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Discussion Starter #1
- Wake-up Call -

It is not only possible, it's already been done. And I must have heard this a million times...

"But why would you want to do that when you can just sell your car and buy a turbo 4G63 like mine?".

Well @#$% you. I like my car. When's the last time you threw a timing belt and just slid another one on and drove along on your merry way? How much time does your car spend with its hood open? Can you change a clutch in 4 hours?

I'm going to be painfully honest. My motor has been smacked around a lot. It's been driven hard, run out of water, run out of oil, neglected, thrown 2 timing belts, and it just keeps coming back like that ugly chick you got drunk and had a 1 night stand with from the club. I could almost weld the hood shut.

New pistons? Machine work? Everything in the my motor is the same piece it was from the factory. No grinding, no boring, no replacement pistons, valves or rods. Just a standard set of rings, bearings and seals after 140K miles and all that abuse.

Reliability. Part for part, he 4G37 IS more reliable than a 4G63 of the same year. So before I get started, I'm going to be forthcoming with this - if you RACE a turbo 1.8, you defeat the entire purpose of having one, so if you want to race, buy a 4G63T to abuse, and leave some spare parts for us enthusiasts.

- My Research -

After I bought my 4G37, I was looking for ways to improve its performance. In the past 4 years, I must have gone through 9 passes at the local scrap yards in search of matching DOHC heads, and turbo options. After extensive research, many calls to Mitsubishi, Chrysler, part stores, supply warehouses, JDM scrap yards and a few psychiatrists, I was able to scrape together some parts to build a turbo 4G37.

The 84-87 turbo dodge colt and 84-87 turbo mitsubishi mirage came with a turbocharged inline 4-cylinder 4G32 motor. (some 1987s were sold as 1988s and came with that motor as well, depending on where you're from, but that's a shakey area, so I'm going to say '87 since that's when they stopped making them). The sister motor, the JDM G37B, was internally the same motor, but with a larger bore, giving it a displacement of 1.8L. Both of these motors have a lot in common with the 4G37 in your eclipse. In fact, if you wanted to, you coould just bolt one in your eclipse, but I wouldn't recommend it. Back to our history lesson.

For 1988, mitsubishi redesigned the motor, giving it a better flowing head, domed pistons, a dome-top combustion chamber and a few other goodies, prepped it for fuel injection and called it the 4G37. The manifolds from a turbo 4G32 bolt right up. The 4G32 turbo motor took a TC03-9A turbo. If you want to use this manifold, you'll want to have an adapter plate made to bolt up a different turbo. Preferrably a Garrett T3/T4. I was in the process of doing this when I came across a custom manifold (a one-off made by a local shop) for sale on a local board, and decided it would be easier to go that route.

Depending on what turbo and intercooler you buy, you may be able to use intake piping made for the 2.0. The throttle body elbow won't bolt up, but you can find silicone elbows to take its place. Exhaust work will have to be custom. If you lower the compression ratio, you should be able to get at least 15 lbs of boost in there without a problem. As with any turbo conversion, tuning is no longer an option. It's a requirement.

- P r e p -

First thing you need to do is improve the volumetric efficiency of your motor. The 1.8 has a volumetric efficiency of 78%. Meaning that when your piston reaches the botttom of its intake stroke, the air in it is at 78% of atmospheric pressure. DOHC motors run around 85-95% efficiency from the factory. You'll top out around there without sacraficing much driveability if you do it right.

Don't let the turbo 2.0 folks fool you. The 4G37 is choked, starved and chained to the ground from the factory. Simple mods like a 2.5" exhaust system will net much larger performance gains (HP/Liter)than they would on a 4G63. If you don't have a 2.5" system, get one before you go turbo - and a high-flow (or hollowed out) 2.5" cat (unless you plan to just cut it off when you convert to turbo).

Perform the free airbox mod on vfaq.com and remove the silencer. If you haven't replaced the capacitors in your ECU, do it. Unlike the 2.0, the 4G37 still uses distributor ignition. So if your ECU craps out under boost, you may still have ignition and go lean and detonate.

I strongly recommend an engine rebuild at this point, and installing a double head gasket to lower compression. I'm sure people will tell you to just buy different pistons. A head gasket is 15 bucks. The geometry of the combustion chamber, including the domes on the pistons was designed by professionals to keep the charge as cool as possible and keep detonation to a minimum. To lower the compression rate with different pistons, you'd need different shaped piston tops, which aren't going to work the way the thermodynamics engineers designed that combustion chamber to work. Don't go messing with factory engineering, unless you know what you're doing. Double head gasket will get you around 8-8.2:1 depending on the manufacturer.

