Mitsubishi 380 DB 6G75 SOHC 24v

Dummies Guide to Vehicle Modifications

The Mitsubishi 380 was the new large sized vehicle released by Mitsubishi to replace the Magna. With the larger 3.8 litre engine, peak horsepower was increased to 180kw compared to the previous 3.5 litre 163kw engine. Torque was increased additionally, with the larger capacity engine. Other improvements were found in a stiffer chassis, conversion to the new fly by wire throttle body control with more combined integrated components.

The engine boasts an increased compression ratio up to 10.0 : 1, but did not receive the variable timing Mivec system as found in the same 3.8 engines in the USA Eclipse / Galant vehicles. Camshafts utlised factory “Ralliart Magna” specs, which were the 10% increased lift over the 6G75 Magna models.

The exhaust systems are considerably choked to meet more stringent European Emissions with a much greater self aware system to pick up on changes to the vehicles emissions. Worst case scenario’s with improper modifications result in limp home modes and locked throttles.

The transmission range was improved with the new 5 speed options including the triptronic. Manuel 5 speed models were also still popular, although gearing ratio were reduced on the manuals to improve throttle response with a corresponding loss of fuel economy. The vehicles brakes were upgraded to the same package as that found on the AWD / Ralliart Magna vehicles.

Problems still exist though, with the factory brake rotors still exhibiting the same warp age tendencies of the earlier magna series. With there tighter emission control systems, forced induction packages are more difficult to work properly, in fact many modifications resulted in CEL (Check Engine Light) Situations.

This section is to be used as a guide in your modification – we will be breaking this into sections to provide a well balanced vehicle. Additionally the modification package will be setup so that as you increase the power of the vehicle, your alternative items like brakes etc are matched to your new power level. This guide has also been done in an order which provides successive gains from the modifications power wise.

Jumping say to number 20 first, may result in a LOSS of power until you have done other items to match its effect.

RPW does not take any responsibility for people performing these modifications on there car without professional involvement. Check with your local government regulations before modifying your car as these items may not be legal in your country.

Group 1 Modifications

The group 1 modifications are designed for the every day driver, wanting improvements across the board without sacrificing road comfort, fuel economy or drive ability. These are also the baseline modifications for the more extensive Group 2 modifications.

1. Quick Shifters

The Mitsubishi gear shifter system is one of the better ones on the market. But that does not mean that people do not want to improve them. This is one of those modifications that can be done at any time. Our modified units suit most people who want something to reduce the long throw and give a more precise feel to where the gears are located. For those performing any level of competition work, or just want something a little more extreme, the Rally Spec Unit reduces overall movement by as much as 65% over stock.

2. Auto Transmission Cooler

We cannot preach this enough on Mitsubishi vehicles. If you have an auto, any model, this should be one of the very first things done to the vehicle. 99% of Mitsubishi transmission failures are as a direct result of the oil being overheated by the lack of factory cooling on the transmission oil. Regular changes every 20,000km should be done regardless on these vehicles. Fitment of an after market transmission cooler, of virtually any design, will improve transmission life and responsiveness by over 100%. The vehicle will shift more consistently, be more reliable and cost a lot less to repair in the future.

This is a very easy thing to fit and as you modify the vehicle more, becomes extremely necessary. They are usually mounted in front of the radiator, although RPW has been using the B&M fan cooled units a lot more which have there own thermostatically controlled fan to further improve there reliability.

3. Air Filters & Cold Air Induction Kits

The factory air box system on these vehicles, is quite restrictive. The 380 utilises the new Hot Wire MAF Sensor, which has minor advantages over the previous MAF units on the Magna’s. There are several ways to free them up – we recommend several options

  1. Fitment of a K&N Factory Replacement Air Filter for those wanting the Stock look, with improved air flow and throttle response.
  2. This can be further improved with the opening up of the factory air intake system. Fitment of a replacement air intake snorkel with a larger 90mm opening has shown significant increases in air flow into the factory air box.
  3. Further options is to remove the lower section of the air box which is a separate part of the air box mounted onto the chassis and clips into the lower portion of the air box. RPW has found that this reservoir, which is factory sealed, if cut on the end enables air to be sucked into the air box. The air is sourced from the inner passenger side guard and not only provides further cold air, but additionally, provides around a 25% increase in air flow into the air box. RPW has successfully done this on many vehicles now with no side effects and fully protected from any water being ingested into the engine.
  4. Fitment of a Full Cold Air Induction Kit. Significant gains are found with larger intake tubing of a 3″ diameter, and fitment of a higher flowing K&N Pod filter.The Cold air kit relocates to the front bumper, pulling cold air and significant improvements in power and torque. Care needs to be taken though, as incorrect set-up of this system will result in a check engine light with possible limp home mode enabled. RPW imports the K&N kits into Australia for those wanting this more show quality look. But in all honesty, stock air box with the modified air intake on both ends is superior to an after market cold air kit.

