Modifying and improving: "4A Modifications"

How to modify and upgrade the Toyota 4A

"Comprehensive guide to tuning and performance parts on the Toyota 4A engine!"

Sites like TorqueCars are regularly getting emails requesting info on how to improve the 4A from people wanting to know what are the greatest 4A power upgrades. So let us look into Toyota 4A parts and outline the best modifications on this great engine and point out some problems along the way.

Therefore we look into 4A tuning and report on the optimum modifications for your car. Toyota 4A are awesome to work on and with a few sensible tuning tuning mods like ECU maps, turbo upgrades and camshafts you will improve your driving experience.

When talking about the optimum parts for your 4A engine, we are going to concentrate on the mods that give the best power gain for you money.

Improving air intake on the 4A

You need fuel and air for an engine to work. If there is insufficient fuel then it will run lean, if there is not enough air it runs rich sapping power . We'll pick up on fuelling later in this article but for now we shall look at air supply.

So Pushing fuel and air into your 4A is the primary aim to any engine tuning project.

It is not unusual that there is a restriction in the air flow sensor MAP/MAF/AFM on the 4A when a lot more air is being drawn into the engine.

We note 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor limited bhp at a much lower level.

Air Intake manifolds flow the on the suck phase from the air cleaner and allow it to be drawn into the engine and mixed with fuel.

Shape and flow rate of the Plenum can make a noticeable effect on to fuel mixing and power on the 4A.

Commonly we find the intake headers are improved through performance upgrades, although some OEM provide fairly well optimized intake headers.

Adding a 4A larger valve kit, doing some port work and head flowing will also lift bhp and torque, and as an added benefit will permit increasing the bhp and torque increase on other mods.

4A performance cam tips.

Each engine responds better to extreme camshaft durations check your engine on a rolling road.

The engine timing and injectors and fuel pump also have an effect on the torque gains you'll get.

Altering valve durations 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.

Significant air intake, and exhaust improvements on the 4A can be made from cam upgrades. Changing the cam profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road camshafts tend to push up the power through the rpm band, you might lose a little low down torque but your high end rpm power will improve.

Race camshafts, push up the high end rpm power band but as a result the car will not idle smoothly and low end power nearly always suffers.

A Race cam is not great driving around busy urban areas.

You should ideally optimize your engines power to your preferences so for a car driven daily stick with a shorter duration 4A cam

Stage 1, 2 and 3 mods for the 4A

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 4A parts:

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

Stage 2 4A parts:

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

Stage 3 4A parts:

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

ECU flashing will help to establish the full potential of all the upgrades you've done to your 4A.

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 the end result usually vary depending on the upgrades you've applied and the condition of your engine.

Turbo modifications on the 4A

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 4A.

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

If an engine has forced induction upgrades are relatively easy and most turbo engines already contain better components.

There are tuning limits for every engine, with some being extremely strong and some only able to handle stock power

We recommend you find these restrictions and fit stronger pistons, crank and engine components to cope with the power.

There are many tuners spending a loads of money on turbo charger upgrades on the 4A only to watch the engine block catastrophically fail just after it's used on the roads.

Big capacity turbo units tend to experience a bottom end lag, and smaller turbo units spool up more quickly but don't have the high rpm bhp gains.

In the last 10 years the world of turbos is always moving on and we now see variable vane turbos, allowing the vane angle is altered according to speed to lower lag and increase top end bhp.

Twin scroll turbos divert the exhaust gases into 2 channels and feed these at differently profiled vanes in the turbo charger. They also improve the scavenging effect of the engine.

Beefing up the air intake by adding a supercharger or additional turbo will help you achieve very large power gains, although more difficult to install. We have this article on twincharging if you want to read more.

Tips about fuel supply on the 4A

Don't omit to improve the fuel system when you are increasing the bhp - it makes the car more thirsty. We strongly recommend you to be generous with your flow rate on the injectors.

The accepted safe increase is to add 15% when specifying an injector, this takes into account injector deterioration and provides 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 4A performance exhaust upgrades

You only need to to replace your exhaust system with an upgraded one is if your exhaust is actually creating a restriction.

On most factory exhausts you'll see the 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 equal out the flow of gases through the engine.

But if your exhaust pipe is too big, ie: over two and a half inches diameter, you will lose a lot of your flow rate and end up losing power and torque.

Usual exhaust restrictions are traced to the catalyst installed, so adding a freer flowing race 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 4A

Like most engines an 4A, 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 4A, failure to do this will exacerbate engine wear, on a tuned 4A 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 4A why not pop over to the forums at TorqueCars where you can chat about 4A tuning options and read about others projects who may be planning to do similar modifications on their 4A.

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This entry was posted under Makes and Models. Tags: engine, toyota
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