- P a r t s -

* 4G32 Turbo manifold - This is off the 84-87 turbo mirage or colt. Should be about 40-50 bucks. They're difficult to find, but if you look hard enough you can get your hands on one. It bolts to a TC09A turbo, so you'll need to have it modified or have an adapter plate made to take a different turbo. You'll also want to have it ported and matched to your exhaust ports, because it's way small. The closer you can match the manifold to the exhaust port, the better.

If you can't find a manifold or you can't find someone to make an adapter plate for you, you'll need to have a manifold made. Mine was custom made out of cast iron tubing by a company which is no longer in business. It's more expensive than the 4G32 manifold, but then you don't have to port or modify it.

* Turbo of your choice - Perferrably a garrett. Mitsubishi turbos are great, but not that great. And they're a pain in the ass to pipe. You'd need to run oil and water lines and work with whatever angle the compressor housing happens to open up with. Garrett turbos are more flexible, and you can rotate the compressor housing to suit your angle needs and ease piping pains. Garrett turbos also have thrust bearings from hell and have proven more reliable than the Mitsubishi units.

Unfortunately, I didn't design my setup with "best-fit turbo" in mind. I bought a turbo that was capable of pushing the HP target I wanted and had a compressor map that I thought I could fulfill the air requirements for, and I set out to build my motor to reach that potential. It will be different depending on your exhaust manifold and the modifications to your motor. My exhaust manifold has much larger runners than a 4G32 manifold, and thus a larger turbo was in order.

You'll want a turbo capable of pushing the amount of air your motor will digest but not so big where it takes 5 minutes to spool. A T3-45 trim will work well, but every motor is different. I've heard of a lot of people opting for T28s in thier 1.8s, so that may be a good option as well. You're welcome to try your own combination. There's a java tool at

http://www.turbofast.com.au/turbomap.html

Bore and stroke are in inches 3.173 x 3.385, use 78% for the VE on a stock motor. Higher after mods. There's common values for intercooler and compressor efficiency on the page. Best match on a compressor map is when your RPM/Boost points are just under the surge limit.

* Wastegate - External is better, but internal is fine. If you don't plan to run a ridiculous amount of boost, and your turbo isn't the size of a peanut (like a T-25) then an internal gate should work just fine. Keep in mind, your motor is not flowing as much as a 4G63T and at a lower RPM (although that can be changed). If you choose an external gate, you'll need to have your manifold machined to accept it. That means grinding down a section and welding in a flange for it - make sure there's room in your engine bay for it (in that location). You don't want to be removing the PS pump or anything to accomodate it.

* Intercooler - Stock one, front mount, doesn't matter. The stock IC will work fine for what you're doing. Your motor won't flow nearly as much as a 4G63 motor because it's smaller and doesn't rev as high. I had a supra MKIV sidemount (way overkill) and lag was horendous. It has since been removed in favor of my "top secret" setup, which is closer to the size of the stock one, only higher flowing. That's all I can tell you about it until it hits the magazines.

* Piping - If you're using the stock intercooler, an aftermarket upper intercooler pipe for the 2.0 MAY work. The upper part that bolts onto the throttle body won't match up but you can get a turbo elbow that will fill the gap. With a little innovative thinking and some turbo couplings you can get an aftermarket upper IC pipe in there without a problem. Don't use the stock one. Aftermarket ones start at about 120.

The lower pipe, you can either have fabricated or use a length of aircraft grade hose. Make sure it's the tough stuff, not radiator pipe. It needs to have that hard treated surface that's heat resistant. It feels almost like canvas. Radiator pipe will just melt and peices of melted rubber will get sucked into your intercooler, where they will dry and clog up the core. Same with the turbo inlet pipe.

* BOV - I can't stress this enough. Stock 1G BOV, or one that routes back to the turbo inlet. Or you'll wonder why you're being left behind. If you vent your BOV to the atmosphere, you're upsetting the air/fuel mixture a LOT. Especially on a 1.8 - enough to drown the motor between shifts. You're also allowing your turbo to spin down. Routing it back to the turbo inlet will keep your turbo in a spool until you open the throttle again. And while ricers with thier loud coughing BOVs drown in turbo lag, you'll see your boost gauge jump from zero, right back to full boost after a shift.

* Fuel Pressure Regulator - You need a rising rate fuel pressure regulator. Don't use the one off the 4G63. That motor has a computer that's designed to accomodate boost. You don't. A rising rate regulator will raise the fuel pressure 1 psi for every psi of boost until the return end of the fuel rail is completely capped and your motor is consuming every drop of fuel the pump is pushing. If you need help hooking it up, let me know. This is only, of course, until you can afford a SAFC and a lot of fuel upgrades.

