Mitsubishi Eclipse FAQ

^*: Bearing manufacturer tolerance.

Oil pressure measured at the oil filter housing

• › 1000 rpm : 20-30 psi
• › 5000 rpm : 70-80 psi

Oil pressure measured at the head

• › 1000 rpm : 5 psi
• › 5000 rpm : 30 psi

These are mean values taken after warm up with 30 weight synthetic oil. Rule of thumb is 10 psi per 1000 rpm.

With balance shafts eliminated I've seen oil pressure spike over 100 psi even on part throttle. You can port your oil filter housing's bypass port to get things back to normal.

When using a forward facing OFH without provisions for oil cooling check for pressure before going havoc with a dremel as my oil pressure were within acceptable range out of the box. It's odd as all internal parts are the same between the two.

Eclipse vacuum at idle

• › Stock : 18-20 in.Hg
• › HKS 264/272 : 14-16 in.Hg
• › HKS 272/272 : 13-15 in.Hg
• › Crane 264/256 : 10-12 in.Hg
• › Crane 280/280 : 00-00 in.Hg

idle set at 750 - 900 rpm

NPT vs BSPT

NPT has one less thread per inch and a slight difference in taper angle compared to BSPT thread. If you try fitting a NPT in a BSPT thread you'll find it only goes in one turn. They're similar enough for one to force the NPT in there, which is not recommended. Rather, re-tap the BSPT with a NPT tap. Once you cut the threads with a NPT tap, both BSPT and NPT threads fit nicely. All taper threads found on the Mitsubishi Eclipse are BSPT.

No matter how tight you make NPT threads, a leakage path still exists. It is the function of the sealant to block the path between the male and female thread. Generally you want 2-3 turns with a wrench after hand tight. Take extra care not to cross thread. You should have 4-6 threads engaged, cut the thread depth accordingly.

Transmission mounting bolt size and under head length (UHL)

• › V : MF140471 : M10 x 65mm
• › U : MF140226 : M10 x 40mm
• › Y : MD740892 : M10 x 43.5mm
• › Q : MD706012 : M8 x 60mm
• thread pitch - 1.25mm
• applies to both AWD & FWD, M/T & A/T
• NOTE : 97+ A/T uses MF140271 for the "U" bolt.

Transmission mounting bolt location

The "Q" bolt (red arrow) is the only one that goes in from the block side and threads into the transmission.

The "U" bolt above the "V" is not used when you swap a 6bolt block to your 2G tranny.

I can't believe how many people ask about missing transmission bolts, so this is for anyone searching for info on what bolts they need. While you're at it check to see you have the dowels at V Q location. It's important you have them so that you can correctly mount the transmission to the block without binding. Always torque these two bolt before the others, else you risk a chance of cracking the bell housing.

1G Thermostat Housing & 1G '90 Air-cooled Oil Filter Housing

All small ports are 1/8"-28 BSPT, and large ports are 3/8"-19 BSPT.

The 2 ports for the cooler lines found on the 90 air cooled oil filter housing are M16 x 1.5.

Master cylinder and slave cylinder thread size and pitch

• › Master cylinder : 10 x 1.0, inverted flare, female
• › Slave cylinder banjo bolt : 10 x 1.0

Building your own stainless steel braided clutch hydraulic line:

• › Hose: AN-4 SS braided Teflon lined hose w/ 1x straight and 1x 90 degree AN-4 female end fittings. The 90 degree end is for the master cylinder side to dodge the clutch fluid reservoir.
• › Master side adapter: AN-4 to 10mm x 1.0 (3/8" - 24) inverted male(brake line fittings)
• › Slave side banjo: straight, 10mm banjo fitting and bolt w/ 2 crush washers.

This is for anyone swapping an auto to a manual and doesn't want to go through installing the stock lines. A full replacement SS line is available preassembled with crimp fittings from various vendors. I mocked up my own because they weren't available at the time and the stock hard line cost to much to ship. Using the stock OEM hard line is absolutely preferred!!!

• › Head: M10 x 1.25
• › Pan: M6 x 1.0 w/ 2 aluminum crush washers

Eclipse turbo oil feed line

With traditional journal bearing turbo, it doesn't matter if you feed the turbo from the head like the 1G or the oil filter housing like the 2G Eclipse. For ball bearing center sections read "Do I need an oil restrictor?".

When feeding off the OFH be sure to use the filtered oil port. The upper ports normally used for pressure sensors are oil before it enters the oil filter.

Oil return line

Since the oil drain is gravity fed, it is important that the oil outlet points downward, and that the drain tube does not become horizontal or go “uphill” at any point. AN-10 is the recommended minimum size.

Ball-bearing turbochargers can benefit from the addition of an oil restrictor, as most engines deliver more pressure than a ball bearing turbo requires. The benefit is seen in improved boost response due to less windage of oil in the bearing. In addition, lower oil flow further reduces the risk of oil leakage compared to journal-bearing turbochargers. The use of an oil restrictor can (but not always) help ensure that you have the proper oil flow/pressure entering the turbocharger, as well as extract the maximum performance.

Garrett recommended oil pressure specified for the oil inlet of the GT CHRA:

• › Idle oil pressure : 9 psi
• › 5000 rpm : 25 psi
• › Max oil pressure limit : 40-45 psi

4G63 Specific info:

When using a restrictor on an oil supply line that originates at the filter housing on the 4G63 engine, the .035" restrictor will reduce an engine with 25psi oil pressure at idle, 75psi oil pressure at 5000rpm to these Garrett recommended pressures.

