MX5 Turbo Guide; How To (Beginner's Guide)

Credit to Mazdabeat for the photo - My mk2.5 turbo!

So you're wanting to turbo your 5 but you're lost on where to start? Luckily for you, so were a lot of people! This guide is a very beginners guide on what to look for, options to choose from and where to start looking.

This is by no means a complete guide but gives people that were in the same position as me a year ago the chance to get a quick insight into the different aspects of how to turbo their Mx5's. Some parts are necessary, some are optional, cost is completely dependent on what you can afford and the extent of build you are looking to do.

This guide broken down into several sections:

• ECU
• Wideband
• Turbo
• Manifold / Downpipe
• Dump Valves
• Oil & Water Lines
• Injectors
• Air Intake
• Intercooler
• Boost Controller
• Spark Plugs
• Clutch
• Tyres
• Exhaust
• Brakes
• Cooling
• Gauges and Sensors
• Mapping/Tuning

First off, a general break down of how everything is connected together. We are going to follow the path of the air to make it easier to understand.

If you don't have a general understanding of how an engine works, you're going to have a bad time, familiarise yourself with the workings of an internal combustion engine, in particular, how a turbocharged internal combustion engine works before trying to read this guide as simple knowledge is required and certainly if you're planning on turbo'ing your 5 it is! 

The exhaust gases from the engine are used to drive a turbine wheel, which is connected via a central rod, to a compressor wheel which compresses and shoves air into the intake. 
Turbine wheel = exhaust side, compressor wheel = induction side. This is all contained within 2 separate housings. This is the basics of a turbo.

When the exhaust gases hit this turbine wheel, they spin it, causing the opposite end (compressor wheel) to spin, shoving more and more air into the engine the faster it spins. The faster the exhaust gases, the faster the compressor wheel spins. After the exhaust gases spin this turbine wheel, they then escape down the exhaust system exactly the same as a normal naturally aspirated car.

While the exhaust wheel is spinning, the compressor wheel is doing it's job and compressing more and more air and shoving it down the intake piping into the engine. Air is drawn through an air filter, to the compressor inlet (the small hole situated right at the front of the turbo). From there, it is then spun around the compressor housing and into the intake piping. Intake piping is just your air intake, however, an intercooler can be placed in series along the way, causing the air to have to flow through it before reaching the engine. As is explained a bit later on, an intercooler is effectively a radiator and uses the incoming outside air to cool the air going through it, providing a variety of advantages.

Once the air reaches the engine, it is mixed with fuel from the fuel injectors in a cylinder and compressed by a piston. A spark plug is then used to provide a starting spark to ignite the mixture. The energy released from this then pushes the piston down, which is connected to a crankshaft that spins. (This is all explained in much greater detail in an internal combustion engine guide). Once ignited, the piston is pushed down to the bottom of its cycle and then pushes these gases out of the exhaust valves and into the turbo exhaust manifold, into the turbo and out through the exhaust system.

http://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/fig4OttoPistons_web.jpg

All of this is done in the blink of an eye and is controlled by the ECU, whether stock, piggyback or standalone, the ECU controls the workings of the engine, the timing of the sparks, the fuel injection and the adjustment of the fuel/air mixture. To help it provide the most efficient outcome it can, sensors are used along the way to accurately measure different variables which can have an effect on the needs of the engine. Sensors such as Intake air temperature sensors are needed to measure the temperature of the air just before it enters the engine, this helps to predict the density of the air, thus how much of it there is and to aid with ignition timing as hotter air will ignite quicker than cool air understandably.

A few pictures to illustrate:

http://www.turbotechnics.com/www/wp-content/uploads/2013/10/TT-Diag.jpg

An exploded view of a turbo. You can see exhaust inlet flange at the back with the red interior. The exhaust turbine wheel coloured in orange at the back, the connected rod pictured in the middle with the oil and water connections surrounding it, the compressor wheel 2nd from front with the turquoise surround and the compressor housing at the front which directs the flow of air to a specified point from which it can then flow into the intake piping.

Here you can see the turbo manifold attached to the side of the engine, drawing the exhaust gases away and leading them into the turbo.

Also pictured is the intake side of the turbo with the inlet facing forwards and the outlet facing almost 90 degrees to the right.

