The Mitsubishi 2.6 Liter Engine
The 2600 Mitsubishi four cylinder was one of the most used engines of the time. This engine was put into minivans, the Dodge D50 trucks, Mitsubishi cars and trucks, the Conquest (a fast turbocharged version), Mazda trucks, forklifts, marine engines, Isuzus, and Hyundais.
I had a 1988 2.6 liter Mitsubishi engine in my Mazda B2600 pickup truck, and have had two Dodge Caravans with that engine. All had that Mikuni carb. Every possible thing had been done to improve drivability/emissions with the carb, and it had gotten so complicated it was almost not serviceable. The carb is electronically controlled and uses the oxygen (O2) sensor for minor adjustments, like many other cars of that time. Weber does make a replacement for this carb, for less than $300.
The choke is almost impossible to service. The oil filter is on the "back side" of the engine. This engine, like the 3.0, was sourced out to help Chrysler in a engine shortage. It was not originally designed to be installed in a FWD car. The trans is the same dependable old three speed automatic used on all the cars and vans, but with the 2.6 bell housing.
All accessories aside, the basic engine is good. I put over 200,000 miles on one before the balance shaft chain broke. Got the engine rebuilt and drove it another 85,000 before selling it. I never had any trouble out of the valve seals. The chains started making noise, and in typical "I drive a Dodge, it'll go away" mentality, I ignored the rattle coming from the front of the engine. I did not realize that the oil pump is driven off of the balance shaft; when the chain got loose and came off the sprocket, my oil pump quit turning.
The major problem is that the chains ride on guides, aluminum bars with about a 1/8 inch thick plastic or Teflon wear surface. This Teflon lasts a long time, but once worn through, the chains rubs right on the guide and starts to make noise. The guides then really start to wear off, letting the chains get loose fast. If I had changed the chains when they started making noise, then engine would have not suffered any damage, and I would have been out the $99 for a new timing chain kit (which includes new guides).
I installed the new chains after they went, but upon restarting the engine, it had low oil pressure because the crank bearings had gotten scuffed. Other than that, I never really had any trouble out the engine. I never replaced the carb, I did have a new head installed under warranty when it was about a year old. I was pulling a 6000-pound trailer through the Ozark Mountains and overheated it. They replaced under warranty.
I have always wanted to get a Conquest and pull the turbo/ fuel injection off and install it on one of these minivans. I have seen many Conquests running low 12 second 1/4 mile times.
I bought two of these engines in minivans. A 15 year old minivan is just that. If you look it over, paying attention to how it starts cold, funny noises, and look at all those hoses under the hood, and all looks good, buy it. If it lasts a year or two, (and there is no reason why it would not) you are money ahead. When it goes, if the body is in good shape, you can drop in any engine you want from a donor van. Just remember that going from carb to FI will require you modify the harness and the fuel tank.
Evan MacDonald added:
The 2.6 was noted for cracking heads (steel jackets around jet air valves in an aluminum head, not a good idea) and the turboed versions were even worse, but the Canadian truck versions didn't have the jet valves (mine even has hydraulic lifters) and work very well with the turbo.
They also were bad for warping heads, this was caused by not re-torqueing the head after putting a few miles on the engine, some were not checked at the factory, thereby allowing heat to wreak havoc on the aluminum, another problem that didn't present itself until late in the life of the vehicle.
I recently rebuilt the engine in my truck, lowering the compression to 7.9:1, and adding the fuel injection, turbo, and the intercooler. I have somewhat more horsepower than stock (112 stock, 205 on the dyno now). The turbo may be useable on the FWD vehicles with this engine, the fuel injection system isn't the best, but is a little better than the carb that came on my truck.
We have a vacuum diagram below from a 1986 2.6l Canadian Caravan, scanned by Norm Petersen and sent to us by Scott Armstrong.
Turbocharging the 2.6
Saw your brief personal note about turbocharging the Dodge/Mitsu 2.6 for a truck. I have built a turbo Dodge D-50 4wd 5spd. using an 85 Mitsu Starion turbo set up, fuel injection, wiring harness, intake and exhaust manifold. Yes, the Starion FI system is a little cranky, and the FI control system is not the best Starion system available (probably the worst), but the donor car was only $300 complete. I added an aftermarket head (AMC) with a thicker deck, more cooling passages, and NO JET VALVES. This truck ran like a scalded dog with stock engine specs.
