Build Vision:
1. Emotion is more important than speed.
2. Analog and spartan, a tribute to simplicity.
3. Reduce complexity and increase reliability.
4. Increase sound pitch without increasing volume.

5. Predictable handling on undulating mountain roads.
6. Grip only slightly greater than the original car. 

7. Quiet for an in-car phone call with the top up. 

8. Low torque, wide modulation, less mechanical stress

9. Strategic Imbalance Leaving Impression

10. Not heavier than a Mazdaspeed NB Turbo (1150kg)

Contents

Overview
Chassis
Engine
Engine Refresh
Engine Reliability
Oiling System
Transmission
Exhaust
Fuel System
Heat Management
Suspension
Brakes
Wheels and Tires
Electronics
Electric Power Steering
The Four Horsemen of Ferramiata

Overview

Adapter Plate
Aside from mating the Toyota 86 gearbox to the Ferrari engine, the adapter plate has to provide for a channel on the bottom right that will allow the oil to return from the oil sump back to the scavenge pumps. The plate will have to be 55mm thick. Dowels will need to be made for both the Ferrari and the Subaru sides. The design was purchased from Jeff from the Alfararri build. In retrospect, the oil return created a packaging nightmare. If I was to do it again, converting the car to left hand drive will mean that the exhaust headers will have more room to be packaged. 

Flywheel
Jeff's approach was to take the stock BRZ/86 flywheel pcd bolt pattern is 36mm the Ferrari is 34mm. The bearing at the back on the Ferrari, the back of the flywheel should be machined out to fit this bearing exactly. Kunahiro-san decided to just make a custom flywheel and clutch package with OS Giken. An S2000 clutch slave will be used, with heat shielding for reliability. In the end Kunihiro-san from Daddy Motor Works just made a custom one.

Starter Motor
There will be a bolt that interferes with the starter motor from the Ferrari side that will have to be dealt with. The transmission tunnel has to be notched to fit the starter.

Intake Plenum Replacement  

The Ferrari 355 intake manifold and throttle bodies bolt right on to the Ferrari 360 engine and is lower. The linkage will be modified to use a single Jenvey drive by wire motor. The Ferrari 355 came with 290cc injectors and the Ferrari 360 with 315cc injectors. The plan is to run velocity stacks and a sock filter, the loss in torque due to the shorter runners helps support the drivetrain reliability. 

Intake Plenum Velocity Stacks
Garage4age has done some great research into runner length, and the conclusion is that 185mm is ideal, and 60mm is a minimum. Sadly, I will only be able to run 30mm lengths to keep the hood line as low as possible. Despite all this, we had to cut the hood and install a 2011 WRX hood scoop in order to get the required height and leave about an inch of space against the bonnet for air to flow in. The plus side of this is that torque will be reduced at lower RPM which should help the driveline stay a little less stressed. 

Exhaust
This will be a simple 4 into 1 design with a CNC merge collector from Elmer Racing on each side. This is by far the most challenging part of the project, with CFD done to try and get the exhaust pulses to scavenge correctly. After about 7 variations and a couple of plastic prints, I was lucky to find Scarbo Performance which is 3d printing it in parts and fabricating it. The OEM cats are being packaged around the transmission tunnel just behind the drivers and passenger seat in an offset way. They are large, but required for homologation in Japan. I will be running stock-ish ride height and will find a way to protect the cats

Trigger Wheel and Dampner
On Jeff's build, he initially used 3 M5 screws to attach the trigger wheel to the dampner but it broke, and he instead opted to go for 6 M6 screws for better reliability. In the end, Kunihiro-san just adapted a off the shelf trigger wheel to the dampner that camee on the engine. 

Dry Sump Tank 
Dry sump tank will be located in the rear trunk of the car, hard lines are run next to the driver side (RHD) frame rail. Total volume is about 8.5L versus the stock Ferrari 9.5L. In retrospect, I could have added more oil in the rear as there was more height than I oringally calculated as the tank was mounted through the floor. The trunk will get hot due to the exhaust, and after the car has been used, and data logged, an approach to managing heat can be considered. 

Fuel 

The upgraded fuel system includes an uprated in-tank fuel pump. It features two levels of filtration: 100 micron and 40 micron, to maintain purity and prevent clogging. A Radium fuel surge tank and fuel hanger will be installed to enhance fuel stability and distribution under various driving conditions. One of the main risks of this car is a fuel leak in the engine bay, and a fuel pressure sensor and cutoff should take care of that.

PPF Modification
The primary function of the PPF is to connect the front and rear of the car, reducing noise, vibration, and harshness while enhancing acceleration response with minimal added weight. Kunihiro-san used the transmission mount he fabricated for the ZN8 gearbox and so given that this car has both tranmission mounts and the PPF it should result in a stiffer, more connected driving experience. 

Brake Booster / Clutch Slave Heat Management 

The brake booster connectors are located just behind the intake manifold and will have to be connected to the miata brake booster. The clutch slave is from an S2000. For both parts,  shielding will need to be made to manage the heat put out by this engine. 

Oil Catch Tank / Overflow Tank
These have been beautifully fabricated by Kunihiro-san. They are two oval tanks that sit right behind the two headlights. 

Carbon Canister
Near where the brake booster connectors are is the carbon canister output, there needs to be a way to capture the vapour and ensures that it does not escape to the atmosphere. 

Coil Pack Adapter Plates 

These have to be machined in such a way to accept the coil packs. R35 GTR coils are going to be used. Ferrari 355 coil covers were made into a cover that neatens up the engine bay. 

