Mitsubishi 4B11T Tuning

"All you need to know about performance tuning the Mitsubishi 4B11 T engine!"

Comparing a 4B11 with the 4G63 we prefer the power curve, it is less peaky and makes a great base for your tuning project.

The cast iron block was replaced with aluminum for the 4B11T and it runs at a higher compression ratio.

Whilst we see many 4G63's reaching high power figures, and tuners have had many years to play with that block.

However there is more potential in the 4B11T and we are already seeing some  impressive power gains on it.

Herein we review and look at 4B11 T tuning and summarise the premier upgrades. Mitsubishi 4B11 T are awesome to work on and with carefully chosen modified upgrades like remapping, turbo kits and camshafts you will certainly improve your driving fun.

History, Power & Specs of the 4B11T Engine

4B11T

  • 280 PS (276 bhp; 206 kW) at 6500 rpm 422 Nm (311 lbft) at 3500 rpm (Japanese market)
  • 291 PS (287 bhp; 214 kW) at 6500 rpm 407 Nm (300 lbft) at 4400 rpm (US market)
  • 240 PS (237 bhp; 177 kW)  353 Nm (260 lbft) at 3000 rpm (Lancer Ralliart)
  • 295 PS (291 bhp; 217 kW) at 6500 rpm  366 Nm (270 lbft) at 3500 rpm (European market)
  • 409 PS (403 bhp; 301 kW) at 6500 rpm  525 Nm (387 lbft) at 3500 rpm (UK only FQ400)

The 4B11T is found in

  • 2007-2016 Mitsubishi Lancer Evolution
  • 2008-2015 Mitsubishi Lancer Ralliart (detuned smaller turbo)

Tuning the Mitsubishi 4B11 T and best 4B11 T performance parts.

Best 4B11 T tuning parts

The greatest 4B11 T upgrades on an engine are typically the ones that give the biggest return for your cash.

We won't be swayed by popular 4B11 T upgrades, they need to be cost effective.

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

Fast road cams usually raise the bhp through the rev band, you may sacrifice a little bottom end power but your higher rpm power will be higher.

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.

On a car used daily, really you should, ideally aim to match your bhp range to your usage of the car.

I'd never have ever thought or claimed that a 4B11 T Motorsport camshaft is a pleasure to live with when on the daily commute, because the lumpy idle will make the car prone to stall and smooth driving at low rpm becomes impossible. If you are developing a track car this doesn't matter as you are in the high end of your RPM range anyway and that is where you want the power to be.

Some 4B11 T engines respond better to more or less aggressive camshaft durations than others.

The ecu map and injectors and fuel pump also will make differences on the torque gains you'll achieve.

Longer 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.

Typical stage 1 mods often include: Sports exhaust manifold, Remaps/piggy back ECU, drilled & smoothed airbox, Intake headers, Fast road camshaft, Panel air filters.

Typical stage 2 mods often include: fuel pump upgrades, Ported and polished head, Sports catalyst & performance exhaust, induction kit, high flow fuel injectors, Fast road cam.

Typical stage 3 mods often include: Competition cam, Crank and Piston upgrades to alter compression, Twin charging conversions, Engine balancing & blueprinting, Internal engine upgrades (head flowing porting/bigger valves), Upgrading forced induction (turbo).

The 4B11 T engines make great tuning projects and thanks to their popularity there are plenty of mods and tuning parts around.

A remap helps to establish the full potential of all the modifications you've done to your 4B11 T.

(In some cases, as the factory ECU is locked flashing is not an option, so an aftermarket ECU is the route to take, and many of these will outperform factory ECU's but make sure it has knock protection and that you get it setup properly.)

It will usually give you around 30% more power on turbocharged vehicles, but the end result usually vary depending on the modifications you've fitted and the condition of your engine.

Forcing more air and fuel into each cylinder is vital to any tuning project.

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

Design and flow characteristics of the Air Intake manifolds can make a substantial effect on to fuel atomisation and engine efficiency on the 4B11 T.

