Batou's 1993 Eunos Roadster NA6CE S-Special

Batou · 1993 Eunos Roadster NA6CE S-Special

Mazda MX-5 (Miata)12-page write-up

Batou's 1993 Eunos Roadster NA6CE S-Special project thread

Read the full write-up at Batou's 1993 Eunos Roadster NA6CE S-Special project thread ↗

Photo: Batou's 1993 Eunos Roadster NA6CE S-Special project thread

A JDM 1993 Eunos Roadster S-Special, modified around a 4AGE 20V ITB conversion

Owner batou documents years of steady upgrades to his 1993 NA6CE Eunos Roadster S-Special, covering coilovers and alignment, rust treatment and wing replacement, brake and interior upgrades, and eventually a DIY Toyota 4AGE 20V throttle-body conversion with a Link ECU. The thread mixes finished work, parts acquired for future fitting, and track day experience that shaped later suspension changes.

Specs

As stated in the original write-up.

Engine: JDM B6ZE(RS) 1.6 fitted with Toyota billet 4A-GE 20V Silvertop ITBs via Hummelink adapter manifold
ECU: Link G4X Plug In ECU
Fuel injectors: Denso EV6 1.8 VVTi 265cc injectors
Exhaust manifold: Racing Beat 4-1 manifold and decat
Exhaust system: RS-Harada/BRAVE Tsunashima Auto Supply 60mm stainless steel exhaust system
Radiator: Koyorad Type M aluminium radiator, 36mm
Clutch & flywheel: OEM replacement Exedy NA6 clutch with OEM flywheel refaced
Suspension: Tein Flex Z VSM40-C1SS1 coilovers, later uprated to 9kgf/mm front springs
Front control arms: Destroyordie adjustable front control arms with IL Motorsport hardened rubber bushings
Rear subframe: Refurbished OEM Mazda rear subframe, suspension arms and chassis brace with new bushings
Roll bar: GC Fabrications GC3 roll bar, fitted in the garage
Brake pads: Roddisons Motorsport front and rear brake pads
Wheels and tyres: Work Equip 03 15in wheels on Nankang NS2R tyres (195/50)
Seat: Recaro Profi SPG FIA bucket seat, drivers side, on Tuckin99 sliding rail

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 3

Toyota 4A-GE 20V Silvertop ITBsToyota
Fitted with Hummelink billet adapter manifold for an individual throttle body conversion
In the shops
Toyota TRD Carbon Fiber Driver Side Mirror Cover (Supra 2020+) ↗JDMuscle — Mazda MX-5· $425.00 USD
Toyota TRD Carbon Fiber Passenger Side Mirror Cover (Supra 2020+) ↗JDMuscle — Mazda MX-5· $425.00 USD
Toyota Oil Filter (4AGE 20V) ↗Techno Toy Tuning· $25.00 USD
ITG JC40 Sausage Filter and backplateITG
Intake filter system for the ITBs
In the shops
ITG Megaflow Sausage Air Filter JC50/S/65 ↗C Bradley Motorsport· £142.00 GBP
Air Filter Box To Backplate Seal ↗MGOC Spares· £4.45
Seal, air filter backplate to air filter box ↗MGOC Spares· £7.20
BLITZ Oil Sandwich Plate Type-DBlitz
Fitted to run an oil temperature sensor
In the shops
M20x1.5 Oil Filter Sandwich Plate Adapter ↗C Bradley Motorsport· £8.80 GBP
Sandwich Plate with M22x1.5 Oil Hose Ports ↗C Bradley Motorsport· £32.90 GBP

Fuel & Ignition 4

Link G4X Plug In ECULink
Chosen over Motec ME442 for tuning software and support, used to run the ITB conversion
In the shops
Link ECU G4X PlugIn (MX5NAX) ↗MiataSpeed· $1,400.00 USD
Link ECU G4X PlugIn (MX5NB1X) ↗MiataSpeed· $1,595.00 USD
Vertical Link Grease Nipple Blanking Plug ↗James Paddock Ltd· £1.70 GBP
Denso EV6 1.8 VVTi injectorsDenso
265cc injectors fitted as part of the ITB fuel system
In the shops
DENSO Iridium TT Spark Plug (4 Pack) ↗MazSpec MX-5 Spares & Accessories· £45.95 GBP
DENSO Nickel TT Spark Plug Set (K20TT, 4-Pack) ↗MazSpec MX-5 Spares & Accessories· £12.45 GBP
DENSO Nickel TT Spark Plug Set (K16TT, 4-Pack) ↗MazSpec MX-5 Spares & Accessories· £12.45 GBP
Racing Beat 4-1 manifoldRacing Beat
Replaced the rattling OEM manifold, bought second hand
In the shops
Manifold, racing beat, Racing Beat ↗Moss Europe (UK)· £804.00 GBP
Manifold, racing beat, Racing Beat ↗Moss Europe (UK)· £804.00 GBP
Manifold, racing beat, Racing Beat ↗Moss Europe (UK)· £804.00 GBP
RS-Harada/BRAVE stainless steel exhaust systemRS-Harada / Tsunashima Auto Supply
60mm main pipe, 70mm exit stainless exhaust bought from a breaker

