Modding upgrading and tuning the Toyota 5A engine!

Tuning guide "5A Modifications"

How to modify and upgrade the Toyota 5A

"Comprehensive guide to tuning the Toyota 5A engine!"

Popular tuning sites like TorqueCars are regularly seeing threads requesting information on how to improve the 5A from people inquiring about getting more power from the 5A and wanting to know what are the premier 5A power upgrades. So let us look into Toyota 5A modifications and outline the best modifications on this great engine and point out some problems along the way.

The Toyota 5A offer good returns when tuned and with the optimum sports mods like remapping, turbo upgrades and camshafts you will certainly maximise your driving opportunities.

We shall provide a guide to 5A tuning and show the ultimate upgrades.

When talking about the optimum parts for your 5A engine, we are going to concentrate on the modifications that give the biggest return for your cash.

5A induction kits

Improving air intake on the 5A

You need fuel and air for an engine to work. If there is insufficient fuel then it will run lean, if there is a lack of air it runs rich losing power and potentially damaging the engine. 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 engine upgrade project to pull air into each cylinder but this has a knock on effect with the air flow sensor.

It is common that there is a limit in the air flow sensor AFM/MAF on the 5A when a lot more air is being fed into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting power at a much lower level.

Intake take the during the engines suck phase from the filter and allow it to be fed into the engine cylinders with fuel for the squish phase.

Structure and flow rate of the Intake headers can make a large difference to to fuel mixing and power on the 5A.

It's not uncommon that intake are in dire need of motorsport parts, although a few OEM provide fairly well optimized intake.

Adding a 5A larger valve kit, carrying out 3 or 5 angle valve jobs and porting and head flowing will also lift bhp, & more importantly will make space for raising the bhp increase on other upgrades.

5A performance cam tips.

Each engine responds better to mild camshaft durations so set your engine up on a rolling road.

The ECU mapping and fuel pump and injectors also have an effect on the bhp gains you'll make.

A longer valve duration can alter the bhp 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 and exhaust durations will alter depending on the chosen camshaft profile, so large engines power gains are on offer for camshaft upgrades.

NB: Fast road cams tend to raise the power throughout the rev band, you might lose a little low end bhp but the higher rpm power will be higher.

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

A Competition camshaft is not great in heavy traffic.

You should ideally optimize your torque band to your usage of the car so for a car driven daily stick with a mild fast road 5A camshaft

Stage 1, 2 and 3 mods for the 5A

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 5A parts:

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

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

Stage 2 5A parts:

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

Stage 3 5A parts:

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

The 5A units are great to work on and thankfully there are increasing numbers of modifications and performance parts about.

ECU mapping allows a tuner to release the full potential of all the tuning parts you've done to your 5A.

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 mileage often depend much on the tuning parts you've applied and the condition of your engine.

Turbo modifications on the 5A

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 5A.

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 your motor has a turbocharger upgrades are more reliable and most turbo engines are made with stronger components.

However you will find an engines have weakspots

Research these limits and fit stronger pistons, crank and engine components to utilize the power.

There are many people spending a loads on turbocharger upgrades on the 5A only to suffer the humiliation of seeing the car go up in smoke on it's first outing after it's been finished.

Big upgraded turbo units tend to experience no power at low rpm, and little turbo units spool up much more quickly but don't have the peak rpm torque gains.

Over the last 20 years the selection of turbochargers is always moving on and we are seeing variable vane turbochargers, permitting the vane profile is altered according to speed to lower lag and increase top end torque.

Twin scroll turbochargers divert the exhaust gases into a couple of channels and direct these at differently profiled vanes in the turbocharger. 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 complex to configure. We have this article covering twinchargers if you want to read more.

Tips about fuel supply on the 5A

You will need to ensure that the engine is not starved of fuel so will need to ramp up the fuelling when you start exceeding 20% of a bhp and torque hike. We would recommend you to over specify your injectors flow rate.

The rule of thumb is to add 15% when fitting an injector, which takes into account injector deterioration and allows a little 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 5A performance exhaust upgrades

Only look to upgrade your exhaust system with an upgraded one is if your current exhaust is actually causing a restriction.

On most factory exhausts you'll find the exhaust flow rate is ok 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 increase the flow of gases through the engine.

But if your exhaust pipe is too large, ie: it's over two and a half inches diameter, you will lose a lot of the exhaust flow rate and end up sapping power and torque.

Typically exhaust restrictions are traced to the emissions filters installed, so adding a freer flowing sports alternative will help avoid this restriction.

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

Faults issues and things to look out for on the 5A

Like most engines an 5A, 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 5A, failure to do this will exacerbate engine wear, on a tuned 5A 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 5A why not pop over to the forums at TorqueCars where you can chat about 5A tuning options and read about others projects who may be planning to do similar modifications on their 5A.

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