whitey382

Well it's been a good 10+ years since I trolled the halls of RX8 club (kids, work, you know the drill). Its also been 17 years since I sold my RX8 and the bug has been biting at me to get back in the game. To this day it's still the most enjoyable driving experience of any car I've driven (that being said I've never driven an FD3S which I would love to).
I've been doing a lot of research on what's been going on in the rotary world and how the RX8 has aged. 2 questions I have as I plan the future:
1. I stumbled onto Rob Dahm and some of his builds/tech advice. The logic sounds good behind the things he does, would anyone say different?
2. I was thinking about getting an RX8 that isnt running for cheap. Then pick up a JDM RX8 powertrain and dropping it in. The ones I've been looking at come with the complete assembly including harness and ECU. Any major issues that i would run into with this scenario?

Thanks in advance for your help.

Brettus

iTrader: (2)

1/ Dahm has some great insight into high power rotary builds on the earlier engines. He's done very little with RX8s though so.............
2/ No problem swapping like for like powertrains ..... IE 6 port manual into a 6 port manual leavng the existing ECU in place.

Loki

iTrader: (1)

JDM power train is the same as USDM, so you don't need to look for JDM, but the plan is still good. Get cheap broken RX8 with a good body, and a good engine you can trust (from Mazda or a rebuilder or a known good used one).

dannobre

iTrader: (3)

The JDM engines have always been a crap shoot.... both for RX7 engines and now for RX8's. Plus there are no warranties for Rotaries from most of these suppliers

Most RX-7 engines we imported had some life left... but to really have a functioning engine they needed to be rebuilt

I would expect the same from RX-8 engines.... except there is more likelyhood that they will have lower compression just because thats what used RX-8 engines do.

The likelyhood that you will get an RX-8 engine that is pristine from Japan isn't higher than a wrecker here. Odds are good that you will be getting a core that may or may not still need lots of new parts

So what I'd do is get a great shell and then look at what's in it for an engine.... and either get it rebuilt or a reman...

JDM engines are too much risk

whitey382

Thanks for the replys.

My idea of picking up a JDM power plant was 2 fold:
1. obviously would be to hopefully end up with a solid second engine that could either drop right in and run or give me something to tinker with and build to desire.
2. Would be to end up with a solid transmission that yet again could either drop right in or provide a second transmission for building.

are the JDM transmissions usually in good condition?

Actually follow up question:
I've been seeing a lot of threads about a 5 speed RX8 transmission, WTF is that about? I thought they all came with the 6 speed? And why would you want to drop down to a 5 speed? I thought the 6 speed was a solid transmission....?

Follow up question #2
would I have a problem buying an automatic S1 and converting to a 6speed manual JDM using that full harness/ecu setup?

TeamRX8

iTrader: (25)

I’m probably the only person here honest enough to steer you away from a RX8. You’re lack of knowledge and understanding is so far out in left field that you’re only going to end up crashing and burning along with whatever finances you put into it. It’s just a fanciful idea not based on any understanding of reality. In all sincerity, do yourself a big favor and go put your time, effort, and finances into something else. Because if you had even the slightest clue, you wouldn’t be talking about JDM wrt an RX8. It comes across more like somebody who watched one too many Fast and Furious sequels. Which is actually more worthy than bringing up Rob Dahm.
.

dannobre

iTrader: (3)

There are answers to all of your questions on here...

This isn't a Acurra or something that the JDM motor is different

6 speeds are fine to about 300 hp if you are careful... any ham handed cramming gears and they break.
5bspeeds are very similar to an FD RX7 transmission

This is a CAN bus car... swapping from an Auto to Manual has been done.... but it is going to take almost the entire car to swap out the differences in the dash, shifter, modules and harnesses to get it to work

Like Team said. Don't expect any of this to be easy... and unless you are a bit nuts maybe stuck to a piston engine... they are a lot easier to play with

Loki

iTrader: (1)

Do you want a project or do you want to drive the car?

Because if you want to drive the car, drop the JDM and trans swap ideas. This doesn't need to be complicated.

The manuals *in the US* all came with 6-speeds, the rest of the world has another trim level with the low power version of the engine and a 5sp. Which brings up another point, if you buy JDM, the seller may not know which version they're selling you, and they're not interchangeable.

​​​​​​

whitey382

QUOTE=TeamRX8;4960625]I’m probably the only person here honest enough to steer you away from a RX8. You’re lack of knowledge and understanding is so far out in left field that you’re only going to end up crashing and burning along with whatever finances you put into it. It’s just a fanciful idea not based on any understanding of reality. In all sincerity, do yourself a big favor and go put your time, effort, and finances into something else. Because if you had even the slightest clue, you wouldn’t be talking about JDM wrt an RX8. It comes across more like somebody who watched one too many Fast and Furious sequels. Which is actually more worthy than bringing up Rob Dahm. [/QUOTE]

first off: I've already got a butthole so you can leave your opinion at the door. I've already owned and operated this car before so it's not like I've never touched one. I'm looking for data so I can form my own butthole which will hopefully stink less than yours.

