4G13 and 4G15 Modification From Mild to Extreme

This post is created for those who wish to modify their 4G13 and 4G15 from mild to extreme machine. From what I understand, a lot of car ent...

This post is created for those who wish to modify their 4G13 and 4G15 from mild to extreme machine. From what I understand, a lot of car enthusiast wish not to go through all the hassle of transplant an engine and they prefer to play on their factory fitted engine. Some will say that you won't gain any knowledge by just putting in a powerful engine without going through the "step by step" modification experience.

Ok, let's start with the 4G13 engine. It is 1.3 liters engine which is known as economic fuel consumtion engine. 4G15 is 1.5 liters model is the base range model and produced a little more HP compare to 4G13. The 1.5 engine is very much your economy engine with only 90hp on engine. It can be modified easily and with surprising results. If going down to NA (naturally aspirated) path, with some modifications you can easily up the HP approximate 120hp on engine. If going to FI (forced induction) path, the low boost turbo systems will easily produce more HP compare to NA path.

For those older 4G13/4G15 from the Saga, Wira and Satria model, it is a standard 12 valves carburator engine. Normally people will upgrade their engine either to a EFI (electronic fuel injection) or to a performance carburetor, to name one WEBER). However, not all mods are for power though, there are many area's of braking and suspension that any stock car can always be improved with. Along with other drive line upgrades, you can have a smooth reliable car, with improved handling, and provide that little bit of sporty power to keep most people satisfied.

So I would like to compile a list of modification that can be done for 4G13 and 4G15. This section is to be used as a guide in your modification - I will be breaking this into sections to provide a well balanced vehicle.

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Mild Modification

The mild modifications are designed for the every day driver, wanting improvements across the board without sacrificing road comfort, fuel economy or driveability.

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. 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. Air Filters and Cold Air Intake Kits

The factory air box system on these vehicles, is quite restrictive.

1. Fitment of an aftermarket replacement air filter. You can get it from K&N which this will improved air flow and throttle response

2. Fitment of a Cold Air Intake Kit.

The Cold air kit relocates to the front bumper, pulling cold air especially where utilized with a aftermarket front bumper. Any aftermarket open pod filter is fine. The plastic pipe kit we honestly recommend, other than being the cheapest, is one of the best bang for dollar modifications you can do.

3. Exhaust System Upgrade

Since you have done a good job for the intake system, now is the time to do something about the exhaust system.Upgrading the exhaust system is one of the most beneficial modification and gain the most HP compare to others. In short, it worth the money to change the exhaust system. For stock 4G13 and 4G15 exhaust system, the size of the exhaust is about 1.5 inches to 1.6 inches. However, before you start to change the exhaust system, you must make a decision on until which level you plan to mod your car. Mild, medium or extreme modification has totally different exhaust size modification. Why I advised you to make the decision before moding the car because  you can save up some money for this modification. To be honest, I wasted a lot of money for my satria's exhaust system. This is because I changed the exhaust for 1.3L engine then change again for MIVEC engine and then change again for my current 4G93T  now. So you can imagine how much I had wasted for only the exhaust system. For moding the exhaust system, I suggested few guidelines as following:-

1. Naturally Aspirated - Carb / Stock ECU- 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 either a rear muffler upgrade only 1.7" flow oval shaped unit, or complete it with a 1.7" press bent exhaust system with new muffler and resonator. Cat converter should remain stock. Any larger on the system would not provide without sufficient more expensive mods, any real gains.

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 2" diameter replacement exhaust with a new resonator and muffler. No need to go mandrel bent unless you have money to throw away. This setup will handle the majority of modifications we have listed short of turbo systems

3. Naturally Aspirated -Standalone ECU - okay you are an extreme modder. Twin throttle bodies, camshafts the list goes on. We recommend in this case either a 2.2" mandrel bent system

4. Turbo Charged - 2.5" is more than enough for a 4G13 or 4G15 stock bolt on turbo.

4. Suspension Upgrade - Level 1

Basically at this point you are still have a midly modified vehicle and want to just improve the looks slightly and handling. I recommend in this situation the following

1. Replacement of stock springs with some lowering units - either 30mm or 50mm lowered units depending upon how low you want to go.

