Ultimate Honda Civic Turbo B/K-Series Conversion Guide

In the last year, we've been asked more and more to supply Honda civic turbo conversions, so it was time for our most extensive write-up.

We will go through a complete Honda turbo conversion guide from start to finish with brands we recommend, parts you'd need and multiple power goals so you can choose the right parts to make it happen or at least know more on the subject than before you came here!

There are many variables in this list, but we aim to give you the most information possible so you can get well on your way to your first Honda turbo conversion.

We get asked all the time about turbo conversions and which parts would be best for specific power goals or just a list of parts customers need so they can buy parts over time.

Today we will cover everything to make it as straightforward as possible for you to order what you'd need, so buckle up and get ready!

What Is Your Budget/Power Goal?

Before beginning a turbo conversion, you must consider your rough power goal. Whether you're going for 300bhp or 1000bhp, you will need to specify the correct parts to all work together in unison and not create a barrier for you to gain the power you want to make.

Reliability is also a massive factor when deciding to do a turbo conversion.

The stock Honda engine internals was only ever designed to be run at stock power, and although you can put boost through a stock block, the higher the horsepower you go, the more likely you are to blow the engine.

Later, we will write a guide on engine building and the best parts to use.

Budget is another major factor in your estimated power goal, and this should also be considered before deciding where you want to end up power-wise.

If you only have £2000 to spend, it's doubtful you are going to get anywhere near the 1000bhp mark (reliably, anyway!), so it would always be best to go through our guide and price things as you go so you know exactly what you would be able to afford.

Some parts mentioned will be overkill for some power goals, but we would always recommend them for increasing power in the future because of how reliable they have been.

It's important to mention that this is only a guide, and there are too many variables to get everything perfect every single time for every application.

If you are still determining if it will work for you, please get in touch with us via our contact form, or leave a comment at the bottom. We will guide you towards the correct parts.

Also, the quoted horsepower figures are only estimates and will factor in multiple things such as tuner, parts used, fuel, etc. Still, we can educate you into making the best-informed decision you can.

Boost Control

Choose Your Wastegate

First on the list is boost control which is, in part, done with a wastegate. Boost control is crucial when deciding to turbocharge your B or K-series Honda.

If the boost control isn't accurate and reliable, you could cause massive engine problems by over or under-boosting, which could cause engine or turbocharger damage! When deciding which wastegate, there are three essential things to choose from, internal or external, wastegate size, and spring rate.

We now have a full boost control guide if you need to learn more about boost control.

How do I choose between an internal and external wastegate?

Whether your wastegate is internal or external will depend on which turbo and manifold you go with and whether it already has an internal actuator on the turbocharger.

If it does, you will not need an exhaust manifold with a wastegate port, as it will only be blanked.

We will go deeper into wastegates in another guide, but overall, going internal wastegate is cheaper. However, external wastegates will give you more accurate boost control for higher power builds.

How to choose external wastegate size

The size of the wastegate would depend on what power you are aiming for and the rough turbo size. For example, if you run a precision 5858 at 400bhp, a Turbosmart 38mm or 45mm wastegate is more than enough to control boost levels effectively.

If you are, on the other hand, going for a Precision 6266 for 600bhp, then something like a 44mm or a 50mm would be the right option to go for, as when you increase the flow to the turbo, you need a more significant wastegate piston surface area to accurate control the boost level.

Choosing a wastegate is not an exact science, but if you've matched parts closely enough, you should avoid problems.

There is a variable here, which is always overlooked, though, manifold design. If your wastegate is positioned at 90 degrees to the exhaust flow, you need a bigger one to compensate for the flow direction; otherwise, you will encounter boost creep.

What is boost creep?

Boost creep is where you hit the desired boost level at the wastegate but slowly rise as the RPMs climb. Boost creep is bad news as you only want to be set to whatever boost you've been mapped to; otherwise, engine damage can occur.

Luckily there is a simple K-series fix for this, and it will save you from having to swap parts out in the long run. It would help if you ran a priority flow manifold to combat boost creep like the LA Fabrication manifold.

As this is running off at a much less harsh angle, the flow is being directed to the wastegate much more smoothly, allowing for easier boost control.

