RLRSK8T: A 1990 Mazda Miata NA6 1.7L Golden-Era Build
1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build
Read the full write-up at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗
1990 Mazda Miata NA6 rebuilt into a golden-era-style 1.7L build
A long-dormant 1990 NA6 Miata, found sitting in a backyard for a decade, is being revived by its owner into a retro-leaning Japan golden-era style build. The project mixes period-correct exterior and interior pieces with a custom-built 1.7L engine using Wiseco pistons, Mazdaspeed cams and other hand-sourced parts. The thread documents the car's recovery, early cosmetic refresh, and the ongoing engine build.
Specs
As stated in the original write-up.
- Engine
- Custom 1.7L build using 81mm Wiseco pistons, 11.5:1 compression, Mazdaspeed 9B1A cams
- Wheels
- TR Motorsports FF10s
- Tyres
- 205/50r15 Federal RS-RR / 595RS-RR
- Suspension
- Tein Flex coilovers, Rod Millen sways
- Steering wheel
- Checkman 320 on Works Bell hub
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
- Wiseco custom 81mm pistonsWiseco
custom set made for the 1.7L build at 11.5:1 compression
In the shops
Wiseco Seamless Piston Ring Installer ↗
Flyin' Miata· $37.99 USD
Wiseco Piston Ring Set ↗Flyin' Miata· $33.99 USD
Forged Turbo Pistons by Wiseco (1.8L NA/NB) ↗Flyin' Miata· $1,099.00 USD - Cometic custom head gasketCometic
custom sized gasket for the 1.7L short block
In the shops
1.6 Cometic Metal Head Gasket (0.040") ↗Flyin' Miata· $119.00 USD
2001-05 Cometic Metal Head Gasket (85mm, 0.040") ↗Flyin' Miata· $119.00 USD
Cometic Gasket MLS Head Gasket - .030in, 85mm Bore ↗
JDMuscle — Mazda MX-5· $96.52 USD - Mazdaspeed 9B1A camsMazdaspeed
mild cams with 256 degrees duration and 8.5mm lift chosen for midrange gains
In the shops
Racing Tow Hook Set, MazdaSpeed ↗Moss Europe (UK)· £114.25 GBP - Maruha adjustable cam gearsMaruha
fitted for cam timing adjustability
- Jackson Racing headerJackson Racing
installed as part of maintenance updates
In the shops
Racing Beat Performance Header ↗
Moss Miata· $595.50 USD
Power Pulse Headers by Racing Beat ↗Moss Miata· $572.75 USD
Header Heat Shields by Track Dog Racing ↗Moss Miata· $148.50 USD
Fuel & Ignition 1
- Racing Beat Power Pulse exhaustRacing Beat
replaced the prior exhaust that was too raspy
In the shops
Exhaust Silencer, power pulse, Racing Beat ↗Moss Europe (UK)· £588.00 GBP
Exhaust Silencer, power pulse, Racing Beat ↗Moss Europe (UK)· £588.00 GBP
Exhaust Silencer, power pulse, Racing Beat ↗Moss Europe (UK)· £588.00 GBP
Gearbox & Drivetrain 1
- Braided clutch line, CMC and slave cylinder
installed to update the clutch hydraulics
In the shops
RIDEX Clutch Slave Cylinder ↗
MazSpec MX-5 Spares & Accessories· £14.95 GBP
Exedy Clutch Release / Slave Cylinder (MK3/NC) ↗MazSpec MX-5 Spares & Accessories· £28.95 GBP
Exedy Clutch Release / Slave Cylinder (MK1/MK2) ↗MazSpec MX-5 Spares & Accessories· £21.95 GBP
Suspension & Steering 3
- Rod Millen sway barsRod Millen
installed as part of handling updates
In the shops
Sway Bars ↗Flyin' Miata· $399.00 USD
Sway Bars ↗Flyin' Miata· $369.00 USD
Sway Bars ↗Flyin' Miata· $369.00 USD - Tein Flex coiloversTein
fitted to tuck the wheel/tyre combo and lower the car
In the shops
Coilover, flex-z, Tein ↗Moss Europe (UK)· £1,608.00 GBP
Coilover, flex-z, Tein ↗Moss Europe (UK)· £1,703.75 GBP
Coilover, flex-z, Tein ↗Moss Europe (UK)· £1,421.00 GBP - Pit Crew Racing strut tower bracePit Crew Racing
restored with gloss black ends, polished bar, new old stock emblem
In the shops
Ultra Racing Front Strut Brace - 4 Point ↗MazSpec MX-5 Spares & Accessories· £184.99 GBP
Ultra Racing Front Strut Brace - 4 Point ↗MazSpec MX-5 Spares & Accessories· £193.99 GBP
Ultra Racing Front Strut Brace - 2 Point ↗MazSpec MX-5 Spares & Accessories· £178.69 GBP
Wheels & Tyres 3
- Kosei wheels
original wheel set fitted with new Federal tyres, later replaced
- Federal 595RS-RR tyresFederal
fitted to the Kosei wheels at 205/50r15
- TR Motorsports FF10 wheelsTR Motorsports
replaced the Koseis for a different look and lower stance
In the shops
Adjustable Timing Wheel (Mazda Motorsports) ↗Moss Miata· $118.99 USD
Non-Slip Mat (IL Motorsport) ↗Moss Miata· $21.99 USD
3 Inch Lift Kit by Paco Motorsports ↗Moss Miata· $301.25 USD
Body & Trim 3
- Mazdaspeed roll barMazdaspeed
installed for aesthetic and structural touch
In the shopsRacing Tow Hook Set, MazdaSpeed ↗Moss Europe (UK)· £114.25 GBP
Hard Dog Deuce Roll Bar ↗Flyin' Miata· $970.00 USD
NA/NB Hard Dog Roll Bar Trim Kit ↗Flyin' Miata· $34.99 USD - Racing Beat Type I front half bumperRacing Beat
