My first turbo build; 230ish HP build thread
 

Okay so I bought all the parts I've been planning on and I'm finally ready to start logging my progress on this build. I have a 1999 base miata with 5-speed manual. When I got the car, the previous owner had installed FM frame rails and some koni coilovers (idk what kind, they just say koni on the side). AFAIK that was all that was done to the car before I bought it.
First I started with a hard dog roll bar as my first upgrade.
Next I upgraded wheels to some wheels sold by flyin miata, but that section of their website is down right now. So I can't remember the specific wheel. I think they were either 15x7 or 15x8. Can't remember.
At this time I also upgraded some tech in the car. I put in a touchscreen double din radio, backup camera, and a usb and aux passthrough for the radio into the ash tray since I don't smoke.
I also replaced the torn factory tan (:barf:) soft top to a replacement black vinyl one from robbins (w/ heated glass).
My radiator decided to crack next so I put in a koyorad radiator to replace the crappy stock one, since I already knew I wanted to turbo.
After that I deployed and didn't touch the car for almost a year. I just got back in May this year and have been seriously planning my build since then.
While deployed, I read and learned a lot about turbocharging and I decided that I want a turbo with my final power to be in the 230ish WHP range since I felt that would be easiest to reach without having to get too far into the weeds with replacing transmissions and building the bottom of motor and all that. I've never done any of this before so I didn't want to bite off more than I could chew either.
Some pics so far:
https://cimg3.ibsrv.net/gimg/www.mia...0d1dd91fd9.jpg
https://cimg4.ibsrv.net/gimg/www.mia...381c7a964c.jpg
The radio and USB passthrough (probably the most life-changing upgrade I did):
https://cimg5.ibsrv.net/gimg/www.mia...53b0623e0f.jpg
https://cimg6.ibsrv.net/gimg/www.mia...2d0cb7e494.jpg
https://cimg5.ibsrv.net/gimg/www.mia...54c7eb2006.jpg

Since then, I decided to go with a Garret GT 2560R build using the flyin miata manifold and downpipe into the stock exhaust. With a goal in mind I bought and installed:
Flyin Miata boost guage w/their pillar guage pod
MSPNP2 (rev v1.3 board i think; the board is green)

All of these had hiccoughs (ie I posted about how I somehow corrupted my megasquirt firmware), but I got them installed and began tuning the car. I wish I had read more about tuning before installing the megasquirt onto my daily driver though (I'd imagine everyone says that, but I'm especially retarded). I had work the next day and didn't check the weather or if my motorcycle (backup transportation) was even running. It's okay though. I survived my extremely poor planning that (very cold and wet) week with many a bump start (I do leg day so it was easy to push back up the hill up to 10x in a row). And I learned a valuable lesson: turns out that it takes more than 2 hours to go from knowing almost nothing about tunerstudio to having a well-tuned, driveable daily driver. Even N/A. Also recently learned that my bike has a prime setting on the fuel selector, reducing my bumpstarts from 10 or so down to 2 or 3.

A couple weeks of tuning and commuting on my crappy $500 motorcycle brings us to today. I got the car to the point where I was confident driving it on the road, so I installed Force Flow 640cc injectors and bought the rest of the parts I've been planning. Tuning for the injectors has been giving me problems, but I already made a post about that here. Here's the list of parts I bought on top of what I already have:
Garret GT2560R turbo
GM IAT sensor
FM happy meal clutch/flywheel (also got a rear main seal since it can't hurt to replace)
FM manifold/downpipe combo
FM hard lines for turbo oil/water
CX racing intercooler (I think it might be too big for my needs, but it looked high quality without being ridiculously expensive)
Forge dual piston BOV (VTA because cool sounds and Megasquirt MAP sensor, AFM/MAF or whatever it had)
Turbosmart manual boost controller

For intercooler piping I bought some stuff from silicone intakes and I'm intending to follow what this guy did on his car. This is the part I'm most unsure about right now. I'm keeping AC and power steering and I want to go with 2.5" all the way from compressor, to intercooler, to throttle body. Cold side of intercooler looks straightforward, but I'm not sure about the hot side. I'm not in love with the idea of cutting through my car to route things, but I'm not too sure about going over the top of the radiator either. Though I'll admit that I haven't looked into how to do that too much. I have some questions about how to mount/create mounts for the radiator to make room for the piping. And also if I can get away with not cutting channels in my hood. I'd also appreciate it if someone smarter than me could tell me I'm being stupid and don't need 2.5" for just 230 WHP.