How to choose a Wastegate spring

The next thing to consider is the spring rate of the wastegate itself and how this relates to what boost level you will be running.

The spring in the wastegate is the minimum boost level you can run when the turbo is fully spooled; for example, if the wastegate spring is 7psi and you aren't using a boost controller, your boost will always be set to 7psi under wide open throttle or full boost.

If you will be using a boost controller and want your boost level to be 15psi, then you can get away with a 7psi spring and use the boost controller to hold the wastegate to 15psi, but 7psi will always be the minimum you can run.

To pick the correct one for you, we go more in-depth later in this article regarding boost controllers and solenoids.

Being a Honda and Front wheel drive, the lower spring rate will always be a better option as this will reduce the risk of wheel spin.

We all know FWD and high power levels are generally unusable on the road, so being able to cap this is the best solution to keeping the car drivable and putting as much power to the ground as possible.

Blow Off Valve

The next item on the list to consider is a blow-off valve or dump valve, as they are most commonly called. The blow-off valve releases pressure in the intake system once the throttle is closed, after having a pressurised system, to prevent a turbo compressor surge.

Compressor surge is when the turbocharger is spinning at high rpm, and the throttle is shut very fast, resulting in the air going back through the compressor, usually making a flutter noise.

This can decrease the life of your turbo bearings in the impeller if repeated over a long period and is not recommended (although we agree it sounds incredible).

A blow-off valve is the easiest thing to put in place to fix the turbo compressor surge, and this most commonly will sit on the intake pipe after the intercooler, but before the throttle body, using a welded flange.

We mainly point customers towards Turbosmart, just like the wastegates, as they are well known for being massively reliable.

How to choose a blow-off valve spring?

Blow-off valves generally come preset with various springs, which differ from brand to brand, to tailor to whatever boost levels you decide to run.

The blow-off valve springs are lower than the boost level you will be running, but most of the time, BOVs will be adjustable, so you can keep changing it until it's working correctly.

Boost control is one of the most important avenues to explore when going down a turbo conversion route, so one place to avoid skimping would be on the blow-off valve or wastegate.

Boost Controllers and Solenoids

Following on from talking about wastegates, the next thing that is quite important is boost controllers.

Installing a boost controller is how you can set your maximum and minimum boost levels in line with the wastegate spring.

What is a boost control solenoid?

A boost control solenoid is a device that wires into your ecu and connects to your wastegate via a vacuum line.

This will bleed pressure off the hose, tricking the wastegate into allowing a higher boost level than the wastegate spring would allow without this.

Because of this, your ecu will control the boost level you need if you are running an ecu such as a Hondata or haltech, and they allow for boost control.

As a general rule of thumb, with a three-port boost control solenoid, you can hold the wastegate spring down to around 2-4 times the spring rate (7psi spring could make 28psi maximum), and a four-port boost control solenoid could make up to 10x the spring rate.

Although this can work in most situations, it's more down to the ecu and how much control it has over your boost before it becomes inaccurate.

For example, using a Hondata ecu, a three-port boost control solenoid is the easiest option as the boost control can hold up to 2-4x the boost pressure.

We generally opt for Speedfactory Racing or Haltech solenoids as we have sold them for a few years and have not had any fail.

What is a boost controller?

If you have a larger budget, you can always opt for a digital boost controller, which would work in the same way, but would allow you to change your target boost level on the fly from the cabin making high and low boost options much more accessible.

Many boost controllers are on the market, so choosing a boost controller depends on whether the brand is reliable and the number of features or preset boost levels you would like.

MAP Sensor

What is a MAP sensor?

MAP or manifold absolute pressure sensors measure air pressure inside your manifold after the throttle plate.

They are generally placed on the throttle body and give the ECU information on keeping the air-fuel mixture correct. It is one of the most critical sensors for figuring out fuel/ignition etc.

The factory Honda MAP sensor is very reliable for stock applications, but once you go down the realm of turbocharging, you must change this out for a higher sensor rating.

The stock sensor will generally read up to around 1.8 bar of pressure (which translates to around 11psi of boost pressure); beyond this boost level, you must run an aftermarket MAP sensor.

Aftermarket MAP sensors are generally plug-and-play such as the Speedfactory Racing B and K series map sensors, and are available in different bar ratings.

