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4D55 Performance Inc.

Mitsubishi 4D55 Performance Information

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The purpose of this thread is to provide as much information about performance upgrades for the Mitsubishi 4D55 engines. I will first start off with the turbocharges found on the 4D55 Turbo Diesel as well as maintanace, upgrades and troubleshooting. This information has not been copied or pasted from anywhere on the internet. This infomation comes from Mistubishi maintainence manuals, owners manual, dealer brochures, and most of all exprience. I would like to thank Mike Warme for his insightful input and expert opinion.

The 2.3 4D55 turbo diesel can be found on 83-85 Mitsubishi Pickups and Dodge Ram 50 which came with one of two Turbocharges. The first turbocharger used on the 4D55 engine was a Mitsubishi TC05. The second turbocharger used was a Mitsubishi TD04-09.

Mitsubishi TC05 Specs:

Part number: MD017658

Used on all '83 model Pickups


Journal Bearing

Oil cooled


Max PSI: 12lbs

Max HP and TQ: 80hp and 125ft lbs.

Mitsubishi TD04-09 Specs:

Parts Number: MD083373

Used on '84-'85 model pickups

Internally Wastegated

Journal Bearing

Oil cooled


Max PSI: 13lbs

Max HP and TQ: 84hp and 136ft lbs.

It is important to note that the TD04 and TC05 turbochargers are interchangeable but the oil supply fitting is different. It is also important to note that the TC05 is noticeably larger than the TD04, but both supposedly provide the same max boost of 13 psi. Rebuild kits are still available for both turbochargers but turbochargers should only be rebuilt by a trained professional with the proper balancing equipment.

Performance differences between the two turbochargers are debateable. But by using common sense it can be determined that the TD04 provides faster spool and less turbo lag due to the wastegate. Pickups equipped with the TD04 are rated as having 4 additional horsepower as well as 11 ft lbs of additional torque when compared to TC05 equipped pickups. Whether the difference in performance is directly related to the turbochargers is unknown at this time.

Maintainence for the 2 turbocharger is similar. Both turbocharges last about 50-70K miles between rebuilds. Simple maintainance and driving habits can reduce the chances of coking and premature bearing and seal wear. The secret is to keep the EGT's as low as possible. Ways to extend the life of the turbo includes:

1. Idling the vehicle for ateast 1 minute before turning off the vehicle.

2. Keeping the rpm's low while driving .

3. If applicable remove the egr system.

4. Use synthetic oil exlusively (no blends or dino oil).

5. Doing an Elephant Hose Mod (EHM) by relocating the crankcase breather hose so it does not run back into the air intake.

6. Add a 2 1/2" free flow exhaust and eliminate the resinator.

7. Properly maintain the cooling system and flush the radiator "annually".

8. Properly maintain your air intake.

9 Add a boost gauge

10. Add a pyrometer so you can monitor EGT's, this is your first line of defense and the most important gauge in your truck.

Things to look for as far as turbocharger wear include, oil leaking from the seals, bent of broken blades and play in the shaft. If you notice any of these problems, it is time for a rebuild.

Upgrades that are known to work and increase performance and turbo life include:

1. Upgrading to a TD04-10T watercooled turbo. This upgrade will require a new turbo, waterpump, as well as additional plumbing that can be purchase from the dealer in Japan. This upgrade will cost you around $900 for parts and fluids, installation is extra. According to ATX, by doing this upgrade you can expect to gain 16hp and 30ft lbs of torque. This will give your truck 100hp and 166ft lbs of torque. It is recommended that you upgrade to a 4D56 head before doing this swap, it is not necessary, just recommended.

Mitsubishi TD04-10T Specs:

Parts Number:

Used on '91-'98 model Pajeros

Internally Wastegated

Journal Bearing

Water and Oil cooled


Max PSI: 15lbs

Max HP and TQ: 100hp and 166ft lbs.

2. Adding an intercooler. Intercoolers will greatly reduce EGT's,which will help your turbo run cooler, not to mention adds 4 hp and 11ftlbs of torque. When combined with a watercooled turbo and a few minor pump modifications this setup will produce 104 hp and 177 ft lbs of torque.

Troubleshooting and FAQ's

I think my turbo is working but why can't I hear my turbo spool like a big Powerstoke or Cummins truck?

First, not being able to hear the turbo is quite common and is nothing to be concerned about as long as your truck is making boost.

So, before doing anything, add a mechanical boost gauge to your truck to make sure it is making boost, it should make 13psi under full load. The best way to do this is get the vehicle out on the open road in 4th gear and then step on it. If you fail to make boost, it is time for a rebuild.

So, I am making boost, now what? Then you're good to go and everything is in working order.

If you still want to gain more turbo whine address these additional issues:

1. You may not hearing your turbo is due to the small and restricted exhaust pipe. The stock exhaust is 2". If you removed the exhaust altogether you will have no problem hearing the turbo. If you add a 2 1/2"-3" exhaust this should help you hear the turbo spool.

2. You may not be hearing the turbo spool is your timing maybe off. To address this issue, you will need to make sure the vehicle is timed properly. You may also want to try advancing the timing a 2 degrees to see if that makes a difference in hearing your turbo spool.

3. Adjust the diaphram in the injection pump. If you are not experienced with Bosch VE pump then have have this done should be done by a deisel performance shop. I may post a how to on this in the future to save you some money.


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