In which I take an XP Miata hillclimbing to answer the question: Is Miata always the answer?

This is a story about a car. There are other characters in the story, but in the end the main character is a beat up little roadster with chipped paint and wind-up windows that was being made in Hiroshima right about the time I was starting high school, in a different era, when computers were expensive and slow and a powerful car had 300 horsepower. A neglected, ratty little car with a leaking head gasket and rotted convertible top.

This car.

There's nothing special about it, and maybe that's what makes it special. It's not rare, it's not fast, it's been gently crashed a few times by various people over the years, but it just works. It's only DNF-ed one run in three years and hundreds of runs for me, and that was my fault. 

I swapped the abused 1.6 out for a low mileage 1.8, and started out taking it to autocross, which put the hook in me immediately. The car was slow and outclassed and I didn't know how to set it up, but losing just made me want to go faster. A gutted interior put me in Prepared, so I could give up on the car or build it into something competitive. Of course, I did the foolish thing, and stuck with the car. Once I started spending money on making it faster, though, autocross just wasn't enough of a return on investment. One of the members on this forum mentioned hillclimbing. I didn't even realize there were events that were accessible to the general public - but there are, and once I looked at some of the events near me I decided I had to try and run the 2018 season with NHA, my local sanctioning body.

My preparation consisted of bolting in an FMII with a 2650 over a couple of weeks in the winter. I'd built an MS2 for the car earlier and tuned the spark and fuel extensively under 100 kPa, and basically just mashed together all the dyno tuned BP maps I could find that people had posted for the cells up to 250 kPa, and pulled a couple of degrees around max torque. Such science! I also swapped out the dated Koni sport based coilover suspension that I had built for the car for some Fox units, which I felt was basically a safety modification given the consequences of any kind of handling quirks on the hill. It's absolutely true that I could have spent far less on the turbo kit, and there might be cheaper suspension options, but unlike autocross the consequences of a mechanical on the hill can be much more significant than a cone under the car and some embarrassment. More on that later. 

Not that I knew what I was doing. The only thing I really was certain of was that I needed tons of power, and as little weight as possible. So, I had a crappy Miata with a nice suspension, 1.8 brakes and diff, and a completely stock 1.8 running 16-17 pounds of boost. I bought a HANs, a compatible helmet, and mounted a shiny new extinguisher on the transmission tunnel. I was ready to go! Right?

---

I wasn't really ready, though, for how intense this first season would be.

At the first event, it snowed. Really. In June. 

That went well, I can assure you.

Then, at the last event, a car went off and burned down the hill. 

From one extreme to another. It's not great being at a corner station watching the hill burn down towards the pits where your racecar sits, helpless. 

---

In the end, though, the car did everything I asked it to, and made it clear to me that I was the limiting factor. It was more competitive on the hill than it is at autocross, or maybe that's just me. We made it to four of the five hillclimbs NHA sanctioned this year. The car had some pretty serious changes over the season, which were generally positive although I can't say I gathered as much data as I should have. Data logging is easy enough when tuning on the street, but I need to mount a computer in the car properly to do it on the hill. Maybe an Android device?

I wanted to start a thread about this build earlier in the year, but in the buildup to the season and during the season I simply didn't have enough time. There was always a thrash to get a clutch, or brake lines, ball joints, or whatever in the car before the next event, and it didn't help that I ran a full season of autocross with NWR, and a bunch of events with other clubs. Writing posts on forums doesn't make the car faster. I think.

---

The season's over, now, though, whether I like it or not. It's something like 8 months until the 2019 Cascade Lakes event, and I'm going to have to do something to avoid full-fledged withdrawal. I have hundreds of videos and thousands and thousands of photos, and rather than let them languish unseen on an SD card in a GoPro on a shelf that's slowly but surely draining its battery, I thought I'd share them with you, the insightful, intelligent and almost certainly charismatic members of this forum. Oh, and stuff about the car. Really, it'll all be about the car. This first hillclimb season has been more about bonding with a very special and ordinary piece of machinery than anything else.

And drinking lots of craft beer, because we're out in the middle of nowhere in the Pacific Northwest, and that's just what you do.