This should produce an approximate gain of around 5-8kw with improved throttle response and torque.

4. Cat Back Exhaust Systems

The Mitsubishi 380 has provided a very quite and effective system with there 2 1/2″ mandrel bent factory system and large muffler design. The cat converter on these are a good flowing unit as well, although with the new Euro spec Emissions, this vehicle utilises the new triple cat converter set-up, with a cat converter off each exhaust manifold, and a third cat converter located in the middle of the vehicle.

At this point you must reach your first major decision on where you wish to go with the vehicle – in summary we recommend the following options

  1. Naturally Aspirated – Stock Computer – You are only after mild improvements to make the car sportier, but don’t intend to do any real serious mods. This being the case stick with replacement of the stock exhaust with a rear muffler upgrade only.
  2. Naturally Aspirated – Piggy Back ECU – you are after mild to medium improvements to make the car sportier, with slightly more than average vehicle modifications. This being the case, we recommend a replacement 2 1/2″ diameter replacement exhaust with a new resonator and choice of canon or oval shaped muffle design. Mandrel bent design is mandatory.
  3. An alternative package which is becoming very popular, is the fitment of a twin system on the vehicle. This can be done several ways, but we recommend a package of 3″ and 2 1/4″ systems. Running a 3″ system after the two primary cat converters, up to the petrol tank. From there splitting of the system to twin 2 1/4″” system running into twin 2″ Lukey Ultra Flow mufflers. Fitment of a single 3″ chambered resonator before the splitting of the system.
  4. With the 3″ system the third (Rear) cat converter should also be upgraded to a high flowing 3″ unit, with Oxygen Sensor Bungs fitted for future extractor upgrade

These can produce small gains with the basic systems of around 5 – 10kw at the wheels, with increased rev ability and torque. Set-up of a 3″ system, either twin or single, has been shown to provide gains as high as 10 – 15kw at the wheels.

5. Suspension Upgrade – Level 1

Suspension Package? Level 1? What is this. Basically at this point you are still have a midly modified vehicle and want to just improve the looks slightly and handling. We recommend in this situation the following

  1. Replacement of stock springs with some lowering units –  30mm or 50mm lowered units depending upon how low you want to go.
  2. Fitment of a rear sway bar. Reduces body roll without reducing drive ability.
  3. Fitment of a strut brace. Reduces the tendency of the vehicle to float on the road and makes it less sensitive to changes in road camber, resulting in less need to constantly adjust the steering wheel to keep the car driving straight. This is highly recommended as it dramatically reduce the tendency of the vehicle to wander on the road.

This package will proved a well balanced vehicle, capable of handling corners at higher speeds, will feel safer at higher speeds especially above 100km/hr. The steering will feel more precise and you will have overall more confidence in pushing the vehicle harder.

Group 2 Modifications

Okay the basics are done and you want to go further? Then keep reading on.

1. Extractor Upgrade

RPW is to date the only manufacturer for the 380 vehicles. RPW Designed header systems, are tuned length meaning that from the header flange to the point at which the two separate header lines merge together, pipe length is identical to produce the same signal strength and air flow equally for both cylinder heads.

  1. RPW 3-1 Race Design Long Tube Headers – bolt on system.  These do not  any require welding and adapting to be fitted to the vehicle and will bolt up directly to the factory exhaust system just before the third cat converter. These are a long tube 1 5/8″ diameter and will produce strong torque gains at low rpm, strong mid range without restricting the top end performance. This design replaces the factory short manifold followed by the primary cat converter with a long tube header. The system will enable the removal of the two primary cat converters, significantly increasing air flow through the exhaust system.
  2. This design has significant improvements over the factory system, and can be set-up to avoid a CEL – check engine light. This requires fitting Oxygen Sensor Extenders into the secondary locations to provided a limited feedback system to the factory ECU. This has a 95% chance of success.
  3. Please note – this vehicle requires very specific extractor design to avoid creating a CEL light, that will not cause a Limp Home Mode Situation. Fitment of Mitsubishi Magna systems will not fit the 380 vehicle due to a chassis change.

This package has been independently tested to adds around 10 – 15kw at the flywheel with increased torque and improved upper acceleration and rpm range.

2. Throttle Body Thermo Block Kit

The stock throttle body, being a fly by wire unit, is water heated. Fitment of a RPW thermo block gasket will reduce heat soak into the inlet manifold. This is recommended to be fitted with the matching inlet manifold thermo block as a package. This will provide reductions of approx 40% heat soak on the inlet manifold compared to stock setup.

The thermoblock kit reduces heat soak and this allows the engine to maintain maximum ignition timing with max throttle response.

