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There is a minor difference with front and rear housings, mainly for EGR passages. If you were buying new rotor housings I'd probably get the correct ones and put them in the correct place just to do it, but if you're buying used or whatever no big whoop. I've built engines with 2 front housings, there's no problem.
The 5th gear synchro problem on the transmission isn't too bad to fix, I've done a few of them. Parts aren't too bad. There are some writeups around.
May also want to look at buying a JDM long block. They pop up on Ebay and there are also JDM engine importers out there. Easy way to get a whole engine, turbos, manifolds, etc. - all the little parts. I've seen them recently for $3500 or so, many times you get the transmission as well. I would plan on reubilding the engine for sure, but you at least will have more good (hopefully low mile) parts to start with.
There's a ton of options out there, it just depends on your budget, your time, and your skill level.
Low budget/high skill - track down used parts, build the engine yourself. Definiltey a higher risk of having problems, having to go back and re-do things, maybe not getting it to run or run right. Most time investment.
Medium budget/medium skill - get a new Mazda short block or a rebuilt short block from an engine builder. Put it all together yourself and get it running.
Higher budget/low skill - pack up all the parts and tow the car to an RX-7 specialty shop. IR Performance and Banzai Racing are relatively close to you (NE USA) and do fantastic work.
Thank u so much for the detail break down.
I have talked to IR performance, $4699 for a new Mazda short block and $7300 for street port short block, these two options r out of my budget. With the $4699 Mazda short block, I will need to get rest of the stock part, my current set up is for street port. With $7300, I can get a G37s which gives me speed and comfort lol, had one before and really like it.
Just talked to my buddy that he used to work for Mazda and rebuilt over 100 rotaries, he told me Front and rear housing r internally the same, yeah ur right I can get two same housings. I also showed my housings and iron plates to him, indefinitely need two housings and the front iron replaced. He also added, the early model FD runs lean, I should get the ecu tuned if it runs lean with the stock setup.
Called JDM engine zone and JDM engine depot today, looks like I can get one full swap for $3000-$3500 with cash deal and pick up myself, sounds about right? And have them to do the compression test on site, anything above 90psi is a good buy? Indicates good housing and iron plates? My plan is rebuilt the jdm engine with all Mazda stock internals, gonna go back to the stock twin turbo setup, if so, can I still use the jdm harness and ECU? I consider myself as medium skill level, this is my first rebuilt but I had done a swap on my FC, been dealing with tight tolerance and capital equipment design as mechanical engineer. Oh, JDM engine zone has 13b engine for $2500, tranny sold, should I just get the engine and rebuild my tranny?
Many thanks for all your inputs, hope I can get my FD on the road before winter.
Like I said, a JDM engine is a great way to go to get all the hard parts but I would spend the extra time and money to open the engine up and rebuild it. You can run it as-is if it has good compression but it's hard to say if that's going to last a long time.
My plan is rebuilt the jdm engine with all Mazda stock internals
Have you priced out the "stock internals". Then throw in 20% contingency. If you are a grand off a brand new engine, you need to ask yourself it it's worth it going used and unknown
I am going to call IR performance to get pricings for stocker internals seals and street port seal upgrades, gonna sort out 4 options. option 1, use IR performance street port brand new(7300), option 2, buy JDM swap for approx. $3500(cash pick up), rebuild with stock internals, remove the FD's existing set up and down grade to stock. option 3, buy two new rotors from JDM planets($600 each), front iron($500) and resurface center and rear irons, street port rebuild with upgraded internals(apex seals along cost $529 from IR performance), with upgrade coolant seals, turblown engine studs($475 from one of the ebay seller), with this option I can keep my FD's existing setup. option 4, buy JDM swap and use its parts for street port rebuild. gonna run numbers for these 4 options, trying to budget under $4500 after selling leftover parts.
You might not like what i am going to say.. get the new engine. If you don't have the $$ right now save a little more and get it. I rebuilt my engine, but at the end i spent more than what i was suppouse to. Tracking down good engine parts its not easy most of the time,.
JDM engine , you never know what is condition internally of that engine.
Used wngine and parts for example: you wilk need new bearings rotors and stationary gears, ne springs, new internal soft seals, clearance rotor side seals(hard one for first timeers).
The only thing you will have to do to the new engine is new soft seals, if your choice of apex seals, porting and close it.. thats it.
Enjoy your experience with this engine.. its lovely.
Nobody else will like this idea but if you are really on a tight budget you could just rebuild everything as is. The engine was technically running with the chatter marked iron and worn housings. If you marked where every apex/side/corner seal came from you could just reuse all the parts and get new coolant seals. If not you can get a new seal kit from somewhere like Atkins for $600. It would essentially be in the same state it was before overheating assuming nothing got warped.
No one in their right mind would do this for a customer car but since it’s yours you can do what you want. There is a slim chance it will work and even if it does you have to live with the uncertainty of how long the engine will last. The current salvageable engine parts aren’t really at any more risk either.