Thanks for the info on the manual trans. Good to know.


funny you should ask, I was Just thinking that exact question when I read your post. As much as I want a project car I suppose at the end of the day right now I'd rather have have something I can be driving and enjoying on a fairly regular basis.

And thanks For the additional info on the 5 speed. Didn't realize that they used that trans in other parts of the world.

Slawekn1

I can offer a recent data point on the JDM swap case.
I recently picked up a rolling chassis with the intention to swap it with a GM's LFX from Keisler Automation but Andrew is now working on a 10-speed auto trans option that I would really like so.... long story short while I am waiting for Andrew Keisler to validate and release his LFX+ 10 speed auto swap kit i wanted something to play with.

I searched around and talked to Rotary Resurrection about getting a complete rebuild long block (my roller was missing a bunch of stuff including all the accessories and actual engine) Kevin from RR did not have anything available at the time and I was bored at work so I just bought a JDM full drivetrain swap from Ebay.

it looked ok in the pictures so I said why not LOL. the engine came in. I did a compression test with a proper rotary tester and got meh numbers of 110, 108, 106 on first rotor and 99, 97, 93 on the second rotor when cold (engine out of the car). I thought to myself that it might be ok for few months and then i would just sell it when I got the LFX swap.... put the engine in the car. put some fresh gas and premixed with idemitsu and started running the motor hard... checked comp after 2 weeks and it improved to over 107 PSI (normalized) on second rotor. Engine sounds good. pulls ok (still slow as any Rx-8) idles well. hot restarts well.... I think it will run. untill I can get the swap going. If it craps out then i might send it for a rebuilt to Kevin at RR.

Overall, i would recomend getting a short block from rottary resurection (if they have one) or sending them what you have for a rebuild.It's the best option out of any... i didnt have any engine components so for me JDM made sense at the time...but i would have purchased a long block from RR if they had one when i was lookling.

delhi

I rather spend the same amount of money (or more) to locate a good well cared for RX8 and enjoy driving it right off the bat. Or as TeamRX8 said, go use your money on something else.

Slawekn1

The beautiful thing is that everyone can choose what to do with their time and money. For me, working on cars is a form of relaxing activity... buying stuff cheap is a hobby of mine and making something work out of almost nothing also gives me pleasure. Rx-8 is a toy and for how cheap they are now ....if it blows up I will have some fun rebuilding it.

whitey382

thanks for the data. Excellent story and good information. How long have you been running that engine now?
I'll look into Rotary Resurrection and see what they have to offer as well. What's the spec compression on the renesis?

And Slawken hit the nail on the head. Not only is working on a car very cathartic and enjoyable, taking something that is broken and making it like new is one of the most gratifying things a man can do.

Slawekn1

I believe anything over 120 Psi is considered great and anything below 90Psi is a sign of a rebuild coming soon. Obviously, you would want the numbers to be consistent between the 3 rotor faces as much as possible and you will need a rotary-specific compression tester. I rented mine on Ebay for $50. If you are to buy any used engine its best to have it comp tested with a rotary comp tester and then you will have no surprises.

blackmount

Save your money, Start with a good running and driving RX-8 that's 100% stock, and well maintained, and the owner has already done so, or will let you take it to the nearest Mazda dealer for a Compression test.

These cars are still cheap enough, and plentiful enough, that buying a shell and having the headache of trying to piece it together just isn't worth it, Especially because you'll spend more then it would have cost to get a running one....

You can find a Good, Well maintained Drivers examples for $5,000-7,500, Stupid clean examples for under $10,000 still, and Ultra Stupid Clean Examples for Slightly More then that.

Slawekn1

That is sound advice. My approach was to look for the best deal available since I was not in a hurry and this is my 3 car (toy). If I was able to find a clean one with everything in shape for a good deal I would have picked it up... but I'm in Chicago and just hate rust so that made getting a good deal locally a bit less likely.. so I started looking everywhere and when the right deal came around I grabbed it.

Plus, a good deal might mean different things for different people. For me a good deal was a salvage title car that was stolen and involved in a fire ...without an engine LOL I had to clean some soot from all over the car but otherwise it's stupid clean. ;-)

blackmount

I found mine in Dixon IL, Completely Rust free, other then some dust and dirt, it looked like a new car underneath, know a few local Wisconsin guys with some ultra clean RX-8s as well, one of them just recently sold his, so don't be afraid to look in the rust belt.

whitey382

I'm not in a rush here so looking for a clean used one will probably be the route I take. Thanks for the pointers and tips, much appreciated.

blackmount

Sure thing man, for a long time I was definitely the one who bought shells and built them up, but with the RX-8 i wanted to take a different route and I'm so happy I did. going on 5 years, and 50,000 miles later it has not missed a beat, I've been able to just enjoy it and drive it, and do the few basic mods I want to it over a weekend here and there.

whitey382

So not that I would necessarily buy a car out of spite/someone telling me I shouldn't/couldn't do something, but I'd be lying if that didn't play into my situation a little bit thanks to a previous post by Team RX8. Anyways, went out and bought myself an 05 MT. A buddy had a friend with one sitting in his back yard. Engine was already out of it. Picked up the whole shootin' sh'bang for $400. She was in a front end collision at some point in the past but whoever did the body work did a farely solid job. Whoever did the paint on the other hand did a terrible job. Either way the interior is super clean and well taken care. I'm getting my garage setup and work bench built. Then I'll start tearing the engine down. I'll try and post my progress as I go along. I plan on staying naturally aspirated with some porting and reliability upgrades.

