Yet another Miata..

So I've never really done a build thread before, but this seems as good a place as any to have one. I've spent a good bit of time over on a particular cat-related boosted Miata message board and while very knowledgeable, you lot seem a bit less serious and that's something I can get behind.

The story starts with some background on myself. I grew up a car guy in California's central valley. Hot wheels, model cars, Gran Turismo - for whatever reason, I was hooked from an early age. In high school I saved up my pennies and bought a 96 Mustang GT. Like any kid with a V8 "muscle car," I thought I was pretty hot E36 M3. But, it was slower than my buddy's LT1 Camaro. Unlike some of my friends, my dad wasn't particularly interested in wrenching anymore, so armed with nothing more than early message board tutorials and a Haynes manual I set about performing the "PI" head/cam/intake swap. My parents thought I was crazy (the car ran, and now it's in a million pieces?!), but the car modification bug had bit me. Soon after followed some Eibach lowering springs and cheapo Tokico shocks. I brought the car with me to Clemson for college, where I discovered autocross, and so did the Mustang.

It didn't help that the course was designed by a guy who drove a Miata:  https://www.youtube.com/watch?v=4q0oHvvMRv4

I laughed at all the so-called "sports cars" in our sports car club (a Civic? Miata? those are for commuting and hairdressing), but was quickly humbled. My car was destroyed in the turns and, let's be real, it wasn't that fast in a straight line.

An internship brought me back to California for the summer, and I needed a commute car. I found a bone stock 1995 Miata for $2200 on Craigslist, sold by an old man because his wife didn't want to drive a standard transmission anymore. It was a little dirty, but it could chirp the tires in 2nd gear, had cold air conditioning and the price was right. Once again my parents questioned my sanity (or maybe my sexual orientation) but I loved it. I later discovered the tan top indicated the Popular Equipment package - which meant my car had the coveted Torsen limited slip differential, and (more important for my daily commute) cruise control.

Of course, the flimsy stock suspension wouldn't do, so I scored a set of coil-overs from a friend at college for $450 shipped across the country. They were a set of spec Miata take-offs - Bilstein shocks, ground control coilover sleeves, ISC racing top hats, and stiff-as-hell Eibach springs. Also included was the SM-spec adjustable rear sway bar. I wrapped the stock 14" wheels in the stickiest rubber my college-strapped wallet could afford (some Falken RT615's) and joined the SFR SCCA for some autocross fun.

https://www.youtube.com/watch?v=C2RpB2sLaRw - SFR SCCA Autocross

This was summer 2010 - and yes, I spent 2 hours a day in a Miata with 200tw tires and SM suspension. In California. If I have back trouble in my old age, it will be the thousands of miles I spent driving over potholes on I-580 in this car. It was around this point that I added a set of FM frame rail braces to try and quell some of the shimmying.

The next year at school, I discovered track days. My roommate had a Miata with which he participated in SCCA time trials. One weekend co-driving at the Talledega Grand Prix course and suddenly autocross seemed pretty... tame. Why stand around in a parking lot all day for 2 minutes of seat time when you could spend a bit (well, a lot) more and get more seat time than you could handle? Here's a video from my very first track weekend... https://www.youtube.com/watch?v=xdA--mLemJI

I had also joined our student ASME chapter, which was building a 240sx for the 24 Hours of LeMons. Talk about jumping into the deep end!

I believe this video is from our second year: https://www.youtube.com/watch?v=H-hCfsGkzAU

Once again summer came and that meant going back to California to work. With my mind on driving some of California's amazing race tracks, I bought an old Hard Dog roll bar from another college buddy. Life pro tip - if you need to ship something bulky, check out Greyhound. If it'll fit under the bus, they'll ship it for far less than any of your more traditional options. However, I was in a bit of a pickle. At 6'3" I barely fit in the Miata to begin with, and I still needed the car to commute in. With a healthy fear of being rear-ended, and in the interest of being secure on track I scored a Kirkey aluminum racing seat off Craigslist and bolted it straight to the floor. With this setup I cleared the broomstick test, with a helmet, by 2 inches.

This did have the added side effect (benefit) of making the car very difficult for shorter people to drive. My mother is 5'8".

With the addition of some free EBC Yellowstuff brakes (thanks to a promotion on Miata.net), and required safety equipment squared away, I signed up for my first track weekend in the Miata.

