MixedBreed's 1993 Miata with a 1999 Engine Swap
MixedBreed's '93 With A '99 Heart
Read the full write-up at MixedBreed's '93 With A '99 Heart ↗
A 1993 Miata (NA) carrying a swapped-in 1999 1.8 engine and drivetrain
MixedBreed, a repeat Miata owner, bought this 1993 NA which a previous owner had already fitted with a complete 1999 Miata engine, Mazdaspeed 6-speed gearbox and diff back in 2007. The thread covers a tune-up, an exhaust swap, suspension bushing and brake work, wheel and interior changes, and a hardtop hunt, with a final update years later describing an engine failure, rebuild and eventual sale.
Specs
As stated in the original write-up.
- Rear axle
- Mazdaspeed differential from the 1999 donor, with poly diff bushings fitted
- Suspension
- KYB AGX shocks and Tein S-Tech springs, carried over from a previous owner
- Exhaust
- RoadsterSport 3 full stainless header-back exhaust from Good-Win-Racing
- Hardtop
- Black hardtop fitted in place of the worn soft top
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
- 1999 Miata 1.8 engine
Donor engine swapped into the 1993 chassis by a previous owner, later carrying on in this build
In the shops
Oil Change Bundle for 1999-05 Miata ↗
Flyin' Miata· $91.64 USD
Mishimoto Radiator (1999-2005 Miata) ↗
MiataSpeed· $255.00 USD
Flyin' Miata Spring Set (NB Chassis) ↗Flyin' Miata· $249.00 USD - Valve cover gasket set
Replaced after finding the original gasket broken and leaking oil
- MazdaComp motor mounts
Fitted as part of the engine bay refresh
Fuel & Ignition 3
- Spark plugs and plug wires
Replaced as part of the initial tune-up
In the shops
Magnecor 8.5mm Spark Plug Wires (2001-05 Engine) ↗Flyin' Miata· $109.00 USD
Magnecor 8.5mm Spark Plug Wires (1990-00 Engine) ↗Flyin' Miata· $129.00 USD
Spark Plug Wires and Components ↗
Moss Motors – Triumph TR6/TR250· $0.00 USD - Rspeed valve cover bolt kit
Allen head bolts fitted to the valve cover
- 2.5 inch intake tubing, couplers and clamps
Parts gathered to build a new custom intake
Cooling 1
- GarageStar radiator cover and cowl cover
Installed with a dress bolt kit in the engine bay
In the shops
Cobalt Radiator Cowl Cover ↗
Moss Miata· $48.99 USD
Spiked Performance NA Radiator Cowl Panel ↗Flyin' Miata· $89.99 USD
Radiator Cowl ↗Moss Motors – Triumph TR6/TR250· $158.00 USD
Suspension & Steering 6
- KYB AGX shocks and Tein S-Tech springs
Installed by a previous owner and retained on the car
In the shops
Springs, lowering, s-tech, Tein ↗Moss Europe (UK)· £274.00 GBP
Springs, lowering, s-tech, Tein ↗Moss Europe (UK)· £266.50 GBP
Springs, lowering, s-tech, Tein ↗Moss Europe (UK)· £309.50 GBP - Prothane master bushing kit
Installed through the suspension with zerk fittings and new ball joint boots
In the shops
Prothane Complete Car Bushing Kit ↗Moss Miata· $414.50 USD
Prothane Rear Sway Bar Bushing Kit ↗Moss Miata· $18.29 USD
Prothane Front Sway Bar Bushing Kit ↗Moss Miata· $31.99 USD - Poly differential bushings
Fitted when the diff was dropped for fluid change and exhaust clearance work
In the shops
Prothane Polyurethane Differential Mount Bushings ↗Moss Miata· $104.99 USD
Shock Bushing Set, Poly SuperPro ↗
bpnorthwest.com· $37.09 USD
Poly Sway Bar End Link Bushing Set ↗bpnorthwest.com· $21.97 USD - GarageStar fender braces
Installed during the fender removal to realign doors
In the shops
Ultra Racing Front Fender Brace Kit - 3 Point (FD3-1320P) ↗
MazSpec MX-5 Spares & Accessories· £193.84 GBP - Powerflex poly exhaust hangers
Fitted as part of the suspension/exhaust refresh
In the shops
Hanger, exhaust, 12mm poly ↗Moss Europe (UK)· £16.00 GBP - Delrin window guide bushings
Installed alongside the valve cover bolt kit
In the shops
Cobalt Delrin Window Bushings (Set of 2) ↗Moss Miata· $29.99 USD
Bush Set, windows, Delrin, Cobalt ↗Moss Europe (UK)· £24.50 GBP
Window Guide / Quarterlight Frame (Mk1) ↗
MX5 City· $67.60 USD
Wheels & Tyres 2
- Toyo Proxes R1R tyres
Fitted to the new Konig wheels after original tyre choice was out of stock
In the shops
215/45R15 85V Toyo Proxes TR1 Tyre ↗
C Bradley Motorsport· £124.50 GBP225/50R15 91V Toyo Proxes TR1 Tyre ↗C Bradley Motorsport· £129.00 GBP
225/45R13 84V Toyo Proxes R888R Tyre ↗C Bradley Motorsport· £142.80 GBP - 949Racing forged aluminum lug nuts
Installed with the new wheel setup
In the shops
Aluminum Lug Nut, Single ↗Flyin' Miata· $6.99 USD
Aluminum Lug Nuts, Set of 16 ↗Flyin' Miata· $111.00 USD
Aluminum Lug Nuts, Set of 20 ↗Flyin' Miata· $138.00 USD
Body & Trim 2
- Good-Win-Racing RoadsterSport 3 exhaust
Full stainless header-back exhaust replacing the previous loud setup
