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2 Posts
There is one thing about this post I’d like to change, a turbo kit (headers, and exhaust), but I’d need some questions answered if I do it. Pm me if you’re interested in it or have experience with the build.

132 Posts
I read that on a GS the automatics don't have room for a long cai due to transmission size ? So only a short ram is compatible , is that bogus ?

2,892 Posts
Yup not too hard to put on, just finding the bolts to the intake resonators, gonna need to take off the drip panel and that’s about it

Make sure to roll the o ring on the MAF sensor up so it seals right

23 Posts
I just recently bought my 2007 GT Spyder and even before laying the money down, did some research, here, disappointingly I must say, because of the dream smashing facts about turbos and whatnot. But made the purchase regardless's a convertible which makes complete sense in New England.

One thing noticed when researching CAI's there are quite a few wolves in sheep's clothing, meaning many are called CAI's but are actually short rams in disguise. Do you have a model number for that suggested Injen? Would it be the INJEN COLD AIR INTAKE SP1873BLK?
this is the injen intake I used on my 07 spyder and it has been amazing. no issues.

2008 Eclipse GT
124 Posts
New member here. I bought an '08 GT-P last November. Timing belt is done. Looking for a new stereo and a sporty muffler.

Premium Member
2009 mitsubishi eclipse gs 5-speed
21 Posts
I just had a life changing moment and I said to myself I am going to do what I truly wanted to do and that was try to make a car I admired into a beast.

Always loved the look of the 4G eclipse(i own a 2009 GS manual, purchased 2 Mo ago), but I hated myself when I let my 2G 1996 GS go in 2005.

To sum up what I've read in this new members section, 4G eclipse is not the model to own if the objective is to tune because of cost efficiency, correct?

Just want to know so I don't waste the time I have left in trying to accomplish something that is absolutely impossible.

1 Posts
sigh this hurts, but thanks for sharing. Wish I would’ve found this before I bought my eclipse. Beautiful car no doubt, but I wanted to learn more about cars and do crazy shit with mine. Doesn’t help that since I’ve gotten this car I’ve learned a lot more and read and read. I’m 20 and I don’t got the kind of money to basically rebuild the entire engine. But hey, I can rice her up just a little and make her reliable while I have her.

Basically Stock
2009 GS Turbo. 2007 Mid Engine GT
7,045 Posts
sigh this hurts, but thanks for sharing. Wish I would’ve found this before I bought my eclipse. Beautiful car no doubt, but I wanted to learn more about cars and do crazy shit with mine. Doesn’t help that since I’ve gotten this car I’ve learned a lot more and read and read. I’m 20 and I don’t got the kind of money to basically rebuild the entire engine. But hey, I can rice her up just a little and make her reliable while I have her.
If you wanted to go crazy with it, it's fine. It's when you want to do cookie cutter builds like you see on factory turbo cars or big displacement cars, that you run into issues. Eg, I've got a turbo GS and a mid engine GT. Turbo GS was less effort than a high power NA build, that's for sure. Mid engined... Is costly.

Welcome to the club.

resident crossplatformer
1,430 Posts
sigh this hurts, but thanks for sharing. Wish I would’ve found this before I bought my eclipse. Beautiful car no doubt, but I wanted to learn more about cars and do crazy shit with mine. Doesn’t help that since I’ve gotten this car I’ve learned a lot more and read and read. I’m 20 and I don’t got the kind of money to basically rebuild the entire engine. But hey, I can rice her up just a little and make her reliable while I have her.
take your time and do the low hanging fruit first, engine builds take a lot of time, other mods can be costly, but above all, have fun, don't let a passion become a job. I started really doing work to my car at 18, and now, 11 years later, I'm still not done with my engine build that I started in 2012 for a large number of reasons, most importantly, I want it to be fun and combined with life factors, it was getting less fun, but now I'm fully into it again and my current stage will get done within a defined timeframe rather than 'when I feel like it', and I'm planning the next stage beyond that. Also doing stuff (building cars, robots, being a shade tree mechanic you pay in booze) like this has more practical benefits, it helped me get my current job, which pays. You can do it, take your time if you have to

5 Posts
So you just bought a fourth generation Eclipse... your first sports car! Possibly your first car, period! You're gonna pimp it out, Need for Speed style! Body kit, turbo, AWD conversion, engine swap, 500 whp, nitrous, the skys the limit! You're going to be an Evo killer, smoke all the domestics, Subarus will cry when you zip by, Honda boys will be filled with rage! You don't care how much money it will take, or how long, you love this car to death! You wan't to be a real rubber-burnin', turbo-screamin', lap-killin' machine! No one can stop you! It's the best! It's the best sports car! IT'S THE BEST!

