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Tips, Tricks, and Other Things You Probably Want to Know



If you are going to build a Starion or Conquest there are a couple of things we would like to say first. Congratulations on not having a Honda or Acura. This shows originality and initiative. Regardless of what Turbo Magazine said about these cars ( Notice they have changed their tune in the last year or so )it is a great platform to go fast with. It is not cheap to make a 12 or low 13 sec. Starion or Conquest but it is not all that hard either. You are starting with a very strong engine, transmission and rear end. The good part is that these cars can be had for a very reasonable price and deliver lots for the money. A 4 wheel Independent suspension, 4 wheel disc brake ABS equipped REAR WHEEL DRIVE car with all of the standard amenities is not an easy thing to come by for $2500-$5500 which is the typical range for a nice car. If you are just looking to buy a Starion or Conquest do your best to buy and 88 or 89 (preferably an 89) The 87’s, which are the most common also suffer from the biggest electrical and F.I. problems. Much of it can be cured by installing an 88-89 ECU but the rest of the electrical in the car can still be a problem.



If you are doing a full on project car it really does not matter which year you start with as you will most likely be replacing all the trouble area parts anyway. 86’s have the worst injection in terms of fuel volume but have the distinct advantage of ( Usually ) being able to be run WITHOUT THE MASS AIR SENSOR. Really, if you have a 1986 car give it a try. Unplug the mass air sensor and re-start the car. Most of the time they idle better and run smoother. All you have to do then is use a big fuel pump with a rising rate regulator and a Fuel-Cut-Defencer and you have a great car capable of in the 260 HP range with the proper Turbo.



If you are starting with an 87 the first thing you should do is have the ECU upgraded to eliminate the boost fuel cut ( Actually it raises it to 19 PSI ) and bring the fuel and ignition standards up to par. This will give you the basis for any other modifications while maintaining the stock fuel injection system. We have to perform the upgrade on YOUR ECU. It takes 2-3 days once we have it in our hands and cost is $300.00 + shipping If your plan is to get rid of the terrible 2 injector TBI then don’t worry about the ECU. We offer a variety of options for induction. Once the ECU is upgraded you have many options. If you want a nice daily driver that can run in the 13’s please look at our T3/T4 page. It does what most people want with minimal effort and a fixed expense. This is the basis for any engine that will make in the 400hp range but works equally well on a totally stock system.



For any year Starion the engine is very strong but for boost levels over 15 psi we highly recommend using forged pistons and head studs. This gives you a huge safety margin with detonation, bad gas, etc.


88-89 cars are the best choices. They are also the hardest to find. 87 was the most common year with numbers declining in 88 and 89. The ECU programs kept getting better with 89 being the best. You cannot swap an Automatic ECU with a 5 Speed ECU or Vice-Versa. You can put an 89-89 ECU into a 1987 and it usually works fine.


1986 cars are unique. The F.I. components are not interchangeable with the 87-89 cars. The difference is that the 1986’s used a simultaneous fire injectors system. Both injectors fired at the same time. The 87-89 cars used a progressive system with a Primary and Secondary injector. The injectors are also not interchangeable. They look the same and will fit the same but they will not work.


The 86’s used 2 same size injectors of about 550 cc. The 87-89 used a primary of about 580 cc and a secondary of about 1000 cc. We say "about" because we have flowed the same part number injectors new from Mitsubishi and gotten different results every time. This seems to be a large part of the performance inconsistency between even the same year cars.


The Mass Air Sensor is the other problem area that cannot be fixed without going to a different style of F.I. system ( Except as noted above about the 86’s ) There is no sure fire diagnostic approach to verify the quality of the Mass Air Sensor. We have seen many sensors test bad yet work fine and have them test perfect yet putting a different one in the car will cure the problem. Go figure. The only way to know if you are having a mass air sensor problem is to switch it with a different one from a good running car.




Cylinder Heads and Head Gaskets:


Okay, we all know that Starions are famous for cracking cylinder heads. It is a 50/50 problem between bad design by Mitsubishi and poor maintenance and abuse on the part of most owners. Since it is more fun to blame the manufacturer we will discuss that first. The jet valves do not belong in a Turbo engine. More specifically the steel jet valve shrouds that protrude into the combustion chamber do not belong there. Unfortunately there is no way to have the jet valves without the shrouds and steel is the only thing that will live in the chamber. The steel shroud gets glowing hot and transfers a huge amount of heat right at the seat area The cooling in the head cannot get rid of this heat fast enough and the head cracks right across the seats or from the exhaust valve to the water port. The answer is to not have the jet valves there at all. We can eliminate them from the head by welding up both sides of the port and blending the chamber. We only feel this is worth doing on a non-cracked head that has quite a bit of money invested in porting. The new non-jet valve head castings we offer cost less than doing a crack repair and jet valve removal with new valve guides.


