Modding uprating the Mitsubishi 4B11T engine!

All you need to know about "4B11T Modifications"

4B11T Modifications Guide

How to modify and upgrade the Mitsubishi 4B11T

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

Our friends at TorqueCars are regularly getting messages about how to improve the 4B11T from people wanting to know what are the premier 4B11T modifications. So let us look into Mitsubishi 4B11T tuning mods and outline the best modifications on this great engine and point out some problems along the way.

The Mitsubishi 4B11T are popular tuning projects and with the right sports upgrades like a remap, turbo improvements and camshafts you will really maximise your driving fun.

In this article we outline options for your 4B11T tuning and outline the best mods that work.

Just because particular modifications are are common on 4B11T it doesn't mean it is good, we shall concentrate on the optimum modifications that will give your 4B11T the best power gain for you spend.

Without us subscribing to the misaprehension of 'if it's shiny and makes more noise it must be good' you seem to get in many tuning magazines and on car forums'.

4B11T induction kits

Improving air intake on the 4B11T

You need air and fuel for an engine to work. If there is too little fuel then it will run lean, if there is insufficient 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 Forcing fuel and air into your 4B11T is the aim to any car tuning project.

It is common that there's a limit in the air flow sensor MAP/MAF/AFM on the 4B11T when loads more air is being sucked into the engine.

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

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

Shape and rate of flow of the Intake can make a noticeable effect on to fuel mixing and power on the 4B11T.

It's not uncommon that headers are ripe for performance upgrades, although a few makers provide well optimised headers.

Big valve conversions on the 4B11T, doing some 3 or 5 angle valve jobs and porting and head flowing will also increase bhp, and significantly will give you a better bhp increase on other upgrades.

4B11T performance cam tips.

Some 4B11T engines respond better to different cam durations so view each engine as unique.

The ECU mapping and injectors and fuel pump also will make differences on the torque gains you'll make.

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.

Significant air intake, and exhaust improvements on the 4B11T can be made from camshaft upgrades. Changing the camshaft profile alters the intake and exhaust durations on the engine and can dramatically change the bhp and power output.

NB: Fast road cams normally increase the bhp and torque throughout the rpm range, you could sacrifice a little low down bhp but your top end will be higher.

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

A Motorsport and race camshaft is not great in heavy traffic.

You should ideally match your engines power to your cars usage so for a typical daily driver stick with a shorter duration 4B11T camshaft

Stage 1, 2 and 3 mods for the 4B11T

Stage 1 4B11T parts:

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

Stage 2 4B11T parts:

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

Stage 3 4B11T parts:

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

Carefully think through your options and then find your upgrades and set yourself a power target to save yourself from expensive mistakes.

Remaps will help release the full potential of all the tuning mods you've done to your 4B11T.

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

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 outcome usually vary depending on the tuning mods you've carried out and the condition of your engine.

Turbo modifications on the 4B11T

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 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 superb power gains.

When the engine is fitted with a turbo upgrades are giving better power gains and you'll see that turbo engines are built using strengthened components.

However every engines will need better parts at higher power limits

It is important to find these limitations and upgrade to better pistons and crank to survive the power.

It's not unheard of tuners spending a lots of money on turbo upgrades on the 4B11T only to suffer the humiliation of seeing the whole thing catastrophically fail on it's first outing after it's used on the roads.

Bigger turbos will usually suffer low end lag, and smaller turbos spool up quickly but won't have the peak rpm power band gains.

Thanks to progress the selection of turbos is always developing and we now see variable vane turbos, permitting the vane profile is altered according to speed to lower lag and increase top end performance.

Twin scroll turbos divert the exhaust gases into 2 channels and flow these at differently designed vanes in the turbo charger. 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 4B11T

When you raise the power you will need to look at to the fuel delivery.

More power needs more fuel. Experienced mechanics will tell you to over specify your injector capacity.

The rule of thumb is to add 15% to the flow rate when buying an injector, this accounts for injector deterioration and affords a little spare capacity should the engine require 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 4B11T performance exhaust upgrades

You only need to to uprate your exhaust system with an upgraded one is if the existing exhaust is actually causing a restriction in flow.

On most factory exhausts you should find that the flow rate is still fine 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 will certainly help air flow from the engine but do not go too large or you may end up will reduce the flow rate. Stick to one and a half to two and half inches as a rule of thumb.

Typically exhaust restrictions can be traced to the catalyst and filters installed, so adding a faster flowing race 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 4B11T

Like most engines an 4B11T, 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 4B11T, failure to do this will exacerbate engine wear, on a tuned 4B11T 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 4B11T why not pop over to the forums at TorqueCars where you can chat about 4B11T tuning options and read about others projects who may be planning to do similar modifications on their 4B11T.

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