Diesel High MPG cruiser

So I bought the 96 wagon with the intention of swapping a 6.5 Detroit Diesel into it. I am aware that it would be more intelligent to use a mechanical, but I intend to splice the wiring from a 96-97 Chevy/GMC truck into the wagon to maintain most functions. The problem is that I cruise at high speeds, and I intend to take the 4L80E from the donor truck, meaning that I loose some of the overdrive ratio. I intend to swap out the 2.93 in the back with a 2.56, I would like to find a posi unit, but I can survive without one, there is usually enough weight in the back that it shouldn't be an issue, also I rarely drive anywhere with inclement conditions and I can adjust my driving habits to suit the road conditions.

Ideally I would keep the 2.93 or perhaps upgrade to a 3.23 and toss in a gear vendors overdrive unit, but they are just so superbly expensive.

Other upgrades so far have included Bilstein HD shocks on all 4 corners, Airlift 1000 helper bags (kept the valve in the compressor, im fine with the back end sitting high, I load a lot onto/into the wagon) Goodyear Wrangler A/T tires on the back (2252-75 R15) and installing a CB radio.

Anyway, thoughts or resources on this build would be appreciated.

I would put a Duramax in it if you really want diesel.

Here's the guy that knows about that stuff: Bill "convert2diesel"

https://gmlongroof.4umer.com/t272-hybrid-longroof-locomotive

Tom

Duramax is too expensive, terrible injector lifespan, and a whole host of clearance issues with the Allison trans and the engine itself. I already looked up what it would take to stick the 4L80E in, apparently no hacking required.

Hardiron wrote:

already looked up what it would take to stick the 4L80E in, apparently no hacking required.

What variant of the 6.5 are you going to use?

Planning on getting a center mount turbo from a Humvee if I can find it.

Best of luck with the swap.

Hardiron wrote:

Planning on getting a center mount turbo from a Humvee if I can find it.

Two things here:

1. When it comes time to buy the engine, be sure you are getting a true AMG 6.5. Lots of sellers out there trying to flog the Van engines (also a center mount turbo), claiming they are the "Humvee" engine. It should also be noted that the Humvee also used the original GM 6.5 during the late 80s and 90s. Still can be considered a Humvee engine but without the advantage of being built by AMG. The date code on the back of the engine (right hand side bell housing flange behind the head) is a different code makeup for the real AMG engines plus you will also find the International diamond logo under the IP in the valley.

2. The main reason I bought the Cadillac was the extra room available at the back of the engine. The "B" bodies tend to tuck the back of the engine underneath the firewall. The specific intake and turbo may not fit under the firewall there, plus you also must accommodate a 3 inch exhaust pipe from the back of the turbo behind the right hand head and down past the starter in an area that is also very restricted (frame and starter gets in the way there). The side mount turbo will not fit as the passenger side exhaust manifold sits too low and interferes with the upper control arm.

If your really looking at getting Hybrid mileage from a full size station wagon, consider a late 80s, early 90s NA 6.2 or 6.5. Unless you really need the extra umph of a turbo, your best mileage will be from a mechanical DB2 pump sized for the NA engine. Has plenty of get up and go and I towed a 3,000 lb camper with mine with no issues what so ever, averaging 38 MPG (IMP gal) on the highway and close to 20 MPG with the trailer out back.

By the way, the Dmax bell housing accepts the 4L80 fine. The vans are available with that combination from GM. Either way, it would be overkill for this application unless your lot in life is sucking the headlights out of hot rod Hondas. Spent some time with the boys over at Gale Banks discussing this and there would be no way that we could match the mileage of a NA 6.2 with a tuned Dmax without seriously de-rating the engine.

Believe it or not, another viable option for these cars is the 3 liter V6 Mercedes diesel used in the Sprinter vans and all of the larger diesel Mercedes cars. The Sprinter used an almost bullet proof Aisan 6 speed automatic that is not significantly larger than the 4L80. Lots of support in the tuner community and if my calculations are correct, could match the performance of the 6.5 and probably push the MPGs over the 40 mark, all in a package that would get lost in the engine compartment of these cars.

Good luck on your conversion and don't hesitate to ask if you want help.

Bill

Thanks Bill, that is a lot of good info. Realistically I may need to go for a 6.5 NA and just back it up with the 4L60E for the time being, will need to look up how to make the two talk to each other.

