Honda D15 Tuning

"All you need to know about tuning the Honda D15 engine!"

The Honda D15 engine is part of the D series family, known for its reliability, fuel efficiency, and potential for performance tuning. Found in numerous Civic and CRX models throughout the late 80s and 90s, the D15 has cemented its place in the hearts of Honda enthusiasts.

We were contacted through email for further information on tuning a customized D15, specifically which turbo improvements and engine alterations perform best. (NB: We have separate articles covering the best mods and upgrades for the D16 D17 & D12 D13 D14)

So we've put together this page that includes our go-to modifications for this engine as well as what we believe are the best value additions you may do. A D Series engine may be SOHC or DOHC, and it may have VTEC variable valve timing.

Earlier versions of this engine also employed a single port fuel injection system termed PGM-CARB by Honda, indicating that the carburetor was computer controlled.

TorqueCars will go through your D15 tuning choices and highlight the best changes. The Honda D15 has a lot of potential, and with properly selected tuned components like a remap, turbo upgrades, and camshafts, you can definitely enhance your driving experience.

As with all other Honda engines, the D15 may be upgraded to provide extra power. However, the D15 lacks an abundance of easy and practical bolt-on modifications, which might make the options appear quite restricted at times. Swaps with other Honda engines are often the best course of action for a serious tuning effort; our Civic engine swap guide should be beneficial in this regard.

Check out our video introduction to Honda Tuning, all you need to know about mods and upgrades on your Honda.

History of the D15 Engine

D15A1

1. 1984–1987 Honda CRX

• 76 hp@5,500 rpm 84 lbftf@3,500 rpm

D15A2

1. 1984–1987 Honda CRX HF Grifin (USA Market and Ethiopia Market )

• 60 hp (45 kW)@5,550 rpm 73 lbft@3,500 rpm

1. 1984–1987 Honda CRX DX and HF (USA)
2. 1987 Honda Civic Wagon RT4WD (Canadian Model)

• 76 hp@5,500 rpm 84 lbft@3,500 rpm

D15A3

1. 1984–1987 Honda CRX 1.5i (Europe)
2. 1985–1987 Honda CRX Si and 1987 Civic Si (AU/NZ)
3. EW3/EW4 1985-1986 before switching to D15A3  in 1987
4. 1985–1987 Honda Civic 1.5i (Europe)
5. 1986–1987 Honda Civic Si Hatch (US)

• 91 hp (68 kW, 92 ps)@5500 rpm
• 100 PS (74 kW)@5750 rpm (Europe) 93 lbft (12.9 kg/m, 126 Nm)@4500 rpm

D15A4

• 92 hp (70 kW, 94 ps)@5500 rpm
• 93 lbft (12.9 kg/m, 126 Nm)@4500 rpm

D15A5

• 93 hp (70 kW, 94 ps)@5600 rpm
• 100 PS (74 kW)@5750 rpm (Europe) 93 lbft (12.9 kg/m, 126 Nm)@4500 rpm

D15B

1. 1988 Honda CRX 1.5X (rare)
2. 1990 Honda Civic 25XXT Formula (JDM Only)
3. Honda Civic Ferio MX (JDM Only) EG8
4. 1998–2001 Honda Capa GA4 (JDM Only)
5. 1988-2001 Honda Civic SH4 EF1

• 103 hp (77.23 kW, 105 PS)@6800 rpm 14.1 kgm (133.4 Nm)@5200 rpm

D15B VTEC

1. 1992–1995 Honda Civic Vti (JDM Only)
2. 1992–1998 Honda CRX DelSol (JDM Only)

• 130 PS (96 kW; 128 hp)@6800 rpm 14.1 kgm (138 Nm)@5200 rpm

1. 1995–1998 Honda Civic Ferio Vi (EK3, JDM Only)
2. 1999-2000 Honda Civic Vi-RS
3. 2001-2005 Honda Civic JDM VTEC (JDM Only, Europe)Bore and Stroke :75,0×84,5 mm