...Slow down there, Tex.

I, too, was in your position when I first bought my GT. I wanted to do all these awesome modifications, price and time be damned. The depressing truth is, though, that these things simply aren't possible for the average Joe like you and I. Think: If these modifications were so simple and do-able by the brand new car owner, why isn't every single 4G eclipse turbo'd AWD with 500whp? A good rule of thumb to always remember; if its cool but not many people do it, there is probably a very good reason.

That being said, I've compiled a list of topics that almost every brand new 4G owner brings up in their first month (or even week) of ownership. Bare in mind... this car, and by extension this forum, has been around for 12 years. When we tell you something isn't feasible, or a bad idea, or simply won't work, we aren't blowing crap out of our ass because we hate you and don't want you to succeed... We tell you because we're trying to save you time, money, and most of all, heartache. We all love this platform and every single 4G made, so when we give you advice its because we don't want another botched up 4G on the road that ends up being scrapped because the engine blows from terrible modifications. Please listen to us! :wub:

At any rate, onto the topics (in no particular order):

- I want to Turbo/Supercharge my Eclipse!
This is the most common topic that comes up with every new owner, but the fact of the matter is... you're not going to turbo your eclipse. Wait! Before you start getting angry and shouting "you're wrong, I'll do whatever it takes!" hear me out... There are a few different reasons.​
  1. There does not exist a bolt-on turbo kit for our vehicle. At all. It doesn't matter where you saw it (especially eBay!). In the GT, there is not enough room to fit an effective turbocharger, so most people who turbo their Eclipse run a rear mount turbo setup. As for supercharging, there is a supercharger kit made for our car, but RIPP stopped producing them years ago so you can only find them used. They are incredibly rare and very expensive, yet still require some degree of fabrication. The GS is a little easier to turbo since there is more room in the engine bay, but still no such kit exists.
  2. Fabrication is required! You will have to cut, weld, delete, drill, and modify many parts and pieces of your engine bay and all of it's components. Unless you have years of automotive experience, a garage full of tools, and a car lift, this simple won't be doable for the regular schmuck like you and I.
  3. Low boost! We are blessed with having stock forged rods, but it means nothing if our heads aren't. The most boost you will be able to run SAFELY is around 6-8 psi. Once you get to 10-12psi, you start to damage your stock internals. You will have to get forged internals, which no one makes for our platform, so you will have to find a fabrication shop that will blueprint and create some for you. Be ready to shell out lots of $$$
  4. Speaking of cost, if you're wanting to fabricate your own turbo, it's going to cost you about $5k-$6k for an extra 30hp, even more if you aren't doing ALL of the work yourself. At that point, it's far more advantageous to simply buy a newer, faster car.

If after this list, you're STILL determined to turbo your eclipse, it's not impossible! There have been a handful of past members who have turbo/supercharged their eclipse, and most have threads detailing their builds. Study study study! If you're shelling out this much money, you NEED to know what you're doing. What works, what doesn't. Stand on the shoulders of giants... listen to the experiences of members with forced induction builds so you don't make the same mistakes they did!​

- I want to engine swap my Eclipse
The same principle applies as a turbo build, but to a much greater degree. This is possibly the most difficult project you can mechanically have on any vehicle platform. When you engine swap a vehicle, you aren't just swapping engines. You have to swap drivetrains, transmissions, fabricating the frame and motor mounts, just to name the big stuff. To boot, our vehicles have transverse mounted engines, meaning the crankshaft is parallel to the axle. In other words, it's sideways! This is the most common engine application for FWD/AWD vehicles. Meaning, you're not going to swap a longitudinally mounted engine such as an LS or a 2JZ into your eclipse. The transmission will stick out the side of your front driver side wheel!​
What about swapping a 6G75 into a GS?
One member did manage to turn his GS into a GT, but it cost him far more time and money to convert it than it would have cost to just buy a brand new GT outright. If you're simply looking for more power, it would be cheaper and easier to trade in your GS for a GT.​

What about the engines from previous generation Eclipses?