My true, sick twisted plan was to actually put a roots style blower on the 6.5 and get rid of the turbo. I have no problem with a buzzard catcher sticking out of the hood as long as it doesn't ruin too much visibility. That motor would need the 4L80E behind it as the 6.5 NA is evidently on the top end of the torque rating for the 4L60E.

I will give the Benz option some thought, I'm worried though about the Allison, as apparently the 4L80E just barely fits. I would also be worried about the cost of components, maintenance, and the electrical nightmare that will happen. The straight 6 3.2 sounds like an interesting choice too, but again, cost and electronics. I've kind of got a thing for the exhaust sound as well, the 6.5's with decent exhaust have a nice growl when you step on them, and I was attracted to them for the ease of finding parts/ mounts/ brackets.

Lesson one:  Lose the electronics.  These engines did not take kindly to having a computer run their throttle, or to adjust fuel delivery and timing.  Just not worth the headaches.  The mechanical DB2 pumps, with religious additive in the fuel will go for 300K plus before needing work.  The DS4 is lucky to make 150K and way more expensive to overhaul.  If you can get a new rebuilt DB2 they even come with the military hardened internals to stave off the jet fuel they fed them.  One of those, with additive should go over 500K.

With the mechanical pump, when you put your foot into it, you get immediate satisfaction.  With the DS4, all you do by pushing the go pedal is open up negotiations with the computer.  Tuning helps some but much of the performance of the pump is hardwired into the design.  The only reason they were forced to go electronic was to keep them from smoking on acceleration.  The result was a mediocre, non responsive pump with a pile of external sensors that can go wrong.

As far as the tranny is concerned, you can get a really good aftermarket standalone unit for around 500 bucks (Beauman) that gives you all the inputs and outputs you will need, including outputs for the speedo, cruise control (the one used on your Buick is ideal) etc. and you can trash most of the current ECM wiring.  Very clean install.  If 500 bucks is too much, I have a standalone tranny controller from a Chevy van that used a mechanical 6.5 NA coupled to a 4L80E you can have for a couple of hundred.

Lesson two:  The 6.2 and the 6.5 are identical engines.  Anything that bolts onto a 6.5, will also bolt onto a 6.2 with very few exceptions.  My 6.2 had the entire front end (timing chain cover, pulleys, AC, power steering pump etc.), the intake and exhaust off of a 6.5.  Straight bolt on conversion.

The Benz does not use the Allison (some of the newer American trucks maybe).  It uses either a 5 speed Mercedes trans (not suggested and only used on the earlier versions) or the Aisan 6 speed.  The Aisan is a very popular tranny and familiar to all tranny shops.  If it can hold up behind the 3 liter hauling a 12,000 lb Sprinter, the Buick should be a breeze.

If you really want to put a blower on it, I also have an Eaton M90 on the shelf you can have for a couple of hundred.  Far more efficient than a Roots and more suited to a low RPM diesel.  Needs a new coupler (about 40 bucks) but the rest is in good shape.  Ideally, if you can get your hands on a Whipple, that would be best.  Much more efficient than either the Roots or the Eaton scroll.

Went through the same thought process when it became evident that the 6.2 just didn't have the umph to tow our new RV (6,000 lbs. and the aerodynamics of a grand piano with the lid open).  The lack of real estate precluded me from installing a turbo so I was trying to design a remote mounted blower, using hydraulics to drive it.  The Cadillac deal came up that would allow me to use the centermount turbo so that wrote paid on that project.  Found the LT1 was more than sufficient and by that time, diesel fuel was priced so high that it just didn't make sense to do the conversion.

Bill

convert2diesel wrote:

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With the mechanical pump, when you put your foot into it, you get immediate satisfaction.  With the DS4, all you do by pushing the go pedal is open up negotiations with the computer.  Tuning helps some but much of the performance of the pump is hardwired into the design.  The only reason they were forced to go electronic was to keep them from smoking on acceleration.  
Bill

If you post this BS one more time i,m going to drive my 100mm 5068 pumped DS4 3/4 4x4 extended cab pickup to ottawa,. and do burnouts all around your place,.with my 33" tires,..and my instant, smoky throttle response'd.. DS4,.

The performance of the pump is like any servo operated diesel throttle,.everything is drive by wire these days,.its ALL in the tuning,.and an electronic pump has an almost unlimited timing map,. compared to the mechanical clunker,.which is like saying an old hei distributor with mechanical weights is superior to an electronic 8 coil system,.that can adjust the timing instantly in any direction the motor needs it,.
(stupid computer)

your experiences are a little outdated, and N/A to boot.

The same pickup that everybody said wouldn't run with a 5521 computer running a 5068 pump,.
What a pantload,.typical sheeple responses,.

just like you can't put a 9c1 rear end under a wagon, oh really? according to the book of sheeples mebbe,.

Analog cell phones were good in their day,.I still have some P4000's in a box,.

You might as well drive a model T,. no darn mechanical oil pump to fail and leave you stranded,..

unless its a common rail all diesels are mechanical pumps,..

I,ve spent a lifetime hot rodding diesels,..AND i still am,..just finished installing the fass airdog on a friends C15,.
AND i have a series 60 12.7 that dyno;s at 568 at the wheels,. sure glad its not an old 855 cummins clunker with its mechanical pump,. yada yada,. yada,.( which i,ve owned and had buttons and shims by the box full,. etc etc,.



please,...enough already,.

^^^Drops the mic....^^^

What is your reason for doing this? If it's any sort of cost savings reason, I think you'd be much farther ahead by just putting in a 4.8L or 5.3L, engines are cheap and the conversion parts are cheaper. Once you start looking at diesels, $$$$ multiplies.

Nick you're always welcome at my place just leave the burn't rubber and the unburn't fuel where they belong.  The neighbors wouldn't take to kindly to it.  Take a break from your high horse for a minute, and read the title to this thread. "Diesel High MPG cruiser".

From the first time we met at Wagonfest 08, you have been obsessed with getting every drop of HP out of your engines and if you remember the first conversation, you gave me crap for not even considering a Dmax conversion.  If it doesn't lay down two strips of expensive rubber you are just not satisfied.  If that is what turns your crank fine, just don't crawl all over someone just because they aren't interested in your ideal of perfection.

And to address your accusation of me being a Ludite, I can't believe I'm saying this, but I agree with you in that electronics have been able to do incredible things with all engines and especially diesels.  Am a huge fan of common rail and actually did do some work trying to convert the 6.5 to common rail, something that AMG is rumoured to have tried.

I have absolutely no trouble wrapping my head around electronic control of engines and actually welcome it.  The issue I have is with the DS4.  This pump was simply a down and out cludge by both Stanadyne and GM in order to comply with pollution standards.  It was a piece of crap from day one and engineered by fright. For gawds sake it took a class action suit and a monstrous settlement to convince GM and Stanadyne to extend the warrantee to 150K miles.  Even then they wouldn't admit to the fact that the problem lay in the positioning of the PMD.  To this day, a GM or Stanadyne replacement comes with the damn thing hung off the side of the pump. In short it was a badly engineered conversion from a good reliable pump to a mare's breakfast of sensors, servos and overheating power transistors.  Add low sulphur fuel to the equation without some extra lube, and you have a totally unreliable pump.  Don't know about you, but I have never had a mechanical DB2 just quit.  They give you lots of warning.  The DS4 just simply quits, no warning, no symptoms, call the tow truck.  Have one on the shelf if you need a spare that was still working (remarkably) when I removed it.  It will never go on anything I work on.

Have spent the last two years working with a local guy here who installed a 6.5 AMG in his Toyota Land Cruiser.  We worked closely with my friend in Georgia who has forgotten more about these engines than you and me combined.  With his help we setup the engine with the ceramics, stud girdle, meth injection, better matched turbo and a 4911 DB2!!!!  The end result I will gladly put up against your tire squeeling smoke belching pickup any day of the week and the only thing coming out of the exhaust pipe is the occasional puff.  By the way, we did go with an electronic 4l80 with an aftermarket controller that makes the GM one look sick.

Maybe it sounds like BS to you Nick but to me its only common sense.  The appropriate technology for the appropriate application.  I don't "Hot Rod" anything.  I build stuff to do a job of work as efficiently as possible.  If it needs a computer or some extra umph to get the job done, then fine, that's what it gets.  If the job requires a 50 year old two cylinder Lister diesel, then that what it gets.  Just don't try to convince me that a technological piece of junk like the DS4 is anything other than a badly designed stop gap to keep the greenies happy.  

Our motivation for doing this stuff is diametrically opposite.  You want HP, I want function.