Engine Lift Mounts 

Some brackets to lift the engine can be done at the spot near the valve covers. 

Engine and Trans Mounts
Engine mounts are from a RB26, chosen mainly because they are available and there are a wide variety of ones and OEM Toyota 86 transmission mounts. 

Electric Water Pump Conversion and Brackets
Two brackets need to be fabricated, one for the electric water pump mount on the bottom right hand side of the engine, and another for the water inlet on the top of the engine. Electric water pumps specced for at least for 10 LPM flow at 500rpm with 50-foot head pressure to solve coolant nucleation.

Radiator
A crossflow radiator and the stage two fan and shroud kit, ducted to exhaust heat through the hood. Jeff's fans initially were rated at a combined 1200cfm. The Flyinmiata fans are rated at 2500cfm max, so can be run at lower rpm for noise and better cooling performance.

Weight Targets

Many who have built completely stripped out MX-5 for racing classes can reach a weight of about 860kg with a quarter tank of fuel. The stock Mazda Speed Turbo NB weighs around 1150kg and so that will be the target of the car. Because of the increased weight of the chassis bracing, engine and ancillaries it will be a challenge, but rather than the absolute weight, I will do my best to move the weight rearwards over the rear wheels through packaging. 

The Chassis

Herb Adams (author of Chassis Engineering) defined torsional rigidity as “how much a frame will flex as it’s loaded when one front wheel is up and the other front wheel is down while the rear of the car is held level.” I've written quite a bit about this in my article that covers all the chassis improvements that will be made to this car. In a nutshell, it will use the last NB chassis with all the improvements which mazda made coupled with a set of Flyin Miata frame rails and a butterfly brace. It is seam welded in the engine bay and along the doors. 

There is a lot of debate as to how much torque and power the chassis can handle. Jeremy Ferber, an engineer from FlyinMiata believes the NA and NB Miata chassis of being capable of somewhere around 350-600whp. This stands in stark contrast to Bob Hall, who was part of Mazda's engineering team who stated that the NB's limit was around 200whp. The chassis improvements I will make will increase rigidity by a conservative 33%.

The engine will but out somewhere around the region of 300whp or so. Unlike turbo conversions, the torque won't come all at once, but rather build up over the rev range due to the short runners, so coupled with some chassis seam welding and bolt on parts for rigidity it should feel somewhat cohesive. 

The Engine 

The idea for this swap came from Toyota 1UZ builds. This engine from the Lexus LS400 is physically larger by around 11% compared to the Ferrari engine, so it helps give an idea of scale and packaging. The Ferrari engine is around 5% smaller based on measurements of the bore size and cylinder spacing. I will have to pay a 30kg weight penalty for using the F131 over the stock BP6D. Fun fact, it is just under an inch shorter than a stock Miata engine.

The airconditioner will be removed that will reduce the front end weight by around 18kg. Typical turbo kits for the Miata add around 25-30kg of weight to the front of the car, so dynamically I think the Miata should retain its original feeling. The 2004 Mazdaspeed MX-5 (turbo) had a 52/48 front to rear weight balance, and I suspect this will be about the same. 

Engine Refresh

While the engine is out, it is being refreshed with a combination of OEM and Hill Engineering parts.

Hill Engineering Tensioner Bearings

Hill Engineering Pulley Tensioner PT-360

Hill Engineering Oil Drain Cover

Rear Crankcase Gasket
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/crankcase/170529-crankcase-gasket.html

Pilot Bearing
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/driving-shaft-connecting-rods-and-pistons/103877-pilot-bearing.html

Rear Main Seal
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/driving-shaft-connecting-rods-and-pistons/200323-rear-main-seal.html

Timing Bearing
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/timing-controls/170787-bearing.html

Timing Snap Rings https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/timing-controls/11060576-saeger-snap-rings-metal.html

Timing O-Rings
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/timing-controls/136140-o-ring.html

Timing Washer
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/timing-controls/133377-washer.html

Timing Segar Rings
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/timing-controls/11060576-saeger-snap-rings-metal.html

Variator Control Solenoid https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/r-h-cylinder-head/195086-variator-control-solenoid-valv.html

Exhaust Variators
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/timing-tappets-and-shields/190042-exhaust-phase-timing-variators-360m.html}

Valve Cover Gasket
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/r-h-cylinder-head/173540-rh-valve-cover-gasket-360.html

Cylinder Head Oil Pipe
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/r-h-cylinder-head/151485-pipe.html

Cylinder Head O-Ring
https://www.ricambiamerica.com/car-diagrams/ferrari/v6-v8/360-group/360-modena/l-h-cylinder-head/147278-o-ring.html

Engine Reliability

Ferrari engines are unusual in that many of their reliability issues stem from underuse, improper usage and poor preventative maintenance. In particular, checking clearances periodically is a good idea for areas like the oil pump. The engine will be limited to 8,000rpm limiter and a 8,250rpm fuel cut to increase the service life and reduce heat. 

The F131's major concern was the exhaust valve timing (cam variator) failure. Ferrari's recommended "VD" stamp on the cylinder head signified corrected variators. Ensuring proper torque values for cam gear bolts after cam seal replacement is also crucial. Here is a list of common issues:

Rattling of throttle butterflies on the intake manifold 

Bolt/Pin (ref. 169594) Near the chain tensioner can fail affecting oil pump 

Injectors can laquer if not driven enough 

Exhaust cam variator needs to be replaced periodically 

Chain tensioners replacement every 3 years or 36,000km 

Thermostat style (ref. 183758) fails occasionally  

O2 lambda probes can fail (before catalysts) (Bosch 0 258 007 001) 

Transmission heat exchanger above the engine block corrodes and fails

Paper Gaskets under intake manifold form holes over time  

Injector o-ring crack over time  

Starter motors get sticky

Coolant and Oil Level
Manual check each after each drive.