Generally, the most common would be 3 or 4 bar, but companies such as Haltech manufacture up to 7 bar for extreme applications.

Providing the MAP sensor is always higher than the boost level you want; this is usually one of the most simple parts on this list to choose from.

Fuel System

Injectors

How to choose an injector size?

Next up on the list are injectors which, in their stock form from Honda, are only designed to flow the correct amount for the power the engine produces from the factory.

Whilst you can squeeze a little bit more from the stock injectors, it isn't recommended, and you will not be able to make, say, 500bhp as they do not flow enough.

Because stock injectors are not big enough, you will need higher flow injectors, but how do you choose what size you need? Luckily there are calculators online, such as this one from FIC, which we regularly use to quote injectors size for customers.

All you need to know is the number of cylinders (in this case 4), your estimated fuel pressure, whether you are N/A, supercharged or turbocharged, the power you aim for at the flywheel or crankshaft, and your estimated injector duty cycle.

For example, we are going to be using the following:

• # of Cylinders: 4
• Fuel Pressure (psi): 43.5psi
• Engine Aspiration: Turbocharged
• Horsepower desired at crankshaft: 500
• Duty Cycle: 85%
• Estimated injector size: 926 cc/min

In this case, we would go with 1000cc injectors to ensure we have enough scope for the tuner, changing a few variables such as fuel pressure/duty cycle etc. If this were a K-series, we would go for a few options here, such as:

Grams 1000cc injectors, FIC 1000cc injectors, or Injector dynamics ID1050X, depending on which option the customer would like within budget.

Fuel Rail

Is it worth upgrading my fuel rail?

After deciding on your injectors, a fuel rail is the next thing you must look into.

The stock Honda B and K series fuel rail can usually handle up to around 500-600bhp without coming into flow issues. One of the main reasons for going with an aftermarket fuel rail would be ease of use with fuel lines, pressure regulators etc.

The stock Honda fuel rails have banjo fittings going into flexible lines and then hardlines, making upgrading your system a pain.

The easiest thing to do would be to go for an option such as the hybrid racing fuel rail, which has ORB08 out of both ends to quickly adapt to any AN line size and other features such as a 1/8npt port for a fuel pressure gauge.

When going through this process, it's worth looking into the fuel line size to ensure the stock line size won't be restricted.

For example, the Honda civic ep3 doesn't have a return line setup from the factory. Hence, most enthusiasts decide to include a return line from the fuel pressure regulator to the tank as a returnless system becomes a restriction around the 400bhp mark.

For more information about building lines or deciding whether you need rubber or PTFE lines and which fuel you will run, refer to our previous guide here, where we run through every application and what each line is generally used for.

Fuel Pressure Regulators

Next up on the list would be fuel pressure regulators, but firstly it's best to understand why it's worth upgrading to an aftermarket option.

The OEM Honda fuel pressure regulators are not adjustable, so you cannot control the exact pressure of fuel that would be consistent with making the power you need.

Also, aftermarket regulators can flow much more fuel and accurately keep the pressure consistent at the rail, so it would always be a worthwhile upgrade.

There are many options for fuel pressure regulators on the market. Still, we generally go with known brands such as AEM and Hybrid Racing, which offer bolt-on systems or are incredibly reliable.

Also, their flow rates are much higher than the OEM counterpart, so your pressure level will be more consistent at a significantly increased flow.

When combing a fuel pressure regulator with a fuel rail, it is now easier to match fittings across the board to make installation a breeze. One example is the Hybrid Racing fuel rail which includes AN06 male fittings and their Fuel pressure regulator, which matches.

This takes out the guesswork, and for most systems up to the 500-600bhp mark, you can run an06 as a plug-and-play option.

Fuel Pressure Gauge

Fuel pressure gauges are optional but are an excellent tuning and diagnostic tool if you ever encounter any issues. You can easily and quickly see your real-time running pressure when you fit this to your fuel rail or fuel pressure regulator.

If this is wildly up or down on the pressure you usually run whilst having problems, you can instantly tell it is a fuel system issue.

Fuel pressure gauges generally come in either white or black with a range of colour schemes so you can match them to the theme you're going for.

