The Ultimate Honda Civic EP3 Engine Tuning Guide

The Honda Civic EP3 Type R has gained a significant following among car enthusiasts keen on customising their vehicles.

One of the primary reasons for this is the car's relatively low price point, coupled with its impressive engine potential.

For those looking to optimise the performance of their EP3 engine, we have prepared a comprehensive guide that outlines affordable modifications that can effectively enhance the engine and overall performance of the car.

Air Intake System

Ep3 Air Intake

When looking to enhance the performance of your ep3 engine, there are various factors to consider, and one of the most important is the air intake system.

An air intake system is responsible for delivering air to the engine, and the quality of the intake system can profoundly impact the vehicle's performance. Luckily, a wide range of options suits different budgets and preferences.

One of the most popular options for upgrading the air intake system is the installation of performance air filters. These filters are designed to increase airflow to the engine by replacing the stock air filter.

A simple drop-in panel filter such as the K&N Ep3 air filter is cost-effective for those seeking to enhance their car's performance.

It is relatively inexpensive at around £80 and can boost airflow compared to the original air filter while still using the stock airbox.

The Hybrid Racing cold air intake system is another option worth considering. This system replaces the stock airbox with a silicone hose construction, which reduces heat soak and enhances airflow.

It can provide up to a 14hp peak gain and a 9hp average gain over a completely stock system. However, it is essential to note that upgrading to a larger throttle body is necessary to use this system.

The Tegiwa Ep3 carbon airbox is a popular choice for those looking for something more advanced. This airbox costs around £420 and is constructed from carbon fibre, making it aesthetically pleasing.

With mapping and improved mid-range performance, Tegiwa has seen up to a 15hp peak power gain over the stock airbox.

However, it is crucial to note that installation of this airbox may require professional assistance.

One of the most appealing features of aftermarket air intake systems is their increased induction noise, particularly at higher revs.

This is an additional benefit for car enthusiasts who desire a more aggressive and sporty sound from their Honda Ep3 engine.

In conclusion, various options are available for those seeking to upgrade their vehicle's air intake system, each with unique benefits and drawbacks.

It is essential to consider your budget and performance needs before deciding. A well-chosen air intake system can significantly enhance your driving experience and your Ep3's performance.

Ep3 Intake Manifold

If you want to improve the performance of your car's intake manifold, consider upgrading to a high-flow and more significant bore option.

Fortunately, Skunk2 offers a range of aftermarket intake manifolds for K20 that are accessible and reliable.

Among the options available, the Skunk2 Pro K-series intake manifold is priced at around £550 and is an excellent choice for those looking to upgrade from the stock manifold.

With this upgrade, you can expect significant gains in power and torque, especially when paired with a remap.

For those looking for even more performance, the Skunk2 ultra street k-series manifold is currently priced at £667.

It offers a two-piece modular design, a 71mm throttle body opening, and velocity stacks inside the plenum for maximum air delivery to the cylinder.

This option is ideal for high compression naturally aspirated builds or up to 500bhp turbocharged/supercharged builds.

If you're running more than 500bhp, you may want to consider the Skunk2 ultra race series manifold, priced at the time of writing £965.

This option features a 90mm throttle body opening and a detachable plenum that can accommodate a 2ltr spacer, increasing the plenum volume from 3.5ltr to a massive 5.5ltr.

This is the perfect choice for anyone running over 500bhp, where the Ultra Street may become restricted due to the plenum and intercooler piping size.

If you're interested in learning more about the real-world performance of Skunk2's Pro and Ultra Street manifolds for up to 500bhp, you can find a detailed test that Jesse from J-Cal conducted on the Tegiwa Imports intake face-off blog.

If you're looking to take your car's performance to the next level, Skunk2's aftermarket intake manifolds range is worth considering.

Ep3 Throttle Body

When upgrading your intake system, the throttle body is a critical component to consider. In factory applications, Honda uses a 64mm throttle body, which is perfect for the 198hp that it makes stock.

However, if you plan to upgrade to a larger manifold like the Ultra Street, which has a 71mm bore, you'll need to port match to ensure you don't lose airflow.