Quarterly Fuel Line Check
Ferrari engines have a nasty habit of self-immolation, and using high quality fittings for the fuel system and inspecting it annually will be very important.

Annual Hydraulic Lifter Check
Diagnostic tests such as using a stethoscope to listen to the engine can help determine if the lifters are failing, which should sound like a ticking at idle.

Annual Compression Test
This can help identify potential valve guide wear or bottom end issues.

Annual Head Gasket Inspection
Let the car at idle and spray carburetor cleaner to the base of the intakes where the gaskets are. If the idle changes, in any way during spraying, then the head gaskets need to be replaced.

Fuel, Oil and Coolant Lines

Annual inspection and ensuring no chaffing or mechanical rubbing. They should also not collapse or degrade under heat, and be replaced when they are. 

Fuel Pump Filter
Fuel pump filter should be changed annually. 

Oil Sump Filter 

Every year or two, it requires replacement

Oil Changes and Oil Leak Inspection
10 month oil and filter change regardless of use. This is a reduction from 12 months as most engine failures have occured due to issues related to oiling. 

Oil Analysis 

Send oil for analysis by external party annually. 

Oil Pump Gear 

Inspect for oil pump gear as it has been documented to chip. Bevel gear damage is likely due to metal fatigue factory parts issue or wear and tear. Filtration (magnetic capturing)  and inspection will help reduce the risk of engine damage. There are rubber o-rings between the oil pump and on the scavange ports that should be all replaced. DIY Rebuild: https://www.youtube.com/watch?v=W1t6zrmB6Po

Oil Fittings 

Replace oil fittings which are known to crack due to vibration.

Oil Grade 

Ferrari specify Shell Helix Ultra 5w40 but in practice any high spec fully synthetic 5w40 will work.10W60 grade oil is used in intensive use or hot climates. Since the car is only driven in spring and autumn, the engine oil will be chosen based ont that.

Oil Drian Plug and Crush Washers 

After draining the oil, remember to reattach the plugs with new copper washers. While the manual suggests a 75nm torque, this is excessive and could harm the sump/gearbox thread. Instead, I hand-tighten the drain plugs and give them a ¼ turn.

Water-Pump 

Using a Pierburg 7.07223.10.0 which is electric and ECU-driven so coolant flow is a map, not a belt: quick warm-up, big flow at hot idle, and after-run cool-down. It is used on a lot of European cars. Decoupling from RPM kills the cavitation/underflow seesaw you get with a high-rev flat-plane and long lines. Mounted on vibration dampers, and low to push through the radiator, which keeps the bay calmer and the pump happier.

Cambelt Replacement
Cambelt replacement every 5 years regardless of mileage, consider doing the variators at the same time as well. Conventionally Ferrari recommends every three years, and I determined this tempo based on this excellent article here. 

Cam Drive Bearings 

Located in the front timing chaing cover, the two lower cam drive bearings are known to deteriorate and seize over time. The original SKF bearing is no longer availible, but Hill Engineering has developed a better version along with improved features like high temperature grease and seals.

Part Link: https://www.hillengineering.co.uk/170787
Tool Required: https://www.hillengineering.co.uk/95972938-a?search=95972938

Belt and Tensioner Management
Consumable item change all every 3 years regardless of use and inspect annually. These are the key killers of the F129 engines. TODA and Hill Engineering bearings are cheaper than OEM and are of higher quality.

Oil Pump Chain Tensioner and Inspection
Check annual that the tensioner does not walk laterally on the mount. Sometimes there is a rattle like a chain rubbing on something that can be verified by using a stethescope.

Tensioner Bushings
Inspect and replace if bushings are hardened.

Valve Timing Adjustment
Engines left the factory timed up on scribe marks made on the camshaft during manufacture. Although the marks are adequate for the engine to run well, the best performance is made when the engine is timed up properly by adjusting the position of each cam individually so that the valves open and close as per the engine design. Precise cam timing using dial gauges and degree wheel.

Cooling System Leak Inspection
Cooling System Problems such as leaks, thermostat failure, and radiator clogging can cause overheating and potential engine damage. Upgrade to motorsport/military-grade fuel lines with AN fittings to prevent failures.

Intake Manifold Screw Inspection 

Check and secure inlet manifold throttle body screws.

Crank Seal Inspection 

Inspect the crank seal for leaks and replace with TODA or OEM part. 

Oil Sump Seal Inspection 

Inspect the crank seal for leaks and replace with OEM part.

Fire Extingushers 

Because Ferrari. 

Oiling System 

The Ferrari 360 originally came with a 10L oil volume. Other naturally aspirated V8 Ferraris, from the 308 to the 458, also varied between 8-10L. There is only between 10-12" of height in the miata trunk, and the tank is about 16" in height. 

• Manage the Adapter: Careful management of the adapter plate and O-rings is required, particularly for the 90-degree oil return turn through the adapter plate. This is an area of potential leaks. 

• Aluminum Hard Pipes with Flexible Joints: Use aluminum hard pipes with flexible joints around the car. This setup maintains overall pressure while allowing small movements to prevent cracking. 