I realize I should have probably made a post like this before spending around $4000, but I'm pretty confident that the big ticket (>$500) items are good choices for my goals. I'd appreciate any advice or suggestions though since I'm pretty new.
It should also be said that although I'm new to DIY aftermarket turbos and tuning, I do have a background in aviation maintenance so I feel pretty confident doing most tasks and installations without screwing things up, it's just the planning and design that's very new to me. Also tuning. I've never done anything like that before, unless you count overclocking a gaming computer.

My goal for this is just to kinda document everything I'm doing and all the problems (and solutions) I run into as I go along.

2in pipes are good for over 300whp. Go around the side of the radiator instead of over the top.

Update, turbo is installed.
https://cimg0.ibsrv.net/gimg/www.mia...0c0a0a3f1e.jpg

Now for the questions:

As you can see from the picture, I have the waste gate safety wired open. I just feel most comfortable waiting until I get to the dyno to tune with boost, so I'm leaving it this way until dyno time. It sees like 1-2psi at WOT, but I'm fine with that for now. I used my VE map from my N/A tune to extrapolate what would be enough fuel for boost in those low boost VE cells, then added a bit of fuel to be safe so it stays rich, plus I just stay away from WOT so it avoids boost in the first place.

If you look at the front of the engine, below the yellow clip, you can see the white plug going to the IAT sensor. I went with the GM sensor that diyautotune recommends for megasquirt. I already notice heat soak being less of an issue than before with the stock plastic sensor. Is this a good spot for the sensor? On the opposite side of that pipe is the tee off for the blow off valve.

I decided to use 2.5" piping on the cold side of the intercooler (since I already bought the piping), but after the pain I had routing the cold side with silicone couplers and pipes, I decided to do the easy thing and buy the FM silicone intercooler hot side piping. It fits fine, but it rubs up against the control arm hardware (not the arm itself, just the washer at the forward end of the link to the subframe). Should I be worried about that or should I find some way to make a bracket that keeps it away from this potential source of friction? Are the FM pipes reliable long-term or should I get a welded pipe setup at some point (for both sides)?

I had an issue rerouting the lower coolant hose because I failed to purchase the proper hose. I eventually went to home depot, bought some copper pipe, rolled some beads on 2" pipe sections, bought some hose clamps, cut up the stock lower rad hose, and figured out a routing that works for me. That said it rubs on almost everything in that area (except the belt), so the proper hose is on its way. I just wanted to finish the project so I MacGyvered the stock hose. Idk how the FM lower rad hose routes, but this might help with the issue above by making more room for the intercooler hose. I won't really see until it gets here. I don't mind paying for it since the stock hose is pretty worn (not to mention the abuse I've been putting it through with chopping it up and routing it different from stock).

I used the hard lines for water and oil, and they seem to be working fine. Driling the oil pan wasn't nearly as bad as I thought it was gonna be, just really tight trying to get a drill in there with power steering and AC.

The only significant issue I'm having right now is that I misread instructions while purchasing and installing the kit, and I'm using the wrong fitting for the oil feed (1/8 npt to -4 AN instead of the correct 7/16x24 flare to -4AN), so I'm waiting on that part to come in before I can enjoy the car :cry:. I went with a fitting with a 0.35" restrictor on it since apparently BB turbos need that. Will 0.35" be a good size restrictor or will I need to drill it out a bit to 0.40-0.50 or so? The 1/8 NPT fitting tricked me by not leaking at idle, so I took it for a test drive. I guess I'm lucky that the thing decided to not fall out and cut off oil from the turbo. After doing some research and troubleshooting is when I learned that I had the wrong fitting (oops). Close call there, but it'll be fine once the correct fitting gets here.

Also, FM said that the EGR pipe from stock 99 NB cars will work with their manifold, but when I tried to connect my pipe, it was female pipe to female manifold port. After research, someone on some forum somewhere said that manual cars come with different EGR pipe than automatics. Is this true? And does anyone know if I can get the automatic EGR pipe to fit on a manual? I'm assuming there's a different geometry with the trans tunnel since they had to change it. I got super lucky and autozone pulled a miracle by having a set of plugs that worked on both the manifold and the EGR pipe, so I can drive it around without either an exhaust or vacuum leak. But it's still pretty annoying that FM was wrong (or maybe the doofus who owned the car before me swapped the exhaust and EGR, but that seems unlikely). So I'll have to buy a 99 automatic EGR pipe and swap that in (for Texas emissions).