The other problem with cracking the heads is the cooling system. The heat generated in a Turbo car dictates that the cooling system be working properly. If the radiator is even 10% clogged your car will run hot. There is no reason for a Starion or Conquest to run hot under normal driving conditions even on the hottest summer day with the A/C on. Running the car hard on boost up a hill on a hot day is a different story. If you are inclined to such silly things than we suggest you upgrade to a 3 row high efficiency radiator or an Aluminum unit.


Make sure your cooling fans Work properly. Almost every car we get in has at least 1 of the fans not working properly. The first time you get stuck in traffic with the main fan not operational the temp will be right up in the red. One or 2 trips into the red and a head gasket or the whole head will go.


Head hardware is another important area. The stock head bolts are a torque to yield style bolt, which means they have to be replaced every time they are removed. If you do not replace them the head will lift from the block and the head gasket will blow. We have had customers replace a head gasket every 3-4 weeks and never understand what the problem is. We use ARP head studs on all our engines. A stud with a nut and washer distributes the load evenly over the head surface instead of a bolt pulling the threads in the block and distorting the block surface. The studs will also allow a higher torque which means better gasket crush and a more rigid assembly. A non-jet valve head with studs will be very unlikely to ever crack or blow a head gasket.






There is nothing wrong with the 2.6 bottom end. It is bulletproof and will survive tons of abuse with no crank or rod failures. The stock pistons are a different story. They suck. Anyone considering anything bigger than a 14G sport turbo and more than 15 psi boost had best start thinking about Forged pistons. It is only a matter of time before the stock ring lands shatter and your car turns into a smoke machine. The other misconception is that the 2.6 engine will not rev. That is total B.S. With a proper size Turbo and good breathing the G54B will easily turn 7000+ RPM.


The balance shafts are a particularly weak area. We eliminate them in all the engines we build. It is very important to have the complete rotating assembly balanced after removing them. If you don’t it will vibrate. The other benefits of eliminating them is an almost 18 HP gain and much higher oil pressure and volume to the more important parts of the engine. That is a bunch of stuff spinning around in there with a gaggle of chains, tensioners, guides, etc. to keep it all in place. The stock con rods are excellent once they have been race prepared. We have never broken one under even the most strenuous conditions. Same goes for the crankshaft. Very strong and reliable.






The flywheel is without a doubt the second most ridiculous part on the car ( next to the size of the stock turbo ) 34-36 lbs stock. We understand the idea was to make the long stroke engine smooth and have great inertia once it was moving, but come on. Geeez. 30+ lbs is just silly. By the same token you cannot install a 10 lb aluminum flywheel in the car and have it work worth a damn. When you go too lightweight there is not enough inertia and the engine will not rev nor will it be smooth at cruise speeds. It is sorta like the 3 little bears and the one that is just right is a lightened stock unit, We can get the 240mm 88-89 flywheels down to about 21 lbs and the 86-87 225mm units to about 19-20 lbs. This gives just the right amount of inertia. The car will rev up fast yet can maintain the RPM and have a nice part throttle cruise. We prefer to use the 88-89 240mm flywheel and clutch. The extra diameter on the clutch disc make a big difference in holding power and the late style pressure plate is just better.




Upgrading the Starion / Conquest:


The stock 2 injector throttle body injection is poorly designed but it is what you have to work with unless you want to jump in and go to a complete new F.I. system. We have been successful in working with the stock system in applications up to about 320 hp although the driveability is not all it could be and they tend to be a bit inconsistent and cranky. The stock system is notoriously unreliable and difficult to troubleshoot and even more expensive to repair. DO NOT attempt any upgrades to your car if the injection system is not working properly. You will lean out or detonate and cause yourself much more expensive problems. Make the car run good before you try to make it go fast.


If you are having a poor idle problem , a bucking under acceleration, or the car revs to about 3000 RPM and falls on its face, the first thing to do is replace the injector clips. A bad Injector connection will mess up the entire system. Clean the injector terminals with a toothbrush ( Not the one you use every day ) and some contact cleaner, Solder the leads to the new injector clips and you may just cure a bunch of problems in the car.