While the car survived the track day, the radiator end tank cracked about 1 mile from the gate on the way to dinner with some friends I had made that day. Thankfully, one of the guys had a trailer which allowed me to tow the car back to the track, where we could figure out what to do with it the next day. After riding in some awesome cars driven by very good drivers (GTR, Cayman R, modified Evo X) one of the guys called AAA to get me to Sacramento. After dumping me in a Walmart parking lot, I then used one of my AAA calls to get the rest of the way home. A Koyo stock-replacement radiator was installed, along with a new timing belt and water pump, because the car had 140k miles at this point and no documentation from the prior owner on when that might have been done.

The car remained dead-nuts reliable and in this state of build for the remainder of its time in California. It made a couple trips to Laguna Seca Raceway, one more to Thunderhill and many drives over Mt Hamilton. I still did a few autocrosses every now and then - Sacramento, Stockton, and San Francisco - but I preferred the flow of track driving to the violence of autocross.

After finishing grad school in 2013, I scored a job with Michelin in South Carolina and had the car shipped out. I guess we'll call this "Chapter 1 - California" of the build. I'll write up what's happened since moving to South Carolina soon.

Subed, I am enjoying this to much! 

Chapter 2 - South Carolina!

After moving from Clemson up to Greenville SC, I finally had a garage (albeit a 1-car apartment garage) in which to put my Miata. First order of business? Road Atlanta track day, still with California plates.

Behold my lack of familiarity with Road Atlanta: https://www.youtube.com/watch?v=HDypnXS3voQ. It was around this point that I realized my car was slow by even Miata standards. I left the car well enough alone for the next year or so, apart from a wheel/tire upgrade, while deciding what to do about the lack of power. Test fit here:

I had also sold the Mustang near the end of my college career to buy something a little more sensible.

A 2005 Subaru Legacy GT. Of course, I can't leave well enough alone. H&R sport springs, Koni yellows, whiteline RSB, downpipe and a tune. Made 250whp on a Mustang dyno and was a joy in the twisties. Think of it as the thinking man's WRX. It ran a 13.5 1/4 mile in Atlanta - over a second faster than I was ever able to manage in the Mustang. And, it could carry 4 people, got 30mpg on the highway and could actually turn. It sounded like a vacuum cleaner with the stock catback, but I enjoyed the sleeper effect. It was here that I was first introduced to the world of tuning, and though I let someone else tune the car remotely, I followed along with the changes and got a rough idea of how it all worked and played together. The open-source community has reverse-engineered these Subaru platforms, so with some free software and a $7 cable you can reprogram the ECU at home.

Chapter 3 - Finally, something GRM might be interested in

Fast forward to 2015. I'm tired of being passed by 1.6 Miatas on the back straight at Road Atlanta. Here's a video, feel free to witness the slowness: https://www.youtube.com/watch?v=t1EkIydgsM0

Along comes a listing for a Miata being parted out, come get what you want. I bribe a couple buddies with lunch and we head up to Charlotte and pull this, along with the header full engine harness, from the 52,000 mile car for $650.

The keen-eyed among you will recognize this as the NB2 VVT engine. This header is desirable over the 99-00 unit for reasons, so I was able sell it for $200. So, $450 for an engine, trans, wiring, and everything attached to it. Pretty good deal if you ask me. The VVT engine was chosen because I like technology, and the strong mid-range would be good for driving through the mountains. The 99-00 engines are desirable for the Spec crowd around here, so they're also far more expensive. My eventual goal was to have 150whp without doing any internal work, a number my Google-fu led me to believe was reasonable. I would try to save money where I could, but given the choice between cheap and reliable I choose reliable.

I would need something to control the whole mess, and the easy button for Miatas is obviously something MegaSquirt. I don't like bandaids, so something MS3-based was required to run the VVT, and the NB alternator should I choose to keep it. I wasn't yet comfortable with my soldering skills, so I hit the easy button and ordered an MS3Labs MS3 Basic. While that was being built, I bought an Innovate LC-1 wideband locally and installed in the car to see what the stock ECU was up to. The LC-1 has two programmable outputs- by default, one is programmed to emulated a factory narrowband signal, and the other is a 0-5V wideband signal (for use in a gauge or aftermarket ECU). After learning what a terrible invention quick splices are, I managed to get this working and drove around for a while learning. It turns out the factory ECU runs the engine at 14.7:1 up to 4k RPM, and beyond that is pig-rich (11.5:1 or so).