• 130 PS (96 kW; 128 hp)@7000 rpm 139 Nm@5300 rpm

D15B1

1. 1988–1991 Honda Civic Hatchback

• 70 hp (52.2 kW, 71.0 PS)@5,500 rpm 73 lbft (11.4 kgm, 112 Nm)@3,000 rpm

D15B2

1. 1988–1991 Honda Civic GL/DX/LX/CX (CX Canadian Market)
2. 1988–1991 Honda Civic Wagon Wagovan/DX
3. 1988–1991 Honda CRX DX
4. 1992–1995 Honda Civic LSi Hatch/Saloon (European Market)
5. 1992–1995 Honda Civic DXi Hatch/Saloon (European Market)
6. 1990–1995 Honda Concerto (European Market)

• 92 hp (69 kW)@6,000 rpm (US)
• 90 PS (66 kW)@6,000 rpm (Europe) 88 lbft (12.2 kg/m, 119 Nm)@4,700 rpm

D15B3

1. 1988–1995 Honda Civic Shuttle GL
2. 1989–1996 Honda Ballade 150-16 & 150 (South Africa)
3. 1992–1995 Honda Civic LX (NZ model)
4. 1988–1991 Honda Civic LX/EX (NZ model)
5. 1992–1995 Honda Civic EX (SA model)

• 77 kW (105 PS; 103 hp)@6000 rpm 89 lbft (13.55 kg/m, 121 Nm)@4500 rpm

D15B4

1. 1989–1993 Honda Civic GL (Australian Market)

• 74 kW (99 hp; 101 PS)@5,200 rpm 122 Nm (90 lbft)@3,800 rpm

D15B5 VTEC-E

1. 1992–1995 Honda Civic

D15B6

1. 1988–1991 Honda Crx HF
2. '88-'89 62 bhp (46.2 kW, 62.9 PS)@4400 rpm
3. '90-'91 72 bhp (53.7 kW, 73.0 PS)@4500 rpm 83 lbft (11.5 kg/m, 113 Nm)@2200 rpm

D15B7

1. 1992–1995 Honda Civic GLi (Australian model)
2. 1992–1995 Honda Civic DX/LX
3. 1992–1995 Honda Civic LSi Coupé (European Market)
4. 1993–1995 Honda Civic Del Sol S
5. 1998-2000 Honda City SX8

• 102 hp (76.1 kW, 103 PS)@5900 rpm 98 lbft (13.5 kg/m, 133 Nm)@5000 rpm

D15B8

1. 1992–1995 Honda Civic CX (U.S. model)Displacement : 1,493 cc (91.1 cu in)

• 70 hp (52.2 kW, 71.0 PS)@4500 rpm 83 lbft (11.5 kg/m, 113 Nm)@2800 rpm

D15Y3

1. 2001–2006 Civic EXi (Africa, Dubai, Pakistan)

• 120 hp (89 kW; 122 PS)@6300 rpm) 149 Nm (14.9 kgm) (110 lbft)@4,800 rpm

D15Y4

1. 2001–2006 Civic VTI (ES8) (VTEC) (Japan, Singapore, Malaysia, Sri Lanka)
2. 2001–2006 Civic EXi (ES8) (non-VTEC) (Japan, Singapore, Malaysia, Sri Lanka)

• VTEC version 130 PS (96 kW; 128 hp)@6200 rpm) 155 Nm @4500 rpm
• non VTEC version 122 PS (90 kW; 120 hp)@6300 rpm) 149 Nm @4800 rpm

D15Z1 VTEC-E

1. 1992–1995 Honda Civic VX
2. 1992–1995 Honda Civic VEi (European Market)

• 90 hp (67.1 kW, 91.3 ps)@5,600 rpm (92 hp@5,500 rpm; USDM) 98 lbft (13.5 kg/m, 133 Nm)@4,800 rpm (97 lbft@3,000 rpm; USDM)

 D15Z2

1. 1993–1995 Honda Civic Breeze (AUDM)

• 89.8 hp (67 kW, 91.1 ps)@6,000 rpm 98 lbft (13.5 kg/m, 119 Nm)@4,000 rpm

D15Z3 VTEC-E

1. 1995–1997 Honda Civic MA9 (European Market)