Cooling 2

Koyorad Type M aluminium radiatorKoyorad
36mm radiator fitted to cool the converted engine
In the shops
Aluminum Radiator by Koyorad ↗Moss Miata· $408.50 USD
Hyper Radiator Cap by Koyorad ↗Moss Miata· $46.78 USD
Aluminum Radiator by Koyorad for NA Miatas ↗Moss Miata· $421.00 USD
NoPro Suzuki Cappuccino washer bottleNoPro
Replacement washer bottle relocated away from manifold after a melting incident
In the shops
BC Racing Coilovers - Suzuki Cappuccino EA11R/EA12R (1991-1998) ↗Paramount Performance· $1,068.17 USD

Gearbox & Drivetrain 1

Exedy NA6 clutchExedy
Replaced as an OEM-spec part during a flywheel refacing job
In the shops
Clutch Kit, stage 1, Exedy ↗Moss Europe (UK)· £528.30 GBP
Clutch Kit, stage 2, Exedy ↗Moss Europe (UK)· £662.50 GBP
Exedy OEM Replacement Clutch Kit ↗Moss Miata· $124.99 USD

Suspension & Steering 6

Tein Flex Z VSM40-C1SS1 coiloversTein
Replaced original Bilstein S-Special dampers, later fitted with stiffer front springs
In the shops
TEIN Street Flex Z Coilovers (Mazda Miata NA/NB 1990-2005) ↗Roadster360· $949.00 USD
Coilover, flex-z, Tein ↗Moss Europe (UK)· £1,608.00 GBP
Coilover, flex-z, Tein ↗Moss Europe (UK)· £1,703.75 GBP
Tein 9kgf/mm front coilover springsTein
Uprated front spring rate after track day revealed excessive compression
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
Destroyordie adjustable front control armsDestroyordie
Replaced front arms for adjustability of camber and caster while keeping standard knuckles
In the shops
Front Upper Control Arm Inner Bushing Kit, Camber Adjustable (Superpro) ↗Moss Miata· $54.99 USD
Adjustable Rear Upper Control Arm Set (NA/NB) ↗MX5 City· $281.83 USD
Adjustable Rear Upper Control Arms by Paco Motorsports ↗Moss Miata· $649.99 USD
IL Motorsport hardened rubber bushingsIL Motorsport
Fitted front and rear during suspension rebuild
In the shops
Non-Slip Mat (IL Motorsport) ↗Moss Miata· $21.99 USD
3 Inch Lift Kit by Paco Motorsports ↗Moss Miata· $301.25 USD
High-Flow Air Intake by IL Motorsport ↗Moss Miata· $484.99 USD
SuperPro rear differential void filling kitSuperPro
Fitted to rear differential during the subframe rebuild
In the shops
Rear Differential Mount Bushing Kit (Superpro) ↗Moss Miata· $129.99 USD
Rear Differential Housing Mount Insert Bushing Kit (Superpro) ↗Moss Miata· $59.99 USD
Rear Differential Center Support Bushing Kit, 80A Durometer (Superpro) ↗Moss Miata· $76.00 USD
GC Fabrications GC3 roll barGC Fabrications
Fitted in the garage with modified cutting versus the official guide
In the shops
Hard Dog Deuce Roll Bar ↗Flyin' Miata· $970.00 USD
NA/NB Hard Dog Roll Bar Trim Kit ↗Flyin' Miata· $34.99 USD
Ultra Racing Rear Anti Roll Bar - 16mm ↗MazSpec MX-5 Spares & Accessories· £206.46 GBP

Brakes 1

Roddisons Motorsport brake padsRoddisons Motorsport
Fitted front and rear along with a handbrake adjustment ahead of a track day
In the shops
Brake Disc Dust Shield by I.L. Motorsport ↗Moss Miata· $54.50 USD
Non-Slip Mat (IL Motorsport) ↗Moss Miata· $21.99 USD
3 Inch Lift Kit by Paco Motorsports ↗Moss Miata· $301.25 USD

Wheels & Tyres 2

Work Equip 03 wheelsWork
Custom-spec 15 inch wheels test fitted and run with Nankang tyres
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
Nankang NS2R tyresNankang
Fitted to the new Work wheels for grip on road and track

