Definitive guide to DMax Conversions? Who's written one?

[Clarke F]

Hi,

Back on the forum after several years away. I currently have a 6.5TD Hummer that needs a new engine and tranny - so my obvious thought was to do a Duramax/Allison conversion, like what are in the new 2006 H1 Alpha's. Seems that I can buy the bits for about the same as a new long-block. The fabrication will cost - but that's part of the adventure.

Have been readings, searching, and browing the various archives here over the past two days and haven't been able to find technical details or detailed know-how from someone who has done one (or more) Duramax conversions. Jim's articles are good - but lack details and the nitty-gritty of getting into the conversion and the got-cha's that you have along the way. Perhaps I'm searching the wrong places, or using the wrong words..

Specifically, I'm interested in the electrical bits - interfacing the DMax wiring into something that's not designed to talk to 6.5TD. The mechanical/fabrication bits seems straight forward - but interfacing the engine and chassis harness I am betting is the difficult part.

So has anyone written up their specific experiences about splicing and tying a non-DMax truck into a DMax harness?

Sure, I could pay someone 50K to do a conversion for me - but if I'm going to live with this beast for years, I need to know the in's and out's of solving problems and understanding how it's been put together and squeezed in . Still, I'd rather not make all those discoveries on my own - and willing to learn from those who have blazed the trail before me....

Looking forward to learning deep secrets!

Cheers,

Clarke

[More