Fuel Pumps

The last thing on our fuelling list is to look at the fuel pump. Fuel pumps are an essential upgrade as the stock unit has nowhere near enough flow to be able to supply enough fuel for a turbo conversion build.

You must know a few things before deciding which fuel pump to use.

What Does LPH Mean?

Firstly, fuel pumps are rated in LPH (litres per hour) at a specific psi, such as the AEM 340lph, rated to this flow rate at 43psi.

Fuel pump manufacturers often have a few different LPH options depending on your fuel pressure, so you can easily decide which is best.

Secondly, you will need to consider the voltage, most fuel pumps are based on a specific psi vs voltage, so if you increase that voltage, the pump will flow more fuel.

In most cases, a car runs around 13.5 volts, but in some cases, you do get voltage drop off, so you may need to run a separate power wire to a large pump, such as an external AEM pump.

How do I choose a fuel pump?

In most cases, the manufacturer will show you roughly what horsepower you should be able to make at a certain psi, to make things easier, such as a Walbro 255lph at 44psi, which can make up to around the 500bhp mark, and the AEM 400lph being able to make up to 860bhp at 40psi.

Working out the flow rate, plus everything we've covered, should make choosing your fuel pump much more manageable.

As a side note, most fuel pump kits are designed to drop directly into the tank to replace the OEM fuel pump.

Still, if you get into a case where you cannot get a pump big enough or need a better system than OEM, it may be worth looking into an option like an external fuel pump, fuel tank and swirl pot setup.

To learn about swirl pots, head over to our previous article, where we run through what they are and their benefits.

Intake Side

Choose Your Intercooler

Now we are on the intake side of the system, and time to choose an intercooler.

Again like most things on this list, this step is down to budget and power rating. Many intercoolers on the market are designed for slightly different fitments or power levels, but generally, there are better and worse options.

For example, if you have an ep3, due to where the inlet and turbo generally sit, the intercooler is better off being a vertical flow or twin pass, such as the Speedfactory 800bhp or 1000bhp options.

This means you can create a much neater install without unnecessarily running piping around the engine bay.

Most intercoolers are power rated but will also give you an inlet and outlet size, so you can match to whatever throttle body size you're using or turbo outlet size.

If you're going for 500bhp, you wouldn't want to go to a massive 90mm size such as the Speedfactory dual backdoor intercoolers, but rather a side mount 2.5", which will flow more than enough.

If you're going for a full-drag build, it would be worth looking at some of the larger 3.5"/90mm options for maximum airflow.

The dual backdoor or SFWD intercoolers are excellent options, supporting up to 1400bhp and with much larger core and inlet/outlet sizes than the rest of their range.

We've mentioned Speedfactory Racing a few times in the intercooler section, but for Honda, they are the go-to option with multiple options and fitments such as vertical flow, backdoor, side mount etc.

If you want to look through their range to decide what would work best for you, head over here.

Intake Manifold And Throttle Body

The next option would be whether it's worth replacing your intake manifold and throttle body. This depends on the power rating you aim for and which manifold and throttle body setup you currently have.

For example, if you are running a genuine Honda RBC on your k20, this is one of the best-flowing manifolds you can get for up to the 300-400bhp mark.

Past this, you may encounter flow issues and have to go to a larger plenum such as the Skunk2 ultra street or, at the higher end of the scale, the Skunk2 ultra race.

You would need to match the manifold and throttle body to whichever intercooler size you went with to keep the airflow the most consistent it could be.

For example, if you are running a 2.5" inlet and outlet intercooler, it would make sense to run a 64mm throttle body and manifold ported to the same size to create the smallest restriction possible.

Skunk2 ultra race manifolds come with a 90mm opening which would be used in high horsepower cases where 64-70mm becomes a restriction and would mate perfectly to something such as their 90mm throttle body.

Another advantage of the skunk2 ultra range is that they run velocity stacks inside to create as little restriction as possible for the air to flow into the engine. Also, as the plenums are removable and the bolt pattern is symmetrical, swapping the plenum 180 degrees for RWD or swap applications is possible.

Like most of this article, this step depends entirely on the power you aim for, but Skunk2 is one of the best direct bolt-on options to increase airflow out of the box, so it is the brand we recommend for this.