• 90 hp (67.1 kW, 91.3 PS)@5500 rpm 98 lbft (13.5 kg/m, 133 Nm)@4500 rpm

D15Z4

1. 1996–2000 Honda Ballade/Civic in South Africa & Venezuela
2. 1996–2000 Honda Civic LXi/EXi in the Philippines/Middle East/Trinidad & Tobago

• 90 hp (67 kW) or 105 hp (78 kW)@5,800 rpm 99–103 lbft (134–140 Nm) :at 4,200 rpm

D15Z6 SOHC VTEC-E

1. 1995–2000 Honda Civic 1.5i LS (European Market)

• 114 PS (84 kW)@6,500 rpm 99 lbft (134 Nm)@5,400 rpm

D15Z7 3-stage VTEC

1. 1996–1999 Honda Civic VTi EK3 and Ferio Vi

• 128 hp (95.4 kW, 130 ps)@7000 rpm 102 lbft (14.2 kg/m, 139 Nm)@5300 rpm

D15Z8 VTEC-E

1. 1997–2000 Honda Civic LS (MB3, MB9), (European Market)

• 114 hp (85.0 kW, 116 ps)@6500 rpm 95–99 lbft (13–14 kg/m, 128-134 Nm)@4500 rpm

Tuning the Honda D15 and best D15 performance parts.

Best D15 modifications

Talking about the best modifications for your D15 engine, we are going to focus on the parts that releases the best value for your outlay.

Please watch our video which covers the 5 principles of tuning your D15. Be sure to keep up with our latest YouTube content and subscribe.

Best mods for your D15

• Low mass flywheel - a lower weight flywheel will noticeably improve the engines ability to rev freely. But not always beneficial for all D15 engines.
• Internal engine mods - crank, pistons, conrods & compression ratio including balancing and blueprinting
• Sporty Profile Camshafts are generally the biggest mechanical mod upgrade, but we strongly suggest they be applied to your engine by someone who can fine tune the cam timing and you might struggle to find one but we are sure you'l; find a local firm to regrind a stock camshaft for you.
• Forced induction upgrades - A New Turbo is the most significant way to increase air supply, ensuring you are able to use more fuel and make more power. It is one of the most technically difficult modifications you'll see massive gains.
• Intake Modifications and high flowing exhausts - NB: on their own these mods will NOT ADD HP , but they enable you to lift power after other modifications by lessening the restrictive flow.

D15 Tuning Stages

Typical stage 1 mods often include: Sports exhaust manifold, Fast road camshaft, Drilled & smoothed airbox, Intake manifolds, Panel air filters.

Typical stage 2 mods often include: Sports catalyst & performance exhaust, induction kit, high flow fuel injectors, Ported and polished head, Fast road cam, Suspension (Sports).

Typical stage 3 mods often include: Twin charging conversions, Internal engine upgrades (head flowing porting/bigger valves), Crank and Piston upgrades to alter compression, Competition cam, Engine balancing & blueprinting, Adding or Upgrading forced induction (turbo/supercharger).

D15 Camshaft Upgrades

This engine's versatility makes it a prime candidate for upgrades, with the camshaft being a popular focus for those looking to enhance performance.

Camshaft upgrades are a pivotal step in engine tuning, as they directly influence valve timing, air/fuel intake, and exhaust expulsion. For the D15, there are several camshaft options available that cater to different goals, from mild street performance improvements to aggressive profiles designed for racing.

When choosing a camshaft upgrade, it's essential to consider how the engine will be used—whether for daily driving, spirited weekend drives, or competitive racing—to ensure the cam profile matches your performance expectations and complements other engine modifications.

Manufacturers such as Skunk2, Crower, and Bisimoto offer a range of camshafts for the D15 engine. These camshafts are designed to increase the high RPM power without sacrificing too much low-end torque, making them more suited to petrol engines.

For instance, a stage 1 camshaft upgrade offers improved throttle response and power gains without extensive modifications.

In contrast, stage 2 and 3 camshafts are more aggressive, requiring additional adjustments such as upgraded valve springs, retainers, and sometimes modifications to the cylinder head and fuel system to achieve optimal performance and not always the easiest to live with on the roads.

Incorporating a performance camshaft into a D15 engine also necessitates tuning the engine's ECU to ensure the fuel and ignition maps are optimized for the new airflow characteristics.

