Long time lurker with a Rotary Miata
 

Hey folks, I'm a long time lurker at the site always watching but rarely posting. Figured I'd finally introduce myself. From Central NY, and have been wrenching on my Miata for the last few years. I started with a 1995 with the sole intention of pulling the 1.8 and swapping in a 13b. I documented the swap on the "other" Miata forum from start to the current iteration of changes and upgrades.

Here's the current setup:

1995 Black and Tan
13B-REW with Single Turbo conversion
Link G4 RX ECU
KG Parts primary / secondary Fuel rails with 850/1600 injector combo
Walbro E85 Pump
Flexfuel sensor plumbed into the return line (it's full flexfuel capable but not fully optimized on both fuels as of yet)
Comp CT3-5862 turbo
6AN from tank to engine bay
3" DP -> 2.5" Cat-back
A/C and PS Delete
V8 Roadsters Frame rails

Next round of mods include:
Rebuild on the engine
Direct Fire conversion using LS2/Truck coils
3" Full exhaust

If I can squeeze the extra cash out also going to swap in a Getrag with 3.42's

Here's a couple Vids I took, first one is a idle walk around the second a rolling acceleration at 14 psi on 93 with a cracked apex seal. Speedo is a bit off due to tire diameter difference between an FD Rx7 and a Miata (25" FD vs 23" Miata).

NB gauge cluster?

Yeah, had to go NB gauges to tie in the VSS from the FD transmission.

Where in CNY? I'm in Rochester. Also know of a guy doing a Rotrex in Canandaigua.

Oswego for the most part, but spend more time in the Syracuse area. How deep into the build is your friend?

Not sure. He moved just before winter, so probably not in too far, yet.

In before the rotary hate. I think it's awesome :giggle:. Did you fix the apex seal(s)?

What bov is that? Sounds pretty interesting.

Alot of folks definitely do hate on rotaries. But to me it was the only option to keep the car under 2k lbs and be able to push 500 hp with ease (and not spending 10k on a race prepped engine).

For those rotary haters who say the rotary isn't that light, here's a pic the last time I had the car weighed. Had about a gallon of gas in the tank, full stock interior with leather seats, spare tire, jack, and stock 18 lb steel wheels:

https://www.miataturbo.net/attachmen...ine=1393210132

Video was taken last fall before I put it up for winter, the rebuild kit should be in this week so when the weather gets a bit warmer the engine can get pulled and rebuilt with the new super seals (engine I started with was a used JDM import).

BOV and Wastegate are both Tial

If you are using E85 then you shouldn't have detonation causing apex problems and it should be good.

That is an interesting car. Never liked the way 13b's sound, but I still respect how they perform.

Do you drag race it?

Welcome

Do you have a link to the build thread?

Very cool. I would never do a rotary swap myself nor am I interested in one, but if you like it then that's awesome. Sounds sick, and is very, very cool. And light!

Would love to see more pics and videos of this thing. Link to build thread on the other site?

Kind of funny you mention that as that's when the seal really started letting go is when I was tuning for E85. Front Rotor was 90/80/80 when I got the engine, so it was obvious there was an issue with one of the seals. After the 93 street tune was decent, I started on the E85. I just started to get into the positive pressure side of the map when it cracked further causing the compression to go to 90/30/30.

Build thread Link:
Engine Conversion: 13B-REW / 13B-TT Build Thread - MX-5 Miata Forum

I haven't made it to the strip or really put the car through it paces as of yet besides shaking it down (beating the crap out) of it on the street.

Thanks for joining, wildman923!

Did it have 2mm or 3mm apex seals?

I'm wondering if the reduced lubricity of E85 was a contributing factor. I seem to recall that the '89 and newer engines had a reduced oil injection volume or frequency for the sake of emissions and to the detriment of longevity, but there were workarounds for that. Oil vapor does increase the propensity for pre-ignition or detonation.

Engine is currently bone stock with the factory Mazda 2mm Apex seals. I'm actually switching to pre-mix instead of using the OMP for oil injection. I'll be pre-mixing Klotz Super TechniPlate for 93 and Klotz Benol for E85.

Sounds like you have it figured out.

Nice, I've been an admirer of the rotary. As any though, not a fan of the "reliability" factor.
Since if I put one in my car it'd need to be ported to hell and be a 20b.
I'd love a 24b as well. Can't be too picky though.

