Hey everyone,

I picked up a 1990 Miata NA this summer. It's pretty much stock except for door bushing upgrades. Came with the hardtop, basically no rust, pretty good condition interior, and a poly bushing upgrade kit that I will not be installing (after watching videos I think i'll by control arms with the bushings pre installed).

The car has 315,000 KM's and I got it all for $6200 CAD ($3.50 USD at today's rate).

Maintenance record is unknown, it smells a bit like oil if I push it, no weird sounds, and it always starts fine. I traded the Daisy wheels + $900 for a set of mint condition black RPF-1's with some whatever tires on them.

WHAT AM I DOING HERE?

I've always dreamed of working on cars. In July of this year I was lucky enough to be in Germany and spend 10 laps of very spirited driving on the Nurburgring in a tuned Focus RS. I am absolutely hooked and ready to spend my money. I am an avid follower of Mighty Car Mods and love the idea of turbo'ing a miata due to the cost for fun (RWD) curve.

GOAL:

I want a fun car to take on spirited drives. I don't need long roadtrips. Once a year I'd like to track it. 2-3 times a year I would autocross. Mostly the purpose is to enjoy windy BC mountain roads. In total I'm looking to spend under $7,500 USD.
I have started a Google Sheet with a parts list/links to what I'd like to do to the car.

In the Sheet are questions that have me a bit stuck. I've searched the forum looking for someone who has been in a similar boat and people seem to either go for a full custom setup or don't show builds of just a normal FM Turbo Miata kit (without changing anything). If there are any threads you think would be helpful I'd love to hear it.

Anyways, wanted to say hi and thank you for having this forum. I see there is a ton of knowledge and resources here.



From the Nurburgring

 

Welcome, decent first post.

If I were starting with nothing but a clean stock car on wheels, I'd do the basics first, in no particular order: New rotors/sporty pads, brake bleed, clutch hydraulics, suspension, alignment, diff fluid, trans fluid, shifter rebuild, clutch capable of handling turbo along with a new rear main seal, ID1050x/ECU/tune, verify health of engine with leak down/compression checks, and if it's ok then replace timing belt/water pump/front main seal/valve cover gasket/CAS o-ring/cam seals/NB lower radiator hose/aluminum radiator/upper radiator hose.

If the engines not healthy, rip it out, do a quick ball hone with new piston rings, refresh the head, throw in some $400 forged rods, then install all the above timing belt components.

Then turbo charge it. These days Kraken is the manifold/kit to get, ranging from just a mani/downpipe for $1000 to a full manifold/turbo/downpipe/cat/exhaust/intercooler/intake/plumbing for $4500.

 

Thanks Curly, that's more than I was expecting to hear back and sounds like a very logical progression.

I am asking around locally for a leakdown tester. I think that would make the most sense to do before the next steps.

I have heard about the Kraken gear. I was not sure as I didn't see a complete set online. It seems like I would be doing lots of piecing different bits together from different people. I'm going to reach out to them to learn more about their offering as the website is not very descriptive.

Out of curiosity, how come you prefer the Kraken kit over FM?

Also nice to see you're in Oregon. I lived in Vancouver, Washington for a year. Used to visit the Portland Speedway.

 

Oh the FM stuff is great, especially their new manifold which looks to me like a copy of the kraken, which is a copy of the non defunct TSE manifold. You're just paying a bit more, plus they seem to be perpetually out of stock every time I look....

For instance, the FM complete kit is $250 more than the one I looked up when i was writing my initial response, and only comes with a downpipe, their full exhaust is another $680, and is only 2.25". A quick search shows they don't have a 3" option. They do have a few nice things to their kit, like a heat shield, boost gauge, and manual boost controller. They also work out of the box with their voodoo system, which adds fueling/retards timing in boost, great for low boost applications. Personally if I'm installing a turbo on a Miata, I want more than 180-200hp, but some people are more than happy with that.

I can't seem to find anything on their site about the voodoo though, so don't quote me on this. They're all 100% CARB legal these days, so I'm not sure what they use for fuel/ignition control.

 

Yea, I browsed through the instruction manual and just saw some kind of inline controller. I do like the idea of doing a standalone. I mean I should, I'm an electronics engineer. But it's like having a wife who is a massage therapist. Good luck getting massages out of her when she's back from work.