- C u s t o m W o r k -

* Downpipe. Someone needs to build a downpipe for you. If you're looking to make it easier for them, I'd recommend you get a turbo with an O2 housing. Mine didn't come with the O2 sensor housing, so I had my pipe welded to a custom flange that bolted directly to the turbine outlet. My Exhaust work from the turbo back cost me about $650 in parts and labor, which is about right for custom work here. Where you are, things will be different.

* Oil lines. Use braided steel oil lines. They sell them at hot rod shops. I tapped my oil feed off the place the oil pressure sender screws into. Just screw in a T-fitting behind the pressure sender. The oil return will depend on your turbo. You will need to drill, tap or weld an elbow onto your oil pan for the oil return. If you use an oil cooler, hook it up to the oil return from the turbo. That's where the oil is going to be its hottest. We want it at about operating temperature. Nothing below.

All turbo couplings and oil lines should be sheilded hoses. They aren't available over the counter at most auto part stores, and can be found at performance shops or aircraft supply shops.

No injector or computer mods are necessary for low boost. What is low boost? Subjective. Depends on your motor, ambient temps, etc.

Anything else you want to know, email it.

[email protected]

- Kalani
 

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Discussion Starter #4
More info for you 1.8 turbo freaks

There's a board dedicated to the 4G32/G32B Mirage/Colt owners, which provides some useful information on motor compatibility.

http://www.4g61t.com/forum/viewforum.php?f=16

This community also has more insight as to where you can find the all-important turbo manifolds and, of particular interest -

THE ADAPTER PLATES for the manifolds.

If you happen to get a late model manifold, you can get a ready-made 9B to 14B adapter plate for the 3000GT, which will allow you to bolt up mitsubishi TD04/05 14B and 16G turbos. The opportunity for a cheap turbo setup is there, it's just a matter of you making it a reality. I'm working on setting up a deal with an aftermarket manifold manufacturer to put some turbo kits together for us, but nobody's called me back yet.

- Kalani
 

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Discussion Starter #5
More info on the Manifolds

Got some pics of the maniofolds you'll need. In case anyone is sceptical about the bolt pattern, fitment, or how hard it will be to modify the manifold for a different turbo - here's the pics. As you can see, the 4G32/G32B turbo manifold uses a triangle bolt pattern (standard for smaller Mitsubishi turbos). It would be very very very easy for a welding shop to make and weld a flange to this to bolt on a T3/T4 or 16G turbo. Or if you're patient, you can wait and get the adapter plate from the site I posted up there.







Happy motor building.

- Kalani
 

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Can't wait to get the money saved up for a brand new motor and getting it turboed! Keep up the good work.
 

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Wow, its almost easier to turbo a 1.8 than a 2.0NT! I may buy a cheap 1.8 to turbo. Thanks!
 

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That is amazing work, can't wait to turbo up my 1.8 now :cool:
 

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Hey Kalani, about how much did your turbo mod cost you? BTW, ever since I heared about your turbo mod, I've been very excited to findo out more. Keep up the good work! ;)
 

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Congrats on building your own turbo system. It's nice to see that some people out there are still coming up with new solutions to problems and not just doing the "cookie-cutter" buildups that som many people do these days.

Have you dynoed this engine yet? I'd be interested in hearing what it puts down.

The other thing I wanted to address is this comment:

"I'm sure people will tell you to just buy different pistons. A head gasket is 15 bucks. The geometry of the combustion chamber, including the domes on the pistons was designed by professionals to keep the charge as cool as possible and keep detonation to a minimum. To lower the compression rate with different pistons, you'd need different shaped piston tops, which aren't going to work the way the thermodynamics engineers designed that combustion chamber to work. Don't go messing with factory engineering, unless you know what you're doing. Double head gasket will get you around 8-8.2:1 depending on the manufacturer. "
Essentially that's what you're also doing by throwing in a thicker headgasket. By doing this you're throwing off the factory quench settings which are highly important when cylinder temps/pressure rise.

It's kind of a catch-22 issue with this. With the thicker headgasket, you screw up the factory quench setting. With pistons, you have to rely on the manufacturer getting the deck shape and piston size correct for your motor.

The quench and dwell on the 4G63 motors is set more for turbocharging and of course performance..also why they're interference motors.

