So I'm rebuilding my 91 vert to use as an autocross car and just to have fun on the twistys. Just want to see if I'm heading in the right direction as far as what I plan on doing to the car. Any advise is welcome. I'm hoping for anywhere between 180 and 200whp. I have done a lot of reading and know that 200 is only acchieved if god smiles on you that day or some other divine event.

ENGINE:
6port S5 block and internals
VDI, emmisions and omp removed
Pinapple racing large street port & 5th,6th port inserts (wired open)
Racing beat road race header with custome collector and test pipe into Corksport catback
Custom intake
Stock injectors
Apexi AFC NEO
Prosport wideband

HANDLING:
Tokico HP stuts
Racingbeat lowering springs & front and rear sway bars
225/40R16 tires (not yet sure of brand)
Hawk HPS pads F&R
Slotted rotors F&R

 

Can you clarify what is meant by "custom intake"? That's going to dictate what my answer will be.

 

for handling go with coil overs and be done with it. spend the money to do it right the first time.

 

Wrong. It bothers me when people say to jump into coilovers. You don't learn anything about driving with coilovers. Keep with what your plans are with the RB springs and KYB struts, you will love them. Also give your bushings an update. Energy Suspension makes a great kit. Iv'e heard mixed reviews about the toe-eliminators, so I would just keep them stock, but if you want to experiment, then buy them and swap them in and out after a few days to a week and review the differences they make.

The best way to enjoy our car is bone stock, and this is an odd statement since our cars beg to be tuned right? Well, the thing is the FC suspension geometry is very racing-influenced, thus a stock car will feel very sporty and fun to drive. A car like a 240sx has terrible stock suspension geometry and thus needs many improvements to be enjoyed. It's not a matter of opinion either, it's fact. How many people have told you hitting the track in their bone-stock 240 was a blast? Now compare that number to the amount of people who enjoy taking their stock to very lightly modified FC's to the track and said it was fun.

In short, unless you really want to change the cars original characteristics, leave it mostly oem, and just "freshen up" the car with new parts. trust me, I enjoy driving my 95% stock FC more than my buddies 10% stock 240. And he did too. So that's saying something about our cars.

 

First I would like to say I'm glad to see you reply. I have watched most of your vids on YouTube with your Cosmo restoration and you really know your stuff. I also know that you are an advocate of the vdi system and Im guessing thats we're you headed with your your question on the intake. But anyways. Just looking to have something made that's similar to what corksport offers.

As for driving it stock. I did that for a couple of months before winter set in. Also the car started to have cooling and hard start issues. So I decided to rebuild the motor and do a little modding while I'm at it. It's going to be a budget build and I'm doing all the work myself. I'm just looking for some good solid advise as far as if I'm on the right track with the modifications.

This is my first attempt at a rotary build but I have a lot of experience with Subarus.

 

. Sorry I made a mis-post

 

Whats up man. First off, welcome to the world of Rotaries! Youll find that the learning curve will be a little steep at first, but the more you learn the more hooked youll be! Starting with the 12A powered RX2s in the 70s right up to the Twin Turbo 13B in the final RX7 platform, a lot of people have kicked a lot of tail with the these motors in professional motorsports over the last 5 decades and the result is a wealth of of knowledge that is available to us. So before you buy a single part, if you can get your hands on it, Racing Beat had a 2nd Gen specific technical manual/catalog. Itll give you a good set of fundamental info on everything about your car. If you cant get a hold of one, hit me up on PM and ill make copies of mine and snail mail it to you.*

Now lets get down to business... 180-200 rear wheel horsepower is not possible from the combination you have in mind (and you cant eliminate your OMP unless your going to run premixed oil/gas like a dirt bike).
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If you wanna make power with a rotary without wasting money, you gotta plan out your upgrades eliminating the most restrictive, power robbing components first and going from there. That component on a rotary, is the stock exhaust system. Its so hard to keep them smog friendly & quiet that the factory had to really choke them down in this department. A good exhaust system will give you a good power increase and set the foundation for all your future mods. Next thing thatll pay off with a noticeable power increase and finish setting the motor up for any future "power mods" is upgrading to an MSD ignition. Powerful, naturally aspirated rotaries live to rev and the stock ignition cant keep up once your motor starts*getting into its "happy zone". Last on the list is of course your intake system. There are a lot of different ways you can go here and you gotta make a choice between sticking with the factory intake/EFI, upgrading to a carburetor (i know it sounds crazy!) or going to an aftermarket intake with a stand alone aftermarket efi set up (Microtec, SDS, etc). Luckilly your stock intake is "ok" enough that you have plenty of time to research and decide what you wanna do before you get to that point. **

