My 90 Miata Turbo (re)build.

I figured I would post this up here as you guys are a little more forgiving of mistakes and kludges than the MT.net guys. I'll obviously try to avoid those things, but given my poor track record on projects I feel a little better about exposing my foibles on here.

Originally I was just going to be adding an MS3 to my car since I already had the thing setup with a Greddy, an intercooler, bigger downpipe and what not and just needed to get off the band aid setup (AFPR + Bipes timing controller etc) and start using bigger injectors and an actual computer. Then I broke a manifold to turbo stud.

So, here is my ugly setup with the stripes IC and the turbo tony downpipe. This is with the heat shield removed from the turbo.

Even if the car sits out that lower panel probably shouldn't be black.

I'm thinking that's possibly due to this leaking...

That's the ATP Turbo hose that I'm using for the oil return (yes it runs all the way around the engine bay), which is some very thick stuff, but that end is toast. The cracks go all the way through. I think I might need to grind down the lip on the turbo oil return outlet, because that hose was nearly impossible to get on there and I'm thinking the stretching probably contributed to its deterioration. As it is though the rest of the hose looks fine so I'm probably just going to clip that end off and put the hose back on.

I did manage to get the manifold off without breaking anything, but the later attempt to remove the turbo from the manifold ended up breaking off two more studs. The first attempt got one stud off and we were feeling good, but then the other two just broke right off.

The turbo looks okay, spins fine, but definitely a gray to white coating on the fins indicating I've run lean. Not surprising with the bandaids and the inexact nature of the tuning. Probably the only thing that has saved me is that I only autocross the car for the most part.

I ordered a new 10mm stud kit for the turbo to manifold connection and we'll see if the manifold can be drilled out for 10mm. A friend has taken it to a machine shop for me after we aborted a try at a DIY fix.

I also ordered an upgraded PCV valve as I'm noticing some oil getting out from the system, I installed that, but I think the spring clamps on that hose have given up the ghost so I need to get some new clamps.

I also got new Mazda Comp motor mounts installed and I must say it is really easy to install them when the manifold is completely removed.

How's that for easy access to the driver's side mount?

This is the old driver's side mount. Nice crack!

This is the other side of that same mount. Hello crack! So, it was a worthwhile exercise to replace them.

This is the view from the passenger side wheel well. The empty holes are where the mount lives normally. Please to ignore rust and dirt as this car sits outside a lot and gets detailed infrequently. It is extremely easy to remove the passenger side mount from in here whereas pulling it out and up past the intake manifold would suck. I will say that it's easier to break loose the bolts from up top, but you can pull the whole mount assembly out through the wheel well.

My major mess up so far is that I had the AIT bung welded to the intercooler, got it back, started to screw the AIT sensor into the bung and then I met some slight resistance. This is the part where you stop and reexamine, which I did, then I put it in again, some more resistance, this time I hit it with a wrench for a turn and that was it, cross threaded it. Idiot! I pulled it out with the impact wrench because it was jammed in really well and then got so pissed that I just blasted the thing back into the hole under the theory that if it was jammed in that well it would just stay there.

Then I came to my senses and ordered another sensor and bung. Back to the welder with my idiocy on full display. This is probably for the best as he welded the bung onto the wrong side of the intercooler and the sensor was pointing forward instead of backward. I hesitate to blame him for this as it is quite possible I just marked the wrong place on the thing. I figure he can cut the busted bung out, close it up and weld the new one onto the other side. Failing that the IC is $70 from cxracing. I feel pretty bad overall for letting that whole situation get away from me.

Sounds like you're doing just fine over there on your own. Modified greddy setup? Have you dynoed the car to see whassup? I'd be interested to see what numbers you're putting down pre and post MS3.

We had a dyno day a while back and it was running lean then (I updated to the BEGI AFPR instead of getting different discs for the Greddy and got a wideband after that) but, at the time it was putting down about 140-145hp at the wheels. Which was basically on wastegate boost pressure which topped out at around 5psi. Most of the components are the same since then. Have the 2.5 downpipe vs the tiny Greddy downpipe, that makes a nice difference in spool up. The intercooler setup keeps the thing from heatsoaking at all, lots of headroom for more boost when I start using the MS for engine management.

I did order a new 3" Enthuza exhaust as part of my upgrade so that will make some difference. As well, I will be removing the MAF as part of the MS upgrade so having the intake opened up will help spool as well. I have a set of RC550 injectors for fueling.

