Mitsubishi Forum - Mitsubishi Enthusiast Forums - GST/GSX Performance Article by get435

Gsx/Gst have what is known as a 4g63 this is the block that is in the car. 4g63 block are very reliable blocks and can take a lot of moding on stock internals. In the 1G model they produce 195HP stock and in the 2G model 210HP stock. These motors are well capable of producing 400HP with the correct mods.

The first thing you will need to do to your car is making sure it is in good mechanical order. Moding before this can result in motor failure or damage. First give it a good look over just to make sure there are no visible defects that could cause you to regret the mods later. The next step is to do a through tune up of the car. In this tune up you will need to do regular maintenance on a schedule. Some of the things to do are as follows: change all filters, check all fluids change if needed, changed cracked or leaking gaskets, change or change plugs and wires, check compression of motor, change regular belts, check timing belt. If there is any visable damage to the timing belt change it. Also if your car has had over or very close to 60k on it and you do not know if it has been changed change it. If the timing belt is to break it will cause a lot of problems with the head such as bending valves and or cracking head. To do some of these and for other maintenance items refer to an aftermarket manual such as Haynes or Chilton this is a must if doing any mods.

Now to go on the mistakes many people make at first.
Turbo:
Getting a huge turbo this is a mistake by many newbies. Without the supporting mods a huge turbo can cause a car to run poorly.
Loud BOV “Blow Off Valve” :
Many new people want the pssshhh sound right off the bat. To make the loud sound requires you to vent the bov to the atmosphere. This can cause some performance problems because the stock ecu compensates for that burst of air going back into the intake. This can cause negative effects on performance.
To much boost to soon:
Same as trying to put a bigger turbo on if raised too much without supporting mods may cause car to run poorly.
There are many other ways we can go on about things like lowering springs and other mods that will for the most part not make performance significant change.

On to the moding there are several stages we will break down the moding of a car.

Stage I:
There are several mods that can be done without buying parts some of the people on this forum have talked about and some have not been talked about.
Intake:
you can cut the air intake box so that the restrictive holes in the box are not the only thing letting air in rather than buying an intake.
Second is cutting the rear portion of the inner fender behind the SMIC to allow more free flowing air movement also make sure the SMIC is free of obstructions.
BCS:
Remove the BCS restrictor. This will allow you to up the boost 1-2psi without problems.
These are the basic things that will allow you to get a little more power for no money

Stage II:
This is where the money as well as the labor will begin. A stage I car can varying cost depending on brand name/new/used parts.
Intake:
This will allow better flow that the plastic stock tube
Second is you need to see how much boost you are running. To do so an aftermarket boost gage is needed this will help with tuning as well.
BOV:
In order to run higher boost levels you will need to invest into one because the stock on will only allow so much boost.
After this it is suggested you get a boost controller they come in electronic and manual version. If you are planning to run over 25psi a manual controller may be right for you.
Exhaust:
full cat back exhaust system more flow in the exhaust will mean more power and faster spooling times. If you are going for a high hp motor a 3” system is suggested. As well as a higher flowing down pipe, o2housing, and exhaust manifold.
Fuel System:
Upgrade the fuel system that will be needed for that larger turbo this is not needed until 16psi but is recommended before that to upgrade to minimum of a 190lph pump a bigger one may be needed for your application.
Intercooler Piping:
Intercooler Piping is the next item that will needed to be upgraded the solid polished piping will allow better air flow from the turbo to the intercooler and to the intake.
Turbo:
It is suggested to get a t28 if you are staying at stage I or a 16g or 18G turbo. Some kits may need special adapter or installation materials make sure to check before purchase so all of the items can be received. Note 2G eclipse come witha t25 turbo which is maxed out. 1G come with a TD05.
Other things that are suggested at this time are
Drivetrain:
Clutch or auto transmission upgrades and limited slip differential.

Stage III:
Now we have the mechanicals well covered it is time to move on to tuning end of it.
Data Logger:
Data logger device of some kind. This will let you know what the motor is doing as you are tuning it and making adjustments. Along with this it is a good idea to get some kind of warning meters. This can tell you important information about exhaust temp, what the o2sensors are reading, and fuel and air mixtures of the car while driving.
Fuel and Air Managment:
fuel and engine management system. This will help you with controlling the flow of fuel to the larger injectors. The stock system cannot make theses changes.
Injectors:
Replacing the stock injectors with a higher flowing injector. Research how much flow you will need for the size turbo you have.
Intercooler:
A better intercooler the stock intercooler is not efficient enough to cool the amount of air you will be pushing into it. Whether you choose a FMIC or a SMIC make sure it will cool the correct amount of air.
Other things that may need to be upgraded
Drivetrain:
Clutch and flywheel or auto transmission if needed.

REMEMBER ALWASE RESEARCHE YOUR PARTS BEFORE BUYING THEM!