Finally - the Megasquirt arrived! Rather than do the reasonable thing and attempt to run my original engine on the Megasquirt, I decided to throw everything in the car at once. What's the worst that could happen? First to go was the air conditioning, because race car. It's only South Carolina, how hot could it be (stupid).

Pulling the engine from the parts car was good practice, so other than an excessive amount of grease and grime (and the space limitations of a 1-car apartment garage) the engine came out with little drama.

Look at all that space!

Did I mention the engine and bay were extremely greasy? A buddy and I rolled the engineless car out of my garage and into a parking lot space we thought my complex wouldn't notice. I was the first tenant of this garage...

We spent the better part of an afternoon and an entire bottle of Scrubbing Bubbles Max Degreaser (this stuff is magic) cleaning. It looked much better when we were done.

At this point, I moved the car back into the garage and spent the next couple weeks making sure all my ducks were in a row. Thankfully, the internet took most of the guesswork out, but I wanted to double and triple check that everything had been moved over correctly. I also found a good deal on the coveted "flat top" intake manifold out of a UK junkyard, and a Racing Beat NA header. Since the NA car runs a return-style fuel system and the NB was returnless, I had to modify a 99-00 fuel rail to accept a 90-93 fuel pressure regulator, mounted upside down, with the fuel inlet bent a bit. Thank you, internet, for figuring that out for me. Once the fuel and intake situation was more or less figured out, the engine could go in.

Install is reverse of removal. Well, except none of the plugs have a home anymore.

I'd never read a wiring diagram, and purchased my first real soldering iron for this project. Wiring between the NA and the NB2 is similar, but different enough that you have to re-do just about everything. Thankfully, my parts car pull came with the entire harness. The IAC valve and TPS sensors were re-plugged. The new engine ditches the NA style coil pack for modern coil-on-plug ignition. The NA also got both cam and crank signals from the cam; the new engine, with variable valve timing, has separate cam and crank sensors. For the VVT solenoid, I repurposed some of the factory EGR wiring. The IAT sensor used repurposed MAF wiring. Power, signal, ground, and on it went. Everything was joined with a lineman's splice, soldered and heat shrunk.

With the rest of the hardware buttoned up and everything on the checklist checked off, I began testing everything in TunerStudio. The TPS was responsive to inputs. IAC valve clicked. VVT solenoid clicked. Injectors clicked. Spark plugs zapped. Starter turns the engine over. Enable the fuel pump. Fuel pump primed. And primed again. And once more, for good measure. Turn the key and....

...Nothing. Panic! My car ran, and I've spent all of this money and ruined it! Calm down, start trouble shooting. I can smell unburnt fuel, so it's getting fuel. I heard the spark plugs when testing, so there's spark. Revisit wiring diagrams... wait a minute. Switch front and rear coil pack plugs (I'm glad I made them long enough to reach). Turn the key and.... noise! Here I am doing my best Dr. Frankenstein impersonation.

https://photos.app.goo.gl/YtHn4W7cc51RkgUx8

Up next... some tuning, and then the dyno!

Chapter 4 - As much power as you can get from a N/A BP without opening it up

The last week has been pretty busy, but I'm back!

I found out after putting everything back together that the shifter for the 5spd in the later 01+ cars was different than the one in the 94-97 cars. The shifter on the trans I pulled had already been sold. I ended up having to buy some new pieces from Mazda and I was back in business - but not before taking the car on a drive around the block without the shifter.

There was a considerable amount of wiring to clean up and fiddling with the tune until I was confident it would survive a dyno session. I also put together this pretty neat intake solution, courtesy of some Miata community members. 3d printing - welcome to the future!

The keen-eyed will notice that is the factory MAF sensor there in front of the intake. I gutted it, drilled a hole through it and mounted the IAT sensor there. Maybe not the most elegant solution, but it worked, as the following dyno chart shows.