Bill

These days i,m wrenching and driving and operating for a wood grinding company,.
the diamond Z grinder has a 16 cyl detroit mtu in it,.I talked the guy that owns it into getting it reprogrammed last month,. it now uses 11 litres an hour less,. down from 102,.its set at 1200 hp at 2000,.and it doesn't drop more than 300 rpm when the tub gets full now,.payback on the programming will be about 1000 hrs,.quicker response on the droop settings and a little better timing,.

there's a pile of kms on my trucks ds4,...

it still functions,.

you had 1 ds4 go bad,.

pmd's are a pita agreed,.

as for economy i have gained another 125 kms per tank with the tuning,. and i can choose to lay down black rubber or smoke any time i choose,.

Just to be clear ,. no malice intended,. a couple of smilies would have set the tone a little better i guess,.

EVERY diesel i have owned when its been turned up,. and then driven conservatively,. it gets much better fuel mileage,.6.5's included,.

Everything automotive in this day and age is electronically controlled ,. multiple injector pulses,. very dynamic timing curves and events,.

Mechanical injection is for ludites,..

Quote :

"lose the electronics"

I rest my case,...

I think the issue here is we are actually arguing the same thing.  If the 6.5 was available with common rail I would be on it in a New York minute.  No better way of controlling things.  My only issue is with the DS4.

For the record, it wasn't just 1 that went bad.  Friend of mine bought a small fleet of 6.5 4X4s and a couple of dualies.  7 in all.  Out of all 7, 4 went bad in the first year with PMDs, 2 lost the optical sensors and 1 just seized up (suspect the PMD cooked the pump).  Yes GM replaced the pumps under warrantee but refused to allow us to relocate the PMDs.  In the 4 years he ran these trucks he lost a total of 9 pumps (or PMDs), all covered by GM but no one compensated him for lost time.

His personal truck, actually went 450K but as soon as the last warranteed pump went south (@ 140K) we did do the PMD relocate and had Banks do their magic on the PCM plus a by pass fuel filter.  Only had to have one pump and injector rebuild after that due to normal wear.  Mind you he kept an extra rebuilt pump in his garage and carried an extra PMD in the dash board at all times.

Had he not traded the truck for a Dmax, our plan was to rebuild an AMG and do the mechanical conversion.  Said the constant waiting for the next shoe to drop wasn't worth the little extra umph he got from the DS4 and the Banks tune.  He traveled all over the US and Canada with a 6,000 lb. trailer out back full of tools and really needed to have a reliable truck.

I'm happy you have had some luck with this pump and hope it holds out for you, especially considering your yearly sojourn to the wilds of Northern Alberta.  For me, I would rather depend on the old and antiquated DB2 in this particular application.  They have served me well over the years.

Now maybe we can let this thread return to it's original topic, helping Hardiron stuff a diesel into his wagon.

Bill

Looks like a 6.2 is going to be the way to go, a lot cheaper to get a fully dressed motor.

Was looking at a 4L65E upgrade, but its still looking like the 4L80E is th way to go, or an 85 is I can get my hands on one.

Aside from motor, trans and controller, lift pump, and water separator, not entirely sure what parts I need. Need to get under the hood and look at how the current throttle is set up.

Curious about how much extra heat the motor will be making over what the stock cooling system can do, as I recall they put oversized rads in the towing package.

If your not towing anything, the 6.2 will do the job fine. Expect performance equivalent to the throttle body LO5 but with about 25% better fuel economy.

When shopping the engine, you are looking for an 88 - 92 "J" code engine (no egr).

Had to fabricate the throttle hookup on mine as there isn't enough head room to install the diesel cable setup. Hunt in the scrap yards for a 93 Cadillac Fleetwood. They used a neat throttle spool unit that they also tied to the traction control. You don't need the traction control so disregard the electrics. What you want from the Caddy is:

1. Cruise control module w cable
2. Accelerator pedal and cable
3. Trans control cable (see below)
4. Throttle cable.

Unit mounts on drivers fender and makes the throttle hookup easy. You will need to fab up a bracket that bolts to the injection pump with a pulley to route the throttle cable down to the quadrant. You will have to lengthen the LT1 cable to make this work. This system gives you everything you need in one package. If you end up using the 4L80, you can get the same thing from a 94-96 Fleetwood (doesn't have the trans control cable).

As far as the tranny, I know I will get some flack for this, but the non-electronic 4L60 (pre-92) tranny did well behind my 6.2. Still have one in my 88 GMC that I use to plow my driveway and it works fine. To convert it for diesel use, you will have to replace the governor ($20), and I recommend a diesel specific torque convertor (1,200 RPM stall). Will work with the gasser TC but the diesel one works better.

Another mod I did was to replace the "throttle control valve" (remember the trans control cable I talked about?) with a unit from Sunnen that prevents the 3/2 downshift till you are almost on the floor. With 3:23 gears, any 2nd gear downshift above 45 MPH will peg the 6.2 at its governed RPM (about 3,400 RPMs). I also added what was called the "Corvette Servo" to increase the line pressure. I gave up trying to get the TC to lock up automatically so just added a switch on the dashboard and locked it up manually.

If you go with the 4L80, you will either need a standalone controller or perhaps someone can figure out how to remove the engine functions from your current ECM. Either way you will have to install a TPS onto the injection pump plus fabricate a tach drive to give the ECM a speed reference. If you go that route let me know, I have a simple circuit that will work using the oil pump drive at the back of the engine or get an alternator with a tach signal terminal.

There is simply no room up front to use a mechanical fan, so you are stuck using the electric fans. In that same 93 Cadillac, grab the radiator, rad surround and electric fan setup. The LT1 rads, if memory serves, have the outlet pipes in the wrong locations, plus the Caddy rad will have the metal tanks. I had my local rad shop, split the tanks and install a 4 core insert. In retrospect, the rad in my car was overkill but mind you, I didn't use it in a hot climate. Fans were set for 203 degrees, and the only time they came on in 5 years was occasionally in traffic, had them wired to turn on with the AC and once climbing out of North Carolina on I77 with the camper out back (10 mile 7??? percent grade) into Virginia.

Keep us posted

Bill

Huh, I was actually thinking about swapping the front clip over from the fleetwood, wanted the more kinda masculine front end of the Caddy/ RM Sedan, maybe ill just try and grab the whole thing, Also was thinking about converting over to fleetwood tail lights. Granted, that's going to be a lot of sheet metal and bondo work for the back end, but it would look cool, right?

I am planning on towing with this vehicle (not huge amounts of weight), and I would like to keep a similar performance to the LT1 if possible, I am planning on supercharging whatever motor I find, as well as swapping the rear end ratios to bring the RPM down on the highway.

You can bolt on the RM sedan front end, but the Caddy front end does not fit.

For best fuel economy, you want to see between 1,700 and 2,000 RPMs (top of the torque curve). With 3:23 gears, 235/75/15 tires and a .75 overdrive that puts you right in the groove at 1,900 RPMs @70 MPG. When towing, I used to use 3rd gear so I dropped the rear ratio down to 2.93 to get back into the power band. Worked well when towing but lost almost 2 MPG without the trailer and in 4th. Not one of my better moves. These engines love 1,800 RPMs.

The NA 6.2 can handle up to a 3,000 lb. trailer as long as it is low profile like a pop up trailer. Much beyond this and it falls flat on its face in the hills. Did manage to pull my new RV (6,000 lbs. normal trailer profile...read barn door aerodynamics) about 200 miles on the flats @ 60 MPG but it was flat on the floor all the way. Anything other than a small hill and it would have been a real issue.

As a side note, on that trip, even with my foot into it, the car still averaged 15 MPG (IMP) and a 6.5 turbo pulled the same trailer without an issue later on that summer. Just needed that extra 50 - 75 HP but at 12 MPG (IMP). Obviously more air equals more fuel.

Bill

Well, I just got notification that I am loosing my room mate, which means my discretionary funding for this just went out the window. For the time being I will tune up the stock LT1 and reseal it, as well as fix up the front and rear suspension (there isn't much in the way of bushings left after nearly 20 years)

I will have to wait on the diesel conversion until I get another job at a shop or find a chunk of cash laying around somewhere, but I think I'm going to wait until I can afford to do it properly with a Navistar motor and the various bits I wanted to add on.

Hardiron wrote:

but I think I'm going to wait until I can afford to do it properly with a Navistar motor and the various bits I wanted to add on.

That'll be interesting,..

Navistar engine? Like a 6.9 IDI?

After 2001, AM General took over production of the GM 6.5. They are using International (Navistar) to cast the new blocks.

Bill

Oh, did not know that Navistar did the casting for the newer engines. Deals can be had on those engines through surplus auctions. Wouldn't mind having one for my old 1-ton.