To pass emissions in Texas, I need to have the stock ECU with no codes in the car. Here's my strategy so far:

1. Swap ECU back to stock
2. Swap injectors back to stock
3. Remove hot side intercooler piping (boost to atmosphere)
4. Connect the AFM pipe and stock temp sensor to the throttle body with a silicone adapter and use a cone filter
5. Connect the crankcase breather to the AFM pipe post-sensor (is this even necessary or could I leave it going to atmosphere?)
6. Reinstall the stock O2 sensor

Am I forgetting anything? The two things that I'm worried about with boosting to atmosphere are FOD and lack of back pressure on the turbine wheel. I'm also worried that the presence of an exhaust restriction (in the form of a turbine wheel) might throw some sort of code (though I doubt the car is smart enough to detect that).

The intercooler will only be exposed to the inside of the bumper so I'm not too worried about road debris, mostly dust, fine particles, and critters crawling in there overnight (I'll only run this way for a few days). That said, my thought is that the turbo will still be putting out positive pressure to the pipe (even at idle), but will that be enough to keep FOD out? Or should I find a way to put a filter on the intercooler for this?

As for the back pressure issue, I'm just worried that I might overspeed the turbo with a 2.5" diameter boost leak and no back pressure to keep the turbo from spinning as fast as it wants. Is overspeeding the turbo even a possibility? If it is, will the intercooler provide enough resistance to overspeeding, or should I find an adapter to put on the intercooler outlet to bring the pipe diameter down to 1" or so before the boost to atmosphere (or filter). Would 1" be too narrow or would 1.25" or 1.5" work?

I know, a lot of questions, but since this car is my daily, and my backup is a rust bucket 71 El Camino that I keep 40 minutes away from here, I want to preemptively fix the maintenance issues that I know I'm going to run into. Also, the El Camino has massive rust holes in the roof and I don't want to get wet when it rains.

I can't speak for all of your questions, but I'll try to answer the ones that I think I can.

Not quite sure where you're describing, but I'm assuming that the IAT is somewhere in the silicone 90 degree elbow that leads up to the throttle body? If so, then I do believe that is a bad place for the IAT as it will still heatsoak there. If I'm correct, most people locate the IAT closer to the intercooler or tap the coldside endtank of their interooler. I'm not sure about the CX racing intercooler, but I have the FM intercooler which already had the endtank tapped. I just had to extend the wires for the IAT.

I have no experience with the automatic EGR, nor do I know if they are different so maybe someone can chime in on that. I do know that the EGR pipe changed between the 99-00 (NB1) and 01+ (NB2) years. It's as you described, the NB1 EGR has a male threaded nut (threads on the outside) whereas the NB2 EGR has a female threaded nut (threads inside). Maybe this is what you're referring to? A picture may help. I believe if you are using the FM manifold for whatever year, then you just need the EGR for that specific year.

I think you're overthinking this. I was able to pass CO emissions which requires an OBD2 check and a I/M 240 dyno and all I did was swap in OEM ECU, Injectors, wire wastegate open (like you already have done) to not build boost, installed the MAF in front of turbo inlet and reinstalled the OEM O2 sensor.

Not sure what you mean about this question? Is this still in relation to having the intercooler disconnected? Or is this related to exhaust diameter and boost creep?

It's in the aluminum pipe right below that elbow. I didn't know it could still heatsoak in that area. I guess I'll have to find a plug for the hole I drilled there and then move the sensor to the aluminum elbow inside the bumper (right after intercooler outlet).

I should have waited to ask about this. I called FM and they said that 99s are supposed to have a cast stock exhaust manifold, I had a tubular. They told me apparently it's common for N/A cars to swap the 99 exhaust header (and EGR pipe) for a VVT tubular header. My car came with the tubular header, so this swap had been done without my knowledge. If only they had given me the VVT engine too :cry:. I have the correct EGR pipe coming in the mail now.

Hmm I'll have to check and see if I have room in front of the turbo to run the MAF tube and a filter, but that's a good idea.

Yes that was talking about disconnecting the intercooler, but if putting the MAF in front of the turbo worked for you, there's no reason for me not to do the same thing.

Overspeeding the turbo is a problem, to answer that question.

Yeah, there is plenty of wiggle room on the stock ECUs that just sticking the maf pre turbo and tieing the waste gate open (with stock injectors) will run the car just fine. We drove my friend's car around like that for a while making about 2psi above 5500rpm.