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1G Common Horsepower Upgrades 90-94 4g63t DSM

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Increasing the Horsepower in a 1G Turbo DSM

So you want more power out of your 1G turbo DSM? Make sure you learn a few things before making some common "noob" mistakes. DSM's have a reputation of going fast for cheap. But they're regularly neglected and have gained an unfair reputation of being unreliable. Most "noobs" want to spend all their money on go-fast parts and put no money or effort into maintenance. Don't be one of those people. Do your maintenance and don't start modding until all the necessary maintenance is done. Otherwise you're just asking for trouble. These cars are old, and many have been hacked up pretty badly.

The first thing you need to do is a complete tune up. Replace all worn belts, including the timing belt and balance shaft belt. If the timing belt/balance shaft belt haven't been replaced within the last 60k miles, or you're not sure when they were last changed - change them now. If they break, you'll be paying for a cylinder head rebuild. You'll also want to change out all filters, fluids, worn hoses, spark plugs/wires, and worn/leaking gaskets. Check the compression, do a leak-down test, check your ignition timing, etc. Basically, do all of the checks that your repair manual tells you to do - you do have a repair manual already, don't you? If not, pick one up now before moving forward with any modifications. All of this is covered in the DSM Maintenance Guide.

Once you've gotten all of the necessary maintenance out of the way, you can start with the modifications. We've broken it down into a couple common power levels below to help you achieve your goals gradually. These formulas have been used by the top DSM tuning shops/racers in the industry for years, though we've included some more recent trends too. Before you start shopping for big turbos, intakes and headers, read our article on the common mistakes and misconceptions by newbie DSMers.

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Required reading before you start modding:

A few things to keep in mind when you start modding:
  • Set a goal/budget before buying any parts. No plan = more money later.
  • Be realistic with those goals and plans. What will your car be used for? Road racing will require different parts than drag racing.
  • Be aware of the emissions laws in your area before choosing parts.
  • Make sure the parts you buy will work together well. Aggressive cams don't make sense with a small turbo.
  • Usable power under the curve is important, not just overall horsepower numbers.
  • Used parts can save you some money, though it's a big gamble in some cases.
Upgrade Paths:
  • Free Mods for HP Bump
    For the people with no budget for mods.
  • Parts List for 275-350hp
    Modest increase in horsepower. Expect to spend a couple thousand on parts, and even more if you need a shop to do the installs. A big turbo isn't necessary.
  • Parts List for 350-450hp
    A bigger-than-stock turbo will be needed, but nothing crazy. Expect to spend a few grand on parts, and more if you need a shop to do installs and tune the car.

**Disclaimer -- This is copied from the site's "Tech Guide: Upgrade Paths" section; I am not the author of this information.**
 
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FREE Mods to Increase Horsepower


Remove Emissions Vacuum Lines

The four small rubber hoses that go from your throttle body into the engine bay have no purpose other than to activate the emissions equipment. Remove all of them. They go down to the thermostat housing and then back behind the engine, and then BLOCK OFF the throttle body ports with little vacuum caps, RTV, and zip ties. This will make your car illegal in the eyes of the emissions test facilities. If you're not worried about passing emissions tests, then proceed with this step and the next. Be sure to read the complete Taboo speed shop vacuum diagram and removal for 1g and 2g article as well.


Block Off the EGR
The EGR valve is located below the throttle body elbow. It re-routes exhaust gases back into the intake manifold for emissions purposes. Use a piece of sheet metal to block it off, just replace the gasket. Many DSM shops sell these, or you can make one from a piece of sheet metal. This will also make your car illegal in the eyes of the emissions testing facilities. In case you missed it, be sure to read the complete Taboo speed shop vacuum diagram and removal for 1g and 2g article as well.

"Hacked" MAF
Be aware of what this actually does: 1g maf hack/silencer removal, some tech questions
There are several "hacks" to the mass airflow meter that will solve a plethora of problems that plague these cars. Take the whole aircan out of the car, and remove the filter. On the intake side, you will see 2 honeycombs. Remove the lower one. Below it, you will see a large plastic screw set up into the bottom of the air canal. Back it out a bit. On the other side of the MAF, there is a star-shaped silencer, remove it.

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Hack Air Can and Intake Area
While the air can is out of the car, do some more hacking. The stock air can has a rather restrictive opening, as well as a restrictive path for the air to take. At the least, drill off the rivets holding the snorkel on, and at best chop the front side of the can off. Also, remove the black plastic screen (encircled below) that is behind the headlight and chuck it.

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Remove Ridge in TB Elbow
The first generation throttle body elbow has a ridge inside it where it bends, remove it from the car and use a tool such as a Dremel or maybe even a file to remove this and smooth the inside out. Make sure to clean all the metal chips out.