Selecting a throttle body that matches the manifold you'll be using is crucial.

For example, if you choose the Skunk2 Ultra Race Centrefeed, it's best paired with a 90mm Skunk2 throttle body.

Throttle bodies usually don't differ much apart from bore size and colour. However, some larger throttle bodies may have different TPS sensor positions, but the wiring can easily stretch to fit the new location.

Another excellent option is the Tegiwa 70mm K-series throttle body which is, slightly cheaper than the Skunk2 version but just as reliable based on experience. Select a throttle body that matches your manifold bore and suits your needs.

Ep3 Exhaust System

Time to delve into the topic of upgrading your EP3 exhaust system. Undoubtedly, one of the first parts that should be upgraded is the factory exhaust manifold, notorious for being quite restrictive.

Regarding the cat back system, you'll be pleased to know that numerous options are available, depending on your budget and availability.

Some individuals prefer to build their system using V-Band clamps for the entire system, while others opt for off-the-shelf options such as the Tegiwa exhaust system.

Thankfully, the Tegiwa EP3/DC5 exhaust manifold is a highly dependable and popular option capable of gaining up to 15bhp with supporting modifications and mapping.

This manifold boasts a 4-2-1 configuration that provides excellent mid-range and peak gains, making it one of the best 'off the shelf' exhaust manifolds.

It fits perfectly with all OEM and aftermarket exhaust systems. However, it's vital to note that this header removes your catalytic converter, so you must plan accordingly.

It's important to note that you'll need a JDM anti-roll bar, such as the Genuine Honda 51300-S5T-J02. This system is a great fit, costing around £490 and featuring 70mm pipework from the manifold back.

The noise levels are within the limits for all UK tracks, making it perfect for daily driving. Not only does it provide performance gains, but it also reduces the vehicle's kerb weight by around 1kg.

The Fujitsubo Legalis r ep3 cat-back exhaust system is an excellent option if you're searching for a street-specific exhaust system.

Although it has a higher price tag of around £990, it offers improved power and torque and a deeper exhaust note that isn't excessively intrusive. This system is designed to provide optimal performance gains without supporting modifications.

Lastly, it's worth considering using polyurethane exhaust hangers instead of OEM rubber to prevent the exhaust from rattling against the chassis or arms or scraping against the ground while driving.

These hangers are more durable and last longer than their OEM counterparts, providing a reliable and long-lasting solution to this common issue.

Overall, upgrading your EP3 exhaust system can provide significant performance gains and improve the driving experience, making it a worthwhile investment for any EP3 owner.

Ep3 Drop In Camshafts

Now it's time to delve into the topic of camshafts. In our previous section, we covered breathing mods. Now, we will focus on camshafts designed explicitly for the EP3 engine.

These camshafts come in a wide range, from those requiring no head work or valvetrain upgrades to those intended for drag racing.

This guide will focus on the drop-in camshafts that do not require head work or valvetrain upgrades. The Skunk2 Tuner Series Drop-In Camshafts are an excellent option at around £820.

They are affordable and provide gains of up to 15bhp, optimizing mid-range and top-end horsepower and torque.

These camshafts are perfect for those who want to improve their engines performance without breaking the bank.

If you are looking for the best drop in camshafts money can buy, the Drag Cartel billet OG drop-in camshafts are what you need.

They are made from high-quality steel billet material and deliver rigidity at an extended RPM range while reducing valve float.

The cost of these camshafts is around £1150, but they are worth every penny for those serious about their car's performance.

Choosing between the Skunk2 and Drag Cartel camshafts ultimately comes down to your budget and preferences.

However, it's worth noting that Motortrend conducted a dyno test that showed the Drag Cartel camshafts produced an impressive 20whp and 10ft/lb of torque.

So, if you want the best performance possible, the Drag Cartel camshafts are worth considering.

Ep3 Fueling

If you're looking to increase the performance of your Honda Civic EP3 K20a2 engine, upgrading the fuel system is a crucial step.

While the stock OEM system may be suitable for stock power or a slight power increase, it can be limiting when it comes to tuning. That's why we recommend upgrading to higher-flow aftermarket alternatives for the best results.

