Brady's Turbo NA6 Build
Brady's turbo NA6 build thread
Photo: Brady's turbo NA6 build threadTurbocharging and resto of a 1991 Mazda Miata (NA6) by its owner
Brady documents turning a cheaply bought, previously drift-prepped 1991 NA Miata into a turbocharged street car. The thread covers the repaint, wheel and interior swaps, a Garrett turbo setup sourced largely from Flyin' Miata, a cooling system overhaul, and later a full engine bay repaint and refresh. It is a useful read for anyone wanting real parts choices and small fitment lessons from a DIY build.
Specs
As stated in the original write-up.
- Engine management
- Megasquirt DIYPNP2 with GM IAT sensor (AFM deleted)
- Injectors
- 420cc RX-8 injectors (195500-4450)
- Turbo
- Garrett GT2554R with 7psi wastegate actuator
- Exhaust manifold
- Flyin' Miata cast turbo manifold
- Downpipe
- Flyin' Miata stainless steel downpipe
- Intercooler
- CXRacing 19.5x6x2.5 in core with 2.5 in CXRacing piping kit
- Radiator
- Yonaka aluminum radiator with dual fans
- Thermostat
- Stant 180 degree thermostat
- Oil catch can
- Ruien catch can with 3/8 in fuel line
- Clutch line
- Stoptech stainless steel clutch line
- Air filter
- AEM cone air filter
- Wheels
- Enkei RPF1 14x7 ET19
- Tyres
- Federal SS-595 185/55R14
- Steering wheel
- Momo Team 280mm wheel with NRG quick release
- Shift knob
- Techno Toy Tuning nylon shift knob
- Stereo
- Alpine head unit with hidden door speakers, Bluetooth control
- Gauges
- Innovate MTX-L wideband, mechanical Autometer boost gauge
- Suspension
- Racing Beat rear sway bar and end links (carried over from previous owner), poly diff bushings, coilovers
- Differential
- Welded differential (from prior owner's drift setup)
- Engine mounts
- New Mazda OEM engine mounts
- Hardtop
- OEM Mazda hardtop
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.
Engine 5
- Garrett GT2554R turbochargerGarrett
Turbo fitted with a 7psi wastegate actuator, fittings sourced from Flyin' Miata
- Flyin' Miata cast turbo manifoldFlyin' Miata
Exhaust manifold for turbo install; a defective unit was replaced promptly by the supplier
In the shops
Flyin' Miata Stage 1 Turbo System (1994-95 Miata) ↗
Flyin' Miata· $4,837.99 USD
Flyin' Miata Stage 1 Turbo System (2006-15 Miata) ↗Flyin' Miata· $5,299.00 USD
1.6 Turbo Manifold (New Design) ↗Flyin' Miata· $549.00 USD - Flyin' Miata stainless steel downpipeFlyin' Miata
Downpipe for the turbo exhaust
In the shops
Flyin' Miata FOX Suspension Kit ↗Flyin' Miata· $2,389.00 USD
Flyin' Miata Crossflow Radiator ↗Flyin' Miata· $499.00 USD
Flyin' Miata FOX Suspension for NA ↗Flyin' Miata· $2,502.72 USD - Mazda OEM engine mountsMazda
New mounts ordered ahead of engine removal to replace worn ones
In the shops
Mazda OE Air Filter (2006-2015) ↗Flyin' Miata· $44.99 USD
Genuine Mazda Clutch Release Bearing ↗
MazSpec MX-5 Spares & Accessories· £59.95 GBP
Genuine Mazda Gearbox Bellhousing Bolt ↗MazSpec MX-5 Spares & Accessories· £4.95 GBP - AEM cone air filterAEM
Replaced a clogged, poor-quality eBay filter
In the shops
AEM DryFlow Air Filter - 2016 Mazda MX-5 Miata 2.0L ↗
MiataSpeed· $75.99 USD
Fuel & Ignition 1
- RX-8 420cc injectorsMazda
Fitted for increased fuel delivery, part 195500-4450
In the shops
Fuel Injector O-Ring ↗
Moss Miata· $5.78 USDFuel Injector Bushing ↗Moss Miata· $14.99 USDFuel Injector Grommet ↗Moss Miata· $4.99 USD