Gyro

Any updates? I paid a lot more than you did for my chassis, but deals like that don't seem to land in my lap. I bought on 07 that is non running (yes, on purpose), and are planning to source an engine for it, or send the original out for a rebuild. Project with my 12 year old son. I actually didn't want to just buy a "good running car" to drive as others have suggested. I could have done that, but instead, set out to do as you did. Wrenching is therapeutic for a lot of us, and the assumption by others here that your making some mistake is curious to say the least. Hearing the swapped motor fire up for the first time after hours of work will live in my sons mind rent free for the rest of his life. And then I get to drive an 8 again.

whitey382

Progress is slow but steady. With family and work I have a lot going on, but i usually spend 5-6 hours late into the night each weekend working on the ole girl.
And it is funny how someone like TeamRX8 can read a couple posts from someone they dont know and make a blanket statement that they have no business near a rotary engine. It's funny that the very people claiming to champion the survival of the brand are the very people doing the most damage. Although i should really thank him. If he hadn't pissed me off with his little comments I might not have made the leap I did, so in my case thanks TeamRX8 for renewing my love of this car.
moving onto the project:
I'll try and be better about posting updates moving forward. Here's where things sit at the moment.
1. engine has been completely stripped down.
. A. Irons were in good useable condition. I bought the racing beat street port template and am almost done porting the irons.
. B. housings had some where but were still useable. I sent them to Adam @ REC for refinishing. They came back looking great. Little bit of edge wear that didnt come out but overall a huge difference from what they were.
. C. Rotors and e-shaft were in good shape. I also sent those to Adam for race clearancing and balancing the rotating assembly and press new bearings. Yet again his work is top notch and everything came back looking great.
2. My goal for this project is a budget performance build. I'm trying to keep to a $4k budget for all the engine/rebuild/accessory work. I should come pretty close. My goal is to hit 200 whp for this build.
3. I need to get a couple more little things like ACT street light flywheel, clutch, clutch line, ignition coils but I'm patient looking for the right deals.
4. I want to be done porting the irons by the end of this weekend. After that I'll get a drill press and setup a custom side seal cutting assembly similar to what "RAD Potential" (YouTube) uses. Once that is done I'll be ready for engine assembly. I'm really going to take my time when it comes to the prep and engine build being my first one, but after that things should some together pretty quick.

Attached are some photos. I'll try and get an update out each weekend moving forward.

For those that have experience and arent complete jerks about it, take a look at my exhaust porting and give me your thoughts. It wasn't originally intentional but I ended up making the exhaust ports quite large. I purchased some used garbage irons from rotary resurrection prior to this work to test where the coolant jackets were and make sure I didnt screw up my good irons. Big picture I tried to make them as big as possibly to get as much exhaust gas out as I could.

PS - anyone have a lead on a racing beat header that would be much appreciated. That'll be the final piece to my exhaust

Initial engine teardown

Front housing before resurfacing

Rear housing before resurfacing

Rotor cleaning #1

Rotor cleaning #2

Rear iron prior to porting

Middle iron prior to porting

Front iron prior to porting

Exhaust porting (with blemish due to my laziness and not putting duct tape around the edge as a precaution). Lesson learned.
equation.

Gyro

Glad your still at it. I cant' comment on the exhaust porting, but I like your approach to a budget performance build. When I rebuild mine, it will be tempting not to throw a few performance parts at it along the way. But I'm fine with stock as well. It kills me that I traded my 2004 with my RB exhaust still fitted. I loved the tone, and probably wont be happy with any other brand. Maybe I'll get lucky on here if someone is selling.

My plan at the moment is replace coils, wires and plugs after the de-flood procedure to see if it will fire. I don't think too much time was put into it by the previous owner to confirm a bad motor (no compression test etc.). I would be buying new ignition parts either way, so its really not a loss to spend a little time on it. If no luck, I'll pull the new ignition parts and save for the new motor. I'm considering Kevin at RR to rebuild. The JDM engines are such a gamble, but I cant say that I haven't considered it. Especially since these usually come fully dressed, with parts that you may up needing, and would add up if purchased separately. I'd start a new thread on my motor swap, or if I have a question about my swap, but I'm testing the waters over here. It's been awhile.

kevink0000

My .02.

No porting=more power, longer life.

Sorry. I hope your build goes well though.