Congrats again on the turbo buildup and I'm anxious to hear what you can squeeze out of the 1.8

This whole topic in general has really captured my attention. After building 4G63 turbo cars for the past 8 years, I'm really starting to get burnt out on these things. Anything new is good. =]
 

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Discussion Starter #12
Thanks :)

It's kind of a catch-22 issue with this. With the thicker headgasket, you screw up the factory quench setting. With pistons, you have to rely on the manufacturer getting the deck shape and piston size correct for your motor.
It's nice to get positive feedback from "the other side" hehehe. The 4G37 came with domed pistons. The way I saw it, I could get shortter connecting rods, flat top or dished pistons, or just another head gasket. To me, adding another headgasket was the same as increasing the deck height, which didn't change the geometry of the chamber as much as different shaped pistons, and didn't change the behavior of the engine as much as shorter connecting rods would.

The quench area in the chamber is different, but since the pistons are domed rather than dished, they don't have that foot-ball shaped quench area, they have a boomerang shaped area. This doesn't appear to affect the engine's attitude toward detonation much. I've actually run the boost up past the limits of the fuel system and injectors (the car was going lean at about 7 psi) and it hasn't ever knocked or pinged. I'm actually thinking about taking the compression ratio back up to 9:1 because I've had problems with oil leaks appearing between the two gaskets. It was running 11 psi at 9:1 for a while (it hauled ass!) but I reverted to the double gasket setup after I chewed a rod bearing. I'm quite sure now that the rod bearing was just from running cheap oil. I only use synthetic now.

------

1.8 owners take note - you need an AFC for SAFE boost above 5 psi! And if you run a boost controller rather than actuating the wastegate from the compressor outlet, you can only get about 4 psi before it starts to go lean. You can get away with just swapping in the 250cc injectors from the 2.0 and get away with 5-7 psi on a boost controller without blowing anything up, but you will be pushing your injectors at or close to 100% duty cycle, which is not good for them. You really need 330cc (some galants) or 390cc injectors (automatic turbo eclipse) and an AFC.

Fuel pump is the same 100lph pump that everyone else has, so you shouldn't have to change that for a while, although it may need a rewire to run high boost (see VFAQ). I've rewired mine just to be safe. Unfortunately, dynojet hawaii is gone. There's just one dynomometer here now, so it may be a while before I get some HP figures. But 0-60 times are under 6 seconds.

- Kalani
 

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this is some great info. Ok, here is a question for you. How bad is the oil leak? I have the money to get custom made pistons for the car? so should i just tell them to make them set for 8.5:1 compression, because i really dont want to have that much of an oil leak problem.
:confused:
 

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Discussion Starter #14
oil leak

The oil leak was minor and is fixed. The problem with using 2 head gaskets is that the stock bolts can't squish them both down enough at the same time for them to work right. I've found that you need to torque one down to 60, then loosen the bolts, take it out, torque the other down to 60, then take them both, spray copper sealant between the two, put them both in, and torque the whole works down to 85 ft lbs (at which point the bolts will begin to stretch. I recommend new bolts, or ARP studs).

Other problems I've run into.

Too much detonation and you'll crack the head. Don't worry about busted pistons, the bridge between the intake and exhaust valve will crack first.

Too much blow-by will push the front crank seal right out of the slot and dump all your oil into the freeway.

- K
 

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Discussion Starter #15
Crankshaft Oil Scraper

Came across this guy who makes oil scrapers for our motors.

[email protected]

Oil is flung all over the place by the crank shaft, but it doesn't all land in the pan. A lot of it gets wound up in orbit with the crank shaft and smacked around by the rods and counterweights. Cutting through the excess oil may seem trivial but oil is far more resistant than air and this does rob you of some horsepower.

The scraper is basicly a plate between the oil pan and block that covers half of the oil pan and sits close to the rotating assembly and in effect "scrapes" this oil out of orbit, so it can drip back into the pan where it belongs. Installation is simple, but tedius. You need to take the oil pan off. Worth a few ponies for those looking for an edge. One is going into my new motor setup.

- Kalani
 

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Discussion Starter #16
Common Problems and Tips

Head Gaskets - Get ready to blow them. If you're using a single gasket instead of a double gasket, your twice as likely to blow gaskets. I use only felpro gaskets. They hold up better than anything else I've ever used. And they're the only ones I haven't blown. Torque to yeild. If you don't know what that means, torque to 70 in 5 even steps, run it, cool it and then untorque 1/8th of a turn and re-torque till the bolt starts to go down in "clicks". Stop before you snap the bolts. If you're overheating due to a leaking head gasket, it's easy to tell. The top of the radiator will be boiling hot (enough to burn your hand), and the bottom tank will be just warm to the touch. You can run a car with a leaking head gasket for about 15 minutes at a time without doing any permanent damage to the gasket. If you see your temperature gauge go over the middle, shut the car off as soon as possible, let it cool for 1 hour, and retorque.

