Tuning the Mitsubishi 6A12

"Comprehensive guide to tuning and performance parts on the Mitsubishi 6A12 engine!"

The Mitsubishi 6A12 have loads of potential and with carefully chosen performance mods like ECU maps, turbo kits and camshafts you will substantially maximize your driving enjoyment.

The 6A12 is a V6 and was incredibly smooth running, and dare we say it, very light (for a V6) and put down quite a bit of power

No doubt you are here to see what improvements can be made and thankfully there are many turning your engine into the powerplant it was indended to be.

We shall review 6A12 tuning and outline the ultimate modifications.

When talking about the best greatest for your 6A12 engine, we are going to focus on the mods that give the best value for money.

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 power band gains are on offer for cam upgrades.

NB: Fast road camshafts normally increase the performance through the rev range, you might lose a little bottom end bhp but high end rpm power will be higher.

Motorsport camshafts, increase the high end 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 you need to optimize your power band to your preferences.

I would be surprised if you find a 6A12 Competition cam is a pleasure to live with when driving in heavy traffic.

Some 6A12 engines respond better to different camshaft durations than others.

The map and fuelling also will make differences 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.

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

Stage 2 mods: induction kit, fuel pump upgrades, Fast road cam, Sports catalyst & performance exhaust, high flow fuel injectorsPorted and polished head.

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

Review your options and then source your parts and set yourself a power target to avoid costly mistakes.

remap helps to establish the full potential of all the parts you've fitted to your 6A12.

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

Shoving more air into the 6A12 engine is the whole point to any engine upgrade job.

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

The size of bore and shape and flow rate of the Intake manifold can make a large difference to to fuel atomisation and engine efficiency on the 6A12.

It's not uncommon that plenum chambers are crying out for a performance upgrade, although some car makers provide reasonably well designed plenum chambers.

Big valve conversions on the 6A12, carrying out port work and head flowing will also improve bhp and torque, and as an added benefit will afford you raising the bhp and torque increase on other modifications.

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 6A12

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

If the engine is fitted with a turbo mods are simpler to install and you will discover turbo engines use more solid components.

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

We recommend you find these limits and fit higher quality components to survive the power.

There are many mechanics spending a loads of money on turbocharger upgrades on the 6A12 only to see the car go up in smoke just after it's finished.

Big upgraded turbo units will usually suffer no power at low rpm, and low capacity turbo units spool up more quickly but won't have the high rpm torque gains.

In the last 10 years the range of turbo units is always moving on and we are seeing variable vane turbo units, allowing the vane profile is altered according to speed to lower lag and increase top end performance.

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

It is not unusual that there's a limit in the air flow sensor AFM/MAF on the 6A12 when a lot more air is being sucked into the engine.

You'll see that 4 bar air sensors coping with quite large power gains, whereas the OEM air sensor sapped bhp and torque at a much lower level.

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

Fuelling upgrades and mods

Don't overlook the need to improve the fuel system when you are increasing the power - it makes the car more thirsty. It is important to over specify your injectors flow rate.

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

Exhaust upgrades and mods

You only need to to improve your exhaust if your exhaust is actually creating a restriction.

On most factory exhausts you should find that the flow rate is still ok 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 the exhaust pipe is too large, ie: it's over 2.5 inches bore, you will lose a lot of the flow rate and end up lacking power and torque.

Typically exhaust restrictions can be traced to the catalyst and filters installed, so adding a higher flowing race alternative will help avoid this restriction.

Weak spots, Issues & common problem areas on the 6A12

The 6A12 engines, if regularly serviced and maintained, are generally very reliable and have few issues.

Regular oil changes are vital on the 6A12, particularly when the engine has been modified and is putting down more power than the manufacturer intended.

There are a few issues with ignition coils, and o2 sensors can get problems but these are easily swapped out and we find that TPS is a recurring issue for many owners.

Oil distribution can be an issue at high RPMS, so choosing the right oil grade is vital, and keep the pump serviced.

History of the Engine

  • MIVEC 197 hp at 7500 rpm
  • DOHC 143–148 hp at 6000–6750
  • DOHC & sports ECU 170–177 hp at 7000 rpm
  • DOHC Twin Turbo 237 hp at 6000 rpm

Engine swaps from the DOHC versions to the Mivec and Twin turbo are quite popular, as it uses the same engine block.

  • 1992-1996 Mitsubishi Galant/Eterna/Emeraude
  • 1992-1994 Mitsubishi Diamante
  • 1994-2000 Mitsubishi FTO
  • 1999-2010 Proton Perdana

There was also a 6A13 engine fitted to the Galant, a 2.4 SOHC version and a Twin Turbo DOHC version as found in the VR4

For more information on Tuning your 6A12 engine please join us in our friendly forum where you can discuss tuning options in more detail with our 6A12 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 improving this article, so please send us your feedback in the comments box below and pass on any tips, points or facts we have wrong or have not covered.

We really like hearing from our readers, and hearing about which tuning parts were the most effective for them, it helps us improve our recommendations and articles to reflect current trends in modifications and ensures that our 6A12 guides and tips are kept up to date.

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