They also have a wide range of fitment, including nearly every B-Series and K-Series engine.

The last thing worth mentioning in this section is thermal gaskets.

They are generally made from PTFE and reduce thermal transfer to the engine.

As we know, the colder the air goes into the engine, the more power it will make, so it is always a good option, even if only by a few degrees.

Plus, made from PTFE, they are reusable, saving you money in the long run. Just make sure to torque down the manifold and throttle body correctly, as it's possible to overtighten thermal gaskets, resulting in weak casting cracks.

Exhaust Side

Choose Your Turbocharger

Finally, we've now reached the point of choosing a turbocharger!

Hundreds of turbocharger options are on the market, and many have advantages/disadvantages, but we should be able to help you decide which would be best. The first thing to consider would be power goal and spool time.

Going with a larger turbocharger such as the Precision 6262, rated up to 700bhp, can make 400bhp, but it needs to be optimised for this and will create massive lag in the process.

In this guide, we will mainly go over precision turbos as we sell more than anything else, are hugely reliable, and have more experience using them for size reference.

If you are going for around the 500bhp mark, then a precision 5858 is our go-to turbo as they are rated up to 600bhp, so they will work efficiently in this range.

There are multiple variations of exhaust housings, such as 0.48 A/R, 0.63 A/R, 0.82 A/R etc., but this would all depend on how much flow you need.

A 0.63 A/R for up to 500bhp on a Honda is a good middle-of-the-road option that will mostly always make the correct power.

One thing to note is that if you go too big on the exhaust housing, you may increase the lag, so always try to match them as closely as possible.

If up to 800bhp is your goal, you would be more suited to a Precision 6262 with a larger exhaust housing.

A 0.82 would be a great option here as you'd need the extra flow for the higher horsepower, and although you would experience more lag than a Precision 5858, you wouldn't run out of steam when trying to get to your power goals.

There isn't a one-fits-all for turbochargers, so if you are unsure, don't hesitate to contact us or your tuner to point you in the right direction.

These are only two examples of turbochargers we would spec out for customers. Still, more variables come into play, such as compressor housing, manifold flange, and exhaust housing size.

You must match whichever turbocharger and wastegate you choose to your exhaust manifold and downpipe size to ensure they all fit and flow correctly.

For example, if you're buying a turbocharger with a T3 exhaust flange, the exhaust manifold would also need a T3 flange to bolt up. This sounds obvious, but it has caught out less experienced builders in the past!

Lastly, when ordering your turbo, oil feed and drain are worth mentioning to ensure it has the correct supply and drainage.

Ball Bearing Vs Journal Turbochargers

Journal bearing has always been the go-to for turbos, but ball bearing is a much more advanced option as times change.

Ball bearings will generally spool between 15% and 20% faster than their journal-bearing counterpart, decreasing lag and getting you going much quicker!

Ball-bearing turbochargers also require much less oil than journal bearings. The reduction in oil capacity reduces the chance of seal leakage and is less prone to oil starvation, reducing the possibility of failure on shutdown.

The only disadvantage to ball bearing is the price, which is considerably higher than its journal-bearing counterpart.

Luckily nowadays, most precision turbos are made in both options, so you can still make the power you need to but not necessarily spend £2,000 on a turbo!

Exhaust Manifold

As mentioned in previous sections, the exhaust manifold is one of the simplest parts of this system. If you've followed our guide from start to finish, you would have probably already chosen your wastegate and turbocharger, so you're already halfway there!

The next thing to decide on would be the style of manifold you would like. For a B or K-series turbo conversion, there are a few best options for the specific engine.

For B-series, we would either go with a top mount manifold or "ramhorn" as these generally flow more than a cast bottom mount, so we would go towards Speedfactory Racing for these options.

For K-series nowadays, the best option for flow would be the sidewinder which sits over the gearbox, instead of something like a bottom mount which is hard to access and has a worse flow rate.

Again, as mentioned in the wastegate section, we would point towards Speedfactory or La Fabrication to reduce boost creep.

La Fabrication design a wastegate priority manifold which helps to reduce boost creep in higher boost-level scenarios and is always an excellent option to eliminate this issue.