• Pressure Sensors: Install pressure sensors in several areas to ensure good oil feed, particularly around the oil return line. AN-16 lines will be used wherever possible.

• Oil Volume: Using a Armstrong Race Engineering Tank 7820A, customized to a 16" height and an 8" base, holding approximately 7.5L of oil. Additional AN-16 lines will add around 2L of oil, bringing the total volume to 9.5L. In retrospect, I could have gone taller. 

• Oil Heater and Cooling: Install an oil heater in the tank to bring the oil up to temperature. After logging some drives, I will decide if a cooling system is needed. 

• Large Diameter Return Lines: Utilize AN-16 or AN-20 return lines for higher volume and better flow. The OEM Ferrari oil line diameter will guide the base return line diameter choice. 

• Air-Oil Separator: Add an air-oil separator near the oil tank to de-aerate the oil as it returns from the engine. 

• XRP Fittings: Use XRP fittings throughout the build, ensuring flexible joints for movement.

• Temperature and Pressure Monitoring: Add temperature sensors to the oil tank and oil return from the engine. Install a mechanical pressure sensor on the engine for on-the-move monitoring.

• Oil Tank Placement: Mount the oil tank in the spare wheel area for protection from the muffler's heat. Ensure the return line runs through the trunk, sloping down to the oil pump without gaining elevation.

• Plumbing: Use a combination of hard lines and braided-over-PTFE hoses for flexibility at the joints. Purchase all parts from the same supplier to ensure interchangeability and fit. Pay attention to clamping torque to prevent damage to the pipes/hoses.

The Transmission 

1. Reasons for Toyota AZ6 

• Feel: Loved the shift feel and gear ratios in my old 2012 GT86 

• Erganomic Packaging: Linkage allows flexible gear shifter placement.

• Torque Compatibility: In stock form, the geearbox handles 184lbft of torque at 3750rpm, however due to me using 355 throttle bodies and deleting the 360 intake manifold, it will only have to deal with approximately 220lbft of torque at about 6,500rpm.

2. Designing and Fabricating Components

• CNC Adapter Plate: Used BuiltbyJeff's design

• Flywheel Modifications:

  • Custom clutch and flywheel from OS Giken

  • Weights of flywheels:

    • Ferrari 360 stock flywheel: 5.56 kg

    • Toyota 86 ZN6 stock flywheel: 9.34 kg

    • Toyota 86 ZN6 TRD flywheel: 5.6 kg

  • Machine the flywheel bolts 2mm inwards to match the Ferrari PCD.

  • Note one bolt in a slightly more inward position than others.

  • Machine the flywheel to center on the bearing.

3. Compatible Parts

• Parts from GT86 Platform: One approach is to use parts like the clutch, pressure plates, flywheel slave cylinder from the Toyota 86 ZN8 platform. I will be going with custom parts from OS Giken. 

• Fasteners: Both Ferrari engine and Toyota 86 gearbox use metric fasteners.

4. Torque and Speed Optimization

• Final Drive Ratio: Aim for a cruising speed of 110 km/h at 2800 RPM in 6th gear.

• Initial Setup: Start with a stock 4.1 final drive and modify downward to approximately 3.72 as needed.

5. If You Are Fabricating: 

• Removing and Replacing Studs:

  • Remove studs from Ferrari block using a stud removal tool.

  • Insert shorter cap head bolts into the Ferrari block.

• Flywheel Bolts: Use M10x1.25 flywheel bolts.

• Trigger Wheel and Sensor:

  • Fabricate a mount on the engine for the crank position sensor. 

  • Use a Link 60-2 crank trigger wheel and create a mount for the crank pulley  

  • Mount a crank angle sensor.

• Adapter Plate Assembly:

  • Use cap-head bolts for mating the adapter plate.

  • Use the stock Toyota 86 TRD pressure plate.

  • Press in the pilot bearing on the Toyota 86 TRD clutch.

  • Use shorter bolts for the gearbox to the adapter plate.

• Starter Motor: Determine the appropriate starter motor to use.

• Slave Cylinder: Notch the slave cylinder on the adapter plate.

The Exhaust 

• Overall Plan:  The 4-1 headers will be routed equally on either bank. They will join merge collector with a spike. This was created by 3d scanning the engine bay, and 3d printing and welding the headers. Will be ceracoated for heat management. The two pipes from the headers go on the opposite side of the PPF, and flow throughout the stock Ferrari cats before heading to the muffler. 

• Gaskets and Probes: I am planning to use a high-temp gaskets around the cat and install a post-catalytic converter temperature probe to ensure temperatures do not exceed 940°C.

• Helmholtz Resonator: Once the exhaust is fabricated, I will try and work out how to package a Helmholtz Resonator to reduce drone at 105 kmh cruising speed. Larger radius attenuates lower frequencies; smaller radius is effective at higher frequencies. Precise tuning is essential for targeting specific sound frequencies.

• Final Muffler is a stock Ferrari 430 exhaust which along with the additional piping should mimic the Ferrari 360 tube length more closely. 

Exhaust System Details

• Flange and Tubes: 7.5mm CNC flange, 38.7mm header primary, 60.5mm secondary, 76.2mm to muffler, stepped down to 63.5mm. (Note a lot of popular S2000 exhausts are 70mm, so given the increased CFM, this will be a restriction done in favor of exhaust velocity and quieter sound. 