 

So what does all this mean as far as horsepower goes? With a good exhaust system, a properly matched intake and a ignition sytem that will keep up with it all, your looking at just shy of the 200hp mark at the flywheel with a stock, unported motor with not that much money. That may not sound like a lot of horsepower, but that kind of power in a platform like the FC3S will definitely more than satisfy your criteria of "autocross & street fun". Over the years ive had an RX2, two RX3s, two 1st Gen (79-85) RX7s, and a Series 5 NA FC3S. Some drag oriented, some autox/solo II oriented, and some just mild, liveable street rotaries. So here are some suggestions based on what ive seen and done along with info given to all us rotorheads by Racing Beat and Mazdatrix. The info ive learned from them back in the day is what I based most, if not all the mods I performed on my cars as I learned what to do and "unlearned" stuff I picked up and heard about from people that didnt have a clue. And again, dont take what im saying as law so much as some general advice thatll get you more power and might save you from spending some unnecessary dough. That being said, heres my take on how one can*achieve your goal of a good weekend autocrosser/"fun" daily driver.

1. Engine - It all starts here. You said you were going to rebuild right? If so, this is my preferred "stock" type combo thatll give you the "best" components for a non-ported motor that will still pass a smog check if you were ever to put the stock intake/exhaust back on for whatever reason. I had one of these in my '89 RX7 and my '85 RX7 GSl-SE.

Side Housings: Use your stock ones
Rotor Housings: 1986-1992 Turbo 2. Non Turbo rotor housings have a cast iron "splitter" in the outlet of the exhaust port that makes the exhaust quieter... good for noise reduction, bad for power! If you cant get your hands on some T2 rotor housings, you can grind the splitters out of your stock housings but be careful not to scratch the rotor housings interior surface!
Rotating Assembly: Use a Series 5 (89-92) rotating assembly. The rotors are lighter and have the highest compression ratio of all the 2nd gen motors. Dont mix n match rotating assembly components, each rotor/eccentric shaft/counter weight assembly is a matched assembly as far as balancing goes. Finally, make sure you have your rotating assembly checked and rebalanced if necessary.*
2. Exhaust - My FAVORITE aspect of the rotary!!! To make power, you gotta let your motor breathe. Naturally aspirated Rotaries make very little torque down low and they never ever will. Theyre designed to rev so 99% of your "performance" will be felt in the midrange-higher rpms. With that in mind, you need to set up your exhaust accordingly. With rotaries you have 3 basic configurations. First is either the stock exhaust manifold (or header with a collector/single*outlet) to a single pipe and finally a single muffler. Next is a "long primary" type system where you have a Header with 2 seperate outlets (aka "road race" header), 2 separate sets of piping going all the way to the back, ending in a single muffler. Third is a "true dual" system where you have a dual outlet "road race" header, 2 seperate sets of piping and finally, 2 separate mufflers.
Because of the dynamics unique to the intake/exhaust pulses of a rotary, the first style I mentioned is least conducive to making power. This is what came stock on every pre-1986 rotary and its best suited for replacing failed factory parts or if simplicity/cost is the primary objective over horsepower. That brings us to the second type of set up I mentioned. Separating the pulses from the front/rear rotors and joining them at the end with a single muffler gives you more power everywhere in the power band, from the bottom all the way to the top. This is a good "all around" street set-up for a non ported or street-ported motor. *Finally, we come to the "road race" set up. Something like this will make the most power at expense of giving some up down low. This is my favorite set up because of the power and the badass looks of those twin mufflers hanging from the back, especially when you can back it up! You know, should you find yourself in a high performance situation like having to use all available engine power to merge from a nice long freeway onramp onto a highway where traffic just happens to be flowing really fast * *
Noise/Heat considerations!!! Two things about a rotaries exhaust are a) its really hot so most aftermarket mufflers will melt within a few months and b) rotaries are just plain louder than any other kind of motor with a similarly set up exhaust system. This is where you can waste some good dough choosing parts that arent gonna last. If you dont wanna replace mufflers every year or so, choose something that is packed with stainless steel wool or some other material specifically rated to handle the hot breath of a rotary. As far as noise goes, a set up with only a muffler (or pair of mufflers) for a means of noise control will be WAY too loud for most people, and depending on what the cops are like in your town or if youre not careful, youll definitely get your share of exhaust tickets! Thats my bain as my all time favorite set up is a road race header piped straight to a pair of Dynomax Superturbos hanging off the back... inexpensive, powerful, sounds awesome, but the mufflers dont last and you get hassled by uptight cops if your not careful but to me this is by far my favorite (mostly for nostalgic reasons). Either way, for you, since your car has a provision for 2 mufflers, this is what id do. A Racing Beat road race header, road race Presilencer, then 2-1/4" piping to a pair of mufflers of your choice (in either 2-1/4" or 2-1/2" diameter max). Regular mufflers will last longer with this set up because the Presilencer soaks up a good amount of heat before it gets to the main mufflers, or you can avoid the whole situation by getting a muffler built specifically for a rotary. Something like this has plenty of flow for your motor and if you build a ported motor down the line, you can get rid of the presilencer, run 2-1/4" piping all the way back to a pair Racing Beat Turbo 2 Mufflers which are quiet enough to run alone on the street, flow good and will last forever.