2. Fitment of a sway bar. Reduces body roll without reducing drive ability.

3. Fitment of a strut brace. Reduces the tendancy 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 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.

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Medium Modification
The medium modifications are designed for those who want more HP from their car.

1. Extractor Upgrade

Original extractors are always not equal. But in reality, any half decent designed unit will be an improvement over the stock manifold on the vehicle. There are two types of designs. One is the 4-1 design which is design to produce power at the high rpm. This setup is suitable for those who always want to rev high. The other design is the 4-2-1 which is design to produce power at the low rpm, better torque response. This setup is suitable for those daily drive machine. 

If your plan is to go turbo, then save your money and jump ahead several more levels. This is not for you. For everyone else, this will complete the balance of your exhaust system modifications.

2. Fuel Pressure Upgrades

This is the one thing we believe that these vehicles should always have fitted regardless of how little, or much you modify the vehicle. Quite simply the factory vehicle has been tuned for maximum Economy. This has resulted in a fairly large flat spot off idle when accelerating hard from a standing start of from a cruise mode situation. The reason for this is Mitsubishi has tuned very lean on the accelerator pump settings, resulting in the lack lustre performance on throttle, but excellent fuel economy.

1. Fitment of the Fuel Pressure Regulator kit eliminates this flat spot, whilst only marginally reducing your fuel economy. Without going into huge detail, trust us when we say, flat spots are eliminated, your car will actually accelerate properly without hesitating and your fear of being run over at stop signs will diminish rapidly. This is an easy bolt on kit and can usually be done in around 1 hour maximum.

2. There are company manufacturing bored out fuel rail, which increases the fuel capacity within the fuel rail. This enables upon acceleration, a greater volume of fuel to become available before leaning out. This also reduces the tendancy to pulse the fuel and create disturbances in the fuel flow, providing a smoother transition to power.

3. Single Throttle Body Upgrade / Thermo Block Kit

Time to look at improving throttle response again. Now if you are wanting to go a little more extreme, to a twin system then you need to wait a little longer. For everyone else, time to start looking at improving throttle response, even if you are going turbo.

The stock throttle body on the 4G15 SOHC engine is 46mm. I Recomends for the majority of owners to do the following

1. For all 1.5 SOHC owners, upgrading the stock to 51mm or a 55mm is very beneficial. However on the SOHC models, anything with the stock manifold and cylinder head over 55mm is really just not effective

2. For all 1.6 SOHC owners, upgrading to 55mm is extremely beneficial.

3. For 1.6 SOHC owners with upcoming computer mods (Piggy back ECU) then a 60mm is also very beneficial if you are remaning Naturally Aspirated and don't plan on going to a twin system. If you are going to a turbo, then stay with the 55mm.

Whilst this work is being done, I recomend fitting at the same time a Thermo Block Kit. Consider this an extension of the cold air intake kit be reducing heat soak into the intake manifold from the engine and the throttle body which have hot water running through them. This drops the average intake tempatures by 25% overall resulting in improved combustion, fuel economy and throttle response.

This package adds 3-5hp, but does improve throttle response and low rpm driveability. The thermoblock kit reduces heat soak and this allows the engine to maintain maximun ignition timing with max throttle response.

4. Drive Line Upgrades

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

1. Lightweight Crankpulley - this unit reduces both the moving mass of the front harmonic balancer, as well as being physically smaller by around 25% diameter over the stock unit. Helps to make the car rev faster, spins up faster and higher. The reduction in drive ratio's means that the power steering and alternator are turning less at higher speeds further reducing engine load. This is just small enough to reduce load without reducing the effectiveness of the operation of the alternator and power steering units. Highly recommended and very easily fitted.

2. Clutch Kit - At some point your clutch will need upgrading. Two options available - for naturally aspirated drivers a standard coverplate with a semi ceramic five pucker clutch disc package. This will increase clutch efficiency by 50% without any extra pedal effort required. For turbocharged vehicles, this is upgraded to a Heavy Duty unit with the cover plate strengthens by an additional 25%. This provides slightly increased pedal effort and more tendancy to be shudder on take off's but will handle the higher torque characteristics of a turbo.

3. Lightweight Flywheel - this has two benefits being increased strength over stock units and also make the semi ceramic clutch units more driveable 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. However, do not skim the flywheel to much because this will cause loss of torque.