Fuel System

For the Ferramiata, I’m going with a return-style fuel system to keep things simple and reliable. It mirrors the original 360 setup and ensures consistent pressure without relying on PWM or sensors. Returnless was considered, but the added complexity and reliance on electronics didn’t feel worth it for this build. With a good regulator, high-flow filter, and upgraded lines, it’ll keep the engine fed cleanly and handle load without fuss. Electrical systems will be required to support this as well. 

Heat Management

To address the heat management challenges posed by doubling the engine capacity and nearly doubling the power, I have outlined several steps to upgrade the stock cooling system. 

• Increased Capacity Radiator: Utilize a radiator with efficient fins designed to optimize heat dissipation and minimize static pressure loss between the front and rear of the radiator.

• Upgraded Electric Fans: Implement more powerful electric fans to improve cooling efficiency.

• Electric Water Pump with ECU Integration: Using a Pierburg 7.07223.10.0 which is electric and ECU-driven so coolant flow is a map, not a belt: quick warm-up, big flow at hot idle, and after-run cool-down.

• Radiator Shrouding with Rubber Flaps: Add shrouding to the radiator with rubber flaps to direct airflow effectively.

• Swirl Pot: Install a swirl pot to reduce air bubbles in system.

• Heat Shield for Exhaust: Add a heat shield to reduce trunk temp. 

• Transmission Tunnel Heat Shielding: Add heat shielding to the transmission tunnel. Use gold reflective foil extensively in the front of the tunnel near the passenger compartment to mitigate heat transfer.

• Louvered Hood Vents: Install louvered hood vents to extract heat from the engine bay, with rain panels for wet weather to prevent water ingress.

• Summer Track Use Avoidance: Avoid running the car on the track during the summer to ensure reliability.

• Redline Reduction: Reduce the redline to 8,250 rpm with an 8,500 rpm fuel cut to enhance long-term reliability.

• Oil Heater in Dry Sump Tank: Use an oil heater in the dry sump tank to help the engine oil reach its optimal temperature quickly.

• Radiator Plumbing: Combine hard lines and braided-over-rubber hoses for added flexibility at the joints, sourcing all parts from the same supplier to ensure compatibility and fit.

  • Braided-Over-Rubber Hoses:

    • Uses: Commonly used for larger hoses like dry sump systems and radiator connections due to their flexibility.

    • Materials: Consist of a rubber core with a braided exterior for durability and flexibility.

• Silicon Couplers and Clamshell Couplings: Use silicon couplers and clamshell couplings on joints to address vibration issues between the engine and the body.

• Relocated Exhaust Muffler: Move the exhaust muffler higher by removing the spare tire area to extract heat in the transmission tunnel.

• 1. Silicone Hoses

• HPS 4-Ply Silicone Hose:

• Why Use: Silicone hoses are significantly more durable and heat-resistant compared to standard rubber hoses, making them ideal for high-performance cooling systems. Their construction allows them to handle higher pressures and temperatures without degrading, ensuring longevity and reliability.

• What to Consider: Ensure that the hose diameter matches your vehicle’s coolant system requirements. Using undersized or oversized hoses can lead to inefficient coolant flow, causing overheating or leakage issues.

• 2. Hose Clamps

• Norma Clamps Hose Clamps:

• Why Use: Norma clamps are known for their strong, consistent clamping force. They’re engineered to handle high pressures without loosening or slipping, which is critical in maintaining a leak-free system in performance cooling.

• What to Consider: Make sure the clamps are tight enough to secure the hoses but not over-tightened, as this can damage the silicone material. Regularly inspect clamps for wear or loosening over time.

• 3. Radiator

• CSF Radiator:

• Why Use: CSF radiators are renowned for their superior cooling efficiency, thanks to their construction materials and design. Aluminum radiators, in particular, are lightweight and dissipate heat better than traditional materials, keeping the engine cooler for longer, especially under high-performance conditions.

• What to Consider: Choose a radiator that is appropriately sized for your engine. A larger or higher-capacity radiator can improve cooling, but make sure it fits within your engine bay without requiring extensive modifications.

• 4. Fittings

• AN Fittings Earls:

• Why Use: AN fittings from Earls are precision-engineered for high-pressure, high-performance applications. They provide secure, leak-proof connections, which is crucial in maintaining system integrity under intense conditions. AN fittings also resist corrosion and wear, ensuring long-lasting performance.

• What to Consider: Make sure you match the fittings to your hoses and radiator to prevent leakage or flow restrictions. Precision is key when installing fittings to ensure a tight seal.

• 5. Avoiding 90-Degree Fittings

• Why Avoid: 90-degree fittings create sharp bends that can restrict coolant flow, leading to pressure drops and inefficiencies in the system. This restriction can cause overheating, as the coolant may not circulate as efficiently through the system.

• What to Use Instead: Opt for straight or 45-degree fittings to allow for smoother transitions and maintain optimal flow. This helps to prevent bottlenecks and ensures your cooling system operates at peak efficiency.

• Additional Considerations:

• System Layout: Plan your cooling system to minimize sharp bends and long hose runs. This reduces resistance in the flow of coolant and keeps the system working efficiently.

• Regular Maintenance: Inspect all hoses, clamps, and fittings regularly to ensure everything is secure and leak-free. Address any issues immediately to avoid overheating or system failure.

Brakes

The stock NB Miata brake system is built for stability: a front‑heavy hydraulic bias (≈66–68% front) with a fixed proportioning valve, small single‑piston sliding rears, and 3‑channel ABS that modulates both rear wheels together so the fronts lock first and the car stays straight.