Ignition - my personal preference is MSD, you can go with a Crane, Jacobs, etc but basically no one box has a signifigant advantage over the other and MSD has a long history of winning so thats what ive always used. Youll be hooking this up to your leading ignition only.

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I don't necessarily disagree with staying with the stock suspension. But IMO it's kind of bold to say "Wrong". That bothers me.
I personally recommend a Ground Control coilover kit. http://www.ground-control-store.com/...tion.php/II=41
It's affordable, quality stuff that can be used with a variety of decent shocks....including KYB's. You also get height adjustabilty for corner weighting and CG, and the flexibility of spring rates/combinations depending on taste for ride quality on the street vs. autocross performance. And if he ever goes with a wider tire/R compound, a little more clearance.
Depends on budget, experience and intended class.

 

Intake
This is where a lot of people go different ways... for a long time, thanks to all the R&D work (and willingness to share the knowledge!) by the big shops like Racing Beat, Mazdatrix, etc in professional racing, carbureted intakes developed by those guys in the early days were pretty much the last word in Rotary Performance for a long time.
•My suggestion if something like this might interest you is pretty much straight outta the racing beat catalog... remove the crank angle sensor assembly for the stock ignition and install a distributor out of an '81-'85 RX7 (it bolts right in). Then get one of Racing Beats side draft intakes and put on a side draft Weber or Dellorto carb. Its a tried and true set up that gets the most out of your motor and good for auto cross/road racing/track days.

In the 90s, the import guys started embracing aftermarket, programmable EFI systems and, in my opinion, pioneered the high performance EFI world were enjoying now. So now you can easily take that Racing Beat intake, sell the carb, slap on the Individual Throttle Body (combatible with a Weber mounting flange) of your choice, combo it with an aftermarket programmable EFI (and proper fuel delivery system) and get the most out of your motor in both power and driveability. This set up will squeeze every horse out of any stock or ported motor you can put together (matching the ITB and injectors to the airflow capabilities of the motor of course). And, the OEM distributor/MSD set up is so good that you can easily go with a "fuel only" engine management system!

And last but not least, nowadays you got people maximizing the oem EFI systems like Pineapple Racing and their slick high flow 6PI actuators, guys that are swapping S5 intakes onto S4 motors like yours, etc. Power production isnt on par with the other 2 setups yet, but its pretty cool stuff and slowly but surely stock, tweaked EFI systems are creeping closer and closer horsepower-wise to the carbureted setups, thanks to message boards like this.

So, this is where you decide which way to go based on what your preferences are, once you get to this point in your build.

 

As far as the 2nd Gen suspension goes, dont have much input here. My 1st Gen RX7 was the track day car (full GForce setup: Trilink, Panhard Bar, Turn In spacers, springs and dampers NOT COILOVERS, stock/modified sway bars...) but none of that advice would be realavant to tuning the suspension of a 2nd Gen. My '89 already had Racing Beat springs and standard Tokicos when I bought it and that was plenty for what I wanted out of the car. One thing I did do was disable that damn "rear toe in" feature the FCs have. After almost losing it and wiping out a bunch of times on the 110 fwy heading into Pasadena (my "home track" back in the day!), I installed the Rear Toe Eliminator bushing kit from yes, Racing Beat! Best thing I ever did and recommend doing this before any other suspension changes. It made the car predictable and easier to drive fast. Never took the suspension any further than that because it was my daily but even with that basic of a set up it handled great.

Well thats pretty much it for my $.02. Good luck with your ride man!!!

 

K.I.S.S.= keep it simple stupid! best advice i can give. However i have only been to a few track days and so far ive learned that you really only need a reliable car w/ good tires to have fun... and thats what its all about