Mitsubishi 4A9 Tuning

"All you need to know about tuning and performance parts on the Mitsubishi 4A9 engine!"

The Mitsubishi 4A9 make awesome project engines and with a few sensible modified parts like ECU maps, turbo improvements and camshafts you will noticeably enhance your driving fun.

This pages aim is review and look at 4A9 tuning and report on the premier upgrades.

History, Power & Specs of the 4A9 Engine

4A90

70 kW (95 PS; 94 hp) at 6000 rpm 125 Nm (92 lbft) at 4000 rpm

  • 2004 Mitsubishi Colt
  • 2004–2006 Smart Forfour
  • 2011 Haima 2
  • 2014 BAIC Up
  • 2016 DFM Joyear X3
  • Zotye Z200

4A91

109 hp (81 kW; 111 PS) at 6000 rpm 145 Nm (107 lbft) at 4000 rpm

  • 2004 Mitsubishi Colt
  • 2004–2006 Smart Forfour
  • 2007 Mitsubishi Lancer
  • 2009–2019 Soueast V3
  • 2010 Brilliance FSV
  • 2011 Haima 2
  • 2012 Senova D20
  • 2013–present Soueast V5
  • 2013–present Zotye Z300
  • 2014 Senova D50
  • 2014–present Zotye SR7
  • 2015–present BAIC BJ20
  • 2016–present Ario S300
  • 2016 Brilliance V5
  • 2016 Senova X55
  • 2016 Yema T70 SUV
  • 2017 Soueast DX3
  • Zotye Z200
  • 2017–present Soueast DX7
  • 2017–present Mitsubishi Xpander
  • 2019–present Nissan Livina

4A92

86 kW (117 PS; 115 hp) at 6000 rpm 154 Nm (114 lbft) at 4000 rpm

  • 2010 Mitsubishi ASX (EU)
  • 2011 Mitsubishi Lancer (EU)
  • 2011 Brilliance H530
  • 2012 Brilliance V5
  • 2012 Zotye Z300 (1.5/1.6L)
  • 2013 Mitsubishi Lancer (PH)
  • 2017/2018 DFM Joyear X3

Tuning the Mitsubishi 4A9 and best 4A9 performance parts.

Best 4A9 tuning parts

The top 4A9 parts on an engine are sensibly the ones that give the best value for money.

We won't be swayed by popular 4A9 parts, 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 and exhaust durations will alter depending on the chosen cam profile, so large engines power gains are on offer for cam upgrades.

Fast road cams commonly raise the bhp and torque throughout the rev range, you could drop a little low down torque but the high end rpm power will be lifted.

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

For a typical daily driver you need to match your engines power to your preferences.

You'll never have ever thought or claimed that a 4A9 Motorsport cam is a pleasure to live with when in heavy traffic because low end power will be very lumpy. Competition cams are designed for maximum power at the top end of the RPM range, a place that most daily commutes will not permit!

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

The engine timing and injectors and fuel pump also have a large bearing on the power gains you'll get.

Extending exhaust or intake 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.

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

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

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

Plan your options and then acquire your tuning parts and set yourself a power target to save yourself from expensive mistakes.

ECU mapping will help to establish the full potential of all the upgrades you've done to your 4A9.

(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 and you can expect to see around 15% on NASP engines, but the outcome usually depend much on the upgrades you've fitted and the condition of your engine.

It is the aim to any tuning project to shove more air into the 4A9 engine

Air Intake manifolds take the air during the suck phase from the filter and allow it to be sucked into the engine cylinders with fuel for the squish phase.

The bore size, shape and flow rate of the Headers can make a substantial improvement to fuel atomisation and engine efficiency on the 4A9.

It's not uncommon that plenum chambers are ripe for aftermarket tuning parts, although some car makers provide fairly well optimized plenum chambers.

Fitting big valve kits, carrying out port matching and head flowing will also improve performance, and more importantly will make space for a better performance increase on other parts.

4A9 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 4A9

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 a car has forced induction modifications are simpler to install and you will discover turbo engines are made with strengthened components.

However you'll find engines will have power limits.Discover these restrictions and fit stronger pistons, crank and engine components to handle the power.

It's not unheard of people spending a fortune on turbocharger upgrades on the 4A9 only to suffer the indignity of watching the whole thing go up in smoke just after it's been finished.

Bigger turbos commonly suffer no power at low rpm, and little turbos spool up much more quickly but do not have the peak end bhp gains.

Thankfully the range of turbo units is always developing and we commonly find variable vane turbo units, permitting the vane profile is altered according to speed to lower lag and increase top end bhp and torque.

Twin scroll turbo units divert the exhaust flow into a couple of channels and push these at differently angled vanes in the turbo charger. They also improve the scavenging effect of the engine.

It is common that there is a limit in the air flow sensor AFM/MAF on the 4A9 when a lot more air is being sucked into the engine.

Going up you'll find 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor was restricting bhp at a much lower level.

Adding a supercharger or additional turbo will make large torque gains, although more challenging to get working. We have this in depth look at twinchargers if you want to read more.

Fuelling

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

The rule of thumb is to add 20% to the flow rate when buying an injector, helps cope with injector deterioration and allows a little spare capacity should the engine require 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

4 Cylinder NASP engines

  • 58 PSI 285cc/min 200hp
  • 58 PSI 426cc/min 300hp

4 Cylinder supercharged engines

  • 58 PSI 312cc/min 200hp
  • 58 PSI 468cc/min 300hp

4A9 Performance Exhausts

You should look to replace your exhaust if your exhaust is actually creating a restriction.

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.

Note that with the widest exhaust you can buy this will slow up the exhaust flow 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.

Typically exhaust restrictions can be located the filters installed, so adding a better 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 4A9

The 4A9 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 4A9, especially when tuned and will help extend the life and reliability of the engine.

If you would like to know more, or just get some friendly advice on Tuning your 4A9 engine please join us in our friendly forum where you can discuss 4A9 tuning options in more detail with our 4A9 owners. It would also be worth reading our unbiased Mitsubishi tuning articles to get insights into each modification and how effective they will be for your car.

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 parts work best for them on each model of car. Comments are used to improve the accuracy of these 4A9 articles which are continually updated.

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