Hopefully you understand where the air goes and how the turbo is used to provide more air for the engine and in turn, more power! The next section will break down the different aspects of a turbo build and help you to understand what is needed, what is not and what you want to get.




ECU

The main hub of any turbo build. Without a capable ECU, you won't get far with a turbo build. There are 3 main options; Stock ECU, Standalone ECU's or Piggyback ECU's. A few choices are as follows:

Standalone

• Megasquirt 1,2 and 3
• Adaptronic
• Omex

Piggyback

• Greddy E-Manage
• HKS F-Con

Of course you can always use a stock ecu and run a small boost set-up (Max ~5 Psi) but this will require the use of a few items such as a Fuel pressure regulator to increase the fuel pressure in relation to the boost seen as the stock ecu is unable to do this.

For this guide I will be expanding on the use of a Megasquirt ECU as well as giving examples of what to use with piggyback and stock ecu options.

When choosing an ECU, you will want to consider a few things such as:

• Compatibility with existing wiring

Buying a plug and play capable Megasquirt ECU in the first place will save a lot of hassle when connecting up to your existing stock ecu wiring and prevent the need to splice into cables etc. Of course this isn't completely necessary but from a beginners perspective, it saves a lot of confusion and work. With systems such as the Greddy E-Manage, short harnesses can be bought to bridge the gap between stock wiring looms and the new ECU.

• Support

Having available support for your ECU can prove priceless when things get tough. This is a big reason as to why I decided to go for a Megasquirt ECU over the other options.

• Compatibility with turbo supporting mods

Buying an ECU and then finding out it doesn't support the 750cc injectors you just bought for £400 isn't fun, make sure everything else you have bought, or plan to buy, is supported by it. If you plan to go big, the ECU is the last place you want to scrimp on.

Some people/companies do offers on supplying and fitting ecu's so this may be an option to look at if you don't feel confident doing it yourself.

- A quick but helpful note is to note if the ECU you plan to buy can support a knock sensor, they are very important, especially if going for big power and many mappers will refuse to map you car if they have no way to easily see if it is knocking!

Wideband

A wideband sensor or o2 sensor is an easy but essential part of any turbo kit. In essence, it replaces the standard o2 sensor with a sensor capable of reading the ratio of air and fuel and translating it into a voltage, the "ideal" idle ratio is 14.7 which is 14.7 parts air to 1 part fuel, you will see many cars idling somewhere around this mark. It is called a "Wideband" as it measures the ratio and transmits the results across a wide voltage range as opposed to the stock Narrow band sensors which only read 'Lean' or 'Not Lean', which gives very little information to tune with. 
These results are then displayed on an Air/Fuel Ration gauge or AFR gauge as shown in the picture above. The AFR target needs to be adjusted using mapping software to provide the best possible ratio across all the rev range and engine load range.

Few options exist, the 2 brands that are mainly used with our 5's are:

• AEM  
• Innovate Motorsports

While debate still exists between the 2 as to which is best bang for the buck, either brand won't do you wrong providing they are set-up correctly. 

Turbo

The fun bit! This all depends on what kind of power output you're looking for. In simple terms, you have journal bearing and ball bearing turbos, ball bearings being the preferred option however not entirely necessary and widely unused with popular turbo choices on Mx5's. After this, you have a massive range of sizes and specs to choose from. Two popular choices are as follows:

• Mitsubishi TD04/05 Turbos

These turbo's were found all a huge range of cars, from early 90's Imprezas to Evo 8 & 9's depending on the model. A popular (and my) choice is a TD04L-13t turbo, these were found in a wide range of WRX Imprezas and so are abundant on the bay and everywhere else. For a decent condition used one, you can expect to pay anywhere from £100-£300. With good supporting mods you can expect up to 230ish hp maybe more at the wheels which is as far as you'd want to push it on the stock internals if you plan on it lasting.

Other TD options include TD04-16t, 19t, TD05-16g, 20g etc. The latter mentioned suit forged, highly modified builds better as they spool later and provide well enough power to make your stock rods take an unplanned holiday out the side of the block.

• Garrett T25/28

Another popular choice coming from many 90's Nissan's, again, very cheap and easy to get a hold of, the T25 providing around the same power output as a TD04L-13t. The 28 being more comparable to a TD04-16T or somewhere in between. Again, you can expect to pay around £100-£300 for a decent condition used one.

