 300hp after that the drivetrain starts to fail. I'm still a ways away from engine start tho.

rotorface85

thanks for the reply, you think i should just run it then and keep the boost down so that i dont flatten the corner seals too fast? i guess i could live with 300 hp for a while. its still double what its putting out now stock port with a holley intake manifold and edelbrock 500cfm carb. msd coils and pacesetter header...

seanrot

iTrader: (2)

Stock port 12a, 225hp to the wheels is a more realistic number at 8-10lbs of boost. That's what my last one had. I'm going for 300 with a street port. I think your being awfully optimistic on your hp goals. You have one hell of a build on your hands too.

Here's what 300 will look like

https://www.rx7club.com/1st-generati...hings-1022443/

rotorface85

I'm still gonna go with a large street port.. I have tons of time into this car as is.. Not cutting any corners now. I'm pulling the engine put next week and I'm going to take the engine apart and inspect everything but I'm guessing I will just replace everything anyways.. I'm street porting my plates this weekend so they are ready to go in.. I will give the exhaust ports a race port how when it's apart. I will post pictures when I start putting it back together..

LizardFC

iTrader: (1)

I've read that the end plate of the 12a becomes a weakness over 300HP or so. The motor doesn't take well to the large torque numbers. Something to consider. Also, dowel pinning would be a good idea. If you're really shooting for 400+ then you might want to look at a TII trans as well. 400 is a lot to squeeze out of a 12a, but it has been done. Not by me! I'm aiming for just over 200hp with my S5 turbo blowthrough setup. Anything more is icing. I'll keep boost down to 10 psi or so.

Jeff20B

iTrader: (13)

Look for an R5 rear plate for your 12A rebuild. The 18 tension bolt variety is the best (strongest), but the 17 bolt version is good too.

The way to tell from the outside is the rib at the oil filter pedestal/dowel pin area.

17 tension bolt has a thin curved rib

18 tension bolt has a thick straight rib resembling S5/Cosmo and all old school non-nitrided R5 and 3B irons.

Only FD and apparently later Cosmo has a thick dowel pin casting. This is only academic as you can't use late plates on a 12A due to coolant seal location changes for 86-02.

Avoid Y plates above 300HP as these lack a rib.

rotorface85

all good information, thanks again. i already have a t2 tranny i was planning on swapping out at the time of the rebuild. i am going to run a chromoly flywheel with a stronger clutch too. i will have to do some hunting for another rear plate as the one i have is a y plate. ive still got a few months to get this thing ready to go to vegas. anything else i should consider? anyone run those solid dowel pins before or should i use all stock spec ones and have a few more machined in? whats the best tension bolt upgrade? ive heard that goopy's were good. if i dont quite make it to thhe 400hp mark i will be ok but i know that this car would really rip with 400 hp. ive got a ford 9" laying around too that i might have to make fit in here at some point.

13x

why so high on the HP?

traction will be a biotch

300HP with the power to weight ratio would be a damn quick car ..

rotorface85

300hp is a good goal to start with but id like to be able to get more if possible... it seems 300 should be easy to get out of it with proper tuning. a streetport 12a can make upwards of 220hp n/a so force fed it should make 300 with ease. i guess il just keep it around 300 hp and maybe it will last a while...