Clean Throttle Body
Using a throttle body or carburetor cleaner, clean the throttle plate and the inside of the throttle body. IMPORTANT: make sure to stuff a rag into the holes at the bottom of the TB, or the cleaner will get in there and kill the mechanisms down there. Then, use the can and a rag to clean it all out. When you're done with that, you can start the car with the intake pipe unplugged, and spray a can right into the throttle body. You can also spray the can into any line that sees vacuum at idle.


Verify that WOT is 100%
With the car turned off, have someone sit in the car and floor the gas pedal, and then check to see if you can rotate the throttle plate any more by hand. If you can, it could be due to the cable being out of adjustment (adjust on the back of the intake manifold, 2 bolts) or something like a floor mat keeping the pedal from going all the way down. Fix this.


Check IC outlet Pipe for Corrosion
The intercooler outlet pipe on the older cars has a tendency to corrode and leak out boost. Take the plastic fender liner off the car (take off passenger side wheel), take the intercooler out, and if it has ANY signs of corrosion, coat the entire upper pipe with JB-Weld. This is also a good time to:


Open up the Fender Liner
(for example: Anyone done anything with the left air duct (RE: brake cooling)?)
You can use a sanding wheel (Dremel, die grinder, etc) to open up the vents in the fender liner behind the intercooler. Some people just cut it out and replace it with a screen/wire mesh, that works too. ALSO, make sure that you have the duct in front of the intercooler in place and that it seals up. While the intercooler is still out:


Clean the Intercooler
Use a cleaner such as simple green, greased lightning, or gasoline to clean out the inside of the intercooler. It gets filled up with oil over time, which can reduce it's efficiency. Make sure to get it nice and clean, until the water and cleaner comes out clear. Let it dry out completely.


Remove the BCS Restrictor
If you do not have a manual boost controller, you can safely up the boost about 1-2 psi by removing the restrictor in the boost control (a.k.a waste gate) solenoid. In the nipple that is perpendicular to the body of the solenoid, you can insert a screw or a drill bit, and then pull out the restrictor. Make SURE not to drill into the body!!!


Check Base Timing
Buy or borrow a timing light. Hook it up as per the instructions. Ground the black timing connector on the firewall behind the battery, and if you have a logger UNPLUG IT. Check to see that the base timing (crank pulley) is set at 5 degrees of advance. If not, loosen and rotate the crank angle sensor until it is. Read this guide if you are unsure of this process: Engine Timing.


Valve Cover Vent Breather
DO NOT replace the hose from the valve cover breather (left side of the valve cover) to the intake pipe with a simple breather filter and cap the intake pipe nipple! Instead, use a catch can. This keeps oil out of the intake pipes and the intercooler. If you want to do this even better, check out: The 4G63T PCV System.


Unplug Clutch Switch
Under the dash on the clutch pedal assembly, there is a switch that will only allow the car to be turned on if the clutch is pushed in. Just unplug this so that you can start the car without touching the clutch, it's better for the thrust bearing. The plug is on the front side of the clutch pedal assembly, so that it is only pressed when the clutch is all the way in.


Pressure Test the Intake
This is one of the MOST CRUCIAL things you can do to make sure your car is running properly! Does your car ever sputter, misfire, fuel cut, bog, idle badly, or smoke (black)under boost? It could be a boost leak! You need to build a pressure tester that will clamp onto the turbo and lt you use a bike pump or an air compressor to send pressure into the IC pipes and the manifold. ANY and ALL leaks should be fixed! The only thing I know of that should leak is the manual boost controller. Want to build your own boost leak tester? Read how here: IC Pipe Tester.


Ready to make more power? Scroll down

**Disclaimer -- This is copied from the site's "Tech Guide: Upgrade Paths" section; I am not the author of this information.**
 
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Parts List for 275-350hp

Intake Pipe and Filter

A high-flow K&N (or similar) intake filter will help throttle response and help all future mods achieve maximum performance. A hard intake pipe will also improve air flow over the factory rubber snorkel. This, along with the MAS modifications mentioned above should take care of your intake needs at this stage.

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Aftermarket Boost Gauge
The factory boost gauge is simply not accurate and shouldn't be trusted when raising boost levels. To avoid severe engine damage when increasing boost levels, an aftermarket unit is mandatory. You'll find many brands to choose from.

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Boost Controller
In order to raise boost levels, you'll need a boost controller. Whether it be a manual or electronic unit will depend on your budget. Electronic boost controllers are cool looking, but some have been known to be unreliable at over 25psi. At this stage, you won't be turning the boost up much past 16psi, so it won't be a problem. But if you plan on moving up to the next stage, a manual boost controller may be better.