A good suggestion is to buy the supporting exhaust bits and then buy a turbo to match as they will be much easier to get a hold of than a decent, compatible turbo manifold and downpipe, which leads us onto the next section.

Another thing to note is the need to "clock" some turbo's. Turbo's such as the TD04-13t from WRX Impreza's have their oil drain facing horizontally in the turbo core. This core will need rotating or "clocking" to make it face downwards, assisting with draining the oil effectively. There are many guides of how to do this online and is a relatively simple job.

Manifold/Downpipe

The manifold and downpipe are 2 separate pieces of exhaust system, the turbo manifold which connected the exhaust ports of the engine to the turbo and the downpipe which connects the turbo to the rest of the exhaust system.

A decent Manifold/Downpipe combo is hard to find here in the UK and options from the US (of which there is a few) tend to be massively expensive.
If you have the wallet, forking out for Flyin Miata pieces will be worth it as these are considered superior to almost every other realistic alternative. Other companies such as Begi and HKS do options for some models of Mx5. Other than this, ask around and search on forums and other internet sources and there are a few people/companies that custom make these pieces for a very reasonable price and while not being as aesthetically pleasing as something made from a very expensive machine, perform just as well and sometimes even better than their much more expensive counterparts.

A common question asked is around the subject of items that are referred to as "Ebay" manifolds. These are cheaply made options and 9.9/10, won't last as long as a more expensive manifold, this is usually due to the poor quality of the metal and welds. Although for some applications, they can be perfectly adequate, if you are building a mid to high range set-up, using a cheap manifold with a turbo charger can be detrimental and the most common advice you will be given is to steer clear and spend more on a better quality one. 

Note: 1.8 and 1.6 manifolds are not interchangeable, similarly with mk1 & 2 manifolds.






Dump Valves

A dump valve or BOV (Blow off valve) is a device which is situated along the intake piping and opens at a pre defined pressure to release the intake air away from the intake piping when the throttle body is closed. It is needed as when the throttle is closed, air is still being shoved towards the engine from the turbo for a split second, without anywhere to go, the only way for this air to escape is to go back through the turbo, causing excessive wear on the bearings and the popular phrase "compressor surge". Debate surrounds the effectiveness of dump valves, in particular the vent to atmosphere types vs the recirculation types.

When venting to atmosphere, the dump valve simply opens and lets the air escape into the engine bay (atmosphere). A recirculating dump valve, does exactly that, it opens but the escape path is routed back round to the intake, just before the turbo. Both options help to relieve the stress on the turbo.

The common "pshh" sound you hear, mostly from fast & furious movies, is the sound coming from the dump valve upon opening. 

These devices are "needed" as such and some argue that they aren't needed at all but I would recommend one as it eliminates the damage that can be done and the type of noise you want is up to you! A few popular brand choices:

• HKS 
• Bailey 
• Forge
• Tial

And many more.

Oil and Water Lines

Threaded hole for the oil return into the sump.

These essential parts of your kit are vital to the longevity and quality of your build. Most turbo's and certainly the ones you're likely to use in a turbo'd 5, need oil and water to cool them. They all need a feed and a drain/return, the oil feed can be taken from the oil pressure sender switch via a T piece in the connection and the return is usually fed into the oil sump via a threaded hold and fixing. With the water, taking the feed and tapping the return into the thermostat housing at the front of the engine is common however seeking professional advice as to which is best for your set up is highly recommended as getting this part wrong WILL lead to things going wrong and big repair bills in future.

Recommended places for Oil and Water line locations

Oil Feed - Tapping off the oil pressure sender switch on the drivers side of the block using an appropriate T piece

Oil Return - Tapping into the front bottom passenger side of the oil sump using appropriate connection. Ensure to use plenty of thread lock/sealant.

Water Feed and Return - These can be tapped into the thermostat and water feeds in the front of the engine.

2 things to ensure, make sure you tighten all connections and make sure the turbo oil drain is facing downwards. 

This process of turning the turbo's core to make sure the oil drain is facing downwards is called clocking, it is explained further in the turbo section.