- Black hardtop
Purchased to replace a worn, torn soft top
Interior 6
- Voodoo shift knob and handbrake handle
Fitted to personalize the interior
In the shops
Voodoo Knobs Billet Aluminum Handbrake Handle - Polished ↗Moss Miata· $86.99 USD
Voodoo Knobs Billet Aluminum Handbrake Handle - Textured Black ↗Moss Miata· $88.99 USD
Voodoo Handbrake Handle, polished ↗Moss Europe (UK)· £107.00 GBP - Grip Royal steering wheel
Fitted, carried over from a previous Miata purchase
In the shops
MK5 Flat Wood Steering Wheel - Thick Grip ↗
Moto-Lita· £305.00 GBP
Flat MK3 Wood Rim Steering Wheel (Thick Grip) ↗Moto-Lita· £295.00 GBP
Dished MK3 Wood Rim Steering Wheel (Thick Grip) ↗Moto-Lita· £295.00 GBP - FatMat sound deadener
Installed under the floor carpet, behind the seats, on the parcel shelf and in the trunk
In the shops
Sound Deadener Kit (7pc) ↗
Collectors Auto Supply - 1969 Camaro· $103.97 USD
Sound Deadener Tar Mat Kit (7pc) ↗Collectors Auto Supply - 1969 Camaro· $127.97 USD
Firewall Sound Deadener Insulation Pad ↗Collectors Auto Supply - 1969 Camaro· $153.97 USD - Racing seat from FC project
Installed after the carpet was put back down
In the shops
Rear Brake Pad Set Racing Type (Project Mu) for Toyota 2000GT ↗
JDM Car Parts· $299.00 USD - Autopower 3 inch 6-point harness
Fitted pending a harness bar
- GarageStar seat mounts
Used to mount the racing seat
Other 1
- Packed exhaust baffle
Added to quiet the exhaust for long highway trips
Photos
59 pictures collected from the write-up, in the order they were posted, shown from MixedBreed's '93 With A '99 Heart. A picture opens larger here, with the way through to the page it is on.
MixedBreed · 2015-02-15T21:24:50-0500 18this post at MixedBreed's '93 With A '99 Heart ↗
MixedBreed · 2015-02-15T21:29:48-0500 18this post at MixedBreed's '93 With A '99 Heart ↗
MixedBreed · 2015-02-15T21:38:05-0500 20this post at MixedBreed's '93 With A '99 Heart ↗
MixedBreed · 2023-08-10T22:42:50-0400 3this post at MixedBreed's '93 With A '99 Heart ↗
How it was done
Car history before ownership
The car was originally bought new and kept stock until a friend began modifying it, including building his own rollbar and fitting KYB AGX shocks and Tein S-Tech springs. In 2007 that friend swapped in a 1999 Miata engine, harness, fuel system, emissions system, dash and drivetrain, plus a new headlight setup, doing the whole job in his parents' garage. The car passed through one more owner before MixedBreed bought it in 2014.
Starting condition and tune-up
On purchase the car had a stutter under acceleration and an oil leak from a valve cover that had not been properly bolted down, with a broken gasket. MixedBreed replaced the valve cover gasket, spark plugs, wires, oil filter and oil, and repainted the stripped valve cover with crinkle black paint.
Exhaust and interior personalising
Finding the existing 2.5 inch exhaust with a Magnaflow cat and muffler too loud for street use, it was replaced with a Good-Win-Racing RoadsterSport 3 stainless header-back exhaust. The interior got a Voodoo shift knob and handbrake handle and a Grip Royal steering wheel, plus new Konig Flatout wheels ordered to replace the stock wheels.
Hardtop search
Wanting to replace a worn, torn soft top, MixedBreed bought a red hardtop with a broken, JB-Welded mounting bracket, then swapped it for a better black hardtop found nearby, selling the red one on to a friend for the price paid.
Suspension, brakes and interior work
A Prothane master bushing kit was installed throughout with new ball joint boots and zerk fittings, arms were repainted, poly diff bushings were fitted and the diff was shaved for exhaust clearance and refilled. A 949Racing brake kit, sound deadening, a racing seat and harness were also installed, though the new poly bushings introduced gear whine and the adjustable sway bar mounts damaged the AC compressor.
Later engine failure and sale
Years after the last build update, MixedBreed reported spinning a bearing on a club trip. A replacement long block from a friend was fitted after checking and resealing it with a new head gasket and timing belt, and the car was driven for about another year before being sold.
A summary in our own words. The full account, with all its detail, is in the original write-up: read it at MixedBreed's '93 With A '99 Heart ↗
Worth knowing
- Adjustable sway bar mounts from a bushing kit can need clearance checked against the AC compressor before driving
- Poly differential bushings can transmit noticeable gear whine into the cabin on long highway drives