I would be happy going and buying each part individually. I'm just inexperienced with this and not sure what all I need. I like the idea of buying a full kit that I can bolt together and drive off. That to me is worth atleast 15% more $. However, if the kit is restrictive, then that starts to be an issue. I've seen megasquirt PCB kits or the Speeduino's. I'm not against trying those. Though the megasquirt PCB kit could be a hastle as it doesn't have the harness connectors.

You're right about the stock levels also at FM. Everything seems to be out of stock...

Power goals for me are more related to budget. I'll do what I can for the money I have. I'd be happy with 200 reliable horsepower and it would buy me some time to find a 1.8 diff until the 1.6 diff gives (if that makes sense).

Is 2.25" too restrictive?

 

Welcome, looks like you got a decent car, seems a good base to be starting out on this ride.

Listen to the voice of experience (above), do it once, do it right. You have a decision point when your refreshed/sound engine is running. That might be a point to stop, take a big breath, and just enjoy the car for a while. All sorts of advantages in that, including building knowledge and funds. You can then decide when to make a decision about power levels.

There is always another way to skin that cat, and I'd suggest you look at the Rotrex type supercharging, it might suit your relatively modest power goals (as I understand them), but if the power drug takes hold you will be limited, whereas the turbo has a higher up-side.

Given you a cat for that gig at the 'Ring. Much envy.

 

Thanks Gee, I did consider the supercharger until watching the Mighty Car Mods Supercharge vs Turbo Miata video. Very entertaining. I can't fight the gobble sound of a turbo. I must have it.

Thanks for the cat! And definitely check out the ring if you ever can. It was an unbelieve experience.

 

2.25" isn't too restrictive for moderate power levels, no. Honestly you could probably make 300hp on 2.25", but you're going to be sacrificing spool and engine longevity making it work that hard through smaller exhaust. 3" is easy to find/fabricate/fit, so you might as well and reach 300hp or whatever your goal is at less boost, less temperature, all with better spool.

Just realized your original post said 1990, for some reason I thought it was a NA8. So yeah, I'd add swapping to 1.8 brakes, diff, and possible engine when budget allows.

I realize I have a lot of experience, but from what I'm seeing on Kraken's site, his kits are complete. Make sure you visit on a desktop/laptop, not mobile. You can select what engine, turbo, intercooler, whether or not you have AC, if you want a intake, etc, all from his little configurator.

 

welcome to the community!
There are some threads on here as to how to reach the Supermiata Race Spec series-allowed 140 hp max, with a normally aspirated 1.8 L.
Those threads are the ones you were hoping to find in terms of guidance, though I just searched and it may prove hard to select the right key words.
The info is also on the 949 Racing/Supermiata website. Lots to dig through for project ideas on their technical info web pages; brakes suspension, engines and so on.
https://www.949racing.com/supermiata/tech-info/

I would consider that route, with a 1.8 swap, compared to going turbo on the 1.6 L.
Just a lot less trouble, and much shallower learning curve when you start.

Later, the FM kit on the 1.8 L will get you above 200 hp at modest boost, but turbo's come with way more challenges with engine heating and cooling, and learning to tune an aftermarket ecu. Their stock seems low on their site now, but usually it comes back in within a reasonable period, so I would not let that put you off.

I installed the FM kit, and it works very well on my 2001 Miata, with an average hp of 211, and a peak of 225 at 8 psi. 2.5 inch downpipe from FM, connecting to stock exhaust cat-delete-back. (Built as a race car) But I did just destroy the engine at the last race of the race season, due to what looks mostly like detonation.
In contrast my 1.6 L Miata turbo gets 160 hp peak with a small IHI Mazda 323 GT turbo at 10 psi, swapped into a Ford Festiva.

Hence the interest in the 1.8 first.

 

FM makes a more handsome profit than other vendors for similar or the same parts.

1.8 diff also requires 1.8 axles.

Get a Megasquirt from DIY Autotune. It will come with a basemap and it will work with autotune for fueling changes when you buy TunerStudio software.

 

Yea the 1.8 swap overs will need to happen at some point. I'm keeping my eyes on marketplace for a 1.8 rear end.

Talking to Kraken now. Very responsive and helpful! I might have to ship to the states and pick it up. He's saying they won't ship to Canada due to cost.

