Tuning the Mitsubishi 4B11T

"Comprehensive guide to tuning the Mitsubishi 4B11T engine!"

We often are seeing threads inquiring about getting more power from the 4B11T and wanting to know what are the best tips for 4B11T modifications. So let us look into Mitsubishi 4B11T modifications and outline the best upgrades on this great engine and point out some frequent tuning mistakes along the way.

The Mitsubishi 4B11T offer good returns when tuned and with the best uprated upgrades like remapping, turbo upgrades and camshafts you will definitely improve your driving opportunities.

This pages aim is review 4B11T tuning and outline the premier modifications.

Just because particular upgrades are are common on 4B11T it doesn't mean its worth having, instead we'll best upgrades that will give your 4B11T the biggest power gain return for your cash.

Altering your 4B11T cam will make a dramatic difference to the engine torque. Choosing a higher performance cam profile raises the torque accordingly.

NB: Fast road camshafts usually push up the performance throughout the rev band, you may sacrifice a little low down bhp but your top end will be higher.

Motorsport and race camshafts, push up the top end band but as a result the car will not idle smoothly and low end power nearly always suffers.

On a car driven daily you need to match your power band to your cars usage.

You'll never find a 4B11T Motorsport and race cam is a pleasure to live with when driving around busy urban areas.

Each engine responds better to less aggressive camshaft durations so view each engine as unique.

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

Longer 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.

4B11T Tuning Stages

Stage 1 4B11T modifications: Intake headers, Fast road camshaft, Panel air filters, Drilled & smoothed airbox, Sports exhaust manifold, Remaps/piggy back ECU.

Stage 2 4B11T modifications: high flow fuel injectors, Sports catalyst & performance exhaust, Fast road cam, Ported and polished head, fuel pump upgrades, induction kit.

Stage 3 4B11T modifications: Internal engine upgrades (head flowing porting/bigger valves), Adding or Upgrading forced induction (turbo/supercharger), Twin charging conversions, Competition cam, Engine balancing & blueprinting, Crank and Piston upgrades to alter compression.

Carefully think through your options and then acquire your modifications and set yourself a power target to void expensive mistakes.

ECU mapping will help unlock the full potential of all the parts you've done to your 4B11T.

It will usually give around 30% more power on turbocharged vehicles and you can expect to see around 15% on NASP engines, but your mileage often differs on the parts you've carried out and the condition of your engine.

Pulling more air into each cylinder is the aim to any car tuning project.

Air Intake manifolds flow the air during the suck phase from the air cleaner and allow it to be drawn into the engine cylinders.

The size of bore and shape and flow characteristics of the Plenum can make a large effect on to fuel mixing and power on the 4B11T.

Commonly we find the intake manifold are begging for an upgrade, although a few manufacturers provide fairly well optimized intake manifold.

Big valve conversions on the 4B11T, doing some 4B11T port enlargement and head flowing will also raise torque, and significantly will allow you to get an improved torque increase on other upgrades.

Turbo upgrades for the 4B11T

NASP 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 4B11T

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

When a car is fitted with a turbocharger modifications are going to net you a larger power gain and we find turbo engines will have uprated components.

There are common areas of failure for every engine, with some being incredibly solid and some only able to handle stock power

See where you'll find these limitations and install stronger pistons, crank and engine components to survive the power.

We see many mechanics spending a loads on turbo upgrades on the 4B11T only to experience the engine block explode soon after it's first rolling road session.

Bigger turbo units commonly suffer no power at low rpm, and low capacity turbo units spool up more quickly but won't have the top end torque gains.

In recent times the choice of turbos is always evolving and we now see 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 gases into 2 channels and direct these at differently designed vanes in the turbocharger. They also boost the scavenging effect of the engine.

You'll commonly see there is a limit in the air flow sensor AFM/MAP on the 4B11T when loads more air is being sucked 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.

Adding a supercharger or additional turbo will make large bhp gains, although harder to get working. We have this article on twincharging if you want to read more.

Uprating 4B11T fuel injectors

When you boost the performance you will need to pay attention to to the fuel system.

More performance needs more fuel. We strongly recommend you to be generous with your injector capacity.

As a rule of thumb add another 20% when fitting an injector, this accounts for injector deterioration and affords a little spare capacity should the engine need 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.

Best 4B11T performance exhausts

Only look to boost your exhaust if your current exhaust is actually creating a flow problem.

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

Don't go with the largest exhaust you can find you'll slow the exhaust rate - the best for power gains are usually between 1.5 to 2.5 inches. It is the shape and material more than the bore size.

Common exhaust restrictions come around the emissions filters installed, so adding a faster flowing sports alternative will help avoid this restriction.

Problems and issues to look out for on the 4B11T

The 4B11T engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the 4B11T, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

For more information on Tuning your 4B11T engine please join us in our friendly forum where you can discuss tuning options in more detail with our 4B11T owners. It would also be worth reading our unbiased tuning articles to get a full grasp of the benefits and drawbacks of each modification.

We need your help to complete and improve this page, so do give us your feedback in the comments box below.

We really like hearing from our readers, and hearing about which tuning mods were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our 4B11T guides and tips are kept up to date.

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