Those numbers sound about right for a Greddy kit with the Greddy downpipe and other support parts. I'd say with your injectors you'll have more than enough fuel room to push it. My Miata was running 10 psi on a BEGI SSM kit and the 440cc injectors on that weren't anywhere near maxed out. Your injectors should do just fine.

Your exhaust setup sounds good for a moderate hp car. You know from spending time at MT.net that they advocate a 3 inch all the way back. That might be hard for you to do due to your Greddy setup and it's high mount point for your turbo. Making that bend to clear the firewall curve down will be tough with a 3 in exhaust. If you're happy with the 2.5 in I'd say don't even worry about it. I do wonder what benefit you'll see from the 3 in exhaust. I'm assuming the Enthuza exhaust is a cat back system.

I had an MSPnP on my car and it was fun. Since mine was a 1.6 it had some trouble idling with the AC on. I was eventually able to get it to work pretty well without changing out the throttle position sensor to a 1.8 TPS. Cold start tuning was a bitch. I know I spent some quality time in the driveway tweaking it. Power tuning was a cinch when I used the autotune feature. Mad Scientist Matt on this board should be able to answer any MS3 questions you might have. He is affiliated with DIY Autotune.. I can say that because they're a GRM sponsor.

What's the goal and purpose for this car?

Btw - don't feel bad about breaking studs. The steel studs get brittle from that exhaust manifold to turbo connection from the heat. If they don't deform and stretch then breaking is the next thing they try. 10mm studs might help a bit on the street but if track time is involved you'll want iconel studs and Stage 8 hardware to lock it in place. You can get that kit from Flyin Miata and some other places. But trust me in that buying from Flyin Miata will spoil you in dealing with other shops.

I've got the Inconel 10mm studs with locking hardware for the turbo to manifold connection on the way. That's one of the set of parts that I've been waiting on.

I've got a BMW TPS with pigtail that bolts up to the stock throttle body. I just have to wire it in. Then I'll have the variable TPS since we know the 90's TPS is worthless.

Yeah, the Enthuza is catback. I'm gonna remove the high flow cat I have on there as well since I don't have to pass emissions anymore and I pretty much just drive the car to races and back. Everyone is saying that even with the 2.5 downpipe that the 3" will make a difference. We'll see. If anything I can always take it forward with the next manifold/turbo/downpipe combo I come up with.

Taking off the airbox is supposed to help a lot with spool up as well since that AFM has such a small inlet.

I just want more power for autocrossing. The car has been upgraded with Tein Monoflex coils (12kg front and 8kg rear springs), poly bushings all around, FM front bar, 97 Torsen rear. Rolled the fenders and it runs on 15x9s 6UL wheels for autocross.

I'm thinking I might just pull the AC as it has a leak and still runs on R12, which is stupid expensive. I haven't used the AC in ages and really have no intent to do so.

At some point I might just swap in a built 1.8 or 2.0 stroker motor, but that's when I have money coming out my ass.

New stuff to mix with the old stuff. Someone will probably buy my old stainless exhaust off me (hopefully) to make up for some of this.

Okay, so I finally got the manifold and turbo back from my friend.

The busted studs are drilled out and the holes redone for 10x1.5, which is fine as the new studs thread in without an issue. The turbo though didn't get drilled out quite enough so I'll need to either massage those holes with a dremel or possibly just go drill a little bit more (better less than more I suppose). Then I need to deal with one hole on the manifold that is slightly pointed off to the side so the stud doesn't point quite the same way the others do. I think once I get the turbo holes to fit the studs I can just put it on that one stud first and then put the others that are straight in and it will work, but we'll have to see.

Stud holes on old manifold did not line up. Needless to say I was pretty pissed since I had to wait for a month to find out that it did not work. Soooo, I contacted the one guy that makes a custom Greddy manifold replacement and this is the result.

And then I took it to an actual machine shop to have 10mm stud holes put in and wonder of wonders it fits the turbo.

Getting it powder coated now.

Manifold ceramic coated (cerakote high temp).

Criminy, got everything together then I went to install the new injectors. I've had the damned fuel rail off several times, but this time the second bolt decided to seize up and break off.

I'll drill it out tomorrow after the little bit of fuel that came out of the rail dries off.