Modding uprating the Honda J-series engine!

Tuning guide "J-series Modifications"

J-series Modifications Guide

How to modify and upgrade the Honda J-series

"Comprehensive guide to tuning the Honda J-series engine!"

TorqueCars often are getting messages about how to improve the J-series from people inquiring about getting more power from the J-series and wanting to know what are the things tuners recommend when it comes to J-series modifications. So let us look into Honda J-series upgrades and outline the best mods that work on this great engine and point out some problems along the way.

Therefore we look at J-series tuning and provide tips on the best mods that work. Honda J-series are awesome to work on and with the right enhancements like ECU maps, turbo kits and camshafts you will positively maximize your driving enjoyment.

When talking about the greatest parts for your J-series engine, we are going to concentrate on the tuning parts that give the best power gain for you spend.

J-series induction kits

Improving air intake on the J-series

You need air and fuel for an engine to work. If there is little supply of fuel then it will run lean, if there is little flow of air it runs rich losing power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So the fundamental goal to any performance tuning task to push air into each cylinder but this has a knock on effect with the air flow sensor.

It is not unusual that there is a limit in the air flow sensor AFM/MAF on the J-series when a lot more air is being drawn into the engine.

When tuning you may well find you need to get an air sensor or flow meter capable of upto 4 bars to cope with quite large power gains, whereas the OEM air sensor was restricting bhp at a much lower level.

Headers flow the air during the suck phase from the air cleaner and allow it to be drawn into the engine cylinders with fuel for the squish phase.

Design and rate of flow of the Air Intake manifolds can make a big difference to to fuel atomisation on the J-series.

Most air intake manifolds are crying out for an upgrade, although some manufacturers provide reasonably well designed air intake manifolds.

Increasing the J-series valve size, doing a bit of port work and head flowing will also boost power, the fantastic side effect is it will raise potential for raising the power increase on other tuning mods.

J-series performance cam tips.

Some J-series engines respond better to extreme camshaft durations check your engine on a rolling road.

The map and injectors and fuel pump also will say much on the power gains you'll hit.

A longer valve duration 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.

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

NB: Fast road cams usually boost the bhp over the rpm range, you could drop a little low down bhp but the top end will be better.

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

A Motorsport cam is not great in heavy traffic.

You should ideally match your torque band to your preferences so for a car driven daily stick with a shorter duration J-series cam

Stage 1, 2 and 3 mods for the J-series

Before we break the best tuning upgrades down into stages of tune, let's list the most effective tuning upgrades for you.

  1. Suspension Upgrades - always improve your cars handling
  2. Brake Upgrades - Even before adding power improve those brakes
  3. Intake - make sure the intake is not restricted, use filters and intake upgrades to improve this
  4. Exhaust - as with 3 ensure there is not restriction in the exhaust, cats are the usual bottleneck
  5. Tunes - remapping, piggyback ECU's and aftermarket ECU's can all make decent gains
  6. Fuelling - when you've increased power you'll need to match this with more fuel
  7. Turbo upgrades - Improving the intake with a large turbo and better flowing intercooler will be the biggest power gain you'll see (but one of the most complex).

This video guide to tuning cars is a great starting point to work from in your project.

Stage 1 J-series parts:

Intake headers, Drilled & smoothed airbox, Fast road camshaft, Remaps/piggy back ECU, Sports exhaust manifold, Panel air filters.

Tuning tips and articles Engine tuning Transmission tuning Care care Intake & exhaust mods Improve handling Forums

Stage 2 J-series parts:

fuel pump upgrades, Ported and polished head, Fast road cam, Sports catalyst & performance exhaust, high flow fuel injectors, induction kit.

Stage 3 J-series parts:

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

The J-series engines are great to work on and thanks to their popularity there is a growing number of mods and tuning parts out there.

ECU flashing will help release the full potential of all the parts you've done to your J-series.

You will typically expect to see gains of approximately 20-30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your results often differs on the parts you've applied and the condition of your engine.

Turbo modifications on the J-series

To get a turbo working on a NASP engine there is a lot involved, from lowering compression ratio to improved fuel supply and mapping, so we have found a great guide to helpavoid the common pitfalls or end up with an unfinished project because you were not told what you were getting into by doing this on the J-series.

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

If a car is turbocharged, mods are giving better power gains and you will discover turbocharged engines will have more solid components.

There are weak spots for every engine, with some being incredibly solid and some only just able to handle stock power

We recommend you find these limitations and fit more solid crank and pistons to survive the power.

There are many drivers spending a lot of money on turbo charger upgrades on the J-series only to experience the whole thing go up in smoke on it's first outing after it's finished.

Bigger turbos commonly experience no power at low rpm, and little turbos spool up really quickly but won't have the high rpm bhp gains.

Over the last 20 years the market of turbos is always evolving and we commonly find variable vane turbos, where the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbos divert the exhaust flow into two channels and push these at differently angled vanes in the turbo. They also boost the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large bhp gains, although more challenging to install. We have this in depth look at twinchargers if you want to read more.

Tips about fuel supply on the J-series

When you lift the power you will need to ramp up to the fuel delivery.

More power needs more fuel. Experienced mechanics will tell you to over specify your flow rate on the injectors.

The rule of thumb is to add 20% to the flow rate when specifying an injector, this accounts for injector deterioration and affords some spare capacity should the engine need more fuel.

Don't forget that different fuel grades will usually require different settings, a high octane fuel will burn more efficiently than lower octane fuel for example. A car will trim fuel supply to keep within the ideal air fuel mix but at the extreme ends you may need to adjust your injector capacity, or the mapping or you'll get flat spots and potential lean or rich fuel issues..

Recommended J-series performance exhaust upgrades

The only time you should look to boost your exhaust system with an upgraded one is if your current exhaust is creating a restriction in flow.

On most factory exhausts you'll see your flow rate is good even on modest power gains, but on a serious tuning project with a big boost in power you will certainly need to get a better flowing exhaust.

Sports exhausts can help equal out the flow of gases through the engine.

But if your exhaust is too big, ie: it's over two and a half inches diameter, you will lose a great deal of the exhaust flow rate and end up lacking power and torque.

Usual exhaust restrictions come around the catalyst installed, so adding a freer flowing performance alternative will help avoid this restriction.

Decats (NB:catalysts reduce harmful engine emissions) is illegal in most countries and regions.

Faults issues and things to look out for on the J-series

Like most engines an J-series, should have few issues if it gets properly serviced and looked after.

We cannot stress enough the need for oil changes with the correct grade of oil on the J-series, failure to do this will exacerbate engine wear, on a tuned J-series this is more important than ever and close attention should be paid to your maintenance schedule.

If you are interested in learning more or getting impartial tuning advice for your J-series why not pop over to the forums at TorqueCars where you can chat about J-series tuning options and read about others projects who may be planning to do similar modifications on their J-series.

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