Injectors

RX7 550cc Injectors

This is a self explanatory subject, the bigger the power you wish to achieve, the bigger the injectors you're going to need. Personally, I am running a safe tune at 218whp and running 620cc injectors. Rx8 Yellow 420cc Injectors are a popular choice as they are cheap, plug and play and readily avaliable. Check that the injectors you are buying are compatible, if not, a different connector and fitting may be required. 

However, buying the biggest injectors you can won't solve your problems, injectors need to run at a suitable "duty cycle %", this is, in simple terms, how hard they are working, for a given power figure, the smaller the injector size, the harder it will be working and vice versa, the bigger the injector, the easier it will be working. Too little and they won't work properly, too much and they will be overworking themselves and fail quite quickly. 

Decide what figure you want to go for and choose an appropriate size on that. Anywhere between 400cc and 800cc will get you anywhere from 200whp to 300+whp.

Air intake

K&N Cone Air Filter

Of course, when attaching a turbo to your engine, a clean flow of air into the turbo is essential, the space available is worth considering as it is pointless buying a huge air filter with visions of it sucking in as much air as a General Electric GE90 turbofan to find out that you have less than half the space required to actually fit the thing....believe me.

Ideally, you want the most amount of the coldest air available to flow into the filter, take a look around your engine bay, see where a good place to mount one would be, consider the natural air ducts and/or custom ones made by after-market bumpers or vents. Mounting an air filter right next the exhaust manifold on a naturally aspirated car will make minimal difference, doing the same to a turbo car will have vastly exacerbated effects, especially with the increased heat generated from the turbo, this being considered, keeping the air filter as far away from heat as possible is a must.

When you have decided upon the placement of your filter and any possible additions such as cold air intakes and/or custom air flow vents to aid with the breathing, you have to choose a filter. Loads of choices exist such as:

• K&N
• Ramair
• Pipercross
• ITG
• Apexi
• HKS
• Cosworth

To name a few...

Genuine examples of any of the above will be good, it's up to you to choose which you prefer, each have their pros and cons.

Intercooler

Medium Sized Intercooler

An Intercooler does exactly that, it 'cools' the intake air by way of forcing it through a radiator style cooler, using incoming outside airflow to draw the heat away from the hot intake air. Technically, the bigger the surface area of the intercooler in contact with cool airflow, the cooler your intake air temperature will be, however, getting an intercooler from a 1000hp Supra and sticking it on your 5psi boosted Mx5 will be pointless, as well as expensive and a pain in the arse to fit!
Look for an Intercooler which can fit comfortably in front of the radiator and provide good cooling properties for your application. Many options are available, from Ebay kits to custom kits sold by forum members and companies, decide how much you want to spend and your skill level as far as installing the kit yourself and buy according to that.

Another thing to consider is the Intercooler piping, a few popular routes to take exist, Over the top or OTT piping refers to piping that goes straight over the radiator and goes down through the slam panel. This is usually the best route however requires cutting into the slam panel and is slightly more difficult to route. 
The more commonly used routes entail routing the piping downwards, behind the radiator and curling it around to the front. Various changes can be made to the routing according to your personal preference.

You will need some silicone joiners in your route as these provide some flexibility for the piping and prevent cracking from repeated movement over time. As well as this, ensure good clamps are used, as ever, having a good seal is paramount.

The below pictures shows my particular routing which was put together by Nick Bailey at Skuzzle Motorsport.

The mocked up routing showing the 2" hot-side and 2.5" cold side

Hot-side routing down the helpfully positioned air inlet hole

2.5" cold side coming up from in front of the radiator into the throttle body

 

Boost Controller

Greddy Profec B-Spec 2 Electronic Boost Controller

A boost controller is a device which limits the amount of pressure a turbo produces by "opening" and routing the pressure elsewhere to prevent the turbo from over-boosting and damaging itself.

2 main types of boost controller exist, Manual/Mechanical and Electronic, Electronic being the better option. Mechanical boost controllers work by having a spring with a pre-defined pressure limit set to open a valve and route air away from the turbo, the limit is set only by the stiffness of the spring, while perfectly usable, a problem exists as the pressure rises and approaches the springs opening point and it opens gradually, preventing full boost being reached as easily and smoothly. Many mechanical boost controllers exist and range from £20-£150

Oppositely, an Electric Boost Controller such as the popular Greddy Profec controllers, only open when a specific limit is reached and only then. These control boost a lot better and provide much better results on the dyno. Again, many options exist such as the Greddy Profec, HKS EVC, Apexi AVCR etc. These range from £150-£400 used to £300-£1000 new.