5. Suspension Modifications - Level 2

Is time to have some upgrade for your suspension again. Since mild mod is only changing to a lowered spring, it is advisable to change the shock absorber as well for a medium modification.

1. Fitment of KYB Excel-G replacement units for the more budget conscious. Retains improved handling over stock.

2. Fitment of KYB AGX units. These are externally adjustable and are perfect for the all round street / strip / circuit car. You can set them soft when your on the road, hard when your driving hard. Adjustment takes less than 1 minute

3. Fitment if Koni Sports Inserts. These are similar to the KYB AGX units, but are serviceable and provide that little bit more control. They are a more precise unit, externally adjustable on the front only, internally adjustable on the rear. For the more sports conscious person these could be the better choice.

6. Brake Upgrades

Since the performance of the car is higher now, so it is better for us to have a good braking system. The stock brakes on the front is a 235mm single piston caliper package with drum rear brakes. There are few ways to improve the braking system.

1. For those already satisfied with the current HP gain, minor improving on front brake is fine by just changing the front brake pad to a performance brake pad and changing the rubber hose to those stainless steel brake hose. I personally recommend Pro-RS because it is cheap and reliable.

2. Next, you can replace the rear drum to rear disc. For Wira and Satria owner who wish to maintain PCD 100, you can always opt for Wira 1.6 rear disc brake, Putra, Satria GTi or Mirage Cyborg rear disc brake. While owners who wish to change to PCD 114.3, you can try to change to Lancer or Lancer Evolution brake system.

3. For those wanting the final level of brakes, fitment of a 276mm Twin Piston front brake and brake master cylinder upgrade is the final step.

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Extreme Modification

Now we are down to the serious modifiers. Comfort and driveability is usually second to engine performance and speed is your goal. These next levels are not only expensive and it require an experience mechanic to perform the modification. If anything goes wrong, you are not only wasting your money but also your time. Besides that, do think of whether after this final stage upgrade will the performance satisfy you? If not it is better to save up the money and go for engine transplant.

The following mods require you to decide, which of the following ways you are going which will be

1. Suspension Modifications - Level 3

 The last stage of suspension modification is changing to either coil over adjustable suspension or just adjustable suspension. There are few guidelines as below:

1. I recommend the Tien units. To put it quite simply, many Japanese units are set very very hard, so even on there softest unit the car is very harsh, hurts kidney's and actually has worse handling as it skips all over the road. The hardest setting on the Tien units, are equal to the softest setting on the Japanese normal imported units. I cannot recommend these enough - they are simply fantastic with the ability to set your road height, rebound levels etc.

2. These Tien Units are also available to be electronically adjusted on there rebound rates via up to one independent controller per corner, or one controller on all four units as an example. Mostly for extreme racing only.

2. Performance Camshaft 4G13 and 4G15

When selecting a performance camshaft, consider the use for which the vehicle will be required. We all know the claims: 20 BHP extra. Be conservative! Don’t over-cam your engine. Choose your cam for the correct application. Consider! Fit a milder cam and increase your power by 10 BHP at 3500 rpm. Remember! You get this 10 HP every time you accelerate through 3500 rpm. Multiply this by 10 HP each time you drive through 3500 rpm then deduct the times you reach 7500 rpm. I’m sure you will find more horsepower on the 3500 rpm side than the 7500 rpm calculation.

From what I observed recently, there is a cam produced by a local brand JASMA able to deliver 8hp on wheel for a totally stock 4G13 engine. 

The specification is :

Intake 270deg lift 9.35mm
Exhaust 275deg lift 9.20mm

Well, I am not saying something without any proof. Here is the dyno graph for before and after JASMA high cam installed (from squiparts.com).  By in mind that the dyno graph below is a totally stock 4G13 carburetor. Without any modification for the exhaust system and etc. The best part is this cam shaft only cost you about RM400++ which is worth to invest for a good performance.

3. Computer Modifications

Sorry to carburetor owner, this modification is only available for those EFI owner. There are two types of choices, either standalone or piggy back.

1. If you are still budget conscious, then stick with the piggy back. However do remember that EFI piggyback with Siemens VDO ECU is not work because Siemens VDO ECU do have the ability of reset the setting after sometimes.