---

The first event of the 2018 season was Cascade Lakes, and things started out swimmingly when the car was too low to go on the trailer. But... that was nothing. Things were going to get interesting. 

The drive down to Ashland went smoothly. Got to registration in plenty of time and passed tech without issue. I was worried about the fire extinguisher mount, but it turned out to not be an issue. I want something better for next year that will hold a larger bottle, regardless.

This car is too low for hillclimbing, and also too low to happily go on a U-Haul trailer without ripping off the front lip or hitting the frame rails. I know because both things happened at one time or another. It looks nice, but the hills NHA runs are way too rough for this to work well. It kept creeping up over the course of the season.

Walking the course on Friday, it was strikingly narrow, much, much narrower than it appears in video footage. There isn't really room for two cars to easily pass at speed, and it's not designed for two way traffic. It's also clearly very rough, with unrepaired frost heave in quite a few places. There was a patch of new asphalt that's about four inches lower than the rest of the road, and there was a lot of concern about people getting over it safely. People will have to slow down and use discretion. Nobody seemed very confident about this as a solution. 

---

Saturday morning, got up early and drove up to the event site. The rain started to turn to ice as the road climbed out of Ashland, and by the time we got to the event site had turned to snow. 

Yay, climate weirdness! I feel like I'm doing the right thing driving a small displacement car up the hill.

I left the car overnight at the pit area, never expecting the temps to drop below freezing in June. Now I was worried about the tires getting frozen. There was some discussion about running the hill, but as the snow intensified the start time was pushed back once, and then we were told there would be no runs on Saturday. No practice runs on my first hillclimb ever? I can't say I was super excited. On the other hand, I could drive the car down the hill to where it was reasonably warm, and make some setup changes that I really wanted to make. 

So, we made the best of a bad situation, and drove back down to Ashland, parked the car in the hotel parking lot, and immediately picked it up and added several turns to the front collars and slightly more in the rear. I wasn't going to get my practice runs, but I wasn't going to fly off the road from lack of bump travel, either. Tire pressures were quite low in the cold already, so I left them alone. 

Then found a really solid pub. 

You could do worse than spend a rainy day hanging out in Ashland. Like... trying to preview the course in freezing conditions. Which some competitors made the decision to do. I'm not going to say that drinking is typically the kind of thing that keeps you from wrecking your E36 M3, because it's not. This time, though, going to the pub for a leisurely pint was the right call. 

I like this already. You sound fun. 

That's a crazy pic w/ the smoke from the car off the hill. Good read so far. Glad you decided to share here!

Sunday brought warmer temperatures, but there was still snow on the ground when we got to the hill. One of the competitors had been previewing the course at normal, non-race speed the previous afternoon, and gone off the road. I didn't feel like this was a particularly good sign. 

Some inventive people had built a bridge out of plywood (!) over the sunken section of asphalt, but it was only on one side of the road. Whatever. It was far better than nothing. 

My work assignment: stop box, top of hill traffic control, and grid. Yes, I somehow ended up with three work assignments, but it didn't end up being too difficult. More importantly, I was working in the morning, and running in the afternoon, and the road ended up being a lot drier later in the day.

---

Morning runs finally started after leafblowers were deployed to dry some of the wettest corners. There would only be time for two runs for each group. One of the cars in my class went off after the straightaway on their first run, and had to go up the hill on the wrecker. Then another car went off in much the same place. First runs still hadn't finished. I resolved to drive... really carefully. 

In the end, that's really all I did. It's a super cautious run, and I only had time to work on some of the corners. It's a long road with a lot of unpredictable bends. I think it'll be interesting when the conditions are better, and I have more time to work on it. 

---

So, I only had two runs at my first event, and spent a lot of the time looking at the weather app on my phone. Still, the car was in one piece, and that felt like a victory. We loaded up the trailer and headed back to the dry, warm, sunny city of Seattle. 

bluej said:

That's a crazy pic w/ the smoke from the car off the hill. Good read so far. Glad you decided to share here!

Thanks! That's not even the craziest image from that weekend. Things escalated quickly. 