Spark Plugs

http://pics.driftworks.com/media/catalog/product/cache/1/image/9df78eab33525d08d6e5fb8d27136e95/n/g/ngk-iridium_30.jpg

This is a brief topic but is easily the cause of a lot of problems with turbo'd builds! When adding forced induction, the way the mixture is ignited in the engine has to change, the way to do this is to use the correct spark plugs for the job. For a turbo'd engine, spark plugs gapped to 0.7-0.8mm is preferable and the heat range of said spark plugs will need to be cooler. A popular and almost universally used choice in turbo'd mx5's are NGK plugs. The model denotes the gap and heat range, for example, an NGK BKR5E-11 is an NGK plug, with heat range 5 and a 1.1mm gap. This is standard for naturally aspirated engines. When turbo'ing, NGK BKR7E's are good and are 2 heat ranges higher, dissipating the additional heat better, preventing pre ignition and gapped to 0.8mm, igniting the mixture more efficiently, if a smaller or larger gap is needed, this can be done to your own spark plugs and checked with a slip gauge.

Clutch

Competition Clutch Stage 2 Carbon Kevlar

Often overlooked aspect of increasing power. You will need a clutch that can handle the power you're planning to put through it and the abuse you're planning to give it. 2 different choice are usually available, organic or paddle.

An organic clutch has friction material the whole way round the clutch plate and is able to "slip", providing some sympathy when engaging the clutch lightly, slipping until it has caught up with the engine speed. If you're planning on driving daily and regularly drive in traffic, this is the clutch for you unless you have a particular interest in exercising your left leg massively and you enjoy launching into the rear view mirror of the person you're behind in traffic over and over again.

A paddle clutch has separated sections of friction material and doesn't slip, it is either engaged or not and while being much less user friendly on a day to day basis, provides much better grip pound for pound than it's organic counterpart. Companies to choose from include:

• Exedy
• Competition Clutch
• Flyin Miata
• Stock OEM Mazda

If you're planning on running a small increase in power and not on track < 200hp, a stock, new clutch from a 1.8 model can do the job. Otherwise, buying an upgraded clutch is very worth while as a slipping clutch can ruin the whole show, especially when everything else is running perfectly and the car is unable to get the power to the ground. Again, decide how much you're willing to part with and what you need from the clutch and base your choice upon this.

Note: A 1.8 clutch will require a 1.8 flywheel to be mated with it to work on a 1.6 model.

Tyres

What's the only thing connecting your car to the road? That's right...tyres. Yet many people continue to shove in an extra 100hp to their lightweight RWD car and run on odd, low tread rubbish tyres. It's a recipe for disaster. Choices include:

• Toyo Proxes T1r
• Kumho KU31 & 39's
• Bridgestone Potenzas
• Michelin Pilot Sports
• Federal RSR 595
• Toyo R888
• Yokohama Advan AD08

And many, many more. Read up on all the different makes available for your wheel, decide on what kind of tyre you want (fast wearing, sticky semi slick tyres or long lasting, less sticky road going tyres), the width and profile you want and how much you can afford to spend and base your choice upon this.

Exhaust

Mongoose 2" Cat-Back Exhaust

Ideally, you want an exhaust with a diameter to match your downpipe and be as free flowing as possible. 2.5" is a popular diameter to go for with turbo exhausts and any combination of silencers and back boxes can be chosen depending on personal preference.

Above this 3" exhausts can be used for high power applications and so forth.

Having said this, I am running ~250hp at the fly and have a 3" downpipe into a 2" straight through system so it is not always completely needed.

As always many options to choose from, from branded items such as Flyin Miatas exhausts, to custom built systems from exhaust fabrication shops, the choice is up to you!

                




                                                                                    

Brakes

Of course, the thing you'll want to do after all this power, is stop. There are many options for bigger brake calipers, bigger discs and so forth, as a minimum, if you're going for a small power increase, get fresh standard pads and some decent brake fluid. If you're going for 200+ whp, getting some upgraded pads, braided lines and good fluid is preferred. Brands such as EBC and Mintex do decent brake equipment. Going more expensive and more track focused than that, companies such as Ferodo and Carbotech make amongst the best pads you can get. 

