my first build thread, i think...
 

the current engine in the FC i built god knows how long ago with the RA coolant seals/Atkins apex seals is finally throwing in the towel with the 200 some odd thousand miles on the major engine components and is eating about a cup of coolant a day while i DD it.

the plan:

9.4:1 comp cast rotors for durability and a longer power band
12.5mm studs replacing the factory flimsy 8mm tension bolts, block milled to suit
Goopy Performance 2mm standard size apex seals
factory engine internal hardware
large street port, to accent the high compression ratio
race clearanced rotors for the unlikely event it hits a hard rev cut past 9k


the block is just a standard S4 TII with good condition rotor housings from an old core i tore apart. studding to prevent iron breakages, since the only S5 thick cast irons i have need major rehab work.

there is nothing spectatular about the engine i'm tossing together, as it's just using good used components that don't need new bearings or major reworking. it's being built to suit 14psi on pump gas with water AI and potentially 25+PSI on ethanol alone or 30+psi with ethanol/water. the turbo is still going to be the old master power T70 journal bearing turbo i put on half a decade ago but eventually i will move up to a ceramic BB larger frame turbo capable of more than it's 600whp limits.

i was cleaning up the 8.5:1 turbo rotors and i just said fuck this, that turbo is going to be still laggy as hell.. it may not push 20+ psi that the turbo rotors could on pump gas but it will actually be faster and more streetable versus a dyno queen.

i opted not to push the engine to its potential years ago because it was already near the breaking point for the weak S4 TII keg.

time allowing it should only take about 3-4 days to build the engine and i will put up a few pics.

don't worry, the old girl will still be torn down and rebuilt to be used for her original purpose, a testing tool. this was the same engine that has been torn apart half a dozen times in learning how to build these engines over 10 years ago, the breaking points of components and how to tune before it was rather common knowledge on rotaries. she will be rebuilt and used to again see the limits of components without fear if it totally grenades or not, if that happens she will get a proper burial.

finished cleaning the S4 n/a rotors and now working on clearancing them.

factory seal slot
https://imageshack.us/a/img94/8556/ilp8.jpg

.5mm cutback and radiused seal slot
https://imageshack.us/a/img34/8999/f861.JPG

the corner tip widths i also didn't knock down all that much, just .15mm to deburr them in case of contact so that minor scuffing wouldn't stuff the corner seals or cook their springs.

this is actually about half what i would do on an actual racing engine, but since i expect to get at least 50k miles out of this engine i am not going to such extremes(i also don't expect it to be going past the factory tach at 8k very often, beyond 400whp it happens though...), just protecting the seals in case of interference. more cutback means accelerated seal slot wear.

i actually don't expect the current setup to do more than roughly 400whp @14psi(limited by compression ratio and pump gas) but it is being built to handle 500-600whp for daily use for future turbo upgrades. basically it is being overbuilt to sacrifice longevity for reliability, or at least somewhere in between.

even minor things help if the e-shaft ever deflects, below 300whp this is almost a non-issue.

Congratulations and welcome to the rotary world!

Please read the FAQ, download the FSM and use search.

Lol...

Can't wait to see how this all comes out.

it's nothing out of the ordinary for the most part, but this time it is of an engine actually being built for myself.

in fact the work is more rushed and probably slightly less than my standard since it wasn't a scheduled rebuild. i knew it was coming but figured now is as good of a time as any.

1 down, 1 to go but will have to wait until tomorrow.

https://img689.imageshack.us/img689/2675/3yn6.jpg

the rotors actually had at least 100k miles on them previously but they were decent candidates(well the only ones really since they were the only perfect weight matched set i have for S4 n/a left without gutting other complete core blocks to search for others).

the rotor edges are sharp enough to cut yourself. maybe i should knock them down, maybe i should stop overthinking things..

Subscribed. I figure if I'm going to learn the niceties of a power build anywhere, I can start by paying attention to what you do to your own car.

subscribed as well! thank you for sharing your knowledge.

man i can feel this is gonna be awesome already!!! subbeedd!!!

now you guys are putting pressure on me!

lol..

if anything though i am more curious about the state of the engine that is in the car, being that it has been through just about everything a rotary engine could ever have to face.

not that i'm proud to admit but being my DD for many years there were plenty of times it had to deal with abuse while i had to meet schedules.

run without premix for weeks at a time, no OMP on the engine(laziness or being poor, i forget, the journey to being a rotary mechanic led to eating top ramen on more than a few nights)
overheated severely about 8 years ago(260F) back before i put the black magic on it and ran the e-fan with a dummy switch(leading to it's current problem, also why i still hate e-fans. strangely the engine didn't exhibit coolant seal issue until a few years later after i didn't drive it for a long-ish period of time)
block sealant treatments twice over the past 5 years(which held up quite nicely but it has the side effect of making the car run naturally hotter with each treatment done)
water only with water wetter in the cooling system since the first block seal
ran for 35k miles before the water injection was fitted, initially ran meth/water but ultimately went to straight distilled
runs up to 245F going over steep long grades in mid summer(110F ambient temp) going between states for work
boosting 15psi with the rather unforgiving atkins seals(arguably easier to break than OEM) on an untouched tune that i set about 6+ years ago and haven't checked up on since

it's lived a hard life and it's time to give the old engine a break. but i'm curious to see how the cooling system looks but also i'm not too anxious to find out.. as well the apex seals have about 80,000 miles on them now and the housings likely have over 200,000 on them. also wondering if the water injection managed to clean out the engine or if some carbon survived from the first leg of the trip. the original engine had severe electrolysis in both rotor housings(replaced after i found out they were the root cause of subsequent failures), i'm betting these will be also nearly through the aluminum(but i could be wrong, the water in the system comes out clean and i flush it about twice a year).