The only commonality between the 4G and the 1G, 2G, or 3G, is simply the name. They are all different cars built on different platforms using different engines, and in no way can be directly swapped with each other without heavy fabrication.​

- I want to convert my Eclipse to AWD
A small handful of members have managed to AWD convert their Eclipse using the drive train from the Endeavor, which is built on the PS platform and uses the 6G75 non-mivec engine. It's compatible, but in no way means it's a direct replacement. Heavy fabrication was involved, ECU tuning, only came in the automatic transmission, and there was still power loss considering it was never meant for a performance car and has only a 50/50 power split. Like the broken record that I am, it would cost more to do this than to just buy an AWD Evo 8/9​

- I found X aftermarket part on eBay for super cheap, Should I get it?
A big fat stinking NO. If you're new to car modding, it is widely accepted that eBay is the WORST place for auto parts that have to deal with functions of the vehicle operation. This does not apply to used OEM parts, or aesthetic things like shift knobs and spoilers. We're talking thinks like intakes, catbacks, headers, turbos, belts, things of that nature. Think: WHY is it so cheap? No business sells their products for stupid cheap unless there is a REASON. Otherwise, they wouldn't be a business anymore. eBay part sellers will acquire aftermarket parts made by reputable manufacturers (and even family-owned local businesses), reverse engineer them but change them slightly to avoid copyright, then mass produce them in cheap food-grade stainless steel that degrades and corrodes quicker than aluminum in salt water. They do this because they KNOW the ill-informed will buy these crap parts that won't fit, require fabrication, and only last a few thousand miles, and they make off with pure profit. This hurts your wallet, your car, and the legitimate modding support for our platform. The only people who benefit from these parts are the sellers. Cut and dry!​

- What's all this hullabaloo about changing the timing belt?
Because of the age of our cars (2005 feels like just yesterday :ugh:) it is EXTREMELY important you get this replaced ASAP if it hasn't been already past 60k/120k miles for the 2006-2008 or 100k for the 2009+. All of our members will hammer this into you until you get it done, because it is simply that important. For the experienced car guys, you already know how important the timing belt is. For those who are new, heres a quick rundown:​
For both the GS(4G69) and GT(6G75), we have single overhead cam interference engines with 4 valves per cylinder. These valves look like upside down Ts that move down when they open. When your cylinder moves downwards to suck in fuel-air mixture, 2 of these valves open to allow to allow the fuel and gas to enter the combustion chamber. Once the piston begins to compresses, the valves close and the mixture is ignited. Once the piston returns to the bottom again, the other 2 valves open to allow the combusted gasses (also known as exhaust) to exit the combustion chamber through the exhaust manifold. All of this happens in a fraction of a second. If you're driving at 2000rpm, your crankshaft (that all your cylinders are connected to) rotates a full 360 degrees 33 times per second! And that's a low RPM! So what keeps these valves timed to open and close with the cylinder?​
Yep. You guessed it. The timing belt. If the timing belt snaps, your valves fail to close in time, and the cylinder slams into your open valves. Your valves will bend, your cylinder head and camshaft will be damaged, and your crankshaft and piston could be screwed as well. What does this mean for your wallet? $5-6k engine rebuild. No thanks. Avoid the headache, get your timing belt changed.​