151whp and 127ft-lbs, torque curve as flat as Kansas, with the engine still pulling hard at the 7000rpm redline. I was pretty thrilled with these results. Finally, I wouldn't have to watch as Miatas and 4cyl E30s left me for dead on every straight and corner exit. The car felt great on the street, and was almost fast. I ran it in this configuration for about 2 years, constantly fiddling with the tune to improve drivability. Tuning for WOT is pretty easy, but ironing out cold starts, smooth idle, elevation changes and acceleration enrichment took considerably more effort. Tuning cruise for decent gas mileage was also a fun challenge. I ended up with a fuel map that looked something like this.

Lean cruise didn't seem to cause any issues with drivability, and I was back around 28-30mpg when I was able to keep my foot out of it (not often). Pretty good for 225 width BFG Rivals.

I did found myself in a bit of a pickle once again on the track, though. Here's a video from Road Atlanta -skip to 1:13 if you want and take note of the closing speed on that Miata ahead of me.

https://www.youtube.com/watch?v=SO8PiynGVuM

I had done such a good job with the power that I was once again in no-man's land. Faster than the other Miatas, but slower than just about everything else in the advanced run groups I ran with. I looked longingly over at the dyno chart from my Legacy GT...

... and thought, wouldn't it be fun if my Miata had that much power?

Looking forward to see how you fit an EJ255 into an NA Miata.

Adam

adam525i said:

Looking forward to see how you fit an EJ255 into an NA Miata.

Adam

Now there's an idea...

I'm jealous of the VVT engine... technology is a good thing!   Is there any chance of getting more pictures of your custom intake system?  are you running a filter?

Also, since i have your attention,  how about a snapshot of your ignition table.... asking for a friend. 

In reply to Doc Brown :

Yep, filter is installed right below where you see the intake going under the finish panel. Positive pressure zone (in front of radiator) and cool air. The 3d printed part is constant cross-sectional area, and the cord length from throttle body to filter is the same as stock. More info here https://www.miataturbo.net/engine-performance-56/3d-printed-intake-n-na-miatas-76193/

I don't have my laptop on me but this is my ignition table now - the sub-100kpa rows are the same as before (just interpolated) 

Tha is so cool!  thanks

Chapter 5 - Boooooost

After a considerable amount of reading, it looked like the most reliable way to get more power out of my car without throwing out all the work I'd already done was to add boost. As I mentioned before, I'm an engineer myself, so I'm a sucker for technology. The BorgWarner EFR series is packed with tech and cool features - super lightweight rotating assembly, built-in bypass valve and boost controller, efficient wastegate design... The combination of awesome transient response and room to grow had me lusting over an EFR6258. On one of my trips out to the Bay Area I stopped by Trackspeed engineering and went on a ride with Andrew in his shop car - an NB Miata with their Trackspeed EFR6258 kit - and I was sold.

So, I took my bonus from that year and threw my credit card at various Miata suppliers from around the country. EFR 6258 kit, Precision 350hp intercooler, and FlowForce 660CC injectors from Trackspeed Engineering. The lovely Flyin Miata Stage II happy meal and 16-row oil cooler from our friends over in Colorado. Full 3" exhaust from Artech. I blew my budget-build guidelines out of the water here but... I like nice things, and since I was building the car with track duty in mind, I figure it'd be cheaper in the long run to build it right the first time.

Stage 1 was to install and tune the car with the new injectors, along with the clutch. I also prepared the turbo for installation - the wastegate actuator and turbine housing have to be rotated to fit. Pretty:

Unfortunately I don't have any pictures of installing the clutch but... it wasn't very exciting. Easiest clutch job I've ever done. Let me say this - The FM Stage 2 clutch is the best feeling clutch I've ever driven. The weight is just right, it engagement is perfectly linear. I couldn't ask for more. I don't understand those guys who do ridiculous puck clutches and sacrifice drivability. The pedal is heavy, on account of the heavy duty pressure plate, but I love it.

After tuning a track day with the new injectors and the clutch was broken in, the car came apart again for the turbo install! Aside from waiting for parts - the exhaust took about 3 months to show up - the install went pretty smoothly. The scariest part, for me, was drilling the oil pan for the drain plug. Here are a couple pictures mid-install.

The TSE kit includes nice hard lines for the coolant, as well as the correct lines and fittings for the oil supply and drain. Oil supply is teed off the line that also feeds the VVT actuator. That area also has the sandwich plate for my oil cooler, so it's a little crowded.

What the kit does not include is provisions for mounting or plumbing the intercooler. I ordered some aluminum tubing off the interwebs and phoned a friend to help me fabricate these. 

