N3v

dont ban me pretty please i browse the megasquirt forum
Chronological order. Yes that is my bedroom floor in most of them.


















insertion into miata is t minus 3 weeks

18psi

iTrader: (76)

going n/a rotary? good luck
post pics

Rotaryman

Pics of the outside irons did you port those too?

How are you going to mount the motor? From what i can gather it would be easier to get a front cover from a FB with a 13b and mount it that way

Do not forget a Quality header it makes a huge difference

You should stomp a few cars with it in a light Miata chassis

Rotaryman

Oh and look up pineapple racing 6 port sleeves they can make up to a 10hp difference on the topend

N3v

yeah i ported the outside irons and got all the irons lapped, but the outside ports have a very small amount of material removed in comparison. I added a pic in.

edit: already have the pineapple sleeves installed, thanks I'm trying to put every go-fast mod I can into this thing and see how much NA power I can squeeze out on a street port. I'll probably put IRTBs on it later, but I haven't yet because I'm tempted to boost it

Rotaryman

I did an S5 6 port turbo on my Rx7 alot of people told me not to just because of the higher comp ratio isn't knock friendly

I just took all the stock t2 stuff and put it on to my 6 port motor and made an easy 260 whp and 260 ft pounds I did it all for less than $400 not including the emanage blue i used

if you do just port the T2 intake manifold to match the 6 port, or just leave that intake on there you should make more torque with it

rider384

iTrader: (3)

Forgive my ignorance towards rotaries, but is that a two rotor?

Also, the engine seems remarkably short, is that just perspective or is it really?

Cool idea man, I look forward to the build thread

Rotaryman

ya it is very short its about the size of a milkcrate :P

N3v

that's awesome! I don't think I'd go too crazy, only enough to get me where I'd be worried about breaking my 1.8L gearbox. Kinda depends on how much power I make in NA trim. I'm shooting for 200whp, but I will have a long tube header, pulley kit, pineapple racing intake sleeves, ls1 coilpacks, and a megasquirt.

rider384

iTrader: (3)

I just got the idea to put one on a gokart or similar

What's the engine code?

N3v

13b.

I did some measuring in my engine bay, the engine block will end about half a foot further back than the stock engine. about where the lettering on the valve cover ends.

Rotaryman

well my car was a Stock port motor and i made that power id imagine you would make abit more :P

I dont think you will hit 200 with the stock intake manifold maybe 180-190ish whp im assuming 9.7 cr rotors

I know what you mean about the n/a tranny there mang i kept my rx7 n/a tranny and 2nd isnt very happy anymore (the gearbox is the same as a miata with different gears)

Dont go boost, it will be very fast with a rotary powerband and the throttle response will be wild

That said when i went turbo it still felt like an n/a car.....

Besides an N/A rotary Will Be Very very reliable esp as a track car (If anyone doesn't believe do some research A P Port 13b making 250whp will out live any 4cyl thats as highstrung on the track)

N3v

Crossposting from RD.com, in case any of you are interested in how to do this:

ok, so far in this thread I have basically only built a rotary engine, but now I'm gonna get into the miata-specific stuff required. This stuff is important and it's tough to find info for it online.

Today I have made some good progress. I've been working on the 1999 transmission I bought for this swap. First thing I did was wrestle the bellhousing off. Not easy. You undo all the bolts that go through the gearbox, and all the bolts on the inside of the bellhousing, then there are a couple of metal C clips that are a huge pain in the *** to get off. Then you can stand the transmission up and rest the input shaft on a block of wood so the bellhousing is off of the ground. Then kick the **** out of it with a rubber mallet. EVENTUALLY it will come off. Then you get this:

Because of the metal C clip that holds it together, it is impossible to use a spacer like I have been planning. (I was hoping I could use a spacer between the gearbox and bellhousing because of the longer miata input shaft) I figured this out a couple weeks ago. The tried and true fix is to cut the input shaft down a little. This picture is from mazdatrix, showing the measurement specs they use. This is done on rx7s if you want to swap the miata gearbox into an rx7, using an rx7 bellhousing and tailshaft.

They do the fabrication by completely disassembling the transmission so they can remove the input shaft and put it on a lathe.

Well, that **** costs ******' money, and is a giant pain in the ***. Because the input shaft is relatively small and lightweight, I figured if I did this modification by hand, my slight imperfections aren't gonna be enough to throw this out of balance where it's gonna **** anything up.

What you see here is the result of about a half hour with a tape measure, sharpie, careful use of an angle grinder, 80 grit sandpaper, and a scotchbrite pad:


I'm confident it'll work just fine. I don't recommend trying this if you don't have experience using an angle grinder. To remove the length off the front of the narrow part of the input shaft, i simply measured and accurately marked it, then used a cutter wheel and slowly cut that **** off. then I switched to a grinder wheel to make a nice radiused edge. I got it level by holding the angle grinder with one hand and spinning the gears of the transmission with the other.

the splines were trickier: I held the angle grinder as flat as i could and began grinding on the area i had to remove while spinning the gears with my other hand. This takes patience, but it's best to go slow. once the splined area was ground down level with the narrow part, it gets even harder.

After that, you mark an area slightly longer than 1/8" further back on the splines. you need to grind this at roughly a 35 degree angle. The angle is probably not important, mazdatrix probably just wanted to match the OEM angle. so, carefully using the angle grinder, i would spin the gears and take material off at an angle. as you can see I cut a tiiny amount inwards on the narrow part of the shaft due to holding the grinder too close. that part is super tricky.

All in all, I'd recommend that for the average person doing this swap they should probably take the input shaft off and do it on a lathe, unless they are a badass like me . After this modification, I can simply bolt the rx7 bellhousing on, and the transmission should work 100% with the rotary. We'll see tommorrow when I get around to that part.

I'm glad I had to end up cutting this, because the engine will sit about 1/2 further back in the engine bay than I had planned, and I won't have to order new gearbox bolts.

dustinb

Doesn't that have to fit inside of a bearing on the flywheel and be like properly centered/balanced? If it's off just a bit it's not going to be happy at all.

And the c-clips come off easily with a proper set of reversible c-clip pliers.

N3v

yes, except on a rotary that bearing is inside of the eccentric shaft. as I stated previously, I don't think my minor imperfections are going to throw it off balance enough to screw anything up. my input shaft will spin to about 9500rpms, yes, but i doubt being a gram or two out of balance is going to do anything besides maybe prematurely mess up the pilot bearing, which will just cause noise, which if it's like my miata, the noise will probably be there from the first day anyway.

NA6C-Guy

iTrader: (1)

Good luck blowing apex seals, rotard ***!

I keed. That is the typical response I see on most forums. I'd like to try out a 13B powered Miata one day. I regret not getting a ride from an old neighbor who I used to know from a car forum. He used to autocross a 13B n/a NA. Just never got around to going for a ride. Almost bought it, but decided against investing that much into a track car.

hustler

iTrader: (6)

awesome pirate rug.

Rotaryman

Good job dude, the balance won't be a big issue the end of that shaft will be supported by the input bearing anyways,

oh just so you know when you get a new input bearing shaft order the Oem seal for it 99% of the time it doesnt come with one and most people dont even know one is supposed to go in there lol

flounder

Before I got my miata, I had a 90 rx7 vert na. Nice car and the power top was nice but I couldn't get past the gas mileage. 15-16mpg and 160hp, count me out.

That's the main reason I left the rotary world behind. I'll take 27mpgs and 140hp in a 2,000lb chassis anyday.

Rotaryman

where are the updates?