- I need a general maintenance replacement part. Do I HAVE to get OEM? Dayco is so much cheaper...
ALWAYS buy OEM for running components that you aren't upgrading with aftermarket. As with eBay parts, the same principle applies. Chinese manufacturers take an OEM part, reverse engineer & blueprint, change the design slightly to avoid copyright, and mass produce with garbage materials. You may see these advertised as "OEM spec". The key word here is SPEC, this means its not true genuine OEM. These parts will last half of what OEM does (if you're lucky), and most of the time won't fit properly.​
For instance, say it's time to change your timing belt. An OEM timing belt is $110, whereas rock auto has a third-party belt for $20. Well geez, why would you even bother with expensive OEM? Just get the cheap part! ...heres the catch. As explained above, the timing belt is a CRITICAL part to your engine operation. If it fails you're out of a car and it's going to cost your first born to get it running again. While an OEM timing belt needs replacing roughly every 90-100k miles, this chinese belt will need to be replaced at 40-50k. Then you have to factor in the cost of buying another belt, and paying another $300-$400 to the mechanic to get it installed. Save yourself some money by spending a little more, an extra $90 isn't worth the added mechanic time and the possibility of your entire engine dying prematurely.​

- I want to run a short ram intake.

The first mod most people do when getting any car is an air intake. Understandable, as it's cheap and simple to do. However, you MUST avoid short ram intakes if you want any kind of improved performance. The 4G69(GS) and 6G75(GT) both run EXTREMELY hot. The point of a cold air intake is to get, well, cold air into the engine. Colder air has more compressed molecules, therefore more can be crammed into the cylinder, equaling a better fuel-air mixture and better combustion, which means more horsepower. However, this is completely negated if your intake is sucking in the hot air circling around your hot engine. The more technical members who work in automotive engineering have proven that short rams perform worse than the stock air box. You are spending $150 for your vehicle to perform worse... why? Stick to cold air intakes that pipe downwards behind the fog light, they perform much better!​

But I live somewhere where it rains a lot...
Many manufacturers make hydro sleeves for air filters that drastically reduce the possibility of water entering the filter without restricting airflow. These work extremely effectively and are pretty cheap. I live in Arizona where it gets real bad flooding in the summer. I've ran a hydroshield on my intake with no problems, just keep your splash guards on!​

What about a short ram with a heat shield?
Heat shields, as cool as they look, do little to nothing to prevent high air temperatures, at least not nearly to the same degree as a piped cold air intake.​

I found this really cool intake called the Weapon R intake... I want it!

This has been a notorious intake with the 4G for many years now, for being so BAD. Horrible build quality, fitment issues, causes MAF sensor problems, and bogs your engine down with hot air since its a short ram. Almost every member who has bought this intake ends up replacing it within a very short time. This "vortex wind tubes for 3x more air" babble is complete crap. It's literally just a pipe with a filter. Save your money!​

Well fine, Mr. fancy pants intake know-it-all... which intake should I get?

This could be considered an opinionated answer, so take it with a grain of salt, however it's pretty commonly accepted that members have had excellent luck with the Injen CAI for the GT and the DC Sports CAI for the GS. As with any part, do your research! :idea:​

- Coilovers or lowering springs?
Coilovers for performance, springs for looks if you're under 120k. Coilovers allow you to adjust ride height and compression, and are necessary for any kind of improved performance suspension work. Lowering springs are cheaper and simpler to install, but past 120k miles, they will blow our your stock shock absorbers due to the added strain on 10 year old parts. When your shocks give out, it will cost more to buy replacements than it was to just buy the coilovers in the first place, so bare this in mind when making your decision.​

- I want to make my GS a GT killer!
This is doable, but will take a lot of money and a lot of work. Weight reduction, motor mounts, intake, exhaust, headers, nitrous, tune, just to cover the big stuff. If 4 bangers are your thing, by all means! However, please be aware that the 4G69 was never intended to be a performance engine. It will cost more to make your GS as fast as a stock GT than it would be to just outright buy a new GT. Does this mean your GS can't be as fun? Of course not! If you still enjoy your ride at the end of the day, that's all that matters. There are more GS members than there are GT members on our forum, and they all enjoy their rides just as much as the GT crowd.​

- I want to make my GT an Evo killer!

Same rules as above apply :wiggle:​

- I want to have my eclipse painted
Automotive painting is extremely costly, time consuming, and meticulous. Because of this, it's not cheap to have a vehicle painted. Depending on the paint you choose and the shop you go to, you're looking at anywhere between $3k-$8k for a full body paint job.​

That's expensive... can't I just buy a few cans of paint from wal-mart?