I decided not to do a build thread on the usual Miata forums, because, while I happened to choose a Miata to learn how to develop a racecar, this is more of a story about going grassroots racing without a ton of money or a fancy, exotic car. I'm also hoping to get useful feedback that I can use to improve the car for next season, and this seems like the best place to get it.

Event #1: Cascade Lakes

Ashland, Oregon - June 10, 2018

Best run: 2:07.29

Run progression: 2:17.26, 2:07.29

10th overall (out of 23)

Tires: BFG Rival-S, 245/40/15

Aero front: GV style lip

Aero rear: Bumper cut

---

This beautiful vintage succumbed to the cold and ended up not running, much to my disappointment. 

This is going to be a fun story.

I’m in to follow along. I’d love to try a hill climb. Does a mostly stock miata require a roll cage to enter?  I have a roll bar but not a full cage. 

The first order of business when getting back to civilization was to place an order with Flyin Miata. There was exactly two weeks until the next event, and I'd noticed some clutch slip under full boost and actually turned the boost down with the EBC table on Sunday. This also made the car a little less likely to break loose in second and third gear, which seemed like a nice side effect at the time.

I pulled the transmission and, yeah, I'm pretty sure this clutch is finished:

It's an ACT Stage 1 organic. It held up well until the end, but I wanted something a bit stronger. The FM Level 2 seemed like it would be overkill, so that's exactly what I got. 

FM managed to turn around my order within a day or so despite a crazy backlog, for which I'm incredibly grateful, because it meant that I had a chance of making the next event. I started taking things apart the weekend before the event, but since there was some transmission oil seeping from both ends of the transmission, I decided to do all the seals at the same time. This took longer than I expected, and by Thursday morning on the week of the event, I was staring at this:

That still had to go in the car, along with the new clutch, and then I needed to load the car on a trailer and tow it 9 hours to Idaho to get registered and teched. Registration was in a public park in Emmett, Idaho, and was scheduled to run until 6pm on Friday. I had time. Barely.

Working by myself, I got everything buttoned up just as the sun was going down, and filled the transmission in the dark.

I didn't have time for a test drive. I had to get up early enough to pack on Friday, which meant very early. So, I went to bed praying that I'd done everything right. If I hadn't, there wasn't going to be any time to fix it.

---

My alarm woke me up at 5am after a night of fitful sleep. Since I don't generally do clutch replacements on my BMWs, this was only the second time I've installed a clutch. On the one hand, this is pretty shameful. Why haven't I done more clutch jobs? On the other hand, maybe it's because I haven't needed to. I tend to drive underpowered, naturally aspirated cars, and simply never wear out their clutches. 150-200k on a clutch? Sure. But then none of these cars got launched over and over at autocross every summer Sunday.

So... had I put everything together correctly? Only one way to find out. I put the car back on the ground, hopped in and stepped on the clutch to take it out of gear and start it.

*Pop*!

The resistance in the clutch pedal suddenly dropped to almost nothing as it went to the floor, the gearshift still frozen in first gear. It was apparent that the clutch wouldn't disengage. Without a working clutch, the car wasn't going anywhere.

---

I'm sure there are plenty of people reading this who know exactly what the problem was. It only took me a few moments to guess that the higher clamping force had caused a marginal clutch slave cylinder to fail. At least, I hoped that was what had happened. 

My friend was on the way with the trailer. I reserved the part at NAPA, she picked it up, I jacked up a corner of the car and installed it, bled the line and crossed my fingers.

Thanks for choosing us to share your story with.  I'm enjoying it.

Lof8 said:

I’m in to follow along. I’d love to try a hill climb. Does a mostly stock miata require a roll cage to enter?  I have a roll bar but not a full cage. 

Not with NHA. Open cars simply require a fixed (not pop-up) roll bar that meets SCCA requirements. This differs from CHCA, they are much more serious and require FIA legal cages. I don't know about the Pennsylvania hillclimbs. 

You will need a HANs next year regardless of your class. It's relatively cheap to rent one for the weekend.

Following along, looks like your somewhat local to me also!

Success!