In for ported rotary miata idle. GO

Welcome. Love the scale numbers.

Holy balls that looks like fun.

So, I know rotaries are known for having issues, especially with apex seals. How long does it take the average rotary-head to replace an apex seal? Does the engines light weight make it easier than say, replacing rings? And what about cost?

Like this?


It's a NB Rotary build in Poland I have been following on Facebook.

Depends on experience swapping them out. If you've done it before it can be done in two to three hours from start to finish if only replacing Apex seals / springs and gaskets. Side seals take the longest to install due to they have to be clearanced to the corner seals.

The engine is actually "layered" (plate / housing w rotor / plate / housing w rotor/ plate). Basically have to disassemble it to the bottom housing to get to the rear rotor in order to swap out the seals. Weight wont have much to do with it.

Apex seals are expensive, factory Mazda's are around 275 a set, aftermarket are around the same price. High end ceramic performance seals are about 1500.

And how long do they last? THe 30k everybody says or better?

Aren't the best apex seals some unobtainium titanium shit? That are like +2000.
I've heard of some using specifically cheerio cereal boxes as seals.

Edit:
Per video - Yes! but much more brap.brap.firball.brapness :P

The rotary hate is the result of misinformation.
Take a factory turbo car that is extremely sensitive to detonation, add years of backyard modifiers who know nothing about tuning EMS and you get a lot of blown up engines. Just swaping exhaust without tuning can make one of these things lean out enough to detonate and a little, and that's all it takes.

This is like back in the 80s when people were spraying dry nitrous into their carburetors and then crying "dang ol' NOS blew up mah 350, that shit is dangerous I tell you what."

Ah FTB, you and your rants. I suppose next you'll suggest this is also a better swap than the K24? :giggle:

Seriously though. Its a very cool motor but.. Poor fuel economy and expensive maintenance. How is that not deserving of a bad rap?

OP can probably offer more insight than I can.
Im not saying theyre perfect DD status or anything, but its all blown way out of proportion. Ive seen people on this board basically say that they are garbage.

They definitely can be reliable. There is no way they could be used in aircraft if they couldnt be super reliable.

I think they make great race engines. Just look at Formula Mazda. They make plenty of power and with a conservative rev limiter and the tuning dialed-in they are very reliable.

My '89 RX7 went 156k miles before needing a rebuild. Then I drove it another 30k before selling it to a guy who still had it last time I checked. Car required no more maintenance than any other. I replaced the clutch and the shifter bushings. That's about it.

I think the same fart can kids that do stupid things to Hondas gave rotaries a bad name. Hondas are just a bit more tolerant of stupidity.

One thing that's bittersweet about this site is the classifieds and vendor section. Since starting this thread I am now also going to be upgrading my primary injectors from 850cc to 1000cc as well as upgrading my 550 cfm intercooler to the 725 cfm stage 2 (in black!) that fab9tuning offers.

Has anyone ever done research about the effect of painted intercoolers?

Depending on the paint but yes most over the counter paints decrease the efficiency. Theres some speciality paints that are extremely thin that dont drop it much but no idea which they are.

Yeah, I doubt that wrinkle black spray would be good for heat exchange.

Sorry I just love this quote

I find it kinda funny that most of the people talking up rotaries don't have one currently, or haven't had one for a very long time, or have never had one.

Also I find it kinda odd that most of those people consider having to mix oil into their gas, WOT the car at least once when driving it, have no torque til like 5k rpm, and even when short shifting and taking it easy still get no more than about 15-17mpg, totally REGULAR maintenance and TOTALLY normal and reliable and great.

Now, I don't own one and never have, but have had friends and relatives with FD's and RX8's so I did get my fair share of feedback on them as well as helped wrench on them. And all were really low mileage very expensive cars that were never hacked or backyard "fixed". All sold them and would never consider a rotary again.

Now, please don't take this as hatred, its not. I really appreciate what these engines/setups do and I admire some of these builds (even if secretly :giggle: ) so keep on keepin on.

:)

Meh. I originally bought the Miata and got rid of the rx7 because the switches and some plastic interior parts were ageing and the Miata was purported to weigh 500 lbs less. Nobody told me the Miata handled like shit out of the box. Miata was seven years newer and had many less miles so I bought it. It's great now but it was a real let down after the '89 rx7 stock to stock.

