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DUDELOL's Rotrex-supercharged Miata (STO)

DUDELOL · Mazda Miata

Mazda MX-5 (Miata)

Rotrex STO

Read the full write-up at Rotrex STO ↗

Photo: Rotrex STO

A Rotrex-supercharged NA Miata built for time attack

DUDELOL documents a mostly stock Miata bought in 2022 that was built up into a Rotrex-supercharged track car, including a supercharger warranty replacement, a flex-fuel conversion, and seasons of time attack racing in the MTTC series. The thread tracks dyno numbers, suspension and wheel changes, and ongoing front-end packaging work for cooling.

Specs

As stated in the original write-up.

Engine
Original 1.6 engine, roughly 100k miles, naturally aspirated base before supercharging
Supercharger
TDR Rotrex C30-94 with 90mm pulley (replaced under warranty with a new C30-94 after internal failure)
ECU/Tuning
MSLabs MS3 standalone with Innovate PSB-1 wideband
Fuel system
DW200 fuel pump with FF640 injectors, later upgraded to ID1050X injectors with a FlexFuel sensor
Ignition
DIYAutotune IG1-NA coils
Intake manifold
ChathamCNC intake manifold
Cooling
Supermiata reroute and crossflow radiator setup, Fluidampr damper, DIY Setrab 16-row oil cooler with custom ducting
Exhaust
GWR header and cat, custom 2.5 inch exhaust with Magnaflow 12578 22 inch muffler
Clutch
Supermiata 1.6 sport clutch and lightweight flywheel (slipping under E85 power, being replaced with a Supermiata 1.6 ceramic clutch)
Gearbox
Original 5-speed manual
Rear axle
4.1 Torsen differential
Suspension
Gen 2 XIDA coilovers, 700/400 spring rates
Sway bars
Supermiata front and rear sway bar kit with tubular front bar
Brakes
Carbotech R12/R10 pads for track use, Carbotech GS-1 for street use
Wheels
15x8 6UL wheels, later changed to 15x9.5 Konigs (sold back) then back to rolled fenders with 6UL/Konig combinations
Tyres
205 RT-660 originally, then 195/50 Yokohama A052 for Super Street class, then 245 RT-660 on Konigs
Seats
Car Make Corn carbon seats on stock sliders
Roll bar
BBFW NB GT3 rollbar with SFI padding under a Bethania Garage leather cover
Steering wheel
330mm Nardi Deep Corn-Rev9 white stitch wheel with Daikei hub and spacer, Revlimiter horn button
Gauges
Revlimiter warbird gauges and HVAC panel with white LEDs, Autometer Stack oil temp gauge and water temp gauge (repurposed to monitor Rotrex traction fluid temperature)
Shifter
MiataRoadster tall/angled short shifter in satin black
Audio
Retrosound Grand Prix radio with 3rd Millenium door speakers
Lighting
FM Morimoto headlights and FM LEDs for other bulbs, LED light sun visor deletes
Interior trim
IL Motorsport center console, MiataGear reproduction STO floor mats, BBFW fire extinguisher mount

Parts used

Parts named as used in the original write-up, grouped the way the Parts page groups them. Where one of the shops we index lists the same thing for this car, it is shown underneath with a link to the shop.

Fuel & Ignition 7

Cooling 3

Gearbox & Drivetrain 3

Suspension & Steering 2

Brakes 2

  • Carbotech R12/R10 pads

    Track-day brake pads

  • Carbotech GS-1 padsCarbotech

    Street use brake pads

Wheels & Tyres 3

Body & Trim 2

Interior 7

Electrical 4

Other 3

Photos

41 pictures collected from the write-up, in the order they were posted, shown from Rotrex STO. A picture opens larger here, with the way through to the page it is on.

Rotrex STO - Miata Turbo Forum - Boost cars, acquire cats. 35this post at Rotrex STO ↗

Photo: Rotrex STO
Interior dashboard with steering wheel and tan leather seatsPhoto: Rotrex STO
Full interior view showing driver and passenger seatsPhoto: Rotrex STO
Black Miata with orange wheels in garage, partial viewPhoto: Rotrex STO
Photo: Rotrex STO
Windshield banner and roll bar viewed from behindPhoto: Rotrex STO
Convertible interior with bucket seats and roll barPhoto: Rotrex STO
Photo: Rotrex STO
Leave a poscatPhoto: Rotrex STO
Leave a negcatPhoto: Rotrex STO
Navy Miata with hood open in garage, three-quarter viewPhoto: Rotrex STO
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Tweet this threadPhoto: Rotrex STO

Rotrex STO - Miata Turbo Forum - Boost cars, acquire cats. 6this post at Rotrex STO ↗

Engine bay with turbocharged motor and componentsPhoto: Rotrex STO
Photo: Rotrex STO
Photo: Rotrex STO
Black Miata racing on track with number 456 visiblePhoto: Rotrex STO
Photo: Rotrex STO
Black Miata competing on autocross course with large wingPhoto: Rotrex STO

How it was done

Starting point and build goal

The owner bought the Miata nearly stock from Florida in January 2022, intending a weekend car for occasional track use. After helping turbocharge his twin brother's car and seeing the cooling demands of that setup, he chose a TDR Rotrex supercharger kit instead once satisfied with the car's naturally aspirated baseline.

Initial powertrain and suspension build

The Rotrex C30-94 kit was paired with MS3 standalone, upgraded fuel system, Supermiata cooling parts, a custom exhaust and a Supermiata clutch and flywheel. Suspension included XIDA coilovers, Supermiata sway bars, Carbotech pads and 6UL wheels. Dyno testing showed 220whp/185wtq on 91 octane.

Belt noise and supercharger warranty replacement

After initial track days, a belt-skipping issue appeared and was partly resolved by belt wear. Later the supercharger began making a worsening noise and slipping; Rotrex found an internal fault and, under warranty via TDR, replaced the unit along with the fluid filter and traction fluid. TDR also supplied spacer washers that fixed the earlier belt issue.

Competing in Miata TT Championship

With the car running well again, the owner entered the new MTTC series, fitting 195/50 A052 tyres on the 15x8 6ULs to qualify for Super Street class. He finished third at the first round at WSIR and eighth at a wet, difficult Buttonwillow round.

Flex-fuel upgrade and dyno results

The owner fitted a ChathamCNC intake manifold, ID1050X injectors and a flex-fuel sensor, with tuning done by Advanced Engine Dynamix. On E85 the car produced 253whp/195wtq, a gain of about 33whp and 10wtq over the prior 91-octane baseline, meeting his power target.

Front-end packaging, cooling and clutch issues

Fitting a new DIY Setrab oil cooler and re-working the Rotrex mounting around the stock bumper bracing proved time-consuming. The Supermiata 1.6 sport clutch began slipping under the higher E85 torque, prompting an order for a Supermiata 1.6 ceramic clutch. Wheel and tyre experiments included 15x9.5 Konigs that were later sold back due to fender rubbing.

A summary in our own words. The full account, with all its detail, is in the original write-up: read it at Rotrex STO ↗

Worth knowing

  • Check for belt clearance issues early; spacer washers between the supercharger bracket and engine stopped belt dusting
  • Flex-fuel capability allowed falling back to 91 octane when the clutch could not hold E85 torque, avoiding a stranded car
  • A clutch rated for one power level may not hold up once E85 tuning adds torque

Rotrex STO

Read in full, all 2 pages, on 7 November 2026. The original write-up and photographs remain with their creators. This page is a catalogue in our own words, and a signpost to the source.

Read the full write-up at Rotrex STO ↗

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