The other problem most people encounter when working on or troubleshooting their F.I. system is establishing fuel pressure and volume. It seems no one has the tools and most repair shops don’t want to deal with these cars. You need to know if the car is rich or lean before you can figure out what to do to fix or upgrade it. To this end we offer a couple of good diagnostic and tuning tools. You also need to establish fuel volume, this will tell you if the fuel pump, pickup or fuel filter are restricting the amount of fuel to your engine. You need at least 40 gallons per hour @ 45 psi to run under boost. This is easily measured by taking a container of known size ( like a 1 gallon plastic bottle ) and running the fuel into it for 1 minute and multiplying by 60 for a 1 hour flow rate. A 150-200 GPH rating is even better, this is the reason for upgraded pumps and additional pumps. Fuel pressure plays a big part in tuning the system. If you cannot change the length of time the injector opens ( as with the stock system ) then raising the fuel pressure will let more fuel in during that time with the added advantage of a better spray pattern and better atomization. Rising rate boost referenced regulators are the best way to accomplish this since the stock regulator does a fine job of running the car at low speeds and off boost. We use an additional rising rate regulator inline with the stock regulator to increase pressure in a linear fashion from 5 psi boost to 18 psi. The amount of pressure varies with the output of your pump or pumps. Upgraded fuel pumps are a great safety item and will assure you of having enough fuel available at all times. A must if you are going to run a Nitrous system or more than stock boost. Not all cars need the extra fuel depending on the amount of power they are making and other modifications that are done. The easiest way to find out if you need a regulator or to install a Halmeter AF/30 Air Fuel Ratio Monitor. The highest quality, most accurate, and affordable onboard rich/lean meter available. Simple 3 wire installation. Hooks directly to your stock O2 sensor wire. Will quickly tell you if you are leaning out and about to make a big mess inside your engine. Also very handy for tuning adjustable pressure regulators and finding the boost limits of your fuel system. We recommend having this onboard at all times to alert you to any potential problems. This should be installed before any additional pumps or regulators are purchased to make sure that you need them. If you are not running lean then putting more fuel will make the car sluggish and unresponsive, not to mention give you horrible fuel economy.




Exhaust Systems:


You do not need a 3" exhaust on a street Starion. You almost don’t need it on a Race Starion. I know, everyone says it will make more power in a turbo car with bigger pipe. Sure, we’ll agree with that but you do not drive the car on boost at 18 psi all the time. Most cars don’t even flow enough to take advantage of a 3" pipe at 20 psi and 7500 rpm. What happens when you put too large a diameter pipe on your car is that the off boost performance suffers terribly. A turbo car has to make boost before it make power. You also have to drive your car normally most of the time. This concept does not apply to a dedicated track car that just stays on boost all the time so don’t call and yell at me about it.


Too large a diameter pipe does not have any exhaust velocity or extractor effect until very high rpm. Removing all the backpressure from a system will allow the turbo to breathe more efficiently once it is on boost, but it will generally delay the turbo from coming on boost. The Catch-22 here is that the engine off boost needs a certain amount of backpressure to develop the exhaust flow that will allow the Turbo to spool-up. You need to compromise with an exhaust size that will allow the car to run correctly over its entire RPM range. In the case of a street and strip Starion that size is 2.5" with or without a Cat. If you have a huge Turbo and just want to make monster boost and HP and don’t give a crap about driveability or performance below 4000 rpm, hey, go for it. 3" pipe is the answer. In an unlimited situation where max power and flow is the consideration and driveability is no issue than a bigger free flow system is the answer. I just guarantee you that 99% of the cars out there do not fit that category. You can find plenty of Starion owners that put a 3" system on their car and will admit that it went slower in the ¼ mile and was much more sluggish around town.




Suspension and Brakes:


One of the strongest points of a Starion / Conquest is the handling and braking. For street and Auto-X use there is not much that needs to be done to make the car work perfectly. Do not try to lower the car any more than the springs allow. Do Not Cut The Springs. I does not matter if you are using our springs, or Eibachs, or whatever. If you cut them the car will bottom out and have no suspension travel. It will be uncomfortable to drive and it will not handle any better. You’ll also wipe out your front spoiler instantly. We have won many Auto-X events with our Starions with nothing more than a set of our lowering coils, bolt on sway bars, and a set of Tokico shocks and struts. The braking system is also great. The stock pads are not very good and should always be upgraded to Metal Masters or Carbon Kevlars. Steel Braided brake lines make a great improvement in pedal feel and are a good safety item. If your plan is to road race the car you have to get a bit more extreme. We have all the parts you need to make a competitive Road Race Starion / Conquest.




What Should I Do First ?


Make it run right and reliable before doing anything else !


This is a very tough thing to tell people. The first thing to do is make sure the car runs perfect. Do not make any mods to the car until it runs good. Fix whatever needs to be fixed to make it right. If the car is a 1986 either upgrade the ECU or get an FCD. If it is a 1987 get the ECU upgraded or install an 88-89 ECU. If the car is an 88-89 and it runs good just jump right in.