I'm pretty happy with how the intercooler piping ended up. We achieved the minimum number (4) of couplers and everything was tucked up pretty well. What followed was some drama with the exhaust (artech used a different flange for the catback than TSE used for the downpipe. However, the car sounded awesome without it... First drive!

https://photos.app.goo.gl/zVtZ3g7SxTk3ER8T8

Double post!

After a considerable amount of fiddling and tweaking on the street, I signed up for another track day at Atlanta Motorsports Park. There is a shop there (Racing Analytics) with a dyno that had graciously agreed to allow me some dyno tuning time the day before. Here's a pic all loaded up for a combo dyno and track weekend.

All loaded up on the dyno

And what's a dyno day without video?!

https://photos.app.goo.gl/yGfrVidRfucEjFgc8

My strategy for track day longevity was to run wastegate pressure at the track, and ~10psi on the street. Here is the resulting 10psi dyno chart...

250whp and 220ft-lbs! Hit my target on the nose.

It made 220whp and 208ft-lbs on wastegate pressure (~8.5psi). Making such big gains with such a small change in boost means the turbo is still well under its efficiency threshold - meaning less heat, and more headroom if I want to crank it up later.

More to come, but it's time to go home....

Well I let this story by the wayside, but between that trip to the dyno and now the car has seen track duty at Road Atlanta and Atlanta motorsports Park. As long as I keep it cool the car runs great. 

About a month ago I took another trip to road Atlanta. To prep for the colder weather I installed the low boost cannister from borg Warner and ran about 4mm of preload, as opposed to the nearly 0 I was running before. The car seemed to like this setup better, and even though I made less boost, response was quicker and better controlled. 

This was also the first outing on a suspension refresh. Xidas gen 2 coil overs and new poly bushings all around. New bfg Rival S tires as well.

All this was good for a 1:44 lap, a solid 3 second improvement over the best I achieved last weekend. I would attribute most of that to the tires, but the car felt pretty stable with no snap tendencies, and some mild turn-in understeer. This was with the stock front sway bar and no rear bar. An upgraded front bar is probably in my future.
The car ran solidly for the majority of Saturday, with the exception of the power steering belt slipping off one rib. I'd feed it back on, and by the next session it'd be off a rib. In the last session on Saturday it launched the belt off completely, so I spent the rest of the weekend without power steering as the Miata gods intended. Neither the crank nor the p/s pulley had any visual runout, so I'm not sure what the root cause is... but I'll just take it as a sign that I should remove the P/S completely.
More seriously, on Sunday AM during my look over the car, I noticed a bit of an exhaust leak around the manifold to head connection. One of the nuts was loose, so I tightened and...

It wasn't the first time I'd found this nut loose, and it looks like the face of the manifold isn't quite flush where the nut is supposed to seat. So I'll have to either grind down that nub on the manifold, or come up with a spacer of some sort so the nut has something to bite on. New studs and nuts are on the way from Mazdaspeed. I still managed to put in about an hour and a half of track time on Sunday, including a successful check ride for Chin's red group. I still can't keep up with a well-driven 911 or Corvette, but I can give some of the Mustang and Camaro guys a hard time. 

Next up, air management... Splitter, under tray, brake ducting, hood vents and likely a rear spoiler. Has anyone used a NACA duct from a splitter/undertray to feed brake ducts and/or an oil cooler?

Of course, this post is worthless without video

https://www.youtube.com/watch?v=RRsk7v1r8to

I'm in Montgomery Al,  3 hours from Atl. Any suggestions on what I need (and how much $) to get on track there?  I have a 2000 NB with a Hard Dog roll bar and EBC pads up front 

In reply to Justjim75 :

That's enough equipment to get you started! Check out Jzilla - they're a more budget oriented group for track days. Really fun group, and they have instructors for all novices. Chin motorsports is more organized and a step above, but also more expensive. I believe both groups have track weekends at Barber motorsports park, which would be a little closer for you. 

https://www.facebook.com/jzillatrackdays/

I love the TSE manifold. Jealous. 

Maybe I should run less timing. Did you tune timing on the dyno? I guess you don't really hit the top of the map yet, are you going to be able to avoid the temptation?

In reply to dr_strangeland :

I tuned everything up to about 175kpa. That's how much I run on the street. I turn it down on the track for heat management purposes.