Providing you check the turbo to manifold flange and wastegate port size on the manifold, everything will fit correctly, and you can move onto the downpipe and exhaust section.

One important thing to note is the material the manifold is made from.

The cheaper manifolds on the market are susceptible to cracking due to poor design and materials.

Still, options such as Speedfactory or La Fabrication are designed from high-grade 1.5" Schedule 40 stainless steel for a thicker wall for strength.

Downpipe And Exhaust System

The last thing to choose in the exhaust section is a downpipe and exhaust system. The downpipe sizing would solely be down to what exhaust side outlet you have on your turbocharger.

For example, if you've gone with a Precision 6262 with a 0.63 A/R exhaust housing and a 3" vband, you'll maximise the flow option by having a 3" downpipe and exhaust system.

Also, the wastegate outlet pipe, commonly called the screamer pipe, is worth considering.

This is either left open or plumbed back into the downpipe, depending on what sort of noise level you are after, once the wastegate opens.

Feeding this back into the exhaust will be quieter, and leaving it open will be much louder, so definitely something to consider when looking at the exhaust side of the turbo build.

Like the intake system, you are better off matching the exhaust side to the turbo housing.

The last thing you would want is a 3" outlet on the turbo, a 3" downpipe and a 1.75" catback, as all this will restrict flow and reduce the power.

There isn't a perfect one-size-fits-all for exhaust sizing, but anything up to the 400bhp mark would generally use a 2.5" and 3" past this point.

Only when you come to the 1000bhp mark will you need to run larger systems than this, but they will most likely be full-drag cars.

Electrical

Engine Management System

Why should i change my ECU?

The stock Honda engine management system, or ecu for short, is perfect for a completely stock car where the factory sets the ignition and fuelling within parameters.

Still, the ecu cannot handle any necessary adjustments once you go turbocharged.

Most of the time, these Ecus are locked from the factory, not allowing for any modifications or changes you will need when changing to larger injectors to get the correct fuel mixture.

Going with an aftermarket ECU opens many more options other than just fuelling and ignition, such as:

• Being able to adjust fuelling and ignition
• Adding safety features such as boost cut
• Features such as flat foot shifting and launch control
• Self-learning, in some cases

Another point worth mentioning is that controlling features such as boost by gear fully will completely transform your grip level by limiting the boost when you are getting wheel spin.

If you need as much control as possible out of your ECU and run multiple extra sensors that aren't included from Honda, then an aftermarket standalone ECU such as a Haltech would be the way to go.

If you want to keep all the stock sensors, fit the turbo kit, and get it mapped, then a Hondata board may be powerful enough for you.

Both have advantages and disadvantages, but you must work within your budget. The standalone option generally has more features but comes at a higher price.

What to do about wiring?

There are generally two options: buying a jumper harness to convert from your stock wiring or getting a piggyback board such as the Hondata, which fits inside the OEM Honda ECU case.

If you went with an option such as a Haltech, they also offer a few options for jumper harness, such as a plug-and-play into an OBD1 loom (90's civic) or ep3/dc5 to be able to cater for most B and K-series builds.

Gauges And Sensors

Next up on the list are gauges to show us those all-important engine vitals and to see what our engine is doing on the fly!

Regarding gauges, it's your opinion which gauges you run and how many you have room for when you decide where they are being mounted.

The Essential Turbocharged Gauges

The only thing most people can agree on is the three most essential gauges for your turbocharged Honda:

1. Air fuel ratio gauge
2. Oil pressure gauge
3. Boost pressure gauge

These three gauges are the most important for being able to check engine health as you go and be able to stop problems before they occur.

Air fuel ratio is important; if you go too rich or lean under boost, you will encounter engine problems. Plus, this is a significant factor in fuel consumption, so if it's running incredibly rich, you know there is an issue, and your MPG will be lower than it should be.

Oil pressure is also significant; if your oil pump fails, for example, and shows 0 Psi, you may be able to turn the engine off before any damage occurs.

On the other side of this, if the oil pressure is much higher than expected, you could, as one example, flood your turbocharger, reducing the lifespan.

Boost pressure is the last influential gauge; if you were mapped at 20psi safely, and the gauge is spiking to 30Psi, this will cause damage as the air-fuel mixture will be out of the mapped parameters.