The second thing is to decide exactly what you want to end up with when you are done. You have to be honest about what you are really going to do with the car.


  • What kind of HP are you looking for ?
  • Do you want to be able to run pump gas ?
  • Will it be raced or just be a street car ?
  • What kind of racing will you do ?


Drag Race, Road Race, Auto-X ?


The third thing is. What condition is the engine in and what do you want to do to it ? Obviously you cannot make 300 HP with an old tired motor that is on its last legs. An engine in good stock condition


  • Does not over heat or use water.
  • Does not use anymore than ½ Qt. of oil every 1000 miles.
  • Has good oil pressure.
  • Has at least 110 psi compression in every hole and no more than a 10% variation between cylinders.


If it has any engine problems you need to fix it before you go any further. A good running high mileage ( About 100K miles ) stock 2.6T is capable of about 250HP safely. A fresh stock engine can handle in the high 200’s to 300 HP for very short periods of time on a reasonably cool day.


Once you have figured out what you want to achieve you should decide what Turbo you will use. Since many of your purchases are tied to the style of Turbo you should make that decision first so as to avoid buying things twice. Here is a list of choices and the Max HP and Performance you will most likely get depending on what other upgrades you make. This is based on the starting point of a 180 HP stock intercooled car running 10 PSI boost.


  • Sport 14G up to 260 HP Mid 14’s


Good every day driver. Long engine life. Fun car for the street


  • Super-60 T3 up to 320 HP Low 14’s High 13’s


Still good every day. Needs engine internal beefed up. Good weekend drag racer


  • T3/T4 System Minimum 300 to 380+ HP High 13’s to Low 12’s


Can be used on a stock engine with low ( 10-12 ) psi boost or be tweaked to make as much HP as you will ever develop reliably from this powerplant.


Okay, hopefully you are getting the idea. Make a plan and try and stick to it. Be realistic. Not everyone wants to make 400 HP and run race gas in their car everyday. Not everyone has a huge budget to spend either. Do what is within your means. If this is your only car and it cannot be down for repairs often then stick with very basic bolt-on items. If it is your second car and can be down for longer periods of time then your options open up a bit. If it is just your weekend toy then go for it.


Here is a list of the basic upgrades that can be done on a stock engine and keep it reliable.


This will get you anywhere from a high 13 sec car to a low 14 sec. Car depending on Turbo choice and how good your engine is.


  • 14G or Super-60 Turbocharger at 12-14 psi boost max
  • High Flow Downpipe Kit
  • 2.5" Exhaust system with high flow catalytic and 3" Ultra-Flo muffler
  • Manual or electronic boost controller
  • K&N Air filter with opened up air box
  • Upgraded Fuel pump with Cartech Fuel Regulator
  • High Flow Inlet Pipe with Racing Bypass Valve
  • TEP Camshaft upgrade
  • Enlarged throttle body with intake manifold mods.


The same thing can apply to the T3/T4 system but you can only reliably run 10-12 psi boost if the engine is old and stock.


I f you have a stock 88-89 and know the engine is in great shape and you want a bolt on high to mid 13 sec car here is what you do.


  • T3/T4 System
  • 2.5" exhaust with no cats and 3" Ultra-Flo Muffler


  • Manual or electronic boost controller
  • K&N Air filter with opened up air box
  • Upgraded Fuel pump with Cartech Fuel Regulator
  • High Flow Inlet Pipe with Racing Bypass Valve
  • TEP Camshaft upgrade
  • Enlarged throttle body with intake manifold mods.




In general the way to approach ugrading you Starion is……


  • Make sure the engine is in good shape.
  • If not, rebuild it to the most extreme level you think you might use in the future.
  • Make sure the F.I. system is working properly
  • If not fix it, or replace it with something better


Make it run right and reliable before doing anything else !


  • Choose the turbo system that fits your needs


  • Do the complete exhaust system
  • Upgrade the Air filter and Air box
  • Install a performance camshaft
  • Add a Compressor Bypass valve to save your investment in a good Turbo
  • Add the Upgraded Fuel Pump and Pressure Regulator to keep you from leaning out.
  • Install a HALMETER to make sure you have the correct amount of fuel


Other bolt-on or non internal engine stuff that is safe to do and will enhance your performance is


  • Intercooler plumbing kit
  • Intercooler upgrade
  • Enlarge the stock throttle body and open up the stock intake manifold
  • Install High Flow Fuel Injectors or an AIC System


Once you get into the engine you can make some vast improvements. Between raising the static compression, Upgrading to Forged Pistons and good rings, losing the jet valves from the head, doing some porting work, Etc you can really crank some boost and take full advantage of a setup like the T3/T4.


