aka_rocket

ok, so i did do a search already...and i did find some good info but i would like to double check on everything and anything i might be missing...and stuff.

here's the deal, i have an 86 gxl and about 168,xxx on the motor. lately, i've been plagued with lots of smoke chasing me around, expecially when downshifting. i've limited my downshifting so that should be ok for a while but i think im in need of a rebuild. it doesn't smoke that much when its flly warmed up. still runs pretty strong but i read somewhere that it will most likekly poop when its like that.(correct me if im wrong on that). i would like to attempt the rebuild myself because it wanna learn how.

i would like to use S5 rotors in my S4 rebuild. everything will stay S4 except for the rotors. im thinking about using S5 rotors because i've heard it creates a pretty good N/A engine in S4s--from what i've read. I have an S5 motor at my disposal (complete) so that's why i wanna do it. did think of putting in the S5 motor in but too many extra steps i can't afford at the moment. i should have about $2000 for the rebuild. this car will be a daily driver but will occasionally be driven hard. i don't want to port anything since i need all the mileage i can get, maybe in my next rebuild. i can't go turbo cuz im a poor college student and can't afford premium gas.

here's what i've collected:
*using s5 rotors in an s4 rebuild
*use appropriate front and rear counterweights..or do i just need the front counterweight.
*The higher compression, the more power. The less weight, the less initial torque (off the line) that is generated
*approx. 10-12hp gain from S5 rotors in S4 rebuild (quoted from I think, aaron cake in another thread)
*3rd gen springs, 3mm 2 pc seals, the other little stuff needed for a rebuild
*If matted to a turboII tranny (mine is on its way out) i would need a TII starter, clutch slave cylinder, and drive shaft. will also need TII flywheel/clutch. if too much extra work, i'll find another NA tranny. this is an if, if i have extra money but will most likely skip if its not really needed.

so i hope to get some constructive help but any little tips from people who've done it already will be greatly appreciated.

razorback

automatic or manual? na im guessing?

aka_rocket

manual. sorry, shoulda had that in there.
yep, trusty ol' N/A for now.

RotaryResurrection

iTrader: (8)

A smoking motor can run another 100k miles if need be, in many cases anyway. IT doesnt necessarily equate to bad compression or other problems like it would in a piston engine...keep it topped off with oil and don't be too hard on it and it'll be fine, unless it gets bad quickly.

I think you read comments that the engines usually blow on a day they're running particularly strong/well, which is often the case for some reason.

You have some misconceptions there. ON a 6 port motor, you can do many different things with teh auxiliary ports with no drawbacks as far as reliability, emissions, idle, low end, or gas mileage (while you drive normally, anyway). Thats the good thing about them, they're only used (effective) in higher rpm's, so you can do things with them that you normally wouldn't want to do with the always-open ports for driveability reasons.

Right and right.


Front AND rear, the rear is either the appropriate stock flywheel, appropriate stock automatic counterweight, or appropriate aftermarket flywheel with automatic counterweight for the YEAR of engine.


I'd love to see proof of that. I had a dude call me up the other day and inquire about s5 rotors in an s4 build...somebody told him they added 40hp or some bs. Some engine builder, at that. psshhhht. Truth be told, you'd be lucky to see more than 5hp between a stock s4 BLOCK and a stock s5 BLOCK, not accounting for differences in ecu/intake manifolds between the 2 control systems. The s4 motor made 14hp less than teh s5, but keep in mind the s5 had one less cat, a newer, faster, revised ecu, a better intake manifold setup, AND higher compression/lightweight rotors. I think 4-8hp on a near stock/mildly modded NA engine is a good estimate of the difference the high comp rotors make. After all, it's only 3/10 of a point of compression.

FD Cornerseal springs are nice for any engine, but don't expect ANY performance gains. They're mainly used because they're flat out a better design than the older ones, and they're not expensive. They probably help boosted engines that are modified, but 2 nonturbo engines built the same way, one with and one without fd css would run the exact same.