2. Since budget is not the concern here then a standalone is what you need. Much more advanced tuning, with options like shift lights, in built boost controllers, many many more mapping points, much finer tuning. Additionally the stock ECU even with a piggy back is unable to cope with any camshaft changes at all.

For piggy back system, I recommend Greddy Emanage. If you have a tight budget, take the Greddy Emanage blue with ignition harness. If you have more budget, you may get the Greddy Emanage Ultimate which provide more tuning capability. I do not really recommend UNICHIP because you need to bring to their authorized dealer to tune your car. This is quite inconvenience for those who stay far apart from those authorized dealers.

For standalone system, I persoanlly recommend Apexi Power FC. This is because it has the commander for you to fine tune your car compare to the rest like Haltech/Microtech which need a special software from the tuner to tune it. However the downside of Apexi Power FC is, it is not universal, which means that it is built for particular car model. You may read my ECU upgrade for my Celica (Apexi Power FC) here. Haltech EMS systems - There is the E6X for those wanting something simple, or the Haltech E8 for those wanting the best. With the inbuilt boost controllers, and hosts of other functions, these are way ahead of trying do piece together a piggy back with separate boost controllers, shift lights, gauges etc.

4. Intake Manifold Upgrade / Twin Throttle Body / 4 Throttle Body Conversion

If you are remaining Naturally Aspirated you have several options.

1. First you can go for a single throttle body with Internal Ram Tubes. Massive throttle response, Haltech piggy back system great looks without extreme levels of tuning required. Significant torque improvements and can be utilized up to a single 60mm throttle body

2. Upgrade utilizing stock manifold, modified with fitment of a second throttle body - twin throttle body conversion. Either twin 46mm or twin 51mm throttle bodies work very nicely for a progressive throttle response and great top end rush of power. This system is fantastic and highly recommended if insurance premiums are a 3. The third option is a combination of a Performance Intake Manifold and twin throttle body. Massive plenum chamber, improved air flow, progressive throttle response, this is nearly equivalent to a quad throttle body kit without the side effects and all of the benefits. Massive air flow and the ability to tune with a piggy back or EMS system. Not turbo compatible of course.

5. 1.6 SOHC Stroker Kit Package

Some people not believe their stock engine can be 1.6 liters. These engine can fit 4G18 Stroker kit which is 1.6 liters in capacity. Stock 1.5 block will be rebore n some modification on the stroker needed. Beside 4G18 from Proton Waja 1.6L, another option is the S4PH from the 1.6 Campro engine. The S4PH is lighter which I believe the engine is easier to rev. Furthermore, SP4H has a longer stroke which capable to bore and stroke it more than 1.6L but the durability and reliable is a doubt here since I personally have not see a 4G15 bore more than 1.6L. Comparing the CC that able to get from 4G15 after the stroker kit are 4G18 -> 1584cc and S4PH -> 1597cc.

6. Turbocharger Conversion Package

What more can I say other than your a horsepower and boost Junkie. Welcome to the rest of the world. This combines extreme levels of torque and power, with neck snapping acceleration. It comes at a cost though, increased fuel economy, higher insurance and lots of money. But lets get something clear first.

1. Anyone believing they can effectivly fit a turbo kit on there car safely, properly and legally.

2. These engines in stock form will not handle above 1 PSI boost without aftermarket computer management despite what people believe. 25 : 1 rising rate fuel pressure regulators, larger injectors, moving the distributor to retard timing all these tricks - none work. Don't skimp.

3. 5th Injector systems are something that came and died in the 80's. Quite simply this does not distribute fuel properly to all cylinders, and still does not provide ignition timing adjustment.

4. For boost levels up to 10 psi can be done safety on the stock head gasket dependent upon tuning and intercooler efficiency.

5. For boost levels up to 14 psi requires an upgraded decompression head gasket.

6. Do not boost above 14 psi on the stock piston / conrod setup otherwise you will learn what a banana conrod looks like.

The 4G15 SOHC engine at around 12 psi is good for around 130kw at the flywheel at the extreme.

Finally, it reached the end of this post. My advice for those who still do not satisfy the power gain from all these modifications, you should instead either look for another car or look to do a engine swap to a larger mitsubishi engine.

If you have any other modifications wish to share with me, do email me at ben9166@gmail.com or drop me a comment. Thanks for the support.