Do you ever drive around and see those beat up Civics with blotchy paint jobs that look like someone took a rotary grinder to the entire body then rubbed the entire thing in acetone? That's a rattle can paint job. Painting your car on your own WILL not work. Period. You would need gallons of paint (equating to dozens upon dozens of rattle cans), a proper sprayer, a clean environment free of dust and particles, power sanding tools, and lots and lots of time. Stripping, sanding, priming, painting, clear coating, buffing, compounding, waxing... all to not turn out quite right. Avoid this!​

What about plastidipping/viny wrapping?
Vinyl wrapping is a great alternative to painting, as it's removable and looks just like a regular paint job. However, much like painting yourself, it is not a task you can do on your own. Unless you're a automotive vinyl wrapping specialist, you will need to go to a shop to do it, lest your car be covered in air bubbles and tears. A full vehicle vinyl wrap costs roughly the same as a paint job, so take that as you will.​
Plastidipping is also a good alternative, Its cheaper and removable. However, much like rattle cans, you would need dozens and dozens of cans to paint your entire car, a particle-free painting space, and a lot of time. They make kits specifically for painting your entire vehicle. It is easier to plastidip a car than it is to paint it, but unless you are experienced with plastidipping, it is not recommended doing on your own without practice and research. I have heard mixed things about full body plasti jobs. Some say it works great for years, others say it lasts no longer than a few months. Research!​

- I want to install a body/lip kit
I'd be lying if I said I didn't want a body kit too. I think most 4G owners do. Out of all the exterior aesthetic upgrades, this is the most doable. However, that doesn't mean its any cheaper or easier. Much like painting your car, body kit pieces will need to be painted by a professional, especially if you're paint matching with the rest of your ride. It's not completely out of the realm of possibility to paint parts on your own, many members have done it, but these members have painting experience and a good idea of what they're doing. Usually, it will cost them only slightly less than to have get it professionally painted (depending on the body shop).​
As well, no body kit will ever fit perfectly when you first buy it. Almost all body and lip kits will need to be fabricated to fit. Cutting, filling, sanding, and shaving, and whatever else necessary to get it to fit. A body shop can do this for you, however, but you're looking at a $1500-$3000 job for a full body kit install and paint, depending on the shop and the paint used.​

- I have CEL code P0421... do I need to replace my cat?
Not necessarily. P0421 is an infamous CEL code with our cars. Out of the factory, Mitsubishi unintentionally tuned our vehicle to run too rich. Because of this, your rear downstream sensor (second O2 sensor on the rear manifold on the GT, not sure about the GS) is freaking out at the rich exhaust moving through the manifold, and throws a code. While this does cause slightly more damage to your catalytic converter than a leaner running Eclipse would, it's nothing to freak out about. You can read more about it here. Most people will replace the sensor and cat, this may work for a short time (a few thousand miles) but the code will come back, because the sensor is not the problem. There are a few solutions you can do:​
  1. If your vehicle is under 80k miles, Mitsubishi will reflash your ECU under a manufacturer recall.
  2. Spark plug defoulers as spacers. This is the easiest and most common fix for this problem. Put 2 between your manifold and the O2 sensor, and not as much exhaust will get to your sensor. Therefore, it won't realize the exhaust is rich, and stop throwing the code. Obviously, this won't stop your engine from running rich, but it will stop the annoying CEL code. Here is a guide on how to make the spacer!
  3. Aftermarket headers. These usually include spacers, and function the same as a spark plug defouler.
  4. Get a tune. Hackish and Stayer both offer tunes for our platform, and along with improving performance, will also tune out the faulty rich mixture.

Hopefully this list will have answered a few questions and topics you may have been wondering about. I will continue to add more topics in the coming weeks. As always, for topics that have not been covered, we are always here to help. I love this platform, and I'm ecstatic to be able to serve such an awesome community of car enthusiasts. Happy modding! :topback:
I appreciate all the time you took into this. Damn!
Looking everywhere and researching for the p0421 code. And trying to figure out what kind to get. There's 400 dollar ones and then 1000 plus ones. (Magnaflow) unsure which to get. Car has 113,431 miles on it. I've deleted code numerous times.
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