Coolant Leaks - If you rebuilt your motor like a good boy, you may notice that after the first really heavy load, the core plugs may be leaking coolant. This is because whoever installed them did not use enough silicone sealant. You'll have to either remove them all and replace them, or put radiator sealant in and hope it doesn't clog your radiator core. It will run a little hot for the first 10-15 miles - don't let the temp gauge go past 3/4 of the dial. Keep the RPMs up to keep the system pressurized and eventually the leaks will stop.

Oil Leaks - It's inevitable. Under high cylinder pressures (more than 7 psi), you will leak oil from the driver's side front corner. Oil normally seeps out between the two head bolts on that side of the block. Not much you can do here if you don't want to remove the head. If you're assembling a new motor, spray the entire head gasket (or gaskets) with copper, let it dry, then coat the outer edge of the head gasket with a thin layer of high temp RTV. Make sure you only coat at max about a 1/4" in from the outside edges of the block.

Low Oil Pressure - You split your main oil supply between the motor, and a big-ass turbo. What did you expect. You NEED to run synthetic and change at least every 3000 miles. It's going to turn black in no time. If you're worried about low oil pressure, install a transmission oil cooler (3/8" line) that taps your turbo's oil drain line and put an extra quart of synthetic in the sump to keep it cool and this will keep it up a few PSi during spirited driving. Or, install an oil filter relocator kit and feed the inlet with an electric oil pump. I'm working on the plans this. Email me for details.
 

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More Turbo Options

Just more information for you turbo junkies.

The 15G is a direct bolt-on for the manifold above, and probably the best suited for a first-time turbo motor builder. Tap the heater hoses for water lines. TEC makes 15G upgrades for 3000GT owners. The 15G is a 3-bolt turbine housing flange, and a bit smaller in size to the 16G, but larger than the 14B that comes on 2.0L turbo DSMs.

http://www.stealth316.com/2-turboguide.htm#at

At the site above, is a list of turbos that will also fit that manifold, since it uses the same bolt pattern as the stealth/3000GT twins. Going this route will eliminate the need for an adapter plate or custom manifold. Mitsubishi turbos spin up quicker than T3 or T4 setups and are of a more modern design. Intercooler piping will present more of a problem, however, and T3/T4 setups will normally yield more top end power.
 

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Kalani I want to say that I am pleased with your concern with this setup. You seem to be a strong believer in keeping this a pure factual FAQ and you have my respect. Keep up the work.
 

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Let's make this QUICK and CLEAR!!

If you don't have any first-hand experience on this type of conversion, then restrain yourself from posting information about this swap in this VFAQ!!:realmad: Bench-racing/bogus info will not be tolerated or allowed in this vfaq or in any other one that is part of this site. Bogus, false or incorrect info only contributes to wasted money, time and personal injury in some cases. It will also get you in trouble with the moderating team.

Have a nice day and keep the tech questions up!!
;)
 

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Discussion Starter #20
More turbo goodness

This Edition of Turbo 4G37 Tips - Oil Coolers

There seems to be quite a bit of confusion about where to tap them, what they do, and exactly why you'd need one. Here's the scenario. You're driving on the freeway, and you decide you romp it and open up the throttle for a little while. You're cruising along at full boost for a few minutes, and eventually slow down and have to stop. Your oil light comes on. So you pull over and check your oil, and you realize it's still full. This is viscosity breakdown. The oil has been pushed to its limits and is now the consistancy of water. Not good. To prevent this from happening (or at least slow it down considerably) you'll want an oil cooler.

If you choose to run an oil cooler, you will want to tap it from your turbo DRAIN line, rather than your pressurized oil supply line. The oil pressure is low enough as it is. A large transmission oil cooler, and 1/8" hose will work for this application. Also, make sure the oil cooler is physically above the oil pan - best place to mount it is right behind the plastic shroud in the front of the radiator. This way, after the makes its way into the oil cooler, gravity assists in keeping it moving. Otherwise, you'll have pressure in the line.

Depending on which turbo you get, and the age of the turbo, some are less tolerant of pressure in the return line than others. If your turbo is one of these finicky ones, it'll let you know it pretty quick by blowing blue smoke out the tail pipe. If your setup does this after hooking up an oil cooler in this manner, the only other option for you is an auxiliary pump. This pump can be a low-volume fuel pump and can be placed inline between the turbo oil drain and the oil cooler to help force oil through the oil cooler.

Or, if you don't mind a plumbing mess and laugh in the face of oil leaks, you could tap another oil line into the pan to feed your electric oil pump, and insert a Y in the turbo oil return line to feed it back after it circulates through your oil cooler.


Prepare for the revolution.

 
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