It make the car difficult to trail brake. I chose Project μ NS‑C (F1100/7112) front + Project μ NS (R401) rear pairing gently shifts that balance to about 63.7%/36.3% without upsetting ABS logic: the slightly lower‑μ front (NS‑C ~0.34–0.38) keeps initial bite smooth and easy to modulate, while the rear’s modestly higher μ (NS ~0.37–0.40) lets the back of the car contribute a bit more torque right at turn‑in. The net effect is clean, predictable rotation on trail‑brake in the dry, yet the system remains front‑leading under hard stops, preserving straight‑line stability and wet‑road safety. 

Wheels and Tires 

The wheels are Konig Freeforms in 15x8 with a 25mm offset. Orignally, the plan was to go with RE71RS tires, however they would not fit give the offset of my wheels. In addition, as this will mainly be a street driven car in colder temperatures, the compound was not ideal.

The ADVAN Fleva because it’s friendlier in cool, wet street conditions. Itwarms up quickly, stays pliable, and has a more progressive breakaway than the RE-71RS. The narrower 205 also reduces hydroplaning and matches your “progressive over peak grip” brief for everyday driving. RE-71RS is brilliant hot on track but can feel glassy when cold, and its taller 225/50 size nudges gearing/ride, so it’s better kept for your track set.

Electronics Package 

Simplicity and reliability is the key focus of the electronics package. The wiring harness will be drawn out, and have a sensor plan that will be developed in a spreadsheet. Part of the controls will be handled by the Link PDM.

Analogue Tach / Digital Dash:

The analogue tach is taken from a Ferrari 550 and mounted centrally. The digital dash is a AIM Strada MXP 1.3 unit that is mounted wher the radio used to be.

Equipment

GPS Logging / Wifi 

Diagnostics WiFi 

Link Looms 

Header Plugs  

Link Razor PDM
CAN Pad 

Sensors from Link 

AIM MXT 1.3 Strada - 11inches across (Miata is 12 inches)
Ferrari 550 Jaeger Electronic Tachometer in Front 

O2 Sensor
I’m going with the Bosch LSU 4.9, one on each bank, because it’s the most balanced and proven option for what I need. It’s fast, accurate, and holds up well even with aggressive tuning and transient conditions—exactly what a high-strung engine like this demands. It integrates cleanly with the Link G4 via the CAN-Lambda module, which keeps things simple and reliable without messing around with analog noise or extra calibration quirks. I looked at higher-end options like the LSU ADV and NTK, but the added hassle and lack of native support just aren’t worth it here. The 4.9 does the job, does it well, and keeps things future-proof.

Sensor Upgrades:

Mass Air Flow (MAF) sensor

Throttle Position Sensor (TPS)

EGT Sensor Left Bank 

EGT Sensor Right Bank 

Knock Sensor Left Bank

Knock Sensor Right Bank 

Coolant temperature sensor (IN)
Coolant temperature sensor (OUT) 

Intake Air Temperature (IAT) sensor

Crankshaft Position (CKP) sensor

Camshaft Position (CMP) sensor

Knock sensor

Exhaust Gas Recirculation (EGR) sensor

Exhaust Gas Temperature (EGT) sensor (4x) 

Fuel Temperature (FT) sensor

Fuel Rail Pressure (FRP) sensor

Oil pressure sensor

Oil temperature sensor

Exhaust thermocouple sensor

Angular speed sensor (for timing)

Air injection system sensor (for emissions control)

Oil Pressure Sensor 

Water Pump Flow Rate Sensor
Full data logging capabilities 

Physical Wiring Specification
Closebarrel autosport connector 

TXL Wire Club Level Wire (125deg heat rating) 

Mounted wires to reduce vibration 

Sheathing and heat protection 

Star Point Grounding
Star point grounding in automotive systems connects multiple circuits to a single ground, resembling a star configuration. This approach reduces electrical noise and interference.

Link ECU Programming. 

0) Channels / Inputs

• EGT_1 … EGT_8 (pre-cat, one per cylinder)

• Lambda_L, Lambda_R (WBO2 per bank)

• P_fuel (rail), P_oil (gallery), T_cl (coolant), T_oil (sump; tank optional), IAT, MAP, TPS, RPM, (optional) VSS, Knock

• Inertia / Start request / Service button Priming / Service Button Oil Heating 

1) Math Blocks (examples)

• Bank avgs: EGT_L = (EGT_1+2+3+4)/4, EGT_R = (EGT_5+6+7+8)/4

• Per-cyl deltas: ΔEGT_i = EGT_i − (bank avg for that cyl)

• Per-RPM EGT limit: EGT_Lim[RPM] (e.g., 850 °C@4000 → 900 °C@6500 → 930 °C@8200; linear)

• Rate-of-change: dP_oil = P_oil − P_oil(−0.3 s), dT_cl = T_cl − T_cl(−1.0 s)

• Bank λ lean flags: Lean_L, Lean_R (λ thresholds below)

2) Start-up Oil Priming & Start Authorization

Goal: build oil pressure before first fire and catch bad priming after start.

• Prime Mode (Virtual Aux V_PRIME)

  • Enable: Key-on, Engine RPM < 50, and (time-since-last-run > 30 min or Service button pressed).

  • Actions (5–8 s):

    • Force Fuel Pump ON (Aux).

    • If you have a pre-lube/electric pump, turn Pre-lube ON.

    • Disable Injectors & Ignition (GP Outputs or GP Limiters) so the engine cannot fire.

    • Require a Start button while V_PRIME active.