Also, on the other side, if you usually make 20psi, and this is now showing 10psi at wide open throttle, you know you have an issue somewhere as an air leak.

After these three gauges, you can add as many as you'd like if you want more gauges, such as oil pressure or exhaust gas temperature sensors.

The last thing worth mentioning is that if you have an aftermarket ECU such as a Haltech Elite 1500, which runs on CAN data, you can plug in a Haltech IC-7 digital dash to show every engine sensor.

These are also much more expensive than just running three gauges but can offer you much more information all on one neat screen.

Service Items and Maintenance

Now you have pieced together your entire turbo kit and are nearly ready, although it would be worth checking a few things before you go to mapping.

This isn't an exhaustive list, more of a rough guide of a few things that should be reviewed to ensure your engine is working correctly and is healthy.

Compression Test

A compression test is one of the most effective ways to tell if your engine has compression across all (4 in this case) cylinders.

This is important because if you have an issue with one cylinder being down on compression and the other three are acceptable, it won't run correctly, and pushing boost through it will be fatal for the engine.

There are cheap compression testers available online; if you wish to avoid buying one, they are standard at nearly every garage.

Providing the compression test comes back with solid numbers over all four cylinders; you can move to the next step.

Spark Plugs

Spark plug heat ranges

Spark plugs play an essential role in turbocharged applications. The stock OEM spark plugs are generally around the heat range of 7 for B and K series engines.

For choosing spark plugs, generally, you would go up a heat range with the hotter the combustion chamber or more power.

Mild turbo builds usually go with NGK BKR8EIX and is the most common spark plugs we sell. As you may lose performance if they aren't matched correctly, it is always best to consult your tuner on this step to ensure you get the correct plug for your application.

Spark plug gapping

The last thing to look at when it comes to spark plugs is the gapping. Most plugs are preset with a gap from the factory to run in most stock applications. As you are turbocharged, you must ensure they are gapped to the correct specification.

This is another step where it would be worth asking the mapper as if you close the gap too tightly, the plugs will possibly not ignite the air-fuel mixture and make the engine run rough, make the opening too big, and the spark plugs will not have a consistent spark, possibly blowing out under boost, which would cause hesitation at the upper RPM levels.

It's always best to get the perfect medium, but this is only done through trial and error, or the most consistent way is to ask your mapper for advice.

Ignition Leads and Coils

Similar to the issues with spark plugs, it's worth checking your ignition leads or coils to ensure you get the most potent spark possible.

The ignition system must work correctly to ensure you can create the strongest pulse to the spark plug for the most consistent burn and fuel economy.

In the case of high-horsepower B-series builds, most owners choose to retrofit the K-series coil packs with a conversion kit. The kit usually consists of a coil-on-plug adapter plate, a distributor blanking cap, K-series ignition coils, and a coil-on-plug converter box.

This is because it removes the distributor and the moving rotor arm making it more consistent in the long term.

The distributor can also cause problems with the ignition coil not applying enough energy.

Still, by swapping to coil-on plugs, they are all controlled independently, creating a more reliable system and allowing for significantly fewer misfires.

Fluids and Filters

The last step in this guide is to refresh all of the serviceable items, such as:

• Engine oil
• Gearbox oil
• Oil filter
• Fuel filter
• Sump plug
• Brake fluid

This will eliminate any contaminants you've picked up over time and allow for the cleanest, smoothest running engine you can. In regards to engine oil, you may get into a situation where you will be burning oil now you are turbocharged, but the usual way to combat this is to go up a weight in oil.

For example, the K20 came with 5w40 oil as standard, but most turbo k20 road cars opt for a slightly thicker weight to ensure they aren't burning it, and the bearings and turbocharger are always fully lubricated.

Again, if you need more clarification, speak to your engine builder or tuner; they should know the correct oil to run for maximum gains with minimal issues.

Conclusion

After reading this guide, we hope you better understand how to choose the correct parts to build your dream turbo Honda.

In the future, we will break down each section and expand upon them to give you complete in-depth knowledge of every part.

Anything we missed in this article?

Has it helped you?

Need any more advice?

Let us know in the comments below, and we'll see you in the next blog; thanks for reading!