BEAVIS Motorsport's guide to Track Building your MX-5 Miata

Over the years, I've learnt many of the strengths and weaknesses of Mazda's "worlds best selling" sportscar chassis. Here is my suggested approaches to building your MX-5 Miata into a great fun weekender, a capable track toy or even a Porsche beating monster.

Build Stage 1 - The Fun Weekender

If you're a weekend warrior, or perhaps you use your MX-5/Miata as a daily drive but you want to have a little more fun, then this build might be the right answer.
This is tailored to a lower budget and with high reliability in mind, but will still offer a great level of satisfaction when behind the wheel with sharper steering and a solid feel.
Induction noise can make a car feel fast, so consider a well designed 'cold-air-intake' however keep in mind they offer minimal performance benefit.

Stage 1 specs:

  • Good budget coilovers, brands such as MCA/Voston, BC BR's, or Megan Racing.
  • A limited slip differential, such as a Mazda OEM torsen - if you have an early 90's 1.6 you will need to change your driveshafts to match the 1.8 sized diff.
  • Good quality street tyres such as Yokohama AD08 on a 15x7 or 15x8 rim.
  • Basic Intake and exhaust mods are also welcome but the performance benefits are minimal.

Build Stage 2 - The Dedicated Track Car / Budget racer

Time to kick it up a notch?
You might be running a dedicated track car, something to wrestle through the corners against Subaru's or Alfa Romeo's, but you want to finally have the grip to outclass a Lotus and the power to try and keep up with a Toyota 86.
Well this is probably going to be the right build benchmark for you.

Stage 2 specs:

  • At this level, I'd still recommend MCA Purple, BC BR's as a best bang for buck coilover.
  • A quicker ratio limited slip differential, such as a Mazda OEM 4.3 torsen.
  • If you can stretch it, time to look at a Semi slick tyre, either the Nitto NT-01 for the more budget conscious, or Yokohama A050 if you can stretch the extra $$$.
  • Time for a quality light weight wheel in at least 15x8 or up to 15x9 if you can, and consider an offset somewhere around +36 to +20 offset - these sizings will fit under any NA or NB MX-5/Miata with a mild guard roll to make some clearance.
  • To get a bit more pep, a set of stainles-steel headers and a 2.5" straight through exhaust with a muffler and a resonator to keep the noise and raspiness under control.
  • You NEED braided brake lines, good pads (I like the Hawk Blue) and any reasonable OEM size brake rotor.
  • A larger Front sway bar will help improve turn in and stiffen the front end, consider the 1.125" Racing Beat bar.
  • Take note, the swaybar mounting point on the NA/NB MX-5 is prone to cracking and failure under heavy use, consider something like the Racing Beat Sway Bar Brace Kit to prevent this.
  • Another item for performance, a well designed 'cold-air-intake' will help with top end... often at the sacrifice of a little mid-low end torque, but for a track car which is always revving at 5000rpm+ that's not an issue. DON'T just plonk a POD filter next to the headers, thats not cold air.
  • Now is the time to think about adding lightness. Remove every creature comfort that can be unbolted, do you really need A/C? Remove all the junk in the boot/trunk, such as carpeting, spare wheel and the cardboard pannelling.
  • The interior carpets are actually fairly light weight, provided the sound deadening mats are removed. So if you aren't an all out racer, don't feel bad if you want to leave the carpet in place.

Build Stage 3 - The complete all out race car beast

Our most complete list of everything you need to achieve a reliable, capable, race winning MX-5 Miata. No penny spared here (within reason).
Our stage 3 build will detail every thing you need to install, upgrade or replace to support your high power, high grip track dedicated monster.
Don't expect much change leftover in your wife's purse when you end up at this level.