It's nice when something just works out. The new slave cylinder worked perfectly and I had a clutch again, albeit with an engagement point that kept changing as it hadn't been broken in at all. Oh well. I'd have to break it in on the hill. We got on the road just before 9am. With a 9 hour drive to Idaho, we figured we would get there right around 6pm. I mean, it's simple arithmetic, right?

If only.

At some point along the way we came to the realization that while we were on track to get to the sprawling urban oasis that is Emmett, Idaho at 6pm - that would be 6pm Pacific time. Idaho, helpfully, isn't in that time zone. Our math was short an hour.

---

Great. Without the ability to bend time, we seemed likely to miss the registration window. So, I did the next best thing and drove basically as fast as I dared with the combination. Mileage was terrible, but we rolled into the park in Emmett at 5:50pm, Mountain time. We'd made it. I had a clutch with zero miles that I hadn't had the opportunity to do a pull with, but it was probably fine. The car went through tech without issues, I picked up the event t-shirts that I'd reserved (always buy the t-shirt!) so there was nothing left to do but to head to the hotel, and enjoy an utterly spectacular sunset.

At least, I thought, it's not snowing. If I get more than two runs, I'll be stoked. I put some Rick and Morty on the television and passed out.

You're reminding me how much goes on right here where I am that I ought to be making it to. Thanks for that, and a generally excellent ride-along!

Also, the Black Sheep is excellent, even if they do close too early. I've only ever been there when in Ashland for plays, which seems silly when there's bicycle and auto racing to be had! It's a place I'm pretty fond of in general.

Freezeout.

The name conjures up images of ice, snow, and that high-school clique you were never cool enough to be a part of. In fact, the source of the name is so incredibly mundane that I won't even bother repeating it here, and spare you the disappointment. Luckily, the road itself is far from boring. It's a challenging hill with a nice blend of corners and straight sections, and the views are simply spectacular. 

---

Freezeout turned out to be one of the hottest events of the season, despite the name. Emmett gets just 12 inches of rain in a year, which will sound great when January rolls around, here in Seattle. Everything that needs to grow is irrigated, and a fairly substantial canal runs right through the event site, filled with crystal clear, ice cold water that looked increasingly inviting as the day wore on. Note to self: next year, pack board shorts.

After all the various issues, acts of god, and vehicular demise that we experienced at the first event, Freezeout was impressively uneventful. I think there were a few people that spun and at least one person had an intimate moment with a guardrail, but none of these incidents happened in a dangerous place on the road. There are definitely places where you don't want to spin. 

Of all the NHA event sites, this one is the closest to 'civilization'. I mean, it's in Idaho, so don't get too excited, but it's nice to have stores and services a few minutes from the pits. If you're daring enough you can even find a hotel in Emmett. All that is great for convenience and accessibility, but this is also the only event on the calendar with private driveways and homes actually on the hill. Not only does this make for logistical hassles when residents want to leave their houses, but it also makes for corners where the consequences of an off could include ending up in someone's living room. 

It's also weirdly fun to drive through what feels like a suburban development absolutely flat out. I can't exactly explain why. The first section of the course up until the first hairpin has some wider corners that are flat or really close to it. This event was the point at which I really became motivated to put aero on the car. It had been on my mind before, but there's a section of road on this hill where the pavement ripples in such a way that the car tends to get launched into the air. If you go fast enough in a light car with no downforce, it's not hard to get the suspension to fully unload. Conveniently, this section of pavement is right before a tight corner. Closing fast on a sharp corner while your car is floating through the air like a beautiful butterfly is unique feeling which I hope never to experience again. The suspension loaded up in time for me to get on the brakes and make the corner, but I had to run out within a few inches of the guardrail.

It was at that moment that I decided the car was not going up another hill without aero.  On the track, a wing might be a performance upgrade, but on the hill it's a safety feature. I decided that this was a place I was willing to spend some money. Flying off the outside of a corner will be expensive, too. 

The MGs lent a nice British feel to the event by breaking constantly. They do look wonderful going up the hill, though.

I struggled with strategy and setup, missed some shifts, and had scruffier runs than I wanted, on both days. There was nothing really wrong with my times, but they weren't spectacular either. Alignment cams were breaking free and moving around, so I ended up replacing several alignment bolts and eyeballing a new alignment.