Cooling 4
- CXRacing intercooler coreCXRacing
19.5x6x2.5 inch front mount intercooler
In the shops
Perrin Front Mount Intercooler Core - Silver ↗
JDMuscle — Mazda MX-5· $690.20 USD - CXRacing 2.5 inch piping kitCXRacing
Used to run full 2.5 inch charge piping since the car lacks AC
- Yonaka aluminum radiator with dual fansYonaka, purchased from Redline360.com
Replaced OEM radiator and single fan, lowering running temperatures
In the shops
Yonaka Aluminum Radiator with Fan Shroud (Miata NB, 1999-2005) ↗
Roadster360· $225.00 USD
Yonaka Aluminum Radiator with Fan Shroud (Miata NA, 1990-1997) ↗Roadster360· $225.00 USD
Yonaka Coilovers Spec 2 (Miata NB, 1999-2005) ↗Roadster360· $465.00 USD - Stant 180 thermostatStant
Replaced old thermostat, car now runs at a steadier 185 degrees
In the shops
Thermostat Housing Gasket (Stant 33631) ↗
Belcher's American Auto Parts (UK)· $2.00 USD
Thermostat Gasket - GMC C1500 79-81 (Stant) ↗Belcher's American Auto Parts (UK)· $2.00 USD
180 Degree Thermostat with Gasket ↗Flyin' Miata· $14.99 USD
Brakes 1
- Stoptech stainless steel clutch lineStoptech
Replaced stock line to ease bleeding
In the shops
StopTech Premium Brake Master Cylinder ↗JDMuscle — Mazda MX-5· $144.00 USDStopTech Stainless Steel Brake Lines, Rear ↗Motorsport Auto (The Z Store)· $69.87
StopTech Stainless Steel Brake Lines, Front ↗
Wheels & Tyres 2
- Enkei RPF1 wheelsEnkei
14x7 ET19 wheels chosen for light weight and looks
In the shops
Enkei RPF1 Wheels ↗Moss Miata· $267.75 USD
Enkei RPF1 Wheels ↗Moss Miata· $301.99 USD
Wheel Hub Cap, Enkei RPF1 ↗Moss Europe (UK)· £44.00 GBP - Federal SS-595 tyresFederal
185/55R14 budget tyres, praised for grip at small size
Body & Trim 2
- TDR Radical splitterTDR
Reinstalled after repaint for front aero
In the shops
Radical Air Splitters by Track Dog Racing ↗Moss Miata· $231.50 USD
Air Splitter, by Track Dog Racing, Radical Style ↗Moss Europe (UK)· £362.26 GBP
Air Splitter, by Track Dog Racing, Radical Style ↗Moss Europe (UK)· £349.75 GBP - Flyin' Miata hood lift pistonsFlyin' Miata
Fitted to clean up the front of the engine bay
In the shops
Flyin' Miata NA/NB Four Piston Rear Brake Upgrade ↗Flyin' Miata· $899.00 USDFlyin' Miata FOX Suspension Kit ↗Flyin' Miata· $2,389.00 USDFlyin' Miata Crossflow Radiator ↗Flyin' Miata· $499.00 USD
Interior 2
- Momo Team 280mm steering wheelMomo
Fitted with an NRG quick release hub
In the shops
Boss, steering wheel, MOMO ↗Moss Europe (UK)· £103.75 GBPBoss, steering wheel, MOMO ↗Moss Europe (UK)· £122.00 GBP
Momo Montecarlo Steering Wheel ↗Moss Miata· $272.50 USD - Techno Toy Tuning shift knobTechno Toy Tuning
Nylon shift knob fitted to the car
In the shops
Cobb Tuning Gear Knob - Satin White / Race Red ↗MazSpec MX-5 Spares & Accessories· £99.95 GBP
Cobb Tuning Gear Knob - Satin White / Stealth Black ↗MazSpec MX-5 Spares & Accessories· £99.95 GBP
Techno Toy Tuning Hub Stands ↗
Techno Toy Tuning· $195.00 USD
Electrical 5
- Megasquirt DIYPNP2 ECUMegasquirt
Standalone engine management, user friendly and feature rich for the price
- GM IAT sensorGM
Used to delete the stock AFM
- Innovate MTX-L wideband gauge
Monitors air/fuel ratio
In the shops
Gauge, wideband, digital, Depo Racing, 52mm ↗Moss Europe (UK)· £191.00 GBP