last time i checked compression about 2 years ago it came back at about 95psi all around, it also passed smog last month with no troubles. starts, runs and drives fine but the change engine buzzer every few days is getting annoying. the only reason it has taken this long to give it a rest is because the engine, regardless of it all, took it in stride.

i bought the car just over 10 years ago, it had 136k on the clock, it now has 212.5k

this engine will be treated a little bit better and may include a V mount with new radiator or broken in temporarily on the existing setup.

Were you running pre-turbo water injection? I am still trying to figure out how I would like to set mine up...

pre throttle body

of course i put it on before even howard became the rx7 preacher he is now(when the AI forum started about 6-7 years ago). i simply haven't felt the need to move it, nor do i like the idea of possibly having water sit in the compressor housing or intercooler. i think it was right around the time rice racing(peter) got banned and i simply followed the manufacturer's advice of 3-4" from the butterflies, most people didn't even consider pre-turbo in the early days. it has worked perfectly fine right where it is, maybe someday i will get a bug up my ass to play with it some more but so far i haven't felt it.

pre turbo may give very minor improvements but i haven't seen evidence that sais it is all that much more superior to pre-TB.

Awesome work!!!!!!!!!!!!!1

I understand where you are coming from. The water in the IC is a concern of mine as well. I am sticking with a S4 hybrid turbo for now, so any little extra I can squeeze out of it would be beneficial for my application - that is why im considering it over pre-TB.

P.S. More pictures :) :icon_tup::icon_tup:

Subd up......definitely going to pay attention considering my engine does not seem far off from needing same treatment

its funny how some cars are like that. i like em that way too!

working on the second rotor, didn't get much accomplished yesterday when an RX8 came in for a "pilot bearing" that wound up having the output shaft come along with the driveshaft for a vacation from transmission.

oh, i'm definitely in for this. sounds like my kind of movie. i particularly like the no fuss approach you're taking

Subscribed! Ben, I'm gonna be out in vegas next week, I'd love to swing by and see the shop! After the help you gave me building my engine, maybe I can buy you a beer in person this time.

feel free to come by, i'm here just about everyday. :)



since the rotors were already just about polished i decided to go a step further, and actually start polishing the faces and the side corner seal tips. not that i expect it to do much, i figured you guys might like it.

https://imageshack.us/a/img407/8933/wat7.jpg


could be 10 times better but the difference between a good polish and a very good polish on hard metals is the difference between 2 hours and 6+ hours. the premix with water injection should keep them polished, pretty much indefinitely.

i am curious if it helps alleviate some heat transfer to the rotors.

the wonder twins oiled up and ready for hardware.

https://imageshack.us/a/img692/4981/v6bv.jpg

Shiny :drool:

i'm actually a major supporter of polishing rotors (though i'm sure i don't do them as well as i could/should). i firmly believe it can help prevent hot spots and heat rejection is a secondary part of the theory, while carbon rejection is primary. also curious if you ever once considered removing the recess flash or are you concerned about changing compression?

i've heard arguments both in our world and the piston world - some for, some against, and some that just say it's useless, dumb and a waste of time. i'm very curious to see where you'll stand once this engine is running and has got some time and boosted miles on it.

just what i needed, wasting time learning how to tear apart and reassemble a 6 speed RX8 transmission.

note: if you break one just get another as there's no rebuild kits, the parts are insanely expensive and the transmission is a jenga puzzle box while the FSM is no help... parts flying all over the shop is no fun.

this is going to set me back a few days.

and for god's sake don't try and drag race an 8. the transmission is glass and the car weighs 3k lbs..

trans has a separate manual, http://foxed.ca/rx7manual/manuals/Ma...008%20RX-8.pdf

the RX8 transmission workshop manual is about as useful as needles under your fingernails. it's actually what i have been using and it does at least give you the basics, although this transmission is far from basic compared to most others.

it uses a generic blown up picture and numbers for disassembly instructions, does not emphasize to hold the shift forks due to the fact that if they move a hair then the detent balls, springs and cogs all shoot out at supersonic speed to where you will never find them.

and some people say this is a good strong transmission, luckily this one i have to practice on with 2 spares for backups.. the gears are about as hardened as toothpaste in the sink after about 3 days. revising the SSM to not break half a dozen teeth in the tight knit gearset while not breaking itself hasn't exactly been easy.

add in fabricating those SSM's that i will probably only use once and i feel like it's just several days completely wasted from my life. a basic overhaul 'kit'(since it's pieced together, there is no overhaul kits) from mazda is about $1500 for the transmission. if any gear or shaft is damaged, double that figure before even adding in labor.

even rolling the dice on 2 used trannies seems like a better option.

/end rant