I mean, who among us has not stopped at the side of the road for a quick touch of the alignment cams? This became necessary after I rotated one of the front cams the wrong way in the pitch dark of the hotel parking lot, and found the car to have some very, uh, interesting characteristics on the drive to the hill. I need a better lighting solution than random LED flashlights. 

I had the brilliant idea of raising the redline by a few hundred RPM for Sunday, so I could stay in lower gears in a few places, and it slowed me down and dumped a ton of heat into the engine. Lesson learned. I dropped my redline back down to 6950 rpm, and I rarely get there anymore. Instead of shifting back and forth to get the last bit of power, I'll just leave the car in a higher gear and drive with both feet. My transmission loves me, I'm sure.

---

Saturday ended up giving me my fastest run. Please ignore the missed shift at the very top, oops! The engine seems none the worse for wear.

You can see how rough the road is. I would definitely set the car up with more travel before running this hill again. Lower tire pressures would be something to mess with. Maybe even go to a lower spring rate, I'm not sure. Anything to get grip on that inconsistent surface. I also decided to add frame rails and a butterfly brace after this event, and the suspension has definitely worked better since that change. The car could still be much stiffer. I have some ideas.

---

Sunday was even hotter, and the changes I made didn't get me anything. Over the course of each run the coolant temps would rise, not to critical levels. Running the heater helped the car stay cooler, but not the driver. I was still pushing, and my last run was fast through the first half of the course. I felt like I was going to be able to improve on my best Saturday time, I'd stayed in third gear instead of downshifting, and reviewed and cleaned up my line through places where I'd been giving up time. 

The car was running great. Temperatures were lower. Maybe I could pick up a couple of seconds!

Then I felt the engine cut out, just for a moment, under full throttle. Boost cut? I kept my foot flat and glanced at the gauges. Everything was normal. Fuel, coolant, oil pressure, everything was where it should be. Stock instruments gave me no insight into whether the turbo was running into overboost. There was nowhere to pull the car over until the last hairpin before the finish, and I still thought I could finish the run. 

I was wrong.

A few hundred yards from the hairpin the tach fluttered violently and then fell to zero. I pumped the gas helplessly, but my weekend was over, and there was nothing I could do about it. The engine stumbled a few times and then everything was silent and I was coasting with the clutch in, keeping the wheel as straight as I could, not touching the brakes, desperately trying to get as far as I could before I ran out of momentum, willing the car to keep rolling. Was the answer to everything going to end up finishing its run on the back of a wrecker? I couldn't let it happen, but gravity wasn't on my side. With the last of my forward motion I pulled to the side of the course and put the car in gear. So close to the safety of the corner, but it wasn't enough. I was stopped on course.

At this point I'd like to thank the corner workers for their quick thinking and making the effort to keep the event running with the minimum delay. A group of people ran down to me, I took the car out of gear and they pushed me up to the corner and off the course. I was impressed. The road is really steep at this corner, but within seconds the course was clear and the car was parked. I'd managed to avoid the wrecker, and runs could continue with the minimum of interruption. 

Well, I certainly picked a beautiful place to break down.

'Break down' isn't quite accurate. It implies unreliability, somehow. This car is the exact opposite of unreliable. I failed to secure the ISCV connector, which isn't compatible with my 1.8 ISCV and wasn't plugged into anything. It went into the alternator belt, shredded, and the car blew the INJ fuse.

I found the issue in a few minutes, ziptied the harness out of the way, swapped the headlamp fuse into the injector socket and the car was running again, seemingly none the worse for wear. I really can't kill this car.

Watching it later, it all seems fairly uneventful. It definitely didn't feel that way at the time.

Event #2 was a wrap. Things had gone so smoothly (until they hadn't) that I'd forgotten all about my new clutch. I babied it on the launches on Saturday, but between driving it to and from the course and the runs on Saturday, it was engaging perfectly and consistently for Sunday and just like so many of the other things in this car, it just disappeared into the background. Most of the time the car works so well, I forget it was almost exclusively bashed together frantically between events or on the road, and has more junkyard parts from more different cars than I care to count. Oh, and a throttle bracket beautifully hand-crafted out of aluminum angle, using a hammer and a hacksaw. It's perfect, is what I'm trying to say.