AEM X-Series Wideband AFR Sensor and Controller Gauge ↗Moss Miata· $259.99 USD
AEM X-Series Wideband Gauge Kit ↗Flyin' Miata· $259.00 USD - Autometer mechanical boost gauge
Shows boost pressure, later planned to be replaced with a vacuum/boost gauge
In the shops
Boost Gauge Kit ↗Flyin' Miata· $129.00 USD
Autometer Tire Pressure Gauge ↗Flyin' Miata· $49.99 USD
Gauge, boost, digital, 0-40psi, Depo Racing, 52mm ↗Moss Europe (UK)· £72.00 GBP - Alpine head unitAlpine
Hidden stereo head unit controlling door speakers via Bluetooth
Other 1
- Ruien oil catch canRuien (Amazon)
Fitted with 3/8 inch fuel line for heat resistance
In the shops
Oil Catch Can ↗Moss Miata· $292.50 USD
Oil Catch Can with Black Hoses ↗Moss Miata· $363.50 USD
Mishimoto Baffled Oil Catch Can Kit - Black ↗MiataSpeed· $343.41 USD
Photos
65 pictures collected from the write-up, in the order they were posted, shown from Brady's turbo NA6 build thread. A picture opens larger here, with the way through to the page it is on.
Brady's turbo NA6 build thread - Miata Turbo Forum - Boost cars, acquire cats. 40this post at Brady's turbo NA6 build thread ↗
Brady's turbo NA6 build thread - Miata Turbo Forum - Boost cars, acquire cats. 25this post at Brady's turbo NA6 build thread ↗
How it was done
Starting condition
Brady's father bought the 113k-mile 1991 NA for $1200 around 2014; the previous owner had set it up for drift with a welded diff, Racing Beat suspension parts, poly bushings and coilovers, plus ill-fitting eBay fiberglass fenders. The car had little rust for a New England car, and an OEM hardtop was later added.
Body and paint
Brady repainted the car himself, first with cheap single-stage paint that required full wet sanding and a respray in a booth. He deleted the antenna hole, trimmed the rear bumper, and shaved front bumper tabs for intercooler clearance, then fitted Enkei RPF1 wheels and Federal tyres and refitted a TDR Radical splitter.
Interior and electronics
While waiting on turbo parts, Brady installed a Megasquirt DIYPNP2 ECU, RX-8 injectors, Innovate wideband and boost gauges, a Momo steering wheel with quick release, a Techno Toy Tuning shift knob, and an Alpine head unit with hidden speakers.
Turbo and cooling build
He built the intercooler piping from a CXRacing kit running full 2.5 inch piping since the car has no AC, fitted a Garrett GT2554R turbo with Flyin' Miata manifold, downpipe and fittings, and later upgraded cooling with a Yonaka radiator and dual fans plus a Stant 180 thermostat, dropping coolant temps noticeably.
Engine bay refresh
In late 2018 Brady stripped and repainted the engine bay, soda blasting the headlight frames, self-etching and painting bare metal with Rustoleum, and wrinkle-coating the valve cover. While the engine was out he replaced worn engine mounts, added Flyin' Miata hood lift pistons, a Stoptech clutch line, and a new AEM air filter after finding the old one full of fine dust.
A summary in our own words. The full account, with all its detail, is in the original write-up: read it at Brady's turbo NA6 build thread ↗
Worth knowing
- Do not use cheap eBay air filters, as they let dust through and barely filter at all
- Cheap single-stage paint can fail and require full wet sanding and a respray
- Heavy duty aluminum foil is a good way to mask wire looms during painting