The lists go on and on. You can spend as much as you want and do an unlimited number of mods. Because of this we always recommend you give us a call if you are going to do a big project all at once. We will always try and make sure that you get the most for your money and do not buy things that are not needed or will not make you happy. The best way for us to ensure that you are satisfied with your purchase is to make sure you buy the correct parts.




My Starion is Broke, What’s the Matter with it ?


I contemplated not even trying to do this part of the catalog. This will be only the most commonly asked questions and the answers we give at least 2-3 times a day. Many of the answers probably lie in the stuff you have hopefully already read. If you just skipped to this section please go back and read through the whole thing again.


Okay, did you really read it all ? Good. Now hopefully this helps you a bit more.


The first thing to do if you are going to own one of these cars is to pony up and buy the factory workshop manual. Yeah I know it’s about $80.00 but you will save that in mechanic bills and incorrect guesses as to what is wrong. Don’t let the dealer tell you it is not available. They have to order them and it takes a week or so but they can get it.


It is also assumed that you can do basic maintenance on your car. Always start with fresh spark plugs, a new cap and rotor. Good spark plug wires. A good coil. Set your timing correctly. ( 10 degrees advanced at 900 rpm. ) Do this first and you may solve all your problems. The little things will kick your butt every time. If you have not replaced the Injector clips, do it. A bad connection will cause untold problems in a Starion. Change your fuel filter. You know you haven’t done it in forever. It really can make a difference.


Idle Problems:


A perfect running Starion still does not have a perfect idle. That is the fault of the demented Mitsubishi engineer who chose a 2 injector wet manifold system. However, it should idle pretty good at about 800-900 rpm. If you installed a camshaft ( Even one of ours ) it is likely that on an older engine it will affect the idle a bit. More so when it is first started in the morning. This still should be an acceptable idle. If it is not, try the following things.


Pull the spark plugs and inspect them. Then change them. NGK BP7ES gapped at .032


Do a compression test.


If the compression is below 100 psi it will never idle right and you have major engine problems


If the compression is off by 15 or more psi per hole then it will never idle right. Engine problems


Inspect all your vacuum hoses and replace any that are broken or cracked. Check the boot between the Turbo and the mass air sensor. These are prone to cracking right at the Turbo inlet. Any leak here will make your car run like total crap and it will never idle right ( Hunt up and down, never idle the same way twice ) If it is bad replace it. No, put the duct tape away. Go buy a new one.


If this checks out okay then restart the engine and let it warm up. Get a can of Starting Fluid ( Ether ) and spray around the throttle body, injectors, manifold etc. Any change in idle will indicate a vacuum leak. Fix it. If there are no leaks, with the car idleing spray a small amount of Starting fluid into the air filter. If the idle perks up for a second then dies off your car is lean. Most likely a bad fuel pump and/or a partially clogged primary fuel injector. If the injectors are leaking it does not mean they are malfunctioning. You should still replace or repair them, but it does not mean that is what is wrong with your car. Leaky injectors very rarely have any affect on the way the car runs ( Except when it catches on fire because of it. )


Questions and Answers to Commonly Asked Questions:


My car cranks but will not start:

I will assume you can check for spark and that the fuel pump is running.

The likely answer is a bad fuel injector or a bad connection on the injector clip.



My car goes to about 2000-300 RPM and falls on its face:

Bad secondary injector on 87-89 or dead TPS


My car makes good power at up to about 3-4 psi boost but then it stops pulling.

My car won’t make any power going up hills but idles good and runs fine on a flat road

Bad or weak fuel pump

Clogged fuel filter


My car bucks and surges under acceleration and won’t rev up

Bad or clogged injectors

Bad injector clips

Weak / Bad fuel pump


My car blows white smoke for a few minutes when I first start it up in the morning My car puffs a big cloud of white smoke every time I start it then it gets better.

Bad Turbo seals



My car blows out white smoke whenever I accelerate hard. 

Bad Piston Rings / pistons 

And / or 

Blown Turbo


My car runs hot on the freeway under load but is fine at low speeds 

Partially clogged radiator 

Too much spark advance 

Lean fuel mixture under load


My car runs cool on the freeway but gets hot in traffic 

Fans not working properly


My car gets hot as soon as the A/C is turned on. 

Front cooling fan not turning on 

A/C condenser in front of radiator clogged with dirt and debris. 


My car uses water but runs good otherwise 

Slight crack in head. It will only get worse


My car uses lots of water and runs crappy 

Blown or leaking head gasket

Huge crack that is drowning a cylinder