Many mass produced engine intake headers are needing an upgrade, although a few manufacturers provide decently flowing intake headers.

Larger 4B11 T valves, doing a bit of port work and head flowing will also raise bhp, and importantly will allow you to get a better bhp increase on other parts.

4B11 T Turbo upgrades

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 4B11 T

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

When an engine is fitted with a turbocharger upgrades are going to net you a larger power gain and you'll see that turbocharged engines are built using harder and stronger components.

There are reliable limits for every engine, with some being incredibly solid and some only just able to handle stock powerSee where you'll find these restrictions and install forged components to handle the power.

We see many guys spending a loads on turbocharger upgrades on the 4B11 T only to suffer the humiliation of seeing the engine throw a rod on it's first outing after it's first rolling road session.

Big turbochargers tend to experience no power at low rpm, and small turbochargers spool up much more quickly but do not have the top end torque gains.

In the last 10 years the range of turbo units is always improving and we commonly find variable vane turbo units, allowing the vane angle is altered according to speed to lower lag and increase top end power.

Twin scroll turbo units divert the exhaust gases into a couple of channels and direct these at differently designed vanes in the turbo. They also boost the scavenging effect of the engine.

It is common that there is a restriction in the air flow sensor AFM/MAF on the 4B11 T when a lot 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 sapped performance at a much lower level.

Adding a supercharger or additional turbo will make large bhp gains, although more complex to get working. We have this guide to twinchargers if you want to read more.

Fuelling

You will need to ensure that the engine is not starved of fuel so will need to ramp up the fuelling when you start extending past 20% of a bhp increase.We strongly recommend you to be generous with your flow rate on the injectors.

As a rule of thumb add 20% capacity when specifying an injector, this allows for injector deterioration and allows 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.

All the following flywheel power targets will assume an injector duty cycle of 80% and a base of 58psi of fuel pressure at idle.

4 Cylinder turbocharged engines

  • 58 PSI 340cc/min 200hp
  • 58 PSI 511cc/min 300hp
  • 58 PSI 682cc/min 400hp
  • 58 PSI 1022cc/min 600hp

4B11 T Performance Exhausts

You may need to increase your exhaust if the existing exhaust is creating a restriction in flow.

On most factory exhausts you should find that the exhaust flow rate is fine even on modest power gains, but when you start pushing up the power levels you will 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 2.5 inches bore, you will lose a lot of the exhaust flow rate and end up lacking power and torque.

Typically exhaust restrictions are in the catalyst installed, so adding a higher flowing high performance aftermarket one will improve air flow, and rather than doing an illegal decat, will keep the car road legal.

Weak spots, Issues & problem areas on the 4B11 T

The 4B11 T engines are generally reliable and solid as long as they are regularly serviced and maintained.

Carbon build up in the head, particularly around the valves which will sap power or create flat spots, this is a larger issue on direct injection engines but should be looked out for on all engines. We have tips on removing carbon build up.

Some of our members have had issues with flat spots or glitches after applying mods and upgrades or tuning, this is not usually related to this engines design, so instead see our article on diagnosing flat spots and problems after tuning which should help you get the bottom of this issue.

Regular oil changes are vital on the 4B11 T, especially when tuned and will help extend the life and reliability of the engine.

Noisy warmup can be caused by worn piston rings, which if ignored will lead to further internal engine damage.

If you would like to know more, or just get some friendly advice on Tuning your 4B11 T engine please join us in our friendly forum where you can discuss 4B11 T tuning options in more detail
with our 4B11 T owners. It would also be worth reading our unbiased Mitsubishi tuning articles to get a full grasp of the benefits and drawbacks of each modification.

Please help us improve these tips by sending us your feedback in the comments box below.

We love to hear what our visitors have got up to and which modifications work best for them on each model of car. Comments are used to improve the accuracy of these 4B11 T articles which are continually updated.

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