So before i go crazy and start ordering millions of parts i wanna do this right. I own a 1988 rx7 s4 fc vert with a 13b na block. Im looking to achieve about 300+ horse power reving to about 8k to 8.5k mostly want mid rainge power. Any way i plan to turbo the na block but before that i wanna just build up the engine first.Ive researched alot and am having mixed opinions regarding a few things. So i have a few questions 1.)It seems to be the forbidden topic, would the turbo housings work with the na plates if not ill have to find some n/a housings no big deal. 2.)For the amount of hp im looking at should i go with the rx8 rear stationary gear and rb front stationary gear, or just through some 3 window bearings in my gears. someone said theres a thread discussing this but i had no luck finding it. a link would be excellent. 3.) the 2mm seals seem to be superior should i go with 2 pc or 3 if they make a 3. or even keep the stock seals if there in spec. 4.) anyone from arizona and know a good place to get your eccentric shaft and rotors balanced.. so thats it if you guys could help an input is greatly appreciated. thanks guys ...

 

You are going to damage your internals revving a S4 that high.

Absolutely they are identical outside of the coolant passage. This would make your turbo project easier some would say.

The benefit is the S5 and FE gears are hardened to handle 8K but you will need the lighter S5 rotors to reach that RPM. The window bearings are not needed but if you need to replace the bearings and don’t mind the couple extra $ sure go for it.

This is highly debated it seems 3pc do have some advantages but tend to roll inside the rotor grove as they wear. I suggest 2pc OEM or Atkins seals and RA and other suggest otherwise.

You would need to send off the whole rotating assembly not just the eccentric shaft. Most rotary performance shops will do this such as RB.

 

thanks for the advice iceblue very helpful. i was wondering 2 things. one being is the turbo block got any more advantages other then the better flowing exhaust sleeves. are the housing made stronger, ive heard that the 13b-rew are probably the strongest housing around right now. Also you said i would need the s5 rotors because the s4 rotors wouldnt line up. at that house power is it really worth it to get the stationary gears.I kinda wanted to go high compression low boost. but if the s5 rotors and stationary gears are worth it i can do that.

 

s4 and s5 rotors are the same as far as fitment goes, the s5's are just a little lighter and have higher compression. I'm not sure if the Turbo housings actually have bigger exhaust ports, I just know that they don't have the diffusers so you can port them. I think they're also cheaper.
Also, there's no need to rev to 8k+ if you have good mid-range power. If your goal is only 300 or so HP, then you can get a smaller turbo that spools faster to get your better midrange.
Aaroncake has a writeup somewhere about turboing his NA. It suggest you read it if you haven't already to get an idea of what all you have to do.
Edit: Heres the site - http://aaroncake.net/RX-7/naturbo.htm

 

Where are you located in Arizona? I can help out with the balancing...

 

yea ive read the aaron cake write up. there used to be a old write up on converting an na without as much fabrication as aaron cake did using more turbo parts like the front cover and intake manifold tb all those goodies. well im looking for around 300-350 hp would the stationary gears even be worth it im fine with a 8k rev limit even 7.5k is fine i just want it to be reliable.

 

Just use a set of s5/s6 stat gears.

 

FD and S5 housings are the same if someone wants to nazz they have different castings over the spark plug socket.

The turbo Irons are different mainly the Int as it has a coolant passage in it and larger ports. You can use this in conjunction with your NA S irons and TII housings. You will need to epoxy that rectangle hole shut.

As said the rotors are identical but have .5. higher compression and .5lbs lighter, this and the conjunction of counterweights and hardened S5 stats will allow you to rev to the 8k redline over the S4 7k.

300hp with high comp rotors can be found with boost alone on the stock turbo or a stage one will give you at least 60more HP over that. You can pick one up on here for around 250$ used.

 

Yea you can port match a TII manifold and bolt up the stock exhaust manifold then. Then use the TII front cover and rear housing that will eliminate most fabing.

 

the front cover i understand but why do you need the rear housing is it for the intake bolts to line up? or something to do with a oil feed/ return? sorry im full of questions

 

Water outlet to turbo

 

That nipple exists on all blocks. N/A or not, you simply use the line that used to run to the BAC/Thermowax/etc.

Stock, TII have a coolant passge from in the rotor housing, which flows through the lower intake manifold.

 

It flows throught the intake manifold from the turbo rear plate to the turbo front plate? im almost wondering if i should by a t2 block sounds a lot cheaper right now. cause if im switching the rear housings i cant use the 6th port plates.

 

Either way it really isn't going to be cheap or a simple swap. Your talking TII front clip or entire engine assembly + tranny + driveshaft + wiring harness/ecu. Then what if it needs a rebuild when you get it, and if you want better braking and suspension well you know where I am going.

There are TII vert conversions out there and if you are up to the challenge then go for it. If not sell and buy a TII.

 

i know both are going to be pricey and there both gonna be a challenge. i just cant really make up my mind i keep going back and forth. you think the turbo intake ports would be better then the 6th ports for midrange. i could hook the walmart air pump to activate the acuators or just take the sleeves out but with the sleeves out there goes some lower end which the rx7 aready doesnt have. i dunno im thinking to much i need to get some parts and start building..o by the way the suspension will have plenty of work done to it. thats not gonna be a problem.

 

No the rear irons both have that nipple it goes to the TB to the back of the water pump housing. He was saying the hole in the rear housing is a passage through the TII LIM. It went along with one of the methods I told you about since you asked about using the TII intake mani.

 

Not sure what happened there, I had put an image in it showing the nipple circled so you knew what I was referring to.

Anyway, I was saying just use that nipple instead, and then use any rotor housings you can find.

 

So ive got my objective. a 93 high compression low boost motor, on a 88 s5 vert with decent low end power and great mid-range Just a fun car to ride around.
so with the high compression i really wanna go with the s5 9.7:1 rotors and maybe the s5 rear iron has the better stationary gear and comes with the 3window bearing. kinda high rev with the lightweight rotor and strong rear stationary gears im only really looking for 8k most. kinda makes me wanna stay with the s4 plates and rotors with the 9.4 compression still high just as much im looking for the high compresssion to spool that turbo up, plus i already have them thats easy. I have the chance to get the get turbo housings because of the better exhaust sleeves, but above the sleeves are the coolant water jackets into the lower intake manifold for the turbo manifold.but i kinda wanted to keep the na 6th port manifold now because im thinking of running slightly ported housing and maybe leaving the 6th port sleeves in and have the port actuators hooked up to the walmart air pump activated by the rev switch(anyone know how realiable it really when you rev quick, can you just time it lower?). back to the main question sorry would the water jacket from the turbo housing just get blocked by the na intake manifold. of course ill have to extend the turbo or get a custom manifold that not a big deal yet. so thats whats been running through my head now for the whole week.and advince would be greatly appriciated. this engine has been in pieces for far to long.

 

does anyone know if theres much of an advantage to using the s5 9.7 rotors the the s4 9.4 rotors on your turbo na is it that much of a power gain on the lower end?