I think most of the guys premix the oil in as an insurance policy in case the built - in system fails. I'm not sure on the specifics of all that. I'm in the category of people that have never owned a wankel.
I have known quite a few Formula Mazda owners and car builders who were ecstatic about the engine. While I was rebuilding my POS reciprocating engines every couple or races they were running 3-4 seasons on their sealed 13Bs. IIRC they contributed a lot of this reliability to the rules limiting revs.

I won't talk "up" a rotary and I own one. They just aren't for everyone plain and simple. I personally wouldn't daily drive one for my 45 mile commute to work.

However, when going for high hp and low weight ... that's where the rotary shines. The rotary definitely has it's "quirks" and those do include either oil injection or pre-mixing (for those not familiar with rotaries imagine what piston rings would do if there was no oil to cool them).

Torque on the rotary is going to be based on porting and turbo sizing. I have seen rotary builds pulling 400 ft lbs by 4k rpm:
400rwtq @ 4100rpms - RX7Club.com
350 ft lbs by 3800rpm:
Autox FD Dyno - RX7Club.com

WOT driving is what these engines are all about, that's why I have one in my Miata. Horrible gas mileage doesn't bother me personally in a weekend warrior, again it's not my daily driver.

Rotard haters are dumb.

This shit is fucking rad.

The quickest Miatas are all rotary powered, and rotaries have won many championships in several different sanctioned motorsports.

Nice car man, I myself am From Auburn.

Glorious. I'm planning on converting my Miata into a Dorito-powered unicorn eventually, as well. It seems like a great swap because of the light weight (bare long block is over a hundred pounds lighter than a B6 bare block), power potential, and the fact that a swap is easy as an RX-8 bellhousing, welding a mounting tab to the front of a V8R subframe, and having a custom exhaust made. Wiring up the Megasquirt is the fun part.

Mostly I'm just making this post so that in six years' time when I'm three years and $15,000 into the swap I can come back to this thread and rage at what a clueless fucking retard I was.

Always nice to see other CNY folks on the interwebs.


Rx8 bellhousing won't swap over to the stock Miata trans. Would need to use an s4 na bellhousing on the Miata trans and slightly shorten the input shaft.

I have actually exceeded the 15k mark with my last iteration of parts I ordered. However my build included alot of bells and whistles (single turbo swap on a 13B-REW, Link G4 ECU, stainless piping / exhaust, stainless AN lines, etc.). It can be done alot cheaper if going na, starting with a turbo 2, using the Miata transmission, and using a Megasquirt for the ECU.

I also have a site I built at: www.rotarymiata.com with links to builds across the internet if your looking for more info on the swap.

NA FC gearbox has a Miata 5 speed inside, RX-8 gearbox has a Miata 6 speed inside. If I buy a complete RX-8 6MT and just swap my NB1 6MT tailshaft onto it, I should be left with a transmission all ready to swap a BP into an RX-whatever. There's got to be at least one person in the entire world that would want to buy that, right?

My plan was to use a stock TII long block with an FB front housing and get everything running, then change things from there. From what I understand, the single turbo fits in a Miata without cutting the chassis.

Thanks for the link, I'll check it out.

LOL that's awesome. I had that URL back in 1998-2006ish. Chronicled the many revisions of my rotary miata. At one time that URL was the number one result for rotary miata searches on Google. Prolly should have sold it at that point :) :)

Glad you have it and are putting some good content up. Carry on!

https://www.miataturbo.net/attachmen...ine=1393910438

Nice edit, I was about to say.. how did rotarymiata> porn.
So rotary still = block?
Haha there is a guy on here with an insane BPrx7 build. But the Miata transmission wouldn't hold well.

That's awesome! I did a DNS Lookup one day and saw it wasn't taken and said hell with it, might as well build a small site. When I started my build I found bits and pieces here and there around the web but nothing as in depth as I wanted all in one place. So figured I'd make the site into a resource for those thinking about swapping in a 13b.

So If you ever want to start making motor mounts let me know. I'd be interested in a set. I been thinking of doing a rotary miata as a side project. Bridgeport is fucking sex.

Says the guy who wants to drop a F2T into the FD in your shop :giggle:

Well yeah... because that's just hilarious on multiple levels, and probably cheaper than sticking a brotary back in it. :fael:

My oh my how times change but things stay the same ... Fresh Frankenstein motor, fresh fuel system, and bigger turbo and I'm back in action: