Chris’ DCT-Swapped Miata: Grasping the Big Picture

While Chris Watson was tracking an RX-8, his friend, a talented driver and builder, was outpacing Chris in their championship-winning TTE Miata by multiple seconds. “I just got tired of paying more to go slower than him,” he admitted. This prompted Chris to buy a lightly-modified 1999 Miata with the intention of turning it into a Spec Miata, but due to reasons of space and another race car entering the picture, he decided to turn the Miata into a wilder kind of machine.

I originally decided to turbo the car when I realized it didn’t have enough power to accelerate on the highway with my bike on the hitch rack. I was already running an MS3 PNP and a friend was selling a DIY turbo kit so I took him up on that.

Building Upon a Proven Base

Working as an engineer with a well-known IMSA team, he made good use of all his contacts and left few stones unturned when developing this well-rounded track car. Building upon the established Supermiata S1 formula, he used the proven parts that’ve made turbo Miatas with relatively little power capable of remarkable times around high-speed tracks.Like the S1, this uses the standard Xida coilovers and square-245 setup to achieve its impressive level of mechanical grip.

It’s nice to be connected; the aero package uses a few parts plucked from retired race cars. The front splitter is made from a hand-formed PVC foam core wrapped in carbon fiber (custom, but informed by industry knowledge), and the rear wing is a prototype wind tunnel section for one of his team’s old Pirelli Challenge race cars, with custom mounts to fit the Miata.

Some of the driveline and the footwork is sourced from odd donors. The differential is a Getrag unit from a Cadillac CTS modified to use Mazdaspeed Miata bushings. The whole car is on Mercedes-Benz spherical joints, the front hubs are from the durable BMW E30, and the rear are custom billet items built to accommodate the 600-horsepower axles needed to handle high power.

The first iterations of the turbocharged motor ran on MegaSquirt for about 5 years. At first, his turbocharger of choice was an TD04-20T with a 0.45 A/R. While this was about as snappy as anyone would want, the small turbine raised EGTs and the engine retained too much heat, plus the setup was limited to about 300 horsepower at the wheels.

The small-displacement engine needed a small turbo for the sort of response and powerband needed to work well with a manual transmission, and while the TD-04’s negligible transient lag and rev range matched the manual transmission and its ratios, the Mazda factory transmissions never really worked. “After a lap or two, they never felt right. I once ran a factory five-speed with low miles at 230 lb-ft and it broke after two hours on track. The ones that lasted, I ended up replacing them every season, too.”

These drivetrain limitations pushed him into looking for an alternative, which was compounded by another desire: to find a better computer. Though Megasquirt’s support was great, Chris ultimately ran into its limits and desired an ECU with more accessible customization. The third reason to change was that he’d stepped up into a new realm of time trials and need more grunt. “Power goals and transmission concerns determined the next iteration. I needed about 450 wheel horsepower to be competitive in Gridlife Street Mod.”

Appreciating the Whole Picture

The turbo that would make that power with a larger A/R was acceptable response was the BorgWarner 7163 EFR. “I picked an 0.83 A/R to free up airflow and gain power, and I’ve run it up to about 400 WHP on track. My previous intercooler would heat soak, but it now has a 900-HP rated Garrett intercooler in it, which has got it to the point that there’s no appreciable power loss over a session.”

Still, the problem with the bigger turbo was that its transient lag would not complement an h-patten synchronized gearbox well. He was convinced he’d be making a significant loss with the delay between gears, which would impact acceleration considerably and make life a little easier on track.

He had to find a faster-shifting solution to make good use of the new turbo. One option was the BMW 7-speed DCT, and the other option was a sequential. “The sequentials are lighter, but considerably more expensive, and I’m not sure they’re more durable than the OEM DCT unit. They’d also put me in another class which I was not interested in joining. The DCT is roughly a hundred pounds heavier than the manual transmission and auxiliaries, but at least the weight is low and in the center of the car.”

The challenge is that modern semi-automatic control is complicated, and the only people who really have the resources to figure it out are the OEMs. Chris’ recommendation is to use the solution that enables you to retain the stock GCU, and in his case, it was the MaxxECU.

“The MaxxECU was already proven to work with the factory BMW DCT GCU and offered native DBW support and good configurability” he explained.

“Other offerings try to directly control the solenoid valves in the transmission. I didn’t even attempt to do that – it still uses the BMW controller. For the price point, support, and interface (with the OEM TCU, which had all the OEM protections in it), as well as the internal configurability of the ECU, I found the MaxxECU hard to beat.”

“Being able to shift instantly with the DCT, despite the additional weight, would allow me to lap about a second faster over a 90-second lap than an h-pattern version of the car, according to my simulations. Plus, there’s the control aspect — I never have to take my hands off the wheel, and I can also left-foot brake.”

Making Good Use of More

There’s a bit of response lag at 4,500 revs, but the seamless power and tighter gear spacing makes the latest iteration of the motor far more tractable than the previous one. It’s also making more power everywhere over 4,000 rpm compared to the old TD04.

“It can still produce more torque than the car can put to the ground in those corners. So I use TC as an anti-lag in hairpins when I don’t want to drop a gear. In those corners, I’ll get harder on the throttle a little sooner and have the TC retard the timing to limit power to the wheels while spooling the turbo, and when the grip is available, the turbo is spooled up and ready to take advantage of it.

The TC slip targets are speed and yaw-rate dependent, so it stabilizes the car and is also on-dash adjustable to suit the tire and track condition. Not intrusive; feels like magic. The only thing I have to be careful about is not to use it too frequently because it will burn up the exhaust. This is a good example of the configurability offered by the MaxxECU. I can make TC dependent on basically anything including pulling it back if EGTs rise too much.”

Lingering Little Fixes

There’s some splitter damage which limits the car’s front end currently. Both the aero balance and the mechanical balance is about what I want it to be. However, because the front end is slightly heavier, it puts a little more heat in the front tires, so as the car heats up, it pushes a bit later in the session.

The tires are really small on the Miata, and many street tires are liable to overheat, but the CR-S compound does really well despite the car’s 2900+ lb competition weight. “With other tires, I only get one flyer per session on the first hot lap. With these, laps two, three, and sometimes four are opportunities to set a fast lap. And with one cool down lap, I can go for a fast lap late in the session.”

In terms of engine heat, he’s managed it well enough to run full sessions without a dropoff in performance. As mentioned before, the larger intercooler plays a part in this, as does its PWR/C&R Radiator (highly recommended for any serious turbo car), Improved Racing transmission and oil coolers, and a Mocal power steering cooler.

“I’ve been informed I might be able to improve the response with more intake cam advance which I haven’t tried to tune on this turbo yet,” he added.

Although he welded the turbine to the manifold to eliminate any chances of studs backing out and gaps forming, it’s not really up to race-spec quite yet. “I’ve got this cast iron manifold hot enough to deform it and crack it, so I’m now looking into ways to better support the turbo and reduce EGTs. I still need to make a cold air intake for the car. The turbo ingests hot engine bay air at low flow rates, which affects the spool up behavior later in the session, but not peak power.”

Over the winter, Chris will keep himself busy installing a dry sump and refreshing the motor to make up for poor wet sump performance. “Once we get a little more cooling air to the brakes, we’re gonna turn the wick up. The turbo can flow over 500 horsepower, but I want the car to remain reliable and driveable, so I’ll gradually turn the power up and solve any issues on the way.”

Though the basic foundation of the car was proven, Chris was convinced that there was a better way to solve the typical turbo Miata problems and paved his own path. Of course, he had some wise and experienced folks helping him along the way, but his consideration of the whole car as an ecosystem helped him make the decisions that have given it greater all-around performance and a service history that any owner of a turbo Miata would envy. The race-proven EFR turbo and the OEM-controlled DCT have performed flawlessly. In fact, there’s been negligible maintenance needed in the last ten months – he hasn’t even had to change the transmission fluid over 2000 miles of track usage.

“I’d like to thank my parents for putting me on a path to be able to do this, my wife Lola for her unwavering encouragement and support, and my good friends Will and Erik at E3Machine for helping me realize the car’s potential.”

Tom’s Miata: Frankenstein Fun

Tom’s story began with his Mini Cooper in the fall of 2018. Then in high school, he cobbled together parts from forums and Craigslist Marketplace postings and ended up pushing a little 230 horsepower and 270 lb-ft from the 1.6-liter. It carried him through his track day foray, but the more he drove it, the more it faltered. He couldn’t keep up with the costs, the fuel, and the track day entries.

His friends suggested a simpler car to try and earn his driving spurs with. By parting out the Mini, he could put together the few thousand he needed to pick up an NC Miata with nearly 200,000 miles on the clock. The NC had lived an unloved orphan’s life; moving through seven households before ending up in Tom’s driveway. Somehow, it was still stock when he bought it. This basic package promised regular attendance at local lapping events, even with his college schedule limiting his time and his finances.

Tom didn’t have the means or the interest in going ga-ga with the mod list. The basic package of Feal 441+ Road Race coilovers, RX-8 sway bars, and Cobra Suzuka buckets did him just fine as he was making his way from novice to intermediate. The objective was to get good enough to feel comfortable at the limit and fix what broke.

Fortunately, little did. The only issue in that busy twelve months was the OEM radiator bursting. In the first year of racing, Tom and a few trusted friends logged over thirty DEs on the dependable little Miata. It actually helped him earn a few bucks, too, after reading Engine Management: Advanced Tuning by Greg Banish, he picked up enough to start tuning the factory ECU and starting a side hustle. That money went to his track fees, and it seemed like he’d found a self-sustaining system for himself. All was well with the world until it wasn’t.

After the engine blew, he borrowed his friend’s daily to finish out the final three weeks of his final semester at school, then bought the remainder of a friend’s parted-out NC track car, which fortunately still had its motor. It wasn’t an ordinary two-liter. His friend had swapped in a 2.5 from a Ford Fusion, a budget upgrade with minor architectural differences to the 2.0 it replaced. Swapping it into his car took less than three days.

Unfortunately, the stock 2.5 fell flat on its face at 5,500. With a set of OEM Mazdaspeed 3 valve springs and a set of Xero Limit “Boost” camshafts, Tom was able to raise the 2.5’s rev limit without any thinning of the functional powerband. The 170 lb-ft on tap starts around 3,000 and carries through 5,000, and the power keeps building to the 7,100-rpm redline, where it makes 197 at the wheels.

A comparison of the 2.5 on E70 (red) versus the 2.0 on 91 (blue).

“The objective has been to see how fast I can go without cutting corners or spending much money,” he elaborated. This is Tom’s main reason to try and use as many OEM components as possible. To avoid dealing with the factory rear hubs shearing, he upgraded to a set of hubs from its stouter older brother, the RX-8.

Though it required a bit of custom work to make it fit, the in-the-family RX-8 differential helped tremendously. Better, more progressive breakaway and improved acceleration from a 4.1 final drive originally suited to a torque-free rotary. After this upgrade, the car no longer lost speed going uphill between Turns 8 and 9 at Thunderhill East.

Because the RX-8 differential is taller, in order to sit in the same spot, Tom had to move the alignment area for the studs to sit in the same spot, which meant losing the alignment dowels. Without these, the powerplant frame eventually started sagging after a few months of hard driving. Eventually, this led to the powerplant frame contacting the midpipe under heavy braking and curb hopping. His attempt at notching the powerplant frame was one piece of trial-and-error that didn’t go his way, but he plans to put a set of custom locator plates to avoid this problem permanently.

Currently, he’s fighting the smaller issues like the one above which make the car hard to drive as regularly as he’d like. “Mostly just little gremlins from the engine swap,” he added. Other than that, it's the wallow from the original bushings which make the Miata a bit unpredictable at times. That’ll be relatively straightforward though time consuming.

If his first year out of school is as lucrative as he hopes, he might assemble a new motor to make the MX-5 a real S2000 rival with the following parts: a Fusion’s 2.5-liter Duratec block and pistons, and a Mustang’s 2.3-liter Ecoboost connecting rods and crankshaft, 12:1 compression and an 8,200 rpm redline, he’s hoping for 270 horsepower at the wheels. “It’s going to take a lot of development on my end, but I’ve got a small group guiding me. I’m in good hands.”

Along with the added speed comes a need for better deceleration, so in addition to a set of four-piston Wilwood calipers and RX-8 Sport rotors (which are only $30 per corner), he’s gone and picked another part within the Mazda lineup that takes a little innovation and forum-digging to swap. The RX-8’s ABS system is less prone to engage ice mode. Though this will be another trek down an unpaved path, he’s been given the schematics from others and feels confident the swap will be successful.

“It’s been fun to Frankenstein because I like doing things that not many have done, but I’m more interested in retaining a lot of OEM equipment since I don’t think it will have many issues in the long run. Hopefully, these parts will make it easier to go out and drive more miles. I still need seat time more than anything. Seat time, saving money, and keeping it reasonably streetable have been my objectives. I think I’ve achieved most of them."

Now, I’m considering making it more of a race car since I’ve got a daily now. But until I can afford a truck, there’s no point in making it a total pain to drive. The added torque is definitely enjoyable in the canyons, where I can keep it in third most of the time.”

How many Miata owners can say that?

