Guide to tuning and performance parts on the B20 engine from Honda

"Honda B20 engine Tuning guide"

We examine the options for your B20 tuning and show the best mods that work. Honda B20s provide a fun base for your project and with carefully chosen tuning mods you can noticeably increase your driving experience.

History, Power & Specs of the B20 Engine

Vtec was not fitted to the B20 series engine, the focus was on reliability and performance.

  • B20B-B20B4  1996–1998  126–142–140 hp 
  • B20B-B20B8  1999 - 2001 148–150 hp
  • B20Z2 1999 - 2001 148 - 150 hp
  • B20B JDM 1995–1997  146 hp

NB: B20A/B20B (The B series components were extensively revised from the A series and cannot be interchanged or swapped)

Best B20 upgrades

When talking about the best and most optimal modifications for your B20 engine, we are going to mods that give the best power gain for you spend.

Significant gains can be made from camshaft upgrades. Altering the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the engines power and power output.

Fast road cams normally boost the bhp over the rev range, you might lose a little bottom end torque but the high end rpm power will be higher.

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

On a daily driver must carefully try to match your torque band to your cars usage.

You'll never have thought a Motorsport and race camshaft is a pleasure to live with when in heavy traffic because low end power will be very lumpy. Competition cams are designed for maximum power at the top end of the RPM range, a place that most daily commutes will not permit!

We have seen some tuners fitting a VTEC head to the B20 engine blocks to good effect, effectively transforming the engine performance and response.

B16 engine  head swaps are popular with VTEC being added to the non VTEC as a relatively simple and significant power hike, although a decent cam profile will virtually match this for top end.

Some B20 engines respond better to more aggressive camshaft durations check your engine on a rolling road.

Dropping in a crank from the B17 is also a popular mod and gives a nice base for tuning up further.

The ecu map and injectors and fuel pump also have a large bearing on the torque gains you'll achieve.

A longer valve duration can alter the torque 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. Mapping - 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, Sports exhaust header/manifold, Intake manifolds, Fast road camshaft, Remaps (Hondata ECU) or piggyback ECU .

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

Typical stage 3 mods often include:
 Internal engine upgrades (pistons/head/valves), Competition cam, Twin charging conversions, Engine balancing & blueprinting, .

The B20 engines are fantastic to work on and service and we're finding that there is a lot of upgrades and tuning parts about.

Remaps using a piggy back ECU will help release the full potential of all the tuning parts you've fitted to your B20.

(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 15% more power on the B20 engines, but you mileage will vary depending on the tuning parts you've done and the condition of your engine.

Shoving more air and fuel into your B20 is the main goal to any performance tuning job.

Intake flow the air during the suck phase from the intake filter and allow it to be drawn into the engine and mixed with fuel.

Design and flow characteristics of the Intake can make a substantial change to fuel mixing and power on the B20.

It's not uncommon that plenum chambers are crying out for a performance upgrade, although some OEM provide reasonably good plenum chambers.

Increasing the B20 valve size, getting 3 or 5 angle valve jobs and porting and head flowing will also raise power, this will give you an improved power increase on other parts.

B20 Turbo upgrades

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

NA (naturally aspirated) engines need quite a lot of work and the B20 requires more than most 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 B20

Adding a supercharger or additional turbo will make large performance gains, although harder to setup however the work involved on the B20 it would be easier to do an engine transplant.

Fuelling

You will need to ensure that the engine is not starved of fuel so must look at the fuelling when you start going beyond 20% of a power increase.

We strongly recommend you to over specify your flow rate on the injectors.

The rule of thumb is to add 20% capacity when fitting an injector, which takes into account injector deterioration and provides you some spare capacity should the engine require more fuel.

B20 Exhaust

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

On most factory exhausts you'll see the exhaust flow rate quite well 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 can usually air flow from the engine but do not go too big or you could very well end up with a reduced flow rate. So generally speaking, keep to 1.5 to 2.5 inches for best results.

Usual exhaust restrictions can be traced to the catalyst and filters installed, so adding a better flowing sports alternative is the answer. This keeps the car road legal and will flow much better due to it's higher internal surface area and design, so has the added benefit of keeping your car road legal. The alternative decat should be considered an off road only mod, as removing a catalyst is illegal in most territories and regions for road registered cars..

Weakspots and problem areas on the B20

The B20 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 B20, especially when tuned and will help extend the life and reliability of the engine.

Check the water pump and head gaskets for leaks, overheating can be costly to fix, so is best avoided.

If you would like to know more, or just get some friendly advice on Tuning your Honda engine please join us in our friendly forum where you can discuss B20 tuning options in more detail with our B20 owners. It would also be worth reading our unbiased Honda tuning articles to get a full grasp of the benefits and drawbacks of each modification.

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