3. Brake Upgrades – to suit all future modifications

Before doing any further power or suspension modifications, brakes now need to be seriously looked at. The stock brakes on the front of the 380 are the larger 295mm Twin Piston Calliper font brakes, 284 vented rear brakes. All model 380’s suffer from warpage of the brake rotors and severe brake fade after repeated braking applications. .

  1. For those wanting something marginally better, and are not planning on doing any major horsepower mods, then minor upgrading of front brakes only. Retaining stock callipers, fitment of some Bendix brake pads and RDA slotted Rotors is very beneficial. Braking by around 10% with better feel and dramatically less brake fade. Brake warp age is eliminated.
  2. For those wanting something for semi track use / repeated high speed braking, we recommend again the RDA Rotors slotted on front and rear, but upgrading the front to EBC Green Stuff brake pads on the front, and EBC Black Stuff on the rear.
  3. For those wanting to go to extreme levels, upgrading to Mitsubishi Brembo four piston 330mm calliper setups front, twin piston 300mm callipers rear are optional as well, but require a minimum of a 16″ rim to clear the larger rotor sizes. These are a direct bolt on with great improvements, will work with all ABS system, but requires custom offset rims to clear the larger offset on the Brembo Callipers.

4. Drive Line Upgrades

There are three main drive line upgrades which can be done, which go a long way towards improving the reliability of the engine as well as drive ability.

  1. Clutch Kit – At some point your clutch will need upgrading there is a range of clutches available but for the majority a Heavy Duty Organic for more moderate drivers, and Heavy Duty Semi Ceramic for more spirited drivers.
  2. Lightweight Billet Flywheel – this has two benefits being increased strength over stock units and also make the semi ceramic clutch units more drive-able by not allowing them to shudder as much. Second benefit is that they are lighter and enable the engine to rev easier, faster with less reciprocating weight. No loss of torque but more willingness to rev quicker and harder.
  3. Manuel and Auto models are known for there weak differentials. Upgrading to a Quaife Limited Slip Differential has many benefits including increased gearbox strength, increased traction, reduction of wheel tramp, better road feel and handling. For anyone considering the following group three modifications, this is something highly recommended. These are not a direct fitment and will require modifications to the gearbox to be made.
  4. For Manuel models, a fifth gear upgrade is available to reduce the rpm’s by 300 – 500rpm compared to factory. The engine is a very torque engine and there is no reason to have it revving at 3000 rpm at 100km/hr like factory. This does not require any modifications to the box to be fitted and is a brand new machined gear set.

5. Computer Modifications

There is now the choice of either a

  • Remapping the Factory ECU.
  • Piggy Back ECU Replacement
  • Haltech Full After market ECU

Remapping the factory ECU has the advantage of being able to delete common Check engine Codes (Especially emission related codes), and reprogram the drive by wire throttle body and other features. Increased throttle response, torque are all improved. Side effects are that the ECU cannot be retuned in real time and can be a little hit / miss on the tuning side of things.

Piggy back tuning is a quick and easy method, providing improved fuel and ignition mapping at medium to high throttle loads. Side effects are no change in throttle response or inability to counter any check engine codes.

Final option is to fit a full after market ECU like the Haltech Elite 1500 / 2500 units. This has major advantages of being able to reprogram fuel, ignition and drive by wire throttle control. This removes factory controls on torque limiting features, and massively improves throttle response, power and torque. We highly recommend this option as the preferred tuning solution for those considering doing serious modifications to the vehicle.

Large fuel economy gains are found with any of the the retuning solutions simply because the factory system run extremely rich under power. Gains of 1 – 2 L / 100km can be achieved. Especially when used in conjunction with the differential drive gear upgrade.

Retuning usually provide around a 10 – 15kw gain at the flywheel, with improved drive ability and torque. .

6. Throttle Body Upgrades

The factory throttle body on the 380 is a large 65mm Bosch unit. RPW can provide a larger 70 upgraded unit which will require minor machining work to be performed on the intake manifold.

Larger throttle bodies allow greater air to be sucked into the engine and improves throttle response. This will require retuning of the ECU, whether by Remapping the factory ECU or full aftermarket. This cannot be done with a piggy back system as the factory ECU will go out of calibration on airflow maps in relation to air flow, throttle position and torque values.

7. Camshaft Upgrades

RPW manufactures our own billet camshafts for these vehicles. As stated previously, these run an improved profile over the magna series. Fitment of RPW Stage 1 camshafts, in conjunction with piggy back retuning has very large gains and still works within the factory tolerances of ecu and throttle body.

Going larger than the stage 1 profile is not recommended with any system including piggy back ecu. This woudl require a full aftermarket ecu system.

Average pricing is around $1500.00 fitted for a camshaft plus tuning. Gains are anywhere from 10 – 15kw at the wheels with much improved acceleration and throttle response.