This may involve adjusting the VTEC engagement point (if applicable), fuel pressure, and ignition timing to fully realize the potential of the camshaft upgrade.

If you have VTEC, instead of fitting a camshaft upgrade you can get the VTEC to cut in at lower RPM ranges, essentially giving you the sportier cam profile over more of the engine's power band.

It is simpler to get VTEC to come in sooner than it is to find and install a fast road cam, thus this is our preferred solution for individuals wishing to improve the cam profile on their D series.

The cam profile plays a big part in the engines power output so cam upgrades make quite a large difference. The intake & exhaust durations will alter depending on the chosen cam profile, so large bhp gains are on offer for cam upgrades.

Fast road cams usually raise the power across the rev band, you might lose a little low down power but your higher rpm power will improve.

Competition cams, raise the higher rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a road car you should ideally to optimize your power band to your driving style.

I'd be shocked if you'd think that a D15 Race cam is at all pleasant when driving in heavy traffic.The low end idle will typically be lumpy and irregular, and this is something you'd notice on a track when you drive in the upper third of the rpm band, but on roads this is a serious issue and we've heard from lots of drivers regretting their decision to install a more extreme competition cam profile to their engine.

Different D15 engines respond differently depending on how well made they are, when camshafts are fitted depending on the camshaft being more extreme camshaft durations and cam profile as unique due to manufacturing tolerances and quality variations so check your engine on a rolling road.

The ecu map and fuelling and fuel pump and injectors also will say much on the bhp gains you'll make.

Longer valve durations can adjust the bhp band, and on most engines there are some advantages to extending the intake or exhaust durations and valve lift.

ECU Mapping Improvements for the D15

ECU mapping helps release the full potential of all the parts you've fitted to your D15. Sadly mapping is virtually impossible on the older D15 engines, so an aftermarket or replacement aftermarket ECU is your best bet.

Aftermarket ECU (Engine Control Unit) options for the Honda D15 engine open up a realm of tuning possibilities, allowing enthusiasts to finely tune their engine's performance beyond what's achievable with the stock ECU.

These aftermarket solutions are designed to provide greater control over engine parameters such as fuel delivery, ignition timing, and, in some cases, variable valve timing (VTEC) engagement. Here are some popular aftermarket ECU options and considerations for the Honda D15 engine:

Hondata

• Hondata S300: A highly regarded option for OBD1 Honda engines, the Hondata S300 system can be installed into a standard Honda ECU casing. It offers extensive tuning capabilities, including but not limited to, adjustable fuel maps, ignition control, VTEC engagement, and data logging.
  
  The S300 is ideal for those who want detailed control over their engine's performance and is suitable for everything from mild street builds to full race setups.

AEM

• AEM Infinity and AEM Series 2 EMS: AEM's offerings are known for their robust and flexible engine management systems. The AEM Infinity and Series 2 EMS provide comprehensive control over the engine's operations, suitable for highly modified engines. They offer features like programmable fuel and ignition maps, boost control (for turbocharged setups), and advanced diagnostics. AEM's systems are designed for tuners and builders looking for maximum customization.

Haltech

• Haltech Elite Series: The Elite series from Haltech is another versatile option, offering a wide range of tuning capabilities suitable for naturally aspirated and forced induction setups.
  
  With features such as multi-fuel support, advanced boost control, and integrated diagnostics, Haltech ECUs are designed for those seeking to push their D15 engine to its limits. The user-friendly interface and comprehensive data logging make it easier to dial in the perfect setup.

MegaSquirt

• MegaSquirt PNP: MegaSquirt offers plug-and-play (PNP) solutions that are budget-friendly and versatile.
  
  The MegaSquirt PNP can be a great entry-level option for those new to engine tuning, providing essential features like fuel and ignition control. It's a DIY-friendly option, with a supportive community and plenty of resources available for those looking to learn and experiment.

Link ECU

• Link G4X: Link's G4X range of ECUs provides cutting-edge engine management and is known for its reliability and performance. Offering a broad spectrum of tuning options, including advanced timing control, wideband O2 feedback, and variable valve timing adjustments, the Link G4X is suitable for both street and race applications.