If you're wanting to upgrade the calipers and discs, a popular upgrade for the earlier mk's in to buy a big brake kit from a mk2.5 sport model with the 270mm front discs and bigger calipers. If you're feeling rich, Willwood, AP Racing and Brembo to name a few, do upgraded kits with 4 & 6 pot calipers etc.

Popular brake pad options:

• EBC Green/Red/Yellow Stuff
• Mintex 
• Ferodo DS2500
• Carbotech XP series

Discs, while remaining important to maintain, don't need changing as much as the pads, although some people will argue that a vented disc (Slotted and/or Drilled) is better, this may be true but usually only proves effective on track.

For fluid, the most recommended one is ATE Super R Blue Dot 4 Brake Fluid. It's cheap and very effective. There are other alternatives that are worth looking at, just be sure to go for a high boiling point, good quality fluid. 

Cooling

Cooling is important, without it, things will start to go wrong very fast. The Mk2.5's have an advantage over the previous models due to their newly designed head gasket which allowed better coolant flow around all the cylinders. Even considering this, it is beneficial on all models to buy a coolant re-route kit which does exactly that, re-routes the coolant to provide an even distribution.

As well as this, an upgraded radiator can be beneficial, particularly if running high power. Alloy radiators are sold by many companies and can be had for relatively cheap. 

Moving onto oil cooling and a separate oil cooler is beneficial to aid in the further cooling of the oil system, keeping running temperatures down. However, when buying one, you want to make sure it is a thermostatic type, this means that the oil will be routed into the cooler only when it is at a high enough temperature, preventing the oil from not being able to reach optimum temperature through excessive cooling.
It takes its feed from a sandwich plate attached in between the engine and the oil filter. A feed and a return nipple sends the oil to the cooler and allows it to flow back into the system. A picture of a typical system is shown below.

http://www.mx5mania.com.au/images/product_pics/1789/medium/nab-5155.jpg

Gauges and sensors

Boost Gauge in the middle and AEM Wideband Gauge on the right

As discussed before, your wideband sensor will take up a gauge space on your dashboard, the addition of more gauges is completely up to personal preference. Gauges like Oil temp, Water temp, Oil pressure, Exhaust gas temp and boost gauges are all completely optional and while not necessarily needed, may be useful to have if running the car on track or if it is regularly given abuse as keeping track of the readings is helpful.

A few sensors which are needed:

• Intake Air Temperature sensor - or IAT for short, this does exactly that and measures the inlet air temperature just before the throttle body to accurately adjust fuelling accordingly. Changing this is only needed if running high boost or a standalone ECU.
• Wideband Oxygen Sensor - This is explained further in the 'Wideband' section but in short is the upgraded o2 sensor you will need for running a turbo. It measures the Air/Fuel ratio and displays the results as a number, allowing for better information whilst tuning.
• Knock Sensor - Whilst not necessarily needed, having a knock sensor is very helpful and can prevent damage to the engine. As well as this, many tuners will refuse to tune your car if you don't have one. A knock sensor senses "knocking" in your engine which can be caused by many things such as overly hot intake air temps or incorrect timing amongst other things and is, in simple terms, your engine internals, hitting against things they shouldn't be hitting against, which is never a good thing!

Mapping/Tuning

This is the final hurdle before you have a working turbo 5!

This isn't required if you're running a stock ECU, if you're running a piggyback or Standalone though, you will need to understand this. "Mapping" is a term given to adjusting settings on the ECU using a computer, you will need the associated software to do this if you're planning on doing it yourself so read up on what is available for whatever ECU option you have chosen. 

Fuel tables, ignition tables and a huge variety of settings will need to be adjusted, especially if you are running a standalone. If you aren't confident setting up your ECU yourself, DONT! Seek a professionals advice first as you can very easily damage your engine by not setting up the ECU correctly.

In basic terms, the ECU will need to know how much fuel is needed and when to inject it, as well as this, when to ignite said fuel. This changes quite drastically as you go up the RPM band and as you put all different kinds of load on the engine. On top of this is settings such as the cranking procedure, the warm-up procedurem setting injector pulse width's and dead times and configuring settings to make the car idle correctly. 

A few programs can be used, one such program which I personally use is Tunerstudio MS which can be used with Megasquirt ECU's.