  • Prime success: P_oil ≥ 1.5 bar OR prime timer ≥ 8 s → set V_PRIME_OK.

  • Start authorization: Injectors/Ignition enabled only when V_PRIME_OK = TRUE.

• Start-up Oil Window (0–8 s after first fire)

  • If P_oil < MinOil[RPM] for >2.0 s → Latch Kill.

  • Rapid drop: if dP_oil ≤ −1.0 bar/0.3 s above 2500 rpm → Immediate Kill.

(If you can’t control the starter, the “crank-no-fire” method still works: it spins the engine-driven pump until P_oil meets the threshold.)

3) Hard Limits (instant cut / latching kill)

Use GP Limiter → Fuel+Ign Cut. Prefer Latch Until Key-Off where noted.

1. Fuel Pressure

   • Expected = base (or base+MAP for boost-ref).

   • Trip: P_fuel < 0.90 × Expected for 0.20 s → Fuel Cut (non-latch).

   • Latch: < 0.85 × Expected for 0.50 s or dP_fuel ≤ −0.8 bar/0.3 s → Latch Kill.

   • Recovery hysteresis: require P_fuel ≥ 0.95 × Expected for ≥2.0 s to clear derates.

2. Oil Pressure vs RPM

   • Map: 2.5 bar@1000 → 4.5 bar@8000.

   • Trip: P_oil < MinOil[RPM] for 0.10 s → Latch Kill.

3. Temps (last-ditch)

   • T_cl ≥ 112–115 °C for 2.0 s → Latch Kill.

   • T_oil ≥ 135 °C for 1.0 s → Latch Kill.

4. Per-Cylinder EGT Critical

   • Any EGT_i ≥ (EGT_Lim[RPM] + 80 °C) for 1.0 s at load →

     • Preferred: per-cyl Fuel Trim = −100% (cut that cylinder) via VA_i.

     • Fallback: Global Fuel+Ign Cut; Latch on 3 repeats within 30 s.

4) Soft Limits (derates before damage)

A) Lambda (bank) under load (monotonic thresholds fixed)

• Stage-1: λ > 0.90 for 0.25 s → +4% fuel (that bank).

• Stage-2: λ > 0.92 for 0.50 s → RPM cap −1000.

• Latch: λ > 0.94 for 1.0 s, or (λ > 0.90 AND any EGT_i ≥ Stage-2 threshold).

B) Per-Cylinder EGT (no ignition retard)

• Stage-1: EGT_i ≥ (EGT_Lim + 20 °C) for 2.0 s → +3–6% fuel (that cyl).

• Stage-2: EGT_i ≥ (EGT_Lim + 50 °C) for 1.0 s → RPM cap −1500 (global), keep Stage-1 fuel.

• Stage-3 (pattern): ≥2 cylinders at Stage-2 within 3 s → RPM cap −2500.

• Imbalance: ΔEGT_i > +100 °C for 1.0 s → +3–5% fuel (that cyl) and RPM cap −1000.

• Clear: when EGT_i < (EGT_Lim + 20 °C) and ΔEGT_i < +60 °C for ≥2 s.

C) Temperatures (pre-limits)

• Coolant: T_cl ≥ 105 °C → RPM cap −1500, clear at <100 °C.

• Oil: T_oil ≥ 130 °C → RPM cap = 4000, clear at <118 °C.

D) IAT & Knock gates

• If IAT > 60–65 °C → subtract 20 °C from EGT_Lim[RPM] and −500 rpm from allowed RPM.

• If Knock events spike at load → favor RPM cap; do not add retard to “cool” EGT.

E) DBW torque limit (if E-Throttle)

• Map a Throttle Target Limit vs a Derate VA to cap load to 20–40% during any derate.

5) Enable, Plausibility & Recovery

• Enable gates: Apply AFR/EGT logic only when MAP > 70 kPa or TPS > 40%, Coolant > 70 °C, and Run-time > 60 s.

• Sensor plausibility:

  • EGT_i fault: stuck <50 °C or >1050 °C at idle → mark EGT_Fault_i; remove that cyl from EGT voting and tighten remaining EGT limits by +20 °C margin.

  • Lambda fault: WOT with λ ~1.00 ±0.01 for >0.5 s → mark O2_Fault_bank; lean ladder falls back to EGT + FuelP only.

• Derate recovery: Use restore points 5–10% safer than trip points to stop chatter (e.g., RPM caps clear after temps drop and hold for 2 s).

6) Fan & Rev-Limiter Behavior

• Fan PWM: 50% @ 88 °C, 100% @ 95 °C (2–3 °C hysteresis via VA).

• Limiter shaping: Fuel cut before spark at hard limit; also scale Max RPM down as P_oil approaches MinOil[RPM] (linear taper).

7) Dash/CAN Warnings

Map Virtual Aux states to codes/colors:

• RED: LATCH (OilP, FuelP, Coolant, OilT, EGT_crit_i).

• AMBER: DERATE (Coolant/Oil/IAT/EGT/Lambda/Imbalance).

• Show cause code (e.g., E1…E8, OILP, FUELP, λL/λR, IAT, COOL, OILT, PRIME).

8) Commissioning Checklist (in PCLink)

1. Calibrate all sensors; verify channel directions & units.

2. Build EGT_Lim[RPM]; populate per-cyl fuel trim tables with VA_i axis.

3. Test Prime Mode (key-on, service button, long-sit condition): confirm P_oil rises and Inject/Ign remain blocked until V_PRIME_OK.