For 4G63 engines that feed the turbo oil off the cylinder head, the .035" restrictor should be drilled out to .125". The normal 4G63 engine has low enough oil pressure at the head oil supply port that the .035" orifice is not required.

There are oil inlet fittings with built in restrictors ranging from .035in, .05in, and larger to accommodate your needs. It is imperative that the restrictor be sized according to the oil pressure characteristics of the engine to which the turbo is attached. Always verify that the appropriate oil pressure is reaching the turbo.

Some people have false beliefs that it's the last place getting oil in the head and/or it's used oil after going through cams lifters etc. The truth is, it's the first place in the head that gets oil and it's always filtered clean oil. Once the oil is used it flows down to the oil pan, it's never reused to lubricate other components. If you think it's going to act as a final protective barrier and makes you feel better, then why the hell not. Personally I see it as a gimmick that can clot and a waste of money. Just use a good oil filter on the block.

Heat Soak

Following a hot shutdown of a turbocharger, heat soak begins. This means that the heat in the head, exhaust manifold, and turbine housing finds it way to the turbo’s center housing, raising its temperature. These extreme temperatures in the center housing can result in oil coking ("coking" is burned oil that deposits on surfaces and can lead to blocked passages).

To minimize the effects of heat soak-back, water-cooled center housings were introduced. These use coolant from the engine to act as a heat sink after engine shutdown, preventing the oil from coking. The water lines utilize a thermal siphon effect to reduce the peak heat soak-back temperature after key-off.

Water Line Layout

The layout of the pipes should minimize peaks and troughs with the (cool) water inlet coming from a lower point in the cooling system up to the center housing.. To help this along, it is advantageous to tilt the turbocharger about 25° about the axis of shaft rotation. The water outlet needs to go from the turbocharger up to a higher point in the system and cannot have any high spots or "traps" in the line.

Water Line Sizing

There are no set flow requirements for the cooling water, since the majority of cooling in the center housing is done by the lubricating OIL while the engine is operating. The most important water-cooling takes place after engine shutdown, at which time the flow of water is a function of the thermal siphon and the flow rate is low. Therefore, the water lines to and from the turbocharger can be sized conveniently. The flow restriction through the center housing is negligible and so would not be of concern for the cooling system capacity.

Which side is the turbo's water inlet or outlet?

You can use either side for the inlet or outlet. It's a matter of convenience plumbing the water lines.

If the water-cooled turbocharger were installed without the water lines being connected, the unit will operate at temperatures similar to, or slightly higher than, the current non-water-cooled unit. Since the majority of cooling in the center housing is done by the lubricating OIL while the engine is operating. However, the water-cooled center housings could be run without the water lines connected with no adverse effects, provided the engine is cooled down adequately prior to shut down.

A turbo timer enables the engine to run at idle for a specified time after the ignition has been turned off. The purpose is to allow the turbo to cool down thus avoiding "coking". The need for a turbo timer depends on how hard the turbo and engine is used. Running at full speed and full load then immediately shutting down (heat soak) can be extremely hard on a turbo. Water-cooling of the turbocharger's center housing has essentially eliminated the need for turbo timers or extended idling periods.

At one time everyone insisted on using one, nowadays all think it's just a fancy gimmick. But, non-water cooled turbo still benefit from using one. There will always be situations when you need to shut off after a spirited drive.

The positive crankcase ventilation system (PCV) prevents the escape of blow-by gasses from inside the crankcase into the atmosphere. Fresh air is sent from the air cleaner into the crankcase through the breather hose, to be mixed with the blow-by gases inside the crankcase. The blow-by gas inside the crankcase is drawn into the intake manifold through the positive crankcase ventilation valve. The plunger inside the positive crankcase ventilation valve is designed to lift according to intake manifold vacuum, regulating the flow of blow-by. The blow-by gas flow is decreased during low load engine operation to maintain engine stability, and is increased during high load operation to improve the ventilation performance.

In boost situation where there is no vacuum in the intake manifold the PCV valve closes and the crankcase pressure escapes through the breather hose on the valve cover side running to the turbo inlet where there is active suction proportionate to how hard the turbo is working.

The factory setup is effective in removing moderate blow-by gasses and the water-fuel-oil vapors by reintroducing into the intake system and burning them off during combustion. The problem is contaminant build up in the entire intake track and is less effective in situations where you have a lot of blow-by whether it is due to bad ring sealing or just insane boost. This is when catch can are installed to overcome the fore mentioned problems.

Catch cans do have their downside and there are so many ways in plumbing it's hard to cover all of them but let try and see where this goes.

pic - First, the most simple and popular way is to remove the PCV and breather hose and route both valve cover opening to a vented catch can with a drain petcock on the bottom. If you have lots of blow-by for a purposely built track car then this is all you need period. If you have a 100K motor bleeding everything past your rings please get a rebuild and you won't have to empty your catch can every other day.

pic - Second, for the daily driver wishing to keep their intake track oil free. Adding a oil separator/filter inline to both the PCV and breather hose can be an easy solution.

pic - Third, any setup with a return line to send the collected oil back to the crankcase is a bad idea if they are not introduced back to the intake track where they can be eventually burned off. None of the catch cans marketed today have the proper filtration to separate clean oil from the combustion gas and water/fuel vapors. They don't separate anything, all it does is collect the oil and it isn't just the oil. The can acts as a condenser and will collect whatever it can, not only from the blow by gas but from the atmosphere since you have an open filter. Have you seen how nasty the collected oil looks like? Why pay to recycle dirty oil...