The 95-99 GS/RS model eclipse come with the engine known as the 420a. These motors are reliable if done right, although not as strong as the 4g63. Parts between the 420a and 4G63 motors are not interchangeable. Remember if this is not done right, there may me serious after effects that can cause a disaster to the motor.



The first thing you will need to do to your car is to make sure it is in good mechanical working order. Moding the engine before this can result in engine damage or failure. 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 thorough tune up of the car. In this tune up, you will need to do the regular maintenance. Change all filters, check all fluids and change if needed, change cracked or leaking gaskets, 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 is at or over 60k miles and you do not know if the timing belt has been changed, change it. If the timing belt breaks, 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



There is a basic concept with these motors. There are motor upgrades and than the forced induction part of upgrading the motor.



Motor upgrades.



Intake:

CAI is recommended as a first upgrade to let the motor breath.



Exhaust

A cat-back exhaust can also be used to help the engine breathe. For a naturally aspired engine, 2.5" diameter exhaust is sufficient.



Header

A header is another part of the exhaust system that will allow the engine to breathe. The quicker the exhaust can be moved from the engine, the more power that can be made.



Intake, Header, and Exhaust are normally the first three mods that people do.



Throttle Body:

You can bore out the throttle body. This will allow for more airflow and eventually, better air/fuel mixture.



Port and Polish:

Port and polish the intake manifold and head. This will increase flow within the manifold into the cylinder.



Ignition System

There are several components in the ignition system that can be upgraded to a better performing part. First off as viewed in the tune-up section, hotter plugs and better conduction wires can be an easy upgrade. If you want to go an extra step, a better coil pack or distributor can be added to the car along with a blaster coil. These items allow more spark to flow through the upgraded wires. The blaster coil will spark 2-3 times rather than the 1 time the stock one does. All of these result in a better fuel burn, which will add HP and better gas mileage.



Cams:

Cams and cam gears. These will allow for more power through timing and adjustments made to the lobe size and gears. Check what size you should go with before purchasing. Bigger is not always better. Underdrive pulleys are another option to consider. A full head rebuild is suggested at the same time cams are to be upgraded.



Air and Fuel Managment:

Air/fuel mixture controller. This will allow you to tune for the new items you have added.



Ignition Timing Controller

An ignition timing controller will allow you to retard/advance timing depending on your needs. This will keep the engine from knocking(predetonation) which can cause harm to the engine.



Forced Induction.

Before pursuing forced induction, it is suggested that the motor be rebuilt to handle the forced induction setup I wanting more that 7-8psi.



Engine Overhaul

There are many kits out there to rebuild your motor. Stroker kits are favored buy most people for the applications that the 420a will be used for at this point in time. If you are not sure how to rebuild a motor or what to buy, have a professional do it. If there are any doubts, go to the local machinist have them do it or tell you what parts would be best. This is highly recommended for your application.



Turbo kit:

This is a complete kit that will give you everything needed to install a turbo on a naturally aspirated car. This results in a huge rise in horsepower. However, few companies offer such a kit. One is a company called Hahn Racecraft. These kits usually come with all the turbo upgrades needed.



Supercharger:

Another way of forced induction is ran on belts not exhaust. Its very hard to find for any DSM when it comes in kits like the turbo.



Nitrous Oxide AKA N20, Go-Go Juice

This is a fast way of making bolt on power that is cheap and easy, but it also can damage your motor if not done right. It can also cause damage if the kit is too powerful for the engine. This is known and as dirty racing by some racers because it is a cheep inexpensive way to make big power.



Motor swap to turbo motor:

Not done by most people because it requires re-welding of motor mounts as well as full wiring harness replacement along with an expensive ecu. The time and money taken to do so, most people will just turbo the 420a because it can be faster and cheaper in most cases.





REMEMBER ALWAS RESEARCHE YOUR PARTS BEFORE BUYING THEM!