Honda L13 Tuning

"All you need to know about tuning the Honda L13 engine!"

The Honda L13 are good project engines and with carefully picked sports upgrades like a remap, turbo upgrades and camshafts you will definitely increase your driving experience.

In this article we review L13 tuning and provide tips on the optimum upgrades. Swapping with the other L series engines makes a good upgrade path, with many going for the 1.5 liter L15 engine. You just need to make sure you have the engine bay space, but relocating the battery can free up some space to work in.

History, Power & Specs of the L13 Engine

The L13 an inline 4 1.3 liter engine, came as a SOHC or DOHC setup and was surprisingly powerful for such a small engine, thanks in part to the high RPM range, and the VTEC setup.

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

L13 engine

  • L13A i-DSI
  • L13Z i-VTEC
  • L13B i-VTEC
  • L13Z1 i-VTEC

The L13 was used in some really popular models

  • 2001 1.3 L L13A (Fit/Jazz)
  • 2001 1.4  L13A (Fit/Jazz)
  • L13A i-DSI Honda Civic Hybrid)
  • Honda Airwave

Tuning the Honda L13 and best L13 performance parts.

Best L13 upgrades

The top L13 mods on an engine are sensibly the ones that give the best power gain for you spend.

We won't be swayed by popular L13 mods, they need to be cost effective.

Altering your L13 cam will make a dramatic difference to the engine bhp. Choosing a higher performance cam profile raises the bhp accordingly.

Fast road camshafts tend to raise the bhp and torque over the rpm band, you might lose a little low end torque but the high end rpm power will be higher.

Motorsport and race camshafts, raise the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Motorsport and race cam makes it harder when driving in heavy traffic. The low end idle will be very lumpy and irregular, so something you would 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 lamenting their decision to add an extreme competition cam profile to their engine.

You should ideally match your torque band to your cars usage so for a typical daily driver stick with a fast road L13 cam

Each engine responds better to less aggressive camshaft durations than others so depending on whether you have the L13A i-DSI L13Z i-VTEC L13B i-VTEC L13Z1 i-VTEC and it's production year your results may vary which highlights the importance of getting a car setup on a rolling road.

The ECU mapping and fuel pump and injectors also will say much on the power gains you'll get.

Altering valve durations can alter the power band and on most engines the exhaust and intake durations do not need to match, although most cams and tuners use matched pairs there are some advantages to extending the intake or exhaust durations.

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Best Engine Mods for your car

    1. Engine Tunes - engine tuning/remapping provides the most advantage in terms of cost savings,  aftermarket ECUs, and piggyback ECUs are all alternatives.
    2. Fast road cams are one of the most significant mechanical changes, but they must be installed by someone who knows what they're doing and they are not always easy to source but you might find a local firm to regrind a stock camshaft.
    3. Intake and Exhaust - Note that on their own these mods will NOT ADD POWER in most cases, but they can help enhance power after other mods by removing the restriction.
    4. Upgrades to turbochargers and superchargers - forced induction is the most efficient approach to increase air supply, allowing you to burn more fuel and make more power. It is one of the most costly upgrades but provides the best gains.
    5. Head work - The goals of porting and flowing the head are to get air flowing into the engine while removing flow restrictions and turbulence.

Typical stage 1 mods often include:
Panel air filters, Intake manifolds, Remaps/piggy back ECU, Fast road camshaft, Sports exhaust header/manifold, drilled & smoothed airbox.

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

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

The L13 power trains are fantastic to work on and we're happy to report there is a growing number of modifications and tuning parts out there.

Mapping allows a tuner to fully realize the full potential of all the upgrades you've done to your L13.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles and you can expect to see around 15% on NA (naturally aspirated) engines, but power output usually vary depending on the upgrades you've carried out and the condition of your engine.

It is the aim to any engine tuning project to shove more air into each cylinder

Air Intake manifolds transmit the air from the air filter and allow it to be pulled into the engine and mixed with fuel.

The bore size, shape and rate of flow of the Air Intake manifolds can make a substantial effect on to fuel mixing and power on the L13.

On popular production engines intake are in dire need of aftermarket tuning parts, although a few makers provide well optimised intake.

Big valve conversions on the L13, doing a bit of L13 port enlargement and head flowing will also lift performance, and importantly will raise potential for increasing the performance increase on other parts.

L13A i-DSI L13Z i-VTEC L13B i-VTEC L13Z1 i-VTEC
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 L13

The more air you can get into an engine, the more fuel it can burn and uprating the induction with a turbocharger upgrade makes major power gains.

When your motor has a turbocharger upgrades are more reliable and turbocharged engines already contain stronger components.

There are reliable limits for every engine, with some being over specified and some only just able to handle stock powerSee where you'll find these limitations and fit more solid crank and pistons to utilize the power.

It's not unheard of mechanics spending a lot of money on turbocharger upgrades on the L13 only to suffer the indignity of watching the engine literally blow up soon after it's finished.

Large capacity turbos commonly suffer low end lag, and little turbos spool up more quickly but don't have the peak end power band gains.

We are pleased that the selection of turbo chargers is always increasing and we now see variable vane turbo chargers, allowing the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbo chargers divert the exhaust gases into two channels and push these at differently profiled vanes in the turbocharger. They also help the scavenging effect of the engine.

You'll commonly see there is a limit in the air flow sensor AFM/MAF on the L13 when a lot more air is being pulled into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting 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 in depth look at twinchargers if you want to read more.


When you boost the performance you will need to look at to the fuel system.

More performance needs more fuel. Most tuners we speak with say to be generous with your flow rate on the injectors.

The rule of thumb is to add 20% capacity when specifying an injector, this takes into account injector deterioration and provides some spare capacity should the engine require 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.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

4 Cylinder turbocharged engines

      • 58 PSI 340cc/min 200hp
      • 58 PSI 511cc/min 300hp

4 Cylinder NA (naturally aspirated) engines

      • 58 PSI 285cc/min 200hp
      • 58 PSI 426cc/min 300hp

4 Cylinder supercharged engines

      • 58 PSI 312cc/min 200hp
      • 58 PSI 468cc/min 300hp

L13 Performance Exhausts

You may need to improve your exhaust if the current exhaust is actually creating a flow problem.

On most factory exhausts you should find that the exhaust flow rate is still good even on modest power gains, but when you start pushing up the power levels you will need to get a better flowing exhaust.

Sports exhausts generally help improve air flow through the engine but avoid an exhaust that is too big or you might just stuff your flow rate and make things worse. So generally speaking, keep to a size of 1.5 to 2.5 inches for best results.

Usual exhaust restrictions can be located the catalyst installed, so adding a higher flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots, Issues & problem areas on the L13

The L13 engines are generally reliable and solid units, as long as you follow the manufacturers service schedules, and use a good quality oil to ensure longevity. Few problems should happen as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Regular oil changes are vital on the L13, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your L13 engine please join us in our car forums where you can discuss L13 tuning options in more detail with our L13 owners. It would also be worth reading our unbiased Honda tuning articles to get insights into each modification and how effective they will be for your car.

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We love to hear what our visitors have got up to and which modifications work best for you on your car. Which helps us keep our guides and tips up to date helping others with their modified car projects. Your feedback and comments are used to keep this page up to date, and help improve the accuracy of these L13 tuning guides which get regular updates and revisions.

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