4.0L SOHC Re-power questions

[USA1169]

I am considering re-powering a 1985 Hagglunds BV206 tracked troop transport (currently has a 136HP 2.8L Ford Cologne V6) with a 4.0L SOHC from a 2001 Explorer. The basic engine architecture is the same so this seems to make sense. Can anyone tell me what electronics (PCM, sensors, etc) and other parts (fuel pump?) I would need to pull out and bring over to support the engine?

Anyone out there done a re-power like this that can give me some pointers... what to avoid, what to make sure and do?

Am I nuts to try this or does this make sense?

Thanks!

 

[2000StreetRod]

2 Port Exhaust Heads?

Doesn't the 2.8L Cologne V6 have heads with 2 port exhausts (to be compatible with the older V4) instead of 3 port exhaust heads used on the 2.9L thru 4.0L engines? If so, you'd need the later exhaust manifolds as well as the electronics.

 

[USA1169]

2 Port Heads

Dale,

Good catch! It has the 2 port heads. See photos attached. I am planning on using the headers off my 2001 Explorer as well as the muffler on the assumption that a 4.0L will need to breath a lot more than the 2.8L did!

The biggest question I have still remains what electronics and sensors do I need to scavenge from my 2001 Explorer to make sure the engine gets managed the way it was designed? We use this thing to climb through over 6,000 feet of elevation and mixture control is a big deal.... that is one of the big reasons I want to go with fuel injection... the others are power and fuel economy.

Thanks for the help.

Henry

 

[2000StreetRod]

OHV vs SOHC

I believe the OHV is a better choice than the SOHC. It is less complicated, more reliable, and easier to maintain. Even though the power of the OHV is less than the SOHC, it's still better than the 2.8L. But apparently you already have an SOHC at your disposal.

I predict the electrical changes will be a much more significant challenge than the mechanical changes (power steering, engine cooling, intake and exhaust, vacuum, etc). You'll need the entire engine wiring harness for connecting to the PCM, fuel injectors, ignition coil pack, IAC valve, and sensors (IAT, MAF, TPS, ECT, DPFE, crankshaft position, camshaft position, knock, etc). Also, if you want the engine to run closed loop you'll need O2 sensors and their associated wiring. I don't know what to suggest on the transmission and security interfaces to the PCM. Another issue is compatibility with your current instrumentation (oil pressure, engine temperature, engine speed).

There is a tremendous amount of electrically associated effort required to convert a carb system to electronic fuel injection. I doubt it could be accomplished in a reasonable amount of time and the result would be plagued with numerous unreliabilities - the last thing you want at 6,000 feet altitude in several feet of snow far from any serviceable road. It would probably be a good learning exercise for a class of automotive engineering students but otherwise I wouldn't recommend it.

 

[USA1169]

OHV vs. SOHC

Okay, that is just what I needed. A good dose of reality! The rule Keep It Simple Stupid is a good one.

I suspected the electrical issues would be far more challenging than the mechanical ones. I am really good with electronics and process control systems... but a few of the things you brought up give me serious doubts.

I assumed that most of the sensors required to interface with the PCM would come over with the engine, manifolds, ignition systems and air box - all of which I planned on using wholesale. The tranny and security interfaces are probably simple to deal with once you know how they work.... the problem is figuring out how they work, the logic and the required signal types. That could be a major time suck. I can imagine that Ford is not eager to share what is required to overcome the security interface!

And you are right, the instrumentation will be a challenge as well.....

Do the earlier OHV V6's have simpler electronics? Just because I have a 2001 SOHC does not mean I have to use it for this project... I could sell it and find a low mileage older model OHV.

Is there a particular year/model that you or anyone else can recommend for this project? Are all the OHV versions fuel injected?

Thanks for the dose of reality!

 

[hunterdan]

I believe there is a way to use the SOHC with an earlier model computer and harness, off of say a 93-94 explorer, but not sure how or who did it. If that is true it would most likely be easier to do as there would be fewer sensors involved.
http://www.explorerforum.com/forums/showthread.php?t=159001

HTH
Dan

 

[2000StreetRod]

91-94 ohv

I assumed that most of the sensors required to interface with the PCM would come over with the engine, manifolds, ignition systems and air box - all of which I planned on using wholesale. The tranny and security interfaces are probably simple to deal with once you know how they work.... the problem is figuring out how they work, the logic and the required signal types. That could be a major time suck. I can imagine that Ford is not eager to share what is required to overcome the security interface!
. . .
Do the earlier OHV V6's have simpler electronics? Just because I have a 2001 SOHC does not mean I have to use it for this project... I could sell it and find a low mileage older model OHV.

Is there a particular year/model that you or anyone else can recommend for this project? Are all the OHV versions fuel injected?

I think that 91 thru 94 would be the easiest to utilize. Yes, most of the sensors will be part of the engine assembly. All of the 4.0L V6s are fuel injected. They all have the sensors that any fuel injection system require.

Before I spend any more time on this, let me ask if you are really in a situation to perform the task. Who owns the troop carrier and would they give permission for it to be converted by you?

 

[USA1169]

Engine swap or not?

Long gap here....

2000StreetRod, you asked who owns the troop carrier. I do. After what I discovered yesterday I am tempted to try to find a 91-94 OHC 4.0L and do a conversion. Is this something I should try or just stick with what I have?

I am now up in the mountains at our winter operation and I pulled the troop carrier in the shop and did a compression test. The results speak for themselves: (1)117 (2)105 (3)118 (4)112 (5)56 (6)22 on a 2.8L V6 Cologne that has only 8,200 km (estimated 400 hours) on it. I put oil in #6 and there was no change in readings.

So I pulled the heads expecting to see burned and sunken exhaust valves since this engine was made for leaded fuel and we have been using unleaded with additive. But the valves look perfect.... the exhaust valves on #2, #5 & #6 sit flush with the chamber where the others sit slightly proud, but we are talking 1/16" difference max (the standard vertical lip on the edge of a valve) and I can't imagine that would cause the low numbers.... but I should have checked the tappet clearances before I took it apart.

I set the heads flat and upside down, put the plugs in and filled the chambers with water to see if anything leaked by the valves. Not a drop passed. Granted there was no pressure but you would expect if the valves were bad enough for those numbers that something would leak past.

The cylinder walls still have hone marks and only a very slight ridge can be felt at the top. Also the engine does not seem to burn any oil, and there is no oil in the crankcase breather vent which goes right to the air cleaner.

There is no foam in the oil, and no sign of coolant leaks. So all the classic signs of a blown head gasket are not present. Except the two bad cylinders are next to each other... maybe the head is warped and/or the gasket was leaking between the two cylinders across the thin wall? Those two exhaust ports a siamesed on this engine so they would be prone to overheating... where #4 is a single port to the exhaust header. That could have caused warping or burned the valve seats down to where they would not close without adjusting the tappets.

So the question is should I have the heads done with hardened valves and seats to handle unleaded, bolt it all back together and add after market fuel injection to deal with altitude..... or go for a conversion to a 91-94 OHC 4.0L from an Explorer?

If I do keep the existing engine should I pull it and do the rings as well? That is going to be a lot of work given how ought the access is.

Thanks for any help or suggestions...

 

[2000StreetRod]

Block height

I don't know if the 2.8 block is the same as the 2.9 block but since Oct I've learned that the 4.0 block is 20.1-20.2 mm higher then the 2.9 block. There could be a problem with your bell housing mating with the 4.0 block.

I would think that your transmission and axle gearing are so low that you really don't need a lot more power.

As I recall at least one year of the European Ford Granada Mark III had the 2.8 engine with fuel injection and was rated at 150 hp. That is the same as the 4.0 rated power. It would be much easier to replace your engine with the fuel injected Granada engine than to replace with an Explorer engine. I've read that the 2.9 heads were prone to overheating and head cracking. I don't know if the same is true for the 2.8. If you decide to rebuild your engine I would check for head cracks before spending any money on them.

 

[repower]

I do this for a living if you hav never done this i think you are nuts i use a chevy drive train, give me your email and i will send specs and pictures

 

[USA1169]

Thanks for the offer, that would be great. Still running the original with a carb. Long past time to make the conversion. The deeper I got into the conversion electronics the more it looked like a mess. So I have been looking at a diesel engine and drivetrain... but I would love to stick with gas for easier starts in the winter. If you actually have made a conversion like this and have plans and photos I would love to see them.

So my e-mail address I am going to give you in a way that some spam-bot cannot find it and send me a bunch of junk. Just add "hfischer" to "gorge" with one of those @ symbols in between the first two and a ".net" at the end ;-)

Thanks!