To start with, upgrading the injectors is vital. The stock 310cc injectors may need to be increased to maximise horsepower, so we suggest looking into the RDX 410cc injectors.

These genuine Honda upgrades can handle low boost or high compression applications and are an excellent first step in fuel system upgrades.

If you're considering a turbo conversion, larger injectors will be necessary. The Grams 1000cc K-Series injectors are our top recommendation for up to 500bhp.

Remember that it's always better to use injectors that can flow more than you need.

Around the 80% duty mark is usually a good range to aim for, and your tuner should be able to advise on the exact injector size if you need more clarification.

Upgrading the fuel pump is also essential.

The Aem 340lph fuel pump is a popular drop-in option that can handle up to 1000bhp at 43psi. Again, we recommend going with a pump that can flow more than you need, as this will ensure optimal performance and ensure you never run out of fuel.

Finally, consider upgrading to an aftermarket fuel rail and pressure regulator if you're looking to build a high-horsepower road, track or race car.

The Hybrid Racing fuel pressure regulator with a matching Hybrid Racing K-Series fuel rail is an excellent option for those looking for a more tunable and high horsepower future.

And for even more performance gains, reading through our swirl pot article can help you understand the benefits and drawbacks of this additional upgrade.

Ep3 Cooling System

Ep3 Radiators And Fan Shrouds

If you want to improve your Civic Type R EP3 engine power output with performance upgrades, monitoring your engine's operating temperature is crucial.

As your vehicle is pushed harder, it heats up more, so investing in an aluminium radiator is wise.

Aluminium radiators are not only more efficient at cooling your K20A engine, but they're also lighter than OEM units and fit perfectly with OEM brackets.

There are two exceptional options for aftermarket radiators. The first is the Tegiwa EP3 aluminium radiator, a direct replacement for the stock radiator that can utilise the stock fan shroud.

With a core size of 37mm, it's guaranteed to keep your temperatures down compared to the factory radiator.

This radiator is relatively affordable, currently retailing at around £180.

The Mishimoto EP3 aluminium radiator is the second option. Mishimoto radiators are designed to optimise cooling and boost engine functions, preventing your car from overheating.

This radiator will enhance your engine's overall performance with a lightweight dual-core design made from 100% brazed aluminium and polished end tanks.

It has a high-pressure 1.3 bar Mishimoto radiator cap and a limited lifetime warranty. While it retails at around £260, it's a worthwhile investment.

After selecting a suitable radiator, the next consideration is a fan shroud that matches your new radiator. We offer a 2442cfm EP3 fan shroud that utilises SPAL fans.

This fan shroud has been tested on high horsepower EP3 builds and has never had any temperature issues, thanks to the mega-flow SPAL fans.

If you're looking for a slightly cheaper option, we also offer an 1818cfm version. However, for only £25 more, it's worth going with the higher flow option.

Lastly, it's critical to consider the thermostat housing, as the OEM plastic housing is known to break over time.

T7Design has developed a swivel neck billet housing that uses an OEM EP3 thermostat for full adjustability in tight spots.

Available in 32mm or AN16, you can use this in virtually every situation you encounter with the cooling system to ensure smooth and efficient functioning.

By considering all these factors, you can increase the power output of your Civic Type R EP3 while keeping your engine operating safely at optimal temperatures.

Ep3 Radiator Hoses

When increasing the power on your Honda Civic EP3 engine, giving special attention to the radiator hoses is crucial.

It's important to note that the OEM Honda coolant hose system can become brittle over time, leading to leaks and even engine failure if not caught in time.

To prevent such issues, it's highly recommended to consider aftermarket kits designed to enhance your cooling system's performance and durability.

One of the best options available is a high-quality silicone hose kit. This kit is a complete solution to your coolant system upgrade, especially if you've already replaced the radiator and fan shroud.

The reinforced, high-grade silicone hoses are engineered to withstand temperatures up to 500 degrees without distorting, which is more than your cooling system will ever produce.

This feature ensures that your cooling system operates efficiently and effectively, even in extreme conditions.