Read up on ECU mapping and seek advice if you're not confident, alternatively, ask a professional to map it for you! 



By now, hopefully you have a slight understanding of how to turbo your Mx5! All you need to do now is decide how much money you have to throw at it and how far you want to take it! A few examples of different set-ups:

Low Budget (~40whp gain):  

• Stock ECU, AFPR, 
• Stock clutch, 
• 1.8L mx5 injectors, 
• TD04-12t/T25 turbo, 
• Ebay manifold and downpipe, 
• Straight through mildly modified exhaust, 
• Mechanical boost controller, 
• Oem brakes, 
• Tyres and spark plugs gapped down by .2mm, 
• No intercooler

Cost excluding labour - £300-£1000

Mid Budget (~80whp gain):  

• Piggyback ECU with associated wiring and sensors, 
• AFPR, 
• Stock/Exedy Stage 1 clutch or similar, 
• 1.8L mx5 injectors/rx8 yellow injectors,
• TD04-13t/T25 turbo, 
• Custom manifold and downpipe, 
• Straight through 2.5" custom exhaust, 
• Mech/Electronic Boost Controller, 
• EBC Greenstuff pads,
• Toyo t1r tyres, 
• 0.8mm gapped cooler spark plugs, 
• Small intercooler, 
• Dump valve
• DIY Mapping software

Cost excluding labour - £750 - £1500

High Budget (~100whp+ gain):  

• Standalone ECU, 
• Wideband sensor, 
• High torque holding organic/paddle clutch, 
• 550+ DV14 injectors, 
• TD04-13t/16t, TD05, T25/28 turbo, 
• Custom manifold and downpipe/Begi or Flyin Miata, 
• 2.5" or 3" downpipe back exhaust, 
• Greddy Profec boost controller, 
• EBC redstuff/yellow stuff pads or Ferodo DS2500 pads, 
• Braided brake lines, 
• Dot 4 racing brake fluid, 
• Semi Slick tyres (R888's, AD08's, RSR's), 
• 0.7/8mm gapped iridium spark plugs, 
• Big intercooler, 
• Dump valve
• Professional dyno tuning/mapping time

Cost excluding labour - £1500+

Again, the above costs are estimates and the items used can change.

The possibilities are endless and you can spend 10's of thousands of pounds on a 450whp, forged internals, huge Garrett turbo and custom made everything build or you can spend £500 on a simple 5psi set-up to give you a bit more of a kick.

The 250whp mark is the most common response you will get when asking what the limit of the standard internals are. Run as close or as far away from this as you like but bear in mind that the more power you run, the bigger the chances of (usually a rod) saying goodbye to your engine is! If you are after big, BIG, power (250whp+), installing some forged internals and other supporting items is necessary. 

Forged internals are internal engine parts such as rods and pistons that are made using the forging technique and are much stronger than their cast counterparts. The rods on our mx5's are usually the first weak point so will usually need replacing first if you're aiming for the 250whp+ mark. I say "usually" as it all depends on what you plan to use the car for and indeed your luck! Some people are running upwards of this mark, on track, on completely standard internals with no problems. As a guide though, forged internals are needed for high power applications.

Decide what you want, read, read and read some more! When you're done reading, read some more and you'll be almost there. 
There are plenty of people who have turbo'd their 5 so, if after you've read all you can, you still have questions, there's plenty of people with answers. 

It isn't a simple job and there is an endless list of variables such as your budget, engine size, location, skills, understanding, final outcome expectation and the purpose for your build to name a few. Just asking 1 broad question like "How do I turbo my mx5?" isn't going to get a good response, help yourself so others will help you and before you know it, you'll have your own turbo'd Mx5 and the knowledge to improve on it to your hearts content. There's always stuff to learn and always someone who knows more than you so lap up good advice from others when you can and learn from their mistakes!

I hope this guide has given you a bit of an insight into the Turbo route, it is by no means to be taken as gospel and is written in good faith and based upon my experiences, people such as Skuzzle Motorsport, Roddisons Motorsport, Ardler Automotive and others know a hell of a lot more than me and are the people to talk to, but, do them a favour and give this guide a read first! 

Feel free to message me with any questions, if I don't know the answer (which is more than likely!) I can point you in the direction of someone that might.

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Keep checking for updates and additions as theres always more to add!