3mm seals are a waste for a NA engine, especially a lightly modded one. Mazda used to use 3mm seals and went away from them in 86. The 2mm seal better resulting in slightly better compression especially at low rpm. Also 2mm seals equal less intertia (of the seal itself) therefore it responds better. The only time you need to go 3mm is when you'll be abusing the engine, such as boost/nos. They're for added protection against tuning mistakes and abuse.

The big t2 flywheel is balanced properly for your engine, but weighs more than the NA counterpart, and will slow the engine down. GO aftermarket if you do this. You need the clutch, flywheel, trans, starter, slave, driveshaft, rearend, and halfshafts (the latter 3 can be deleted if you make or buy a custom driveshaft).

aka_rocket

awesome comments. good point with the seals...im ok with that.
sounds good to me.
thanks alot.

WAYNE88N/A

With 168K on her, you'll need to think about new (or lower mileage) rotor housings, also...Kevin might disagree with this, but since the housings ARE wear items, it's money well spent towards a rebuild that will last a long time...

I spent approx $2600 on my rebuild, which included new housings, hoses, mounts, etc, and the RA master rebuild kit. If you already have $2K, you're not that far away...

RotaryResurrection

iTrader: (8)

I think I am destined to fight this battle for all of life...

Wayne88na is banzaityoyta reincarnated, it seems...

"You get what you pay for, buy new rotorhousings, blah blah..."

Actually, I totally agree that new (or like new) rotorhousings make a BIG difference in how the new engine runs. More so how it runs for the first startup and first few thousand miles thereafter. Not necessarily in how long it lasts, but this is a moot point anyway because most rebuilds are capable of 100k miles or more and almost no one here will keep the same car with the same engine for that long...it'll have been wrecked, sold, parted out, engine swapped, etc.

My point (and the premise of my business) is that you don't have to have new housings to have a decent running car that is reliable. Most any FC is worth $1000-2500 book value. We as enthusiasts sometimes assign them a higher value, but that's the bottom line. Who the heck wants to spend more than the car is worth on just the engine?

Last week I checked with my engine parts supplier on new rotorhousings, and cost has went up to between $6-700 PER HOUSING, up from $400-425 per. And that's when they're available at all...Mazda is having a hard time keeping up with renesis production and remans/parts (so we're being told) and there was (could be again) actually a waiting list for FD remans up until last month because of this.

So in the end, we're talking a minimum of $1000, right now closer to $1400 for these all-important new housings. The difference in a used housing build and a new housing build can be as little as 15psi compression...most new housing builds get to 125psi, most used ones get to 110 if not more. I know RX-7 owners talk about their compression numbers like mustang owners talk about what rearend gearing they're running, but is 15-20psi after 3000 miles really worth $1000-1400 to you?

You said you have $2600 in your build, but some of those were extra parts, so we'll come down to 2400 for the engine itself. That's not a bad number, but you did all your own labor. Say someone wants to buy the same engine and pay to install it, if they dont have tools, knowledge, or space to do the work themselves? Should they then be expected to pay ~$4000-5000 just to get their car running well again? I can build 2.5 engines for the cost of your one, and that accounts for my labor charges. I can build and install 3 engines for what one would cost elsewhere. Even if your claim is that new housing engines last longer than used housing ones, I can bet with you that it won't outlast it by 2-3 times.

Like I used to tell John when we had our discussions about this...I'd like to see a new housing motor bought or built, with exact costs documented. And I'd like to build an equivalent used housing engine, but with the same budget. Then take the difference and apply towards mods. Then head to the dyno.

Aaron Cake

iTrader: (1)

I didn't say that. The power gain in the S5 is due to the compression increase, intake system, better engine management and higher redline. It's not the rotors alone.

Travelintrevor

^^^^the man just saved me from buying new housings...and yes..I will measure to see if they are withing specs....I always wante dto knwo how you can buid your motors so cheap...If I was back in the US, I would be a regular customer because I can't do it any cheaper myself..my free time is very valuable to me...I usually times the amount I make an hour times the amount I spend working on my car and it would be cheaper to have Kevin do it...Kevin-you ever ship a motor overseas?? Sorry..did not mean to steal your thread...this was my first thread theft..really!

aka_rocket

sorry about that aaron, it is due to other components as well...i should have quoted all of it so as not have any misunderstanding. due to the higher compression was what stuck in my mind. i closed then window and sorta quoted from memory only.

https://www.rx7club.com/showthread.p...ression+rotors

thread stealing..nah..as long as it benefits another, its all good.