 

Thanks and that's good to read. I was thinking 180-200 whp but I must have mixed the numbers up between the 1.8 and 1.6. That's a pain! Sorry to hear about the blown motor. Know what it is?

 

Thanks, I'm talking to DIY Autotune now. Yea, I heard I need the axles also thanks. Might ride till I blow it or a new one comes around at a good price, whatever comes first I suppose.

 

So this guy just popped up with a 1.6 short nose that was previously boosted and has 200kkm on it. He's selling for $300 and has a mega squirt pnp2 for $500. Wondering if I should pick up the lot and just clean up that engine with light refresh, put the turbo kit on it and slap her in.

 

Not terrible, however I would wait for a 1.8 if you're doing a engine R&R. You could buy the MSpnp2 for $500, save the $300 for injectors and a wideband. Tune on the stock injectors, then put the aftermarket larger ones in, reset injector settings, and retune your fuel table.

 

Detonation, but why it lasted the season and popped in the last race is unclear so far. Subject of its own thread at some point.

Not sure why you would buy one 1.6 L when you have one already, but that is a nice price on the MS2.
If you are committing to 1.6 L then having a spare core for that price is great.
Is the MS2 PnP, and for the 1990, or for a different year? The harnesses to the ECU change throughout the years, as you can see on the DIY PnP sales list.

I know someone who really needs a core 1.6 L, so if you don't get that engine, can you pm me so I can forward that info to them in Calgary?

 

Thanks Curly, I like that idea. Sounds like a good way to step into the world of tuning. That's all stuff I could do with a laptop and my senses and some sensors or would I need to dyno each time?

The more a read the more it sounds like a 1.8 is the way. I saw a 1994 1.8 pop up. I could just get that and sell my one. It would work out cheaper and less time consuming than buying a 1.8 motor and drivetrain.
​​​​​

 

For sure, I'll think more about it today. If you don't hear back from me it's because I'm tied up with work. I can only think about these things on the weekends mostly...

 

When you do the 1.8 swap, you'll be swapping over or wiring up your outputs, which are injectors, coils, and idle valve, and you'll swap over or wire all your sensors, including coolant temp, air temp, and TPS. None of our cars come with a wideband oxygen sensor, so you'll have to add that for any standalone ECU. You also need a load sensor, which from the factory is the AFM on the 1.6, or MAF on the 1.8s, you'll get rid of this and use the MAP sensor which is usually a vacuum port on the ECU, by running a vacuum line from the intake manifold to the ECU. When you do this you also get rid of the air temp sensor in the AFM, so most people buy a GM air temp sensor and install it in the intake pipe or intercooler if turbocharged.

Also your TPS isn't a variable TPS like all the 1.8s, it's just a switch, so google all the VTPS kits available from FM and other sources to adapt a VTPS to your throttle body. You also only have batch injection, where the ECU fires injectors 1&3 and 2&4 at the same time. Sequential injection is preferred, which involves opening up the injector harness, cutting two wires out of the splices, and extending them to the ECU.

On any 1.8 swap, stock or standalone ECU, the 4 CAS wires need to be extended from the intake to exhaust side of the valve cover, the coils don't bolt up, and the throttle body doesn't bolt up. Solve the coil issue by using aftermarket COPs, 1.8 coils, or FM's coil bracket. Solve the throttle body issue by using the 1.8 throttle body, which magically gives you the VTPS you need as well. FM has an adapter to bolt the 1.6 throttle body on the 1.8 engine, but it spaces it forward ~1", plus the 1.8 motor sits ~1" further forward than the 1.6, making for difficult intake installations, so I don't recommend it. The '94-'97 throttle body has a ~1" hose barb where it grabs air for the idle valve, which you need to plumb into any intake/intercooler setup. I prefer the NB throttle body, which grabs air pre throttle plate and meters it to post throttle plate, all internally, making intake/intercooler setups much cleaner. Find a used throttle body online with wiring pigtails, cut them off a junk yard car, or there's a couple sites online offering Miata wiring pigtails. https://www.bmotorsports.com/shop/static.php/post/miata

NA8 throttle body:

NB throttle body:



Hint: press the multi quote button on every post you want to quote except the last, then press the quote button. Voila! multiple quotes in one post.

 

That's the smartest route you could choose. There were many other refinements we haven't even discussed yet.