It will usually give around 10-15% on NA (naturally aspirated) engines, but the outcome may depend much on the parts you've chosen to fit and the condition of your engine.

D15 Intake Mods & Upgrades

Induction kits play a pivotal role in enhancing the performance of the Honda D15 engine by improving the way air is delivered to the engine. The aim is always to remove restrictions, for a stock D15 the gains are negligible, but with other mods you may well start to see a restriction.

These kits replace the factory airbox and filter with a high-flow air filter and sometimes a new air intake pipe. This modification allows for a higher volume of cooler, denser air (if fitted in an air box or shield and fed with cold air feed from outside the engine bay) to reach the engine, which is crucial for making more power.

Cooler air contains more oxygen per volume, and more oxygen in the combustion chamber means the engine can burn more fuel, producing more power.

Benefits of Upgrading to an Induction Kit

• Increased Airflow: Induction kits are designed to reduce restriction and increase airflow to the engine compared to the stock airbox, which is often quite restrictive to minimize engine noise and cost.
• Enhanced Engine Sound: Many enthusiasts appreciate the more pronounced engine intake sound that comes with an induction kit, adding to the driving experience.
• Improved Throttle Response: With more air readily available for combustion, you'll often notice an improvement in throttle response.
• Potential for Increased Power: Especially when combined with other modifications like exhaust upgrades and ECU tuning, induction kits can contribute to noticeable power gains.

Recommended Induction Kit Brands for the D15

Several reputable brands offer induction kits that are compatible with or specifically designed for the Honda D15 engine. Here are some of the top choices:

K&N Filters

• K&N is perhaps the most well-known name in high-flow air filters and induction kits. They offer kits that are designed to increase horsepower and torque, with the added benefit of reusable filters that can be cleaned rather than replaced.

AEM Induction Systems

• AEM specializes in cold air intake systems, which are engineered to draw air from outside the engine bay, ensuring the air entering the engine is as cool as possible. AEM's systems are known for their performance gains and include a Dryflow filter that doesn't require oiling.

Pipercross

• Pipercross air filters and induction kits are known for their high flow rate and dust filtering capability, making them a great choice for both street and track use. Their foam filters offer a unique alternative to traditional cotton or paper filters.

The primary objective of modifying an engine, such as the Honda D15, is to maximize the volume and efficiency of air and fuel delivery to each cylinder.

This process is crucial for enhancing power output, torque, and overall engine performance. A critical component in this system is the intake manifold, which serves to channel air from the air filter into the engine, where it can be mixed with fuel before combustion.

Intake Manifold Upgrades

The design and flow characteristics of the intake manifold, particularly the shape and flow rate of the plenum, play a significant role in fuel atomization.

Improved fuel atomization ensures that fuel particles are finely dispersed within the air, leading to more efficient combustion and, consequently, increased power and efficiency.

Most stock intake manifolds, especially on older or more economy-focused engines like the D15, can significantly benefit from an upgrade to enhance performance.

We've also seen throttle bodies used to good effect and these allow you tailor the power delivery more precisely.

Recommended Intake Upgrade Brands for the D15

Several aftermarket brands specialize in high-performance intake manifolds and related components for the D15 engine. These brands offer products designed to increase airflow and improve the engine's breathing capability:

Skunk2

• Skunk2 Racing is renowned for its performance intake manifolds, which are engineered to maximize flow and improve power across a broad RPM range. Their products are a popular choice among Honda enthusiasts looking to extract more performance from their D15 engines.

Additional Performance Enhancements

To complement an upgraded intake manifold, other modifications can further enhance the D15's performance:

• Big Valve Kits: Installing larger valves increases the engine's ability to intake air and expel exhaust, thereby improving breathing and power output.
• Port Enlargement and Head Flowing: Porting and polishing the intake and exhaust ports on the cylinder head can reduce restrictions and improve airflow, leading to better fuel atomization and increased power. This process should be done by experienced professionals to ensure optimal results.
• Performance Throttle Body: Upgrading to a larger throttle body can increase the maximum flow rate of air into the engine, complementing the improved intake manifold and other modifications.

When upgrading the intake system and related components, it's important to consider the engine's overall setup and the specific performance goals you aim to achieve. An integrated approach, where each modification complements the others, will yield the best results.