Alex’s FL5 Type R: Best of Both Worlds

For Alex Peysakhovich, living in NYC had its perks, but easy access to track days was not one of them. When he relocated to Los Altos and found himself with a backyard and a garage, he decided it might be time to purchase that car he’d always wanted and take advantage of California’s temperate weather and multiple tracks within a few hours’ driving distance.

His heart was always with Honda, but the then-current FK8 Type R was too boy-racer for his liking. “I really loved the car, but thought about some things you have to do with your only car, like go to a business meeting or drive in a funeral procession, and I couldn’t really imagine doing those in an FK8.”

So instead he began tracking with an ND Miata. Heavy modification made it a capable cornering machine, but its impracticality became a constant pain; it needed a trailer for long drives and couldn’t be used to take his dog and his girlfriend on weekend trips. He thought about getting an electric daily that he wouldn't track or modify, but that idea didn't last long. “What’s the point of buying a car you’re never going to take to the race track?” he asked himself.

Enter the FL5 Civic Type R, which debuted after a couple years of tracking the Mazda. The new Civic traded its predecessor’s divisive looks for more subdued styling, so Alex had to check it out for himself.

“I used to think Type Rs were a little overhyped, but after seeing it in person, I recognized why the car has a cult following,” he said.

He appreciated the way Honda’s engineers made this fifty-grand Civic feel unmistakably upmarket. But more than presence or build quality, it had real-world usability going for it. On longer trips, the comfortable seats were a welcome upgrade from his Miata’s race buckets. The interior space, the fit and finish, and the performance made the FL5 a great candidate for a daily driver-come-sleeper, and once the premiums started to shrink, Alex pulled the trigger and brought one home.

Before his first track outing, he made a few adjustments. He’d learned enough to know that a ~3,200 pound front-driver would wreck its Pilot Sports fairly fast, so he ditched those for a set of 265-section Bridgestone Potenza RE-71RS tires wrapped around Apex VS5-RS wheels. Along with a set of eccentric lower ball joints to increase negative camber at the front axle, he replaced the stock pads with a set of Ferodo DS3.12s to help clamp the factory two-piece rotors.

He broke it in over 600 miles then took it to Thunderhill West for its shakedown, where he was pleasantly surprised. The steering was quick, despite a dead spot at twelve o’clock, and the gearbox was, well, Honda. If the interfaces were lacking in any way, it was the position of the throttle — as he put it, “in another zip code.” Thankfully, the auto-blip function facilitated heel-toe shifts despite the awkward pedal placement.

Being a front-drive car, he had expectations for how it might handle on a damp morning. Those were dashed on his first fast lap after mounting the dorito at Turn 3, when it hung the rear out in a big way.

“As far as a car that can pack a weekend of camping gear and do great times around Laguna, it’s a hard car to beat.”

The FL5’s mechanical LSD and brake-based stability control system do a commendable job getting the middleweight to rotate. What was less than impressive were the thermal problems which have been associated with the turbocharged Type Rs. Though not catastrophic, the heat causes the motor to pull timing by the end of a long session, but never puts it into limp mode. “I think there’s only so much you can expect from a turbocharged two-liter making over 300 horsepower,” Alex added.

Fortunately, these issues are not new to the Type R lineup and the FL5 was designed to make them easier to address than its predecessor ever allowed. The ducting routes have been established from the factory, along with a functional hood vent. Honda laid the groundwork, but more needs to be done for hot summer days. “It isn’t imperative, but it could use a bigger radiator and an oil cooler. I’ve got those sitting in my garage in anticipation for the summer.”

“The designers cared about the experience of the car; they wanted it to feel special, even when parked.” Alex added. Credit: Tokumeigakarinoaoshima CCA-SA 4.0.

Beyond that, any remaining mods are far from necessary. The FL5 is well-balanced out of the box and does not need much more power. “The engine is certainly strong. If it could use something to make it feel a little sportier, it would be an exhaust — it’s too quiet.”

That subdued exhaust note is part of what makes the car so versatile, and its wide repertoire comes at a premium. Besides requiring pricier fuel, the turbocharged front-driver is hard on its front brakes and tires, and it goes through consumables far faster than a lighter, better balanced car like a Miata.

There’s no denying the running costs are too high to track a Type R regularly — multiple track days per month will continue to be the Miata’s job — but the Civic will be doing daily driving, mountains, longer trips, and rear its head at Laguna and Thunderhill East a few times a year.

Four years ago, Alex thought fifty thousand for a Civic was steep, but he’s changed his tune as of late. “I know that sort of money for a Civic sounds crazy, but you really need to try it. It’s tough to think of something similarly priced that handles so many different tasks as well as the Type R. If I could only have one car, this would be it.”