Aaron Cake

iTrader: (1)

Well, FWIW, my original post was a little ambiguous.

aka_rocket

ok, so had a slump in cash flow at the moment but planning to rebuild motor during winter break. something else came up while checking my engine/oil pan. after coming back from 7stock (car was the red,black,white one) my car was smoking really bad and i went through a ton of oil to get home! the oil pan's bolts were sooo loose i was surprised i made it home without starving the engine of oil. oil was practically dripping out. i could sorta screw in some of the screws back in with my bare fingers, worried alot now. anyway, i tightened them all up but there were two screws that kept screwing in but never tightening, which im guessing the threads are jack or something is wrong with the holes for the screws.

my question is, since im gonna be using the s5 rotors in my rebuild, will there be any problems if i slap on the accompanying s5 rotor housings into my rebuild and use the s4 front and rear plates. i think the place where the holes are messed up for the oil pan is on the rotor housings. plus, my oil pan is kinda jacked up so would i be able to use the s5 oil pan. any difference between the two series's oil pans? so will any of this part swapping pose any compatibility problems with my 5th and 6th and s4 electronics/hoses?

i haven't had a chance to look over the s4 and s5 engines closer to really compare them yet (because im at school and the s5 is at my parent's house) so any info on this would be great.

RotaryResurrection

iTrader: (8)

No diference in oilpans or bolt patterns at all. No problems putting s5 rotors in, with the right front and rear counterweight to match. No problems using s5 rotorhousings, so long as you dont use one s5 and one s4. Usually s5's show much less wear, anyway.

aka_rocket

thanks a lot.

WAYNE88N/A

Kevin, you are entirely right in your "line" of reasoning, and I am entirely right in mine, we think about things just a bit differently, that's all.

I rebuilt at 186K. You think if I would have reused the housings I would have gotten another 186K out of her? Hell no. Those housing had some nice grooves running around 'em, on both sides at that. You think it's feasible to get another 186K out of her with the new housings? Hell yes (I plan on tearing her down again before 250K and replacing the side housings & bearings, and maybe oil pump and rotors, because they'll be the next items to hit limits, by my reckonong). I plan on keeping this car for a long, long time, because I enjoy driving her, so when I rebuild, I do it to last a long, long time. Nothing wrong with that, in my book...

So, your cost structure can be viewed both ways- If I spend $2600 to go another another 150K+ with her, and another guy spends $1500 and gets 80K more out of her (just picking these numbers out of my butt, of course, but you get the drift), we both get about the same "bang for the buck", don't we?

Besides, I look at it this way, right or wrong- if you had a V-8 with 150,000 miles on it, would you rebuild her just by replacing the rings, and do nothing about the cylinder bore wear?

mcnannay

yeah but a piston engine is different, you can hone out the cylinders and be good to go, not the same with a rotor housing...

im not going to name names yet, but i know there are lots of companies out there experimenting with rechroming rotor housings, well... pretty soon here there is going to be a MUCH cheaper alternative to replacing worn rotor housings with mazdas stick it up your *** pricing (i've already seen the rechromed housings personally). Myself, i would have loved to have replaced my rotor housings, but the cost did not outweigh the benefit in my opinion, and thats really where its at, cost to benefit.