---

My work assignment for Saturday: Driveway #1. My responsibility - to ensure that the residents of the houses didn't drive out onto a hot course (!!). 

I had fun at this hill. The road has a lot of camber and flows nicely. I can clean up my lines substantially, and simply set up the car better. I think the last minute thrash took a lot out of me, and I didn't have time to fix easy and obvious issues with the car like loose alignment cams. All things considered, however, I was willing to consider this event a success. The car seemed none the worse for wear, and hopefully it's forgiven me.

Event #3 on the NHA calendar: Larison Rock. 

Event #2: Freezeout

Emmett, Idaho - June 23, 2018

Best run: 1:41.502

Run progression: 1:48.316, 1:42.034, 1:41.502, 1:45.550, 1:43.908, DNF

21st overall (out of 47)

Tires: BFG Rival-S, 245/40/15

Aero front: GV style lip

Aero rear: Bumper cut

Ransom said:

You're reminding me how much goes on right here where I am that I ought to be making it to. Thanks for that, and a generally excellent ride-along!

Also, the Black Sheep is excellent, even if they do close too early. I've only ever been there when in Ashland for plays, which seems silly when there's bicycle and auto racing to be had! It's a place I'm pretty fond of in general.

My pleasure!

You know, I think people in Ashland don't even know that the hillclimb is there. The site is extremely remote, and aside from a few fairly nondescript racecars coming into town, there's very little evidence that anything is going on. Other sites like Maryhill are much more visible. Still, hillclimbing is pretty much invisible to most people. I didn't know it was a thing, and I sort of pay attention.

Larison Rock was the third event in the 2018 NHA season.

It's the oldest active hillclimb in Oregon, tends to have really good turnout and is one of the more popular events on the calendar. The road is tricky and fast, with sections of shade and sunlight with different levels of grip, a long straight section, and there's even a narrated course preview on YouTube. I was really excited to run this hill.

Unfortunately, it wasn't to be.  A scheduling conflict meant I was sitting in the Moore theatre watching Steve Martin and Martin Short on the first weekend of July, instead of finessing a sketchy, overpowered roadster through the Oregon forest.

Oh well! I learned a lesson about scheduling and the show was fantastic.

Since there was a bit of a break between events, I decided to take the opportunity to do some upgrades to the car. So, instead of this next post being about Event #3, it's going to be about the car. This is a build thread, after all.

---

So, I started out with this:

My classic red 1992. It was really slow and neglected when I got it, and the 1.6 had been overheated. After fussing with the B6 for a while, I decided my goals for the car were better served by a 1.8 swap. 

The majority of the upgrades to the car came from places like this:

I liberated a Torsen, 1.8 axles, driveshaft and rear brakes from a totally safe and not precarious source for $250 about a season ago. 

I was holding the differential up when we finally got it free, but it's not actually possible to hold a Miata diff at arms length when you're standing on the rear bumper of a PT cruiser, as I discovered. It may have gone through the back window. Oops! I hope nobody was looking for an intact PT cruiser hatch.

---

The car - At the beginning of the season

I know I said it was mostly stock, and compared to the cars that I tend to run against in Prepared, that's not wrong. Still, some aspects of the car are fairly(?) well developed, at least for a budget build. So, this is what I started with - a 1992 base model that I bought on Craigslist for $2200, with some changes:

Drivetrain

• JDM 1994 1.8, stock, never opened
• FM2 diy kit w. 2560R and hardlines
• danscreations DP6061 exhaust
• FM silicone coolant hoses
• Koyo 36mm radiator
• Stock 5 speed
• Torsen Type 1 from a 95
• Mazda comp motor mounts
• Energy Suspension poly diff bushings
• stock 1.6 coils
• stock fuel pump/rail
• flow-matched 460cc rx8 yellow injectors
• DIYPNP2 running EBC

EBC solenoid detail.

Brakes

• junkyard 1.8 calipers f/r
• NAPA 1.8 rotor blanks
• Hawk HP Plus pads
• stock master, lines

Suspension/steering

• Energy Suspension poly bushings
• FM front sway, no rear
• Fox coils, 750/450 lb/in eibach springs
• 949 endlinks
• RB sway bracket braces
• Superpro poly steering rack bushings
• 5X racing steering rack spacers

These pieces are just so pretty.

Wheels/tires

• BFG Rival-S, 245/40/15
• Advanti S1 in 15x9

Weight reduction

• complete AC delete 
• PS delete
• NB heater core
• removed soft top
• interior carpet, sound deadening and trim removal
• removed windshield washer system
• cat delete
• baby teeth and rear tie down mounting points
• OMP racing seats
• radio/speakers/wiring removed
• spare/jack removed, trunk gutted
• airbag, battery, computer and sensors removed
• evap system delete

Chassis stiffening

• doors seam welded
• Blackbird Fabworx single diagonal rollbar

There's still a proper heater, most of the dash, and the doors are fully intact. All the glass is there. It has a factory hardtop with a glass window. Lights are still heavy sealed beams in the stock popups. I feel like the obvious weight reduction has been done, and now it's going to be harder. That's going to be a primary focus for next season.

This season, I had two things I wanted to improve: aero and suspension.

With aero, the issue was simple. I didn't have any downforce and I needed as much as I could get. I also felt that the car needed to be stiffer to take advantage of the high spring rates I run and the increased grip that's available. 

So, let's get to it. Time to bust out the sawzall... and the checkbook. 

Event #3: Larison Rock

Oakridge, Oregon - July 8, 2018

Best run: DNS

My first change to the car's configuration was to bolt the hard top to the car and make it a permanent addition to the vehicle. Taking it off the car made sense for autocross, where speeds are low and the car spends all the time changing direction and velocity. The increase in drag is worth the reduction in weight.

At the hill, though, speeds are much higher, and unlike an autocross course, roads aren't deliberately designed to slow you down. It's true that some hills have had to add chicanes to their straight sections as speeds have increased over the recent years, but still, these features aren't designed to force competitors to brake and accelerate as is typical in autocross, but more to moderate top speeds. You can see chicanes on the Cascade Lakes video I posted earlier, for example. 

My math says that at Freezout I ran a 1:41, so that works out to an average speed of 56.75 mph over 1.6 miles. The fastest car ran ten seconds faster for an average of 63.3 mph. This seems pretty typical. Peak speeds in the fastest cars are 100-110 mph, I haven't examined the in-car video from the last runs of the year, but at Maryhill the miata was running right around 95 mph at the end of the straightaway, on a normal run.

I can't find much data on how much having the top installed on a car with a windshield affects the Cd on the first gen Miata, or really any miata. Autobild put an NC in a wind tunnel and measured 0.45 with the top down and 0.37 with the PRHT up. At my average speed that difference in drag only requires 14 vs 12 hp, which is not crazy, but at 95 mph the difference is 53 hp vs. 44. This is significant, but it becomes more significant when there's a wing on the back of the car, hanging out in that turbulent air.

This post analyzes a miata with aero, and came up with a Cd of .58 with a top and 1.36 without.

https://forum.miata.net/vb/showpost.php?p=4798979&postcount=15

That's bad. Based on those numbers I'd need 148 hp at 95 mph topless, vs 67 hp with the top on. That would be huge. 

I don't know how much I trust those numbers, but unless I do some testing on the highway with datalogging in different configurations, I won't know for sure. I think the data strongly indicates that aero benefit is worth the extra weight. There's another reason integrating the top is a good idea. Bolting it to the car does improve the rigidity of the chassis and ties the windshield header to the rest of the unibody. I've found the car is less unsettled over rough sections and is easier to drive. 

The top is bolted down with some aluminum bar stock.

Simple, light, and effective.

Now, I needed downforce.

Go big or go home

Once I decided to put aero on the car, I decided to go as far as I reasonably could within the constraints of the rules and the time I had available. I had about a month to source whatever it was I needed and get it on the car. 