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Cat-back Exhaust System
A 2.5" or 3" high flow exhaust system is needed to gain more power. You can choose between aluminized steel or stainless steel depending on your budget. If your power goals are over 400hp, you'll want a full 3" system from the turbo all the way back. A "cat-back" system replaces the exhaust components from the catalytic convertor to the exhaust tip. A "turbo-back" system replaces the entire exhaust system, and is made up of a "cat-back" plus a downpipe and high-flow cat/straight pipe.

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High Flow Cat/Straight Pipe
Replace the factory catalytic converter with a larger, higher flowing unit. For off road use, simply bolt up a straight pipe in it's place - of course, this is obviously not street legal in most states.

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High Flow Downpipe
The factory downpipe is very restrictive and should be replaced with a larger, better flowing unit. For Stage 1, a 2.5" downpipe will do. If future plans involve 400+ horsepower, consider a 3" downpipe. These are available in press-bent aluminized steel for those on a budget, or mandrel-bent stainless steel for those with a little more cash to spend. This too is not street legal in most states for on-road use.

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Exhaust Manifold
The exhaust manifold on 1G DSMs are notorious for cracking and leaking. The solution is to replace it with a ported factory 95-99 exhaust manifold, an Evo 3 manifold, or an aftermarket tubular header (Morrison Fabrication makes some great ones). The manifold you choose will need to be matched up to the turbo, so plan accordingly.

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O2 Sensor Housing
In between the turbo and the downpipe is a 90 degree elbow called the O2 Sensor Housing. The O2 sensor screws into this housing. This is the last restriction in the exhaust system. The stock unit can be ported out, or you can simply buy a better flowing unit. If you choose to go with a "turbo-back" exhaust system, this housing will usually be included.

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Fuel Pump
The stock fuel pump will not be able to supply the needed fuel for anything over 16psi of boost. Though you won't need to go past that in this stage, it's still cheap insurance to put in at least a 190Lph fuel pump to ensure you have enough fuel in case you want to raise the boost with race gas in the tank. It's also a good idea to re-wire the fuel pump for consistent fuel pressure. If you go with a 255lph pump, you'll need an adjustable fuel pressure regulator.

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Intercooler Piping
The rubber intercooler piping should be replaced with better flowing solid pipes. Some replacements will come with a larger throttle body elbow (which is needed also). The turbo outlet elbow should be swapped out for a larger unit as well. Please note that if bigger power is in the plans, this upgrade may not be necessary as the intercooler piping will likely be routed differently with a front mount intercooler.

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Drivetrain Upgrades

Performance Clutch

With more power on tap, a stock replacement clutch probably won't last that long. It will start to slip, especially in the higher gears. This means it's time for a high performance clutch that can handle the increased horsepower.

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Shifter Mods
If you have a 5-speed tranny, you'll notice that the shifting is likely less-than-desirable on the 90-94 cars. These transmissions tend to be notchy from the factory to begin with. The best solution short of a rebuild is to put in some good tranny fluid and replace the rubber bushings in the system with some metal bushings. This should help with grinding and missed shifts as well.

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Limited Slip Differentials
If you have a front wheel drive DSM, you'll probably need an aftermarket LSD to keep the tires from spinning - especially if you plan on making more than the stage 1 power levels. FWD cars will have a more difficult time achieving fast 1/4 mile times compared to the AWD cars due to traction. Transmission rebuilds are the most opportune time to install LSDs, since the transmission is already being taken apart.

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Auto Transmission Upgrades
The number of turbocharged automatic transmission DSMs around is growing and there are modifications available to those looking to improve shifting, help handle increased horsepower, and just make driving more enjoyable.

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Please Note: 1G automatic transmission cars have a smaller stock turbo (the Mitsubishi 13G) than the 5-speed cars and will require a turbo upgrade in order to achieve Stage 1 performance levels.
See all available Turbo Upgrades.

350hp not enough? Check the 350-450hp list below

**Disclaimer -- This is copied from the site's "Tech Guide: Upgrade Paths" section; I am not the author of this information.**
 
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Parts List for 350-450hp

Most of the parts from the
list above, plus the following:

Logging/Tuning Software
Before you can safely add bigger injectors and and more airflow , you'll need a way to tune the car and check data logs. There are a variety of ways you can go here. The most common route is a piggy-back style computer which still uses the factory MAS in combination with a reprogrammed EPROM chip that plugs into the factory ECU. The most common option has been ECMlink - a system designed specifically for the DSM ECU. The caveat here is that some cars didn't come with an ECU that utilizes an EPROM, making an ECU swap necessary for some cars. You can also look up ecuflash and megasquirt.