I don't even know if my rotor housings were completely in spec, i was too scared to even check, seeing as i had already dropped $400 on new side and intermediate housings lol...i called it good, there where no scars or lines through them, and honestly i think they will be absolutely fine.

aka_rocket

im just about getting ready to get all my parts in order before i start ordering. just ordered the vid 2 days ago. kinda exciting that i will do it myself but kinda scared it might not start up when i finish. i bet you've had that feeling before.

anyway, i was thinking about getting the basic kit from RA and the seals from atkins. anything else i may need, i will order later. is it possible the mixmatch parts and not cost that much more then the pre-package kits?

i haven't done ACTUAL calling around to check for apex seal prices except looking on websites for prices but stuck on apex seals choice. Atkins or RA or Mazda. i think i will call up Atkins and RA but maybe later since RA said they are on vacation or something (flood or something i forgot from website). im assuming mazda seals are more expensive but read on other threads that they are pretty much the best for stock rebuilds.

i don' think it will matter THAT much since this will be a stock rebuild (sorta-with S5 internals and housings) but i'd still like to get the best product for the buck. my motor has bout 168,000 and just when i thought the smoking had subsided, smoking is appearing again and my idle climbs now, not drop. it climbs to from 1200 to 2,000 for a long time then after a lot of driving, it's at 900. my car doesn't feel as strong now, going up a ramp is kinda hard now, so i don't drive it much anymore. i will post a tentative list of the stuff i plan on getting. to double check.

anything? i read the other threads but didn't help much, kinda got strayed.

RotaryResurrection

iTrader: (8)

The choice of seal should probably rely not so much on price but on availability and reputation. You've mentioned the 3 main suppliers of seals in the US that Im aware of.

atkins- been around forever, well priced, well respected. Softer seal, breaks in well to used housings, holds up fair to mods and abuse but will break when pushed hard. Excellent for a nonturbo street engine.

rotaryaviation- relatively new seal that is pretty well reputed so far and priced perfectly, but still largely untested. Ive installed 4 sets, one of which didnt do so well...wouldn't seal up for some reason. Put in a set of atkins seals and got double the compression numbers with the same housings. No complaints with the other sets, even under *heavy* abuse theyve held up perfectly. Probably a better choice for new housings and a high boost or highly abused motor.

mazda--the original 2mm 3pc seals have been around forever and are well documented to be excellent for all purposes. They take a while to break in, especially to used housings, and the tear up your rotorhousings due to the sharp corner assist piece (this is responsible for the grooving you see on all stock housings). They were a bit more expensive but probably worth it, you cant go wrong with these.

mazda--the new rx-8 2pc 2mm seals have apparently replaced the older 3pc 2mm seals. It seems like a lot of people are having issues with these seals in the older peripheral exhaust port engines with warpage and loss of compression. The apparent problem occurs mainly in boosted and modified (ported) engines but may be present in others. Right now it's a touchy subject and no resolution is in sight, in fact a problem has not even been admitted by anyone other than the select group of builders and tuners who use them in high power engines. For now I think I'd stay away from these...and I dont think you can get the old style seals, so that looks bad for mazda seals right now.

aka_rocket

thanks kevin for the quick response. atkins sounds good then. might even be quicker if i were to get all the parts from the same supplier. i'll check the pricings for each supplier again but they seemed to be pretty competitively priced already.

RotaryResurrection

iTrader: (8)

I get all my parts through atkins unless otherwise requested...great to work with, priced right too. I have no complaints with their parts, unless you're dealing with someone really picky or someone trying to make more power than a stock c5 corvette.

RETed

I dunno if most of you guys have seen the new RA apex seals, but the triangle assist piece looks almost like the Mazda ones.

If you're using "used" rotor housing, there is going to be a groove on one side of the rotor housing.
Using any of those "long" assist piece apex seals will not seal as well on these used rotor housing.
Thus, we're stuck with a catch-22 - go with brand new rotor housings which cost ($500+), or deal with the grooved used rotor housings.

I gotta side with RotaryRessurection here.
I prefer Mazda OEM apex seals.
The Mazda OEM apex seals have the triangle assist piece that will fit into the existing groove.
So, why not take advantage of it?
So you're not going to get that last 5psi of compression - most people won't feel the difference.

If we're talking about race motors that need that last hp or expensive clients that have the money for brand new rotor housings, then I understand the dilemma.