Body & Trim 3

OEM genuine Mazda front wingsMazda
New wings fitted both sides, arch-rolled and repainted during a full front end respray
In the shops
Mazda Motorsports front hub ↗Flyin' Miata· $579.00 USD
Genuine Mazda Front Wheel Stud / Hub Bolt ↗MazSpec MX-5 Spares & Accessories· £5.85 GBP
Roller Bearing Front Hubs (Mazda Motorsports) ↗Moss Miata· $458.66 USD
MazdaSpeed racing tow hooksMazdaSpeed
Fitted front and rear
In the shops
Racing Tow Hook Set, MazdaSpeed ↗Moss Europe (UK)· £114.25 GBP
Racing Tow Hooks by MazdaSpeed (Pair) ↗Moss Miata· $97.99 USD
Tow Hook Set by AWR Racing ↗Moss Miata· $79.00 USD
Aftermarket rear lip (R-Package)
Fitted as an exterior addition
In the shops
Club Package Lip Spoiler ↗Moss Miata· $210.50 USD
Club Package Lip Spoiler ↗Moss Europe (UK)· £169.75 GBP
Factory Style Front Sport Package Lip Spoiler by RSpeed ↗Moss Miata· $312.75 USD

Interior 3

Recaro Profi SPG FIA bucket seatRecaro
Fitted on drivers side for support alongside the roll bar and harness
In the shops
Recaro Profi SPG Seat ↗West Wales Rally Spares· £1,206.00
Tuckin99 Super Down sliding seat railTuckin99
Allows the Recaro seat to slide, fitted drivers side
Greddy/Trust 52mm oil temperature gaugeGreddy/Trust
Old-style retro gauge fitted with sensor and wiring
In the shops
Greddy 2016 Mazda Miata ND Front Lip Spoiler ↗MiataSpeed· $290.00 USD
GReddy Supreme SP Axle-Back Exhaust (2016+ Miata) ↗MiataSpeed· $995.00 USD
GReddy R35 Pandem GT Wing ↗JDMuscle — Mazda MX-5· $3,775.48 USD

Photos

271 pictures collected from the write-up, in the order they were posted, shown from Batou's 1993 Eunos Roadster NA6CE S-Special project thread. A picture opens larger here, with the way through to the page it is on.

batou · Oct 22, 2020 20:58:12 GMT 39this post at Batou's 1993 Eunos Roadster NA6CE S-Special project thread ↗

Photo: Batou's 1993 Eunos Roadster NA6CE S-Special project thread

batou · Oct 23, 2020 19:21:59 GMT 15this post at Batou's 1993 Eunos Roadster NA6CE S-Special project thread ↗

batou · Nov 14, 2020 18:36:39 GMT 7this post at Batou's 1993 Eunos Roadster NA6CE S-Special project thread ↗

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How it was done

Starting condition and early maintenance

Batou bought the Roadster in 2014 needing a timing belt and a new hood. Over subsequent years he carried out routine OEM maintenance: cooling system parts, battery, clutch, rear calipers and slave cylinder, alongside small jobs like turret oil refreshes and shift boot replacements.

Suspension and alignment

The original Bilstein S-Special dampers were replaced with Tein Flex Z coilovers, set up with a full geometry alignment aimed at a neutral, controllable handling balance. After track experience showed excessive front compression, he fitted stiffer 9kgf/mm front springs.

Rust treatment and bodywork

Batou treated underbody surface rust over two winters, replaced both front wings with new OEM panels that were arch-rolled and later repainted at Deepcar Autobodies, giving the front end a full repaint.

Brakes, interior and track day

He fitted Roddisons brake pads, a Recaro SPG seat on a Tuckin99 sliding rail, and a GC Fabrications roll bar, then ran the car at a Llandow track day, which revealed handling limits that fed into later suspension changes.

ITB engine conversion

Working largely solo, batou installed Toyota 4A-GE 20V Silvertop individual throttle bodies via a Hummelink adapter manifold, a Link G4X ECU, Denso injectors, and a new radiator, also refreshing wiring and grounds, then began dialling in the tune on the road.

Rear suspension refurbishment

In parallel he pulled the rear subframe, diff and arms for a full refurbishment with new bushings, refurbished anti-roll bars and bolt kits, rebuilding the rear end before refitting it to the car.

A summary in our own words. The full account, with all its detail, is in the original write-up: read it at Batou's 1993 Eunos Roadster NA6CE S-Special project thread ↗

Worth knowing

A full geometry alignment tailored to driving style worked better than generic settings
Rubber bushings were judged adequate for this build rather than polyurethane
Lightweight flywheels did not seem worth their cost or driveability tradeoff on this engine
Track driving revealed front suspension compression issues that led to stiffer springs rather than a bigger anti-roll bar
Taking time to fully clean and prep mating surfaces before fitting the ITB manifold avoided leaks