I am currently building an 87 Dodge Raider 4wd 4spd auto with an 89 Dodge Conquest FI and intercooled turbo. in both cases I used the stock computer and wiring harnesses. The biggest problems with the swap were the oil pan (the Starion/Conquest pans won't fit due to interference with the front differential, and the stock truck pans don't have the fittings for or have the fittings in the wrong place for the turbo oil lines and dipstick. I solved this one by cutting the fittings out of the turbo pans and welding them into the truck pan.
The only other problems were with the wiring harnesses mating up for stuff like 12V power and speed sensor connections. The turbo down pipe and catalysts fit under the truck, and are only about 2" too long to bolt straight up to the truck exhaust. This was another simple welding fix. The oil pickup tube in the pan had to be extended about 3/4" to have the correct reach. I used the stock turbo oil cooler, re-cored the radiator, and will use the stock intercooler on the Raider. Future plans include a custom multiport intake and programmable FI control system, probably a Simple Digital Systems FI and ignition timing controller.
As engine swaps go, this one is very simple. I have no experience with this swap in FWD cars, and do not recommend it due to suspected driveline weakness. I am also reluctant to recommend it for manual transmission trucks, as I have had a transmission failure in the D-50 (which may not be torque load related). The folks at Mitsu customer service asked some questions of the teck folks, and assure me that the 4spd auto in the Raider will handle the 250-300 ft.lbs. of torque the modified turbo engine will produce. This leaves only a few RWD 2.6 cars and a fairly large number of trucks and SUV's as candidates. I'll be happy to answer any questions I can.
The notoriously weak head in the 2.6 fails for a lot of reasons. I note that you touched on one when you recommended re-torquing the head. I further advise that you replace the head with the aforementioned aftermarket head (about $500), throw away the head bolts after each tightening (they are really crappy torque-to-yield type) or better yet, replace them with an ARP head stud kit, REPLACE THE CATALYST(S) (they get clogged up very easily by an engine with incorrect air fuel ratios or misfiring or water/oil leaks from a blown head gasket and heat up the head near the exhaust ports, causing warping and loss of head bolt clamping force), and never fail to clean out the head bolt threads with a bottoming tap in the block and a wire brush on the threads.
The aftermarket head has survived the abuse of the turbo and several overheating incidents during shake-down with no ill effects. Overheating a stock head just once is an almost sure ticket for a blown head gasket.
I have found the balance of the stock parts to be very strong, with the exception of the balance shaft assembly. I use a balance shaft eliminator kit on all the 2.6's I build, but you have to have the reciprocating assembly balanced statically and dynamically for this to be completely satisfactory. The cost for balancing is about the same as for the new balance shaft drive and tensioning parts.
Many frustrated owners simply want to swap in another engine. Justin Kaszowicz wrote: "The easiest swap would be a 2.2 carb engine. You can also carb a 2.5 if you use an intake off a carb 2.2 [there was never a carbureted 2.5]. You would need the harness from a carb 2.2 van as well as a tranny. If you use the A5220 or a weber down draft you can get an aftermarket ignition and not have to worry about rewiring the compartment. If you are going manual definately put a A520 in there.
In my area there are loads of vans in the junkyards especially 84-86 vans. This is great for me since mine is an 84. The only problem is that out of all the vans there is a total of 2 in all the junkyards with a 2.2.
I have a 2.2 in my van with a A520. It does not have any power but the engine runs great. I feel it has more zip than a 2.6 auto. I have heard of guys with vehicles with 2.6's swapping in the multiport injection from newer 2.6 from like Isuzus etc. When installing a manual you have to either fabricate a rear mount on the K-frame or get one and have it welded on. Mine was welded on twice. Once when my dad hit the Kframe off a divider ( The new Kframe was from an auto) and when I did my A520 tranny conversion when the POS A525 went got the second time. The A520 has the mount in a different place.