-Ted

aka_rocket

car is 86 gxl n/a
engines involved are complete 86 na and complete(fairly low mileage) 91 na
i need egr for smogging so s4 intermediate iron will stay.

ok, got my rebuild kit (decided to go with RA basic kit). so its 2 weeks left until my first rebuild. got an experienced fellow rotorhead to help me out (thanks karack). now just to be careful about what is interchangeable/to use in terms of the irons and housing. im not doing the manifold swap anymore.

so here are the ideas i have. if anyone could correct them, thanks alot. by the way, i have a spare (new exedy S5 clutch (kit) for my bro's 90 gtu, he totalled the gtu so now it has no home.) anyway can I use it with changes in my engine parts. don't know much about flywheel interchangeabilities and if i would need an s5 flywheel to use the clutch. i do have an S5 tranny (GTUs one) too that i could swap over if i need an s5 tranny for it to work.

1. use s4 front, intermediate, rear irons with s5 rotors & housings with s5 counterweight.

2. use s4 front and intermediate iron (smogging reasons) with s5 rotors, housings, rear iron, counterweight, flywheel (so i can just use the s5 clutch).

3. or recommendations on major parts from both s4 and s5 engines to make an overall bettter engine. i still need it to go into an s4 with s4 accessories, including egr.

thanks.

aka_rocket

if too much work, i can always just get an ACT heavy duty clutch kit. my bro is looking to buy another s5 so he can use the exedy one (its only a stock clutch). if i go ACT with heavy duty pressure plate, u recommend:
4 puck racing-$290.19
6 puck racing-$306.24
performance organic street disc-$324.39 but $291.95 after 10% sale discount(<--thinking bout this one)?

prices found at prostreetonline.com

anyone know where i can find it cheaper. these are the best prices i've seen yet.

aka_rocket

kinda long but here is the progress

S5 everything except intermediate iron (EGR purposes) and S4 front cover.
pineapple racing sleeves (don't know how much that will matter but since i have it already)
Rotary Aviation Basic Rebuild Kit - nice price since i was able to use a few parts from the old motor
banzai racing poly motor mounts

well just updating the status of the rebuild. opened up the s5 parts motor and everything was pretty much ok. off to cleaning it goes. i pull the motor out of my car to get the intermediate iron. since i was using most of the s5 parts, i needed that piece. tearing it apart, i found what was wrong with my engine. i was missing a piece of the iron that separates the seal from the coolant. my seal was sticking into the coolant passage. i was able to get a free core from a buddy of mine and decided to try my luck getting the intermediate from that core. as it turns out, his core had the exact same problem. darn! then i found one from Dan H earlier and decided, i need to get it done quick since school was only a couple days away. i drove up to San Francisco and met up with Dan H, check out the iron, bought it, and came back down. Dan's a pretty cool guy.

i had driven for more then 24 hours in the last 3 days so i was really tired. got back and was too tired so i called Ben up and told him i got the last piece. the next day, i went over and we started the final cleaning of the little pieces and i replaced the hoses and thermostat and such stuff. then it dawned on me that i had taken the wrong flywheel (86) to get resurfaced so now i had to take the right flywheel (91) to get resurfaced. we were talking about s4's and s5's a little before i left so when i was about to leave, i just grabbed the s4 one. now i have that corrected and we have the motor together now. i just have to get back home this weekend so we can install it. we did have a heck of a time getting two seals to sit still on the intermediate iron. it was kinda frustating but it was kinda funny. it was a really close tolerance fit but we finally were able to get the seal in the grove without popping out

it was a pretty good experience all and all. it was pretty easy and straight forward with the right tools. i have to thank Ben since he did most of the work. THANKS BEN (Karack). very knowledgeable guy. hopefully we can get it back together this weekend since school has started now. i still need to go and get an OMP line from the junk to replace the one we broke off while trying to get it off the housing. i was thinking of pre-mixing but i don't know enough about it yet (plenty of reading already) so i will wait.

i've never ridden in a good running FC so i don't know how its suppose to feel. hopefully everything goes well and i get to see how a healthy FC feels like. that's bout it for now.

RotaryEvolution

iTrader: (30)

i still suggest pre-mixing, it offers the best protection for all the moving parts.