4. Induce safe faults using Runtime Value Overrides to confirm:

   • FuelP cut → latch; OilP map → instant latch; Coolant/Oil temp derates; EGT Stage-1/2/critical per cylinder; Lambda ladder.

5. Validate recovery hysteresis and derate clear timers.

6. Save Tune A (normal) and Tune B (diagnostic) with softer thresholds.

Suggested starting numbers (tune to your data/fuel)

• WOT target: λ 0.85–0.88

• λ ladder: 0.90 (trim), 0.92 (−1000 rpm), 0.94 (latch)

• Fuel P: pass ≥ 90% expected; 85% latch; recovery ≥ 95% expected for 2 s

• Oil P map: 2.5 bar@1k → 4.5 bar@8k; start-up window 0–8 s

• Coolant: 105 °C derate; 112–115 °C kill (2 s)

• Oil: 130 °C derate; 135 °C kill

• EGT per-cyl: limit line +20/50/80 °C (Stage-1/2/Critical)

• ΔEGT: trip +100 °C, clear +60 °C

• IAT gate: >60–65 °C → −20 °C EGT limit, −500 rpm

Electric Power Steering 

I am planning to go with an electro-hydraulic setup that was used in the Toyota MR-S with a sensor to detect pressure loss and leaks. The bushings should be replaced and the lines will have to be of the highest quality to reduce the possibility of a fire.

Plumbing of the power steering will be a combination of hard lines and braided over PTFE hoses for flexibility at the joints. My plan is to purchase all parts from the same supplier to ensure interchangeability and fit. 

Silicon couplers and clamshell couplings on joints to be used. Special attention should be paid to clamping torque to prevent damage to the pipes/hoses. 

Aerodynamics 

Convertible cars typically have poor aerodynamics when the top is down, leading to turbulent airflow that renders rear wings ineffective, as shown by data indicating a significant decrease in downforce, ranging from 50-80%. Consequently, the focus shifts to aerodynamic manipulation under the car.

The rear diffuser's downforce, crucially located ahead of the rear wheels, distributes downforce evenly across the front and rear tires. To ensure proper cooling for the differential, the diffuser throat will be positioned after it, with an open transmission tunnel accommodating exhaust piping. A front diffuser will be installed to cover the radiator area. Opting out of a wing, I'll employ a ducktail-style trunk to generate downforce without relying on clean air, accepting the drag penalty.

My aerodynamic objective is twofold: reducing overall lift and increasing rear downforce as speed rises. Avoiding a rear wing, which loses effectiveness with an open top due to turbulence, I'll implement the following:

- Front diffuser and wheel spats to minimize front-end lift

- Rear of the front diffuser will remain open for heat management

- Fender vents, remade in aluminum, following the front bumper line

- Flat underfloor design with heat management considerations

- Exhaust relocation and installation of a well-packaged rear diffuser

- Positioning the diffuser throat behind the rear wheels for increased rear bias

I considered several options for the spoiler. On one end of the specturum are tall, 70 degree spoilers that usually have stays that are not asthetically pleasing attached to them like the Blackbird Fabworx Spoiler. After trying to look at several clean ways to implement this, I gave up. That left either trunks with integrated ducktails or spoilers that attach onto the existing trunk. The former ended up making more sense.

Hood Vents:

1. Starts 2" behind the radiator 

2. Centralize from sides by 15"

3. Should be located 20" in front of glass

4. Vents should extend above and below hood

5. 1" gurney flap in front of vent perpendicular to airflow
6. Duct the front of the radiator does not flow around it.

The Four Horsemen of the Ferramiata 

A car with such an extensive swap is bound to have things to work out. Going through my build thread, I have determined 4 key areas I need to keep and eye on to ensure safety. With each of these, there will be warnings built into the ECU to mitigate any potential issue.

1. Oil Tank and Lines 

Vibration or hose failure is a very real threat. Quarterly (and track) inspections needed.

2. Fuel Lines
The fuel lines in the engine bay can leak on to the hot exhaust header in the engine bay.

3. Bellhousing Oil Port Area
At the 90 degree bend, inspections need to be done for leaks and damage.

4. EPS Hose Failure
Checking all the high pressure lines to ensure that the power steering fluid is intact. 

Aerodynamics 

I must credit Occams Razor for his excellent research on Miata specifc aero. For a front-engine Miata, a balanced setup puts 40–45% of total downforce on the front axle at the reference speed. That keeps the steering loaded without making the rear nervous. In the example below (splitter not yet counted), the car sits at ~4.0 kg front and ~15.0 kg rear—about 21% front, which is markedly rear-biased. Adding ~6–8 kg at the nose (primarily via a well-designed half-splitter and cleaner cooling airflow) moves the split into the sweet spot.

Example contributions (kg at test speed)

• Front tire spats: +2.74

• Hood vents: +1.22

• Rear bumper cut: –0.39

• Rear ducktail: +10.26

• Rear diffuser: +5.10

• Front half-splitter (target): +6–8

Best-practice notes for Miata aero

• Chase balance first, then total load: Aim for 40–45% front, then scale everything up.

• Seal and vent the cooling path: Duct the radiator and vent through hood/fenders so air exits up, not under the car—more front grip and lower temps.

• Splitter fundamentals: Full-width, rigid, and well-sealed to the bumper/undertray; even modest overhang adds the missing 6–8 kg.

• Rear stability: Ducktail + diffuser work well; avoid excessive bumper cuts that bleed rear load.

• Iterate at speed: Adjust in small steps and recheck the split at the actual test speed