These silicone hose kits are available in various colours, making them popular among car enthusiasts worldwide. Apart from enhancing the performance of your cooling system, they also add an aesthetic appeal to your engine bay.

Moreover, investing in a complete 13-piece kit that includes all necessary hoses is available for around £100, making it an affordable and practical solution for Honda owners who want to ensure the longevity and reliability of their cooling system.

In summary, upgrading your Honda's cooling system with a high-quality silicone hose kit is an excellent investment that offers numerous benefits, including improved performance, durability, and aesthetics.

By opting for an aftermarket kit, you can avoid potential issues caused by the OEM Honda coolant hose system and enjoy peace of mind with a reliable and efficient cooling system.

Ep3 Turbocharging And Supercharging

After exploring the naturally aspirated parts for EP3 engine builds, it's time to delve into the turbo and supercharger section.

When considering a turbo conversion, it's essential to have a clear idea of your desired power output.

Whether you aim for 300bhp or 1000bhp, you must select the appropriate parts that work together seamlessly to achieve your power goals without obstacles.

Moreover, reliability plays a crucial role when opting for a turbo or supercharger conversion. Remember that the Honda engine's stock internals are designed to handle only the stock power.

While it's possible to put boost through a stock block, it becomes increasingly likely to damage the engine as the horsepower increases.

Saying that, we have customers who are running 450bhp on a completely unopened k20a2, but for how long is the question!

Therefore, choosing the right parts that complement your engine's current condition and power output is essential to ensure reliability.

We will, in the future, be putting together a guide on everything you'll need to be able to build a forged engine, but for now, if you're unsure, please get in touch, and we can guide you through everything you need to know regarding EP3 engine internals.

Budget is another crucial factor to consider when estimating your power goals. Suppose you have a budget of only £2000.

In that case, it's unlikely that you can achieve 1000bhp reliably. Hence, estimating the budget required to complete your power goals is crucial.

Considering these factors, you can choose the best parts and assemble your turbo kit accordingly. However, we must note that building an entire turbo conversion is too lengthy to cover in this guide.

Hence, we have created a separate B/K-series turbo conversion guide that can help you select the right parts that work together to achieve your EP3 turbo goals.

Ep3 Plug-And-Play Ecu And Remapping

In this tuning guide, we will now delve into the ECU, a critical component in your car's performance.

While selecting an ECU depends on your personal preference or the tuner's preference regarding brand and capabilities, we can help you make an informed decision.

Currently, there are three main options for plug-and-play ECUs in the market, each with advantages and disadvantages.

These options include the Hondata K-PRO, the Haltech EP3 Platinum, and the Haltech Elite 1500 with a plug-and-play harness.

Firstly, let's examine the Hondata K-Pro, the most economical choice among the three, retailing at approximately £1075.

It is a powerful ECU that can transform your car's factory Honda EP3 ECU into a fully reprogrammable engine management system.

With a K-Pro system installed, your EP3 engine can be tuned on a dyno for maximum performance, regardless of your modification levels.

Next, we have the Haltech EP3 Platinum Pro plug-and-play ECU, an upgrade from the Hondata K-Pro, but at a slightly higher price tag of £1300.

It is an easy and quick solution if your car still has its original engine and wiring.

You unplug the factory ECU and plug in the Haltech ECU, load your base map, and you're ready to go!

The Haltech platinum also has some extra features that the K-Pro doesn't, such as an inbuilt MAP sensor and auto-tuning.

Lastly, the Haltech Elite 1500 ECU with EP3 plug-and-play harness is the most expensive but powerful option, costing just shy of £1700.

It has many more features than the two previous ECUs and is the best option for anything turbocharged.

It also has multiple race functions built-in and extra inputs and outputs for expansion.

Additionally, it is fully CAN-based, offering expandability to products such as CAN keypads and digital dashes.

While many other ECUs are not plug-and-play, we recommend these three options for ease of use.

However, if you're planning a complete race build with custom wiring or k-swapping, other options, such as the Haltech Elite 2500 or Nexus ECU, would be worth considering.

To learn more about the distinctions between these ECUs and their in-depth differences, check out our Haltech article.