installed on the exterior
In the shops
Drop Links, front, Racing Beat ↗Moss Europe (UK)· £155.50 GBP
Anti-Roll Bar, front, solid, Racing Beat ↗Moss Europe (UK)· £277.50 GBP
Anti-Roll Bar, front, solid, Racing Beat ↗Moss Europe (UK)· £277.50 GBP - Minnam bumperMinnam
rare bumper purchased used, repaired and prepped for paint shop
Interior 4
- Checkman 320 steering wheelCheckman
fitted on a Works Bell hub replacing the OEM wheel
- Works Bell hubWorks Bell
mounted for the aftermarket steering wheel
In the shops
Cold Air Induction Kit, DDM Works, with heat shield ↗Moss Europe (UK)· £184.00 GBP
Cold Air Induction Kit, DDM Works, with heat shield ↗Moss Europe (UK)· £184.00 GBP
Cold Air Induction Kit, DDM Works, with heat shield ↗Moss Europe (UK)· £184.00 GBP - Burst Craft horn delete and shift knobBurst Craft
fitted during interior refresh
In the shops
Cobb Tall Weighted Shift Knob ↗Flyin' Miata· $119.00 USD
Cobb Short Weighted Shift Knob ↗Flyin' Miata· $119.00 USD
Mazda Gloss Mahogany Wood Shift Knob (M10x1.25) ↗
Sports & Classics· $129.95 USD - JDM Eunos floor mats
installed during interior refresh
In the shops
NB Miata Floor Mats ↗
MiataSpeed· $185.00 USD
ND Miata Floor Mats ↗MiataSpeed· $185.00 USD
NC Miata Floor Mats ↗MiataSpeed· $185.00 USD
Electrical 1
- TSI lens replacement (orange)
replaced yellowed plastic lenses with new orange lenses
In the shops
Orange Lens-Trafficator ↗MGbits4U· £20.17 GBP
Orange Indicator Lens - MG, Triumph ↗Betaset (France)· €6.75 EUR
Front Turn Signal Lamp, Orange Glass Lens ↗
bpnorthwest.com· $49.98 USD
Photos
21 pictures collected from the write-up, in the order they were posted, shown from 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build. A picture opens larger here, with the way through to the page it is on.
rlrsk8t · 2020-05-21T06:14:03-0400 4this post at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗
rlrsk8t · 2020-05-22T00:35:57-0400 4this post at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗
rlrsk8t · 2020-06-05T01:15:52-0400 3this post at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗
rlrsk8t · 2020-07-01T03:52:35-0400 4this post at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗
rlrsk8t · 2020-08-25T06:16:43-0400 3this post at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗
rlrsk8t · 2020-09-07T17:58:55-0400 3this post at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗
How it was done
Starting condition
The car had sat for about ten years in a backyard under a walnut tree after its prior owner left it behind. Despite the long neglect, the red paint, dash and interior were in reasonably good shape when the current owner acquired it.
Initial cleanup and cosmetic refresh
After towing it home, the owner washed out years of grime and squirrel-stashed walnuts from the engine bay and interior, removed an old alarm and fog lights, swapped wheels and tyres, and began sourcing parts like a Works Bell hub, Mazdaspeed rollbar, Pit Crew Racing strut tower brace and Tein Flex coilovers.
Pre-Miata Reunion build-up
Ahead of a track event, the owner repainted the intake manifold and throttle body, restored the Pit Crew Racing bar, fitted a Racing Beat Power Pulse exhaust, installed interior pieces including the Checkman wheel, Burst Craft shift knob and horn delete, JDM Eunos floor mats, and fitted a Racing Beat Type I front half bumper along with the Kosei wheels on new tyres and coilovers.
Engine build planning and progress
Originally wanting a 1.6L for a custom VVT idea, the owner instead committed to a built 1.7L using custom Wiseco pistons, a Cometic head gasket, a long-nose crank, and Mazdaspeed 9B1A cams with Maruha adjustable cam gears. The block was machined and painted, and the crank test-fitted, while rods and an oil pump were still awaited.
Other mechanical and aesthetic updates
The owner also fitted a Jackson Racing header, a braided clutch line with CMC and slave cylinder, and performed a full factory A/C delete. A rare Minnam bumper, sourced after years of searching, was repaired and prepped for bodywork and paint.
Progress so far
At the time of the last updates, the short block was nearing completion and the Minnam bumper was being prepared for the body shop. The owner also swapped the original Kosei wheels for TR Motorsports FF10s and lowered the car further for improved handling and looks.
A summary in our own words. The full account, with all its detail, is in the original write-up: read it at 1990 Miata NA6 'RLRSK8T': a golden era-esque 1.7L build ↗