Stage 3 specs:

  • For boost, use NGK BKR7E Spark Plugs
  • Proper coil packs (not mazda factory items) - we use only LS2 GM coils as they are fantastic bang for buck.
  • Run a proper modern injector, not used OEM ones from 10 years ago and not chinese injectors - we like Deutschwerks or the FlowForce injectors.
  • Don't run on batch fuel delivery (NA6 came with this from factory).
  • Always run highest octane fuel you can source/afford, E85 is always the best.
  • The factory Mazda Throttle body is known to come loose and fail under heavy use - avoid issues by securing it with epoxy.
  • Avoid running completely solid motor mounts - the mazda BP motors are not particularly smooth running engines.
  • As soon as you want power - upgrade your Rods, pistons and oil pump.
  • Use proper Inconel turbo/manifold studs to ensure the turbo stays secure to the manifold.
  • Ensure your Blow Off Valve is sufficiently sized, too small can cause issues.
  • Avoid intercooler piping blowouts with proper beading on your hoses.
  • Believe it or not, typical worm type hose clamps actually work reasonably well.
  • Avoid use of rubber lines for your turbo / oil / coolant - particularly in areas near the exhaust system.
  • A bar & plate intercooler is almost always better than a tube & fin style... even generic/budget bar & plate items are very capable.
  • Don't want a cracked exhaust manifold? Make sure you have mounted your exhaust sufficiently, under supported exhausts fail.
  • Use consistently sized intercooler tubing, turbo to I/C, and I/C to throttle - avoid tube diameter changes between these points.
  • Don't go using ebay turbos or a turbo of unknown history.
  • Upgrade your diff mounts to something stiffer - delrin items are available nowadays at a reasonable cost.
  • If your car comes with the clutch switch which requires the clutch to be depressed to start the car - bypass it! This will save your thrust bearing.
  • Are you running a 5 speed transmission? Time for a 6 speed - which are good for about 350torques...
  • Still running an NA6 diff? Still running an open (1.8) diff? Neither of these will cut it. Upgrade to at least a torsen. Even a torsen starts to suffer at the track when you are over 250rwhp
  • You will need to be looking at 9 inch wide wheels and proper 225 wide rubber to ensure you get the power down.
  • Sorry, but Coilovers from ebay or budget suspension are not going to work if you want to come first.
  • It's time to update ALL your suspension bushings - OEM rubber is no longer the best solution.
  • The factory brakes are no longer going to handle the power and grip levels of the rest of the car - time for a BBK - check out our brake guide for more info.
  • Suspension setup is important, you need to set your swaybars correctly with adjustable end links.
  • Time for around 3.5 degrees of negative camber at the front and 2.5 at the rear.
  • A coolant reroute is a MUST
  • You NEED an oil cooler, trans cooler and diff cooler.
  • Be sure to run complete heat shielding for turbo hoses, around the trans tunnel, anywhere that is near the hot bits.
  • No matter what your 'mate' told you, run the water cooling lines on your turbo.
  • You will definitely NEED a proper aftermarket ECU, we like the ME221 from Motorsport Electronics, or the Megasquirt MS3.
  • You should be monitoring your engine, and have appropriate warnings for AFR, TEMPS and PRESSURES.
  • Your ECU should be monitoring your engine, as above, along with things like overboost protection.
  • Mount a Wideband O2 sensor vertically near the gearbox.
Body & Aero:
  • Correctly positioned vents in your Hood/Bonnet - location is critical, as the pressure differentials change over the surface of the bonnet, mount your vents no further back than the first cylinder of the engine.
  • It is time to consider AERO, a rear wing, a front splitter, minimise drag by blocking off all those front facing holes except an opening for the radiator approx 30% of the size of the radiator core.
  • A full width, full depth proper splitter/undertray, it's important for aero and cooling.
  • Aero balance is important, so ensure you have a suitable rear wing and/or diffuser to match the front splitter.
  • Completely sealed/ducted radiator to manage air flow and aid cooling.
  • Don't use a soft top, and don't run with the roof down, for the best aero drag, you need a hardtop.
  • At the top power levels you need a real roll cage.
  • It's time to strip the car of unnecessary items such as interior plastics, carpets, A/C etc.

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