D15 Turbo upgrades

NA (naturally aspirated) engines need quite a lot of work when you add a turbo, so we have a separate guide to help you take into account the pros and cons of going this route on your D15

The more air that can enter an engine, the more gasoline that can be burned, thus improving intake with a turbocharger upgrade results in good power improvements.

However, with greater power levels, engines will need better components. Determine these constraints and add hardened components to handle the power.

We've seen individuals spend a lot on turbo improvements for the D15, only to have the whole system fail shortly after installation.

Larger turbos often have bottom end latency, while tiny turbos spool up rapidly but lack the top end engine power improvements.

Fortunately, the turbocharger industry is always evolving, and we now see variable vane turbo chargers, which enable the vane angle to be adjusted based on speed to reduce latency and boost top end horsepower and torque.

Twin scroll turbochargers split exhaust flow into two channels, which are directed towards differentially profiled vanes in the turbocharger. They also improve the engine's scavenging ability.

When more air is sucked into the engine, you'll often notice a restriction in the air flow sensor AFM/MAP on the D15.

You'll notice that 4 bar air sensors can handle significant power improvements, however the OEM air sensor restricts bhp and torque at a much lower level.

Adding a supercharger or additional turbo will make large power gains, although more difficult to configure. We have this article covering twinchargers if you want to read more.

D15 Fuelling Upgrades

When you increase the bhp you will need to look at to the fuelling.

The early carbureted D series engines may be modified to dual carburettors or numerous throttle bodies for increased power.

You'd be better off upgrading to fuel injection since it's simpler to tune and set up for higher power improvements.

The fuel pressure regulator is an excellent addition for injected vehicles since it enhances throttle responsiveness.

More bhp needs more fuel. Fuel pressure boost valves raise the fuel pressure, providing a more snappy throttle response.Don't forget to over specify your injector capacity.

The rule of thumb is to add 20% capacity when specifying an injector, this takes into account injector deterioration and affords you some spare capacity should the engine need more fuel.

We think this one is common sense, but you'll need to match your fuel injector to the type of fuel your car uses as well.

D15 Performance Exhausts

If your present exhaust is causing a flow issue, you should consider upgrading it.

Most factory exhausts should have adequate flow rates even with minor power improvements, but once you start pushing the power levels, you will need to upgrade to a stronger flowing exhaust.

The passage of gases through the engine is balanced by sports exhausts.

However, if the exhaust is excessively large, i.e. more than 2.5 inches bore, you will lose a significant amount of flow rate and, as a result, power and torque.

For road-going vehicles, upgrades such as a sports catalyst essentially eliminate this limitation due to its bigger size and surface area, and will effectively enhance the performance to levels you would anticipate without a catalyst fitted while keeping the car road legal.

And, as a result of its larger interior surface area and design, it will flow considerably better. Because removing a catalyst is unlawful in most areas and locations for road-registered automobiles

NB:(In others, you can't even replace a functional catalyst), the alternative decat or catalyst removal should be regarded an off-road only alteration.

Weak spots, Issues & problem areas on the D15

The D15 engines are not bad as far as reliability goes as long as they are looked after and serviced.

Carbon build up in the head, particularly around the valves which will reduce power, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon By avoiding short journeys where the engine doesn't warm up and using good quality fuel you can reduce this risk.

Frequent oil changes are highly recommended on the D15, and more so when the car is modified and will help maintain the long life of the engine.

If you want to disover more, or just get some friendly advice on Tuning your D15 engine please join us in our friendly forum where you can discuss D15 tuning options in more detail with our D15 owners. It would also be worth reading our unbiased Honda tuning articles to get insights into each modification and how effective they will be.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to know what our users have got up to and which parts work best for them on each model of car. We use your comments and feedback to improve the accuracy of these D15 tuning guides which get regular updates and revisions.

This article is flagged for an update, so please pass on specific tips below that I can include. All articles, and content was written by me, Waynne Smith TorqueCars founder. Some outlines are just too general so I appreciate your feedback and suggestions. This entry was filed under Honda. You can leave a response below or join our forum to discuss this article and car modification in detail with our members.

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