Worst case: you lose $600 and a weekend but you now have taught yourself the basics of rotary engine building. Most of us have lost that much money and time on worst things (some at the same time). Consider it as training and research.
Best case: you have an engine on borrowed time that you can thrash around carelessly while saving up for your “real” rebuild.
Nobody else will like this idea but if you are really on a tight budget you could just rebuild everything as is. The engine was technically running with the chatter marked iron and worn housings. If you marked where every apex/side/corner seal came from you could just reuse all the parts and get new coolant seals. If not you can get a new seal kit from somewhere like Atkins for $600. It would essentially be in the same state it was before overheating assuming nothing got warped.
No one in their right mind would do this for a customer car but since it’s yours you can do what you want. There is a slim chance it will work and even if it does you have to live with the uncertainty of how long the engine will last. The current salvageable engine parts aren’t really at any more risk either.
Worst case: you lose $600 and a weekend but you now have taught yourself the basics of rotary engine building. Most of us have lost that much money and time on worst things (some at the same time). Consider it as training and research.
Best case: you have an engine on borrowed time that you can thrash around carelessly while saving up for your “real” rebuild.
your right, i should consider of using what i have as tutorial.
Gonna replace apex seals and coolant o-rings, using rx parts apex seals and heavy duty coolant o-ring, replace rest of the o-rings as well, the corner seals and side seals seem fine to me. Upgrade the engine stud with turbolwn studs. Gonna use 400 sand paper to remove the side seal grooves on the irons surfaces, then use valve grinding paste rub against each other to obtain the flatness. Give a good cleaning to the rotors and housing. There r small bumps build up along the irons oring groove, besides keep scrapping, another other ideas to get rid off these lil bumps inside the groove?
It is gonna be a cheap rebuild/research project for me, any suggestions would be appreciated! Cleaned groove. Build ups inside groove.
Throw in a set of new rotor housing as well, anyone has experience with jdm planets? https://jdm-planet.com/product/genui...rx-7-fd3s-oem/
their housing is $601/piece while others cost $8-900. I am really curious about the price difference.
The bumps are normal. I typically take a sharpened mini screwdriver that can fit in that groove and scrape it out really well. Big thing is it needs to be clean of all the old seal and debris.
need advices at the rear rotor, All three apex seal groove r straight and within the spec for 2mm apex seal, as u can see from the last pic, the corner chipped and it seems the previous owner continued his rebuild as is and the engine ran well until I blown the inner coolant seal, I will be using superseals and planning to reuse both rotors, this would be research type of rebuild for me and I expect to take it apart again if I need to. What u guys think, this chip corner shouldn’t cause compression right?
Its Not worth using it,. Add a rotor the the bill. You might chenge your mind down the road on your rebuild. Keep inspecting parts and you will know where you stand.
Lapped the irons with valve grinding compound and sanded with #180 sand paper with piece of glass to ensure the flatness, dial gauge show .0005-.001” around all surfaces and 0.002-0.003” at the grooves. I decided to use existing plates housing and rotors. Will be replacing the pilot bearing, corner seals(solid type from Atkins), corner seal springs, side seals, side seal springs, oil ring springs and o-ring. Using superseal(apex seal) and racing springs from rotary aviation. Does anyone have experience with Atkins viton oil ring o-ring? It seem a bit harder than the OEM(green color) ones. Gonna replace the rotor bearing and stationary main bearing as well. The turblown engine stud is the last thing I am waiting for.
I believe the .003” groove gonna cause compression issue? Anyone has experience with used iron plates with groove?
I personally did not like the irons from the first picture...engine looks high mileage. Buying the engine for 4500 was probably the better route in my opinion.
rebuild kit cost about 1k
you mostly likely have to get used rotors and housings. 1500
about $200 in misc. stuff
So i rebuilt the engine with all existing engine parts, besides apex super seal and racing apex springs, the rest r all Mazda oem seals including the oil ring o-rings, not comfortable with the oring from Akins.
anyways, engine started up and ran for 10-15 seconds with starting fluid spraying into the upper intake manifold, tried that couple times, it ran like it should. However engine won’t run under the condition of Fresh 91 octane with 1:1 premix. I had tried both start ups under cold start.
fuel injectors been serviced, there’s full of fine gasoline mist inside my garage after cranking for 30 seconds, which I suspect a good working fuel system? Fuel pressure set at 40 psi, pressure drop to 20 after few mins of not running the fuel pump, bran new optima battery with 800cca.
any suggestions on what I should look for next? Maybe I should trying using New fuel without pre-mix?
If engine ran with starting fluid, it indicates good spark and acceptable compression correct?
Do you have a PowerFC? It's worth going through the sensor check screen and the monitor screen to see if any sensors aren't reporting in or are faulty.
the car came with a fc commander not hooked up, i never mess around with it, do I plug into the power FC(if there’s one) and key on, it should show me all the sensors condition?
I rather check the sensors with old fashion way using voltmeter.
10-04-19, 03:19 PM