Another option is a complete stand alone fuel system, like LinkECU, Haltech, or AEM, which completely replaces the factory ECU altogether. Stand alone systems give you much greater tuning capabilities but require a LOT more knowledge of fuel tuning than the average weekend warrior may possess. Most people who go stand alone ECU end up taking their car to a shop to get tuned. Chances are, if you know how to tune a stand alone ECU, you wouldn't be reading this guide.

Either route you choose will allow you to run larger-than-stock fuel injectors - which will be needed.

Warning Meters
This might seem obvious, but you'll want some gauges to help monitor the engine. While dataloggers allow you to analyze data after doing some test runs, gauges are easier to read while driving. An EGT (exhaust gas temperature) gauge and probe will allow you to monitor the exhaust temperature exiting the engine. Extremely high temps generally translate into a lean condition and can be catastrophic. You can also go with a Wideband O2 system that will allow you to monitor the air/fuel ration of your car while driving. This will tell you exactly how rich or how lean the car is running, allowing you to adjust the fuel curve accordingly. Water and oil temp gauges are a good idea as well.

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Bigger Fuel Injectors
To You're going to need a bigger turbo to hit your goal. The stock injectors won't be up to the task. The larger the turbo you plan on upgrading to, the larger the injectors you'll likely need. If swapping in a 16G turbo, you could get away with 550cc injectors, but most go larger since you can always control injector flow with the tuning software. If you think there's a good chance you might want to go with a larger turbo later, just get injectors that will support that turbo. Fuel Injector Clinic has always had quality options for every HP goal.

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Front Mount Intercooler Kit
The stock side mount intercooler will have to go to support higher horsepower levels. Time to look for a Front Mount Intercooler. This install is pretty involved, especially if you choose a kit that routes the piping around the sides of the radiator. Most kits require some trimming of the steel bumper and some dremeling of the plastic bumper cover. Most "street" kits will do for modest horsepower levels. But if more than 400hp is in the plans, consider a "race" kit which will have a larger core for better cooling characteristics.

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Turbo Upgrade
Finally, the step everyone wants to skip to. The stock 14b turbo, though a great option for quick spool on the autocross course, won't be big enough to put down big power efficiently. You'll need something larger than a 16G or 18G in order to efficiently achieve power levels above the 400hp mark. A Mitsubishi 20G, a Mitsu-Garrett hybrid, or a full Garrett setup will be needed for higher horsepower levels. Keep in mind that any non-Mitsu or non-Mitsu hybrid turbo (exhaust housing) will require a special exhaust manifold, external wastegate and O2 sensor housing. This is the point where you'll have to decide what your car will be used for and how much you want to spend. The larger turbos are great for drag strip action, but not so great for road race and autocross use - something to keep in mind.


Additional Drivetrain Upgrades


Axles

The factory axles will be strong enough at these power levels, but if your axles have a lot of miles, it might be a good idea to replace them. If your plans include higher power levels, consider getting some upgraded axles.

Driveshaft
Same with the axles - the factory piece is plenty strong. But be sure the carrier bearings are in good shape. The Driveshaft Shop makes a light weight driveshaft for these cars.

Rear End Swaps
With the axles and driveshafts upgraded, the rear end will take the brunt of the force. Stock rear end rebuilds have been known to handle bigger power, but some have upgraded to 3000GT rear ends and even Evo 8/9 rear ends for added strength.


Other Upgrades/Modifications to Plan For

Helmet
If you're planning to be putting down a ton of power and running fast times at the strip, get a helmet. Most tracks require you to wear a helmet if your car runs a 13.99 second 1/4 mile time or faster. If you're doing any road course or autocross racing, a helmet is always required.

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Roll Cage
Most tracks require your car to have a roll cage installed if your car runs an 11.99 second 1/4 mile time or faster. If you're doing any road course or autocross racing, a roll cage is totally necessary.

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Racing Seats/Harnesses
For more safety and driving control, look into some good supportive racing seats and harnesses to keep you firmly planted in the proper driving position. You'll find a variety of manufacturers for the racing seats, including Sparco, Corbeau, Recaro, etc. Sparco Racing seats tend to be quite popular among DSMers for some reason.

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Once you get to this point you'll have a pretty good idea of what it will take to hit the higher horsepower levels. That's when you'll start breaking things and gaining more knowledge through the process.
You'll start looking into forged pistons, strong rods, more aggressive cams, porting the cylinder head, stroker kits, etc. It's not cheap, but you already knew that.

**Disclaimer -- This is copied from the site's "Tech Guide: Upgrade Paths" section; I am not the author of this information.**
 
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