I needed whatever I went with to be effective at low speeds but not add a ton of drag at the top end. I could knock up a spoiler for next to nothing, but it wouldn't be as efficient as a wing, and there's also a pretty dramatic discrepancy between the size of the spoiler I can run vs the wing area I'm allowed. Spoilers can extend 10 inches from the trunklid, with a width of 55 inches (wider than my trunk), that works out to 3.8 square feet of spoiler area. XP cars can run a total of 8 square feet of rear wing, provided it's below the roofline of the car, and doesn't extend behind the rear bumper or beyond the sides of the car. I had some DIY ideas around pre-fabbed aluminum airfoils, but I didn't have time to experiment with unknown quantities, so I went looking for an off-the shelf solution for rear downforce.

This seemed like a good place to start.

This is APR's largest Miata specific wing, the GTC300.

I want to make it clear that I really don't consider this a 'budget' solution, at least by the standards of the typical miata build. It's beautifully made and finished, it's expensive, and it might take a couple weeks for APR to lay one up for 949 and drop ship it to you. It does what it says on the tin, though. There's a huge amount of downforce even at zero AOA. I had to raise the rear of the car more than an inch to regain proper rake on the highway, and with my rear spring rates, that's a lot of force. I haven't even installed the gurney flap it came with.

The wing didn't come with any instructions. I don't know if there actually are any specific to this wing, since the GTC200 is the one most people seem to buy. The mounts are the basically the same, as far as I know, so I just used the GTC200 instructions as a guide. In the instructions, they said to drill the mounting holes in the trunk lid so that the bases of the uprights sit basically flush with the edges of the trunk lid. This places the base entirely on the trunk, and all the force generated by the wing goes directly into the edge of the trunk lid, which is some pretty thin steel. People running the smaller wing reported distortion of the trunk after running on track, especially with a wickerbill installed. I couldn't see how the trunklid could possibly be strong enough for this wing on it's own.

After some messing about with the uprights, I found that moving them to the outside of the mounting tabs placed the upright bases slightly outboard of the trunk lid, so they overlap the fender. When the trunk is closed, the bases are sitting on the fender as well as the trunk, and they fit the curve of the NA fender perfectly. When the trunk is open, the bases stick out somewhat, but it doesn't affect the trunk's functionality. I still have a usable trunk, which kind of blows my mind. Given that I use that space every time I take the car to a show or autocross, I'm not complaining.

With the uprights mounted like this, the base is still supported by the trunk lid, but for the lid to distort the base would have to also crush the fender at a spot where the metal is folded at a right angle. The rear fender is part of the unibody and much thicker than the trunk lid. I haven't experienced any distortion of the trunklid at all since mounting the wing this way. I didn't have to do any reinforcing underneath the trunklid as other people have documented. 

Once the wing was mounted and the top bolted down, the aero mods were done... for the time being. I would see how well they worked at the next event. 

Stiffening things

Bolting the top on the car made it a tiny bit less flexible, but the car was still seriously lacking in torsional rigidity. It might have worked for the car's original levels of power and grip, but on the hill it didn't just feel sketchy, inconsistent contact patch loading was hurting peak grip and contributing to wheelspin out of corners. I was tired of it.

Ideally, I'd like to get door bars that integrate with my rollbar, but there was something simple that I could do that would also make the car easier to work on. I'm talking about frame rail reinforcements.

Yeah, those aren't doing the job they were designed for. Bashing them back into shape was harder than I expected. By all appearances the frame rails are made out of something with the approximate hardness of marshmallows, but this is not actually the case. 

It looked so shiny and pristine! Not for long, though.

I'd be willing to debate whether the butterfly brace is worth the weight penalty. I think I was so tired of the car flopping about that I was willing to take the hit to make the car even a little bit more rigid. 

This is a proven part that's popular because it works. I'm not worried about ground clearance with this car, so that's not a downside. Installing the reinforcements and brace was a big improvement, and the car felt very different. Would it make a difference on the hill, though? Only one way to find out.

I am thoroughly enjoying this build and event(s) writeup. Thanks for sharing with us here! 

Yes, thanks for sharing this tale! I'm following interest to see where it leads!