Ep3 Dyno Preparation

Great job on finishing your engine build! A thorough inspection is vital to ensure your engine is in excellent working condition as you prepare to head to the dyno.

It's important to note that this is not an exhaustive checklist but rather a guide to ensuring that your engine meets your expectations regarding dyno preparation.

Taking the time to check these key factors will give you the peace of mind to avoid dyno issues costing you time and money.

Compression Test

Performing a compression test is an excellent way to determine if your engine has compression across all four cylinders.

It is highly recommended to check that all cylinders function correctly, even if one cylinder has low compression.

At the same time, the remaining three are fine; the engine will not operate efficiently.

Therefore, it is crucial to ensure that all cylinders work optimally to avoid further damage or complications.

Spark Plugs

Properly tuning an engine requires careful consideration of all components, including the spark plugs. The original equipment manufacturer (OEM) spark plugs typically have a heat range of 7 for K-series engines.

However, choosing the appropriate spark plugs involves selecting a higher heat range for hotter combustion chambers or increased power.

The NGK BKR8EIX is a popular spark plug for mild turbo builds, but choosing the correct plug for your specific application is critical to avoid losing performance.

To ensure optimal performance and prevent potential issues, it's always best to consult a professional tuner who can provide expert guidance on spark plug selection.

Spark plug gapping

It is crucial to ensure that the spark plug gap is checked. Usually, the plugs are pre-set with a gap from the factory that is suitable for most stock applications.

However, if the aim is to attain maximum power, ensuring the plugs are gapped to the correct specification is recommended.

This can help optimise the engine's performance and improve its overall efficiency.

Therefore, if necessary, checking and adjusting the spark plug gap is advisable.

Ignition Coils

Ensuring that your ignition system is operating effectively is essential for maximising the power of your spark and improving fuel efficiency.

To achieve this, checking your spark plugs and inspecting your ignition coils is vital. These components are critical in generating a strong pulse to the spark plug, leading to consistent and efficient combustion.

By thoroughly examining your ignition system, you can avoid potential issues.

Fluids and Filters

To maintain the optimal performance and cleanliness of your engine, it is recommended to refresh all of the serviceable items listed below as a final step of your maintenance routine:

1. Engine Oil: Changing your EP3 engine oil is crucial for the longevity of your engine. Fresh oil helps lubricate the engine's moving parts, reduce friction, and prevent overheating.

2. Gearbox Oil: The gearbox oil is responsible for lubricating your transmission's gears, bearings, and synchros. Regularly changing this oil will help ensure smooth shifting and prolong the life of your transmission.

The best option here would be to go with genuine honda MTF gearbox oil.

3. Oil Filter: The oil filter is responsible for trapping any contaminants or debris that may be present in the engine oil.

Replacing the oil filter before dyno time will help ensure your engine oil remains clean and contaminant-free.

4. Fuel Filter: The fuel filter is responsible for trapping any impurities or debris that may be present in your fuel system.

Regularly replacing the fuel filter will help ensure that your engine receives clean fuel, essential for optimal performance and efficiency.

Regularly refreshing these serviceable items will help ensure your engine runs smoothly and cleanly for years.

Conclusion

Now that you've had the chance to read through our comprehensive guide, you should feel confident in your ability to select the appropriate parts for your EP3 build.

Whether you're looking to create a mild bolt-on build or a full-fledged race car, our guide has equipped you with the knowledge necessary to make informed decisions.

One of the many reasons Honda Civic EP3s are such a popular choice among car enthusiasts is their impressive tunability, and the fact that new parts are constantly being released only adds to their appeal.

In the coming weeks, we'll publish more EP3 guides that explore other areas of the car in detail, such as the transmission and interior modifications.

The next step you should take is to upgrade your brakes. Luckily, we have written the 6 best Honda Civic Ep3 braking upgrades guide!

If you have any lingering questions or uncertainties, please contact us by leaving a comment below or sending us a message.

Our team of experts is always available and willing to assist you with anything you require.

We hope that our guide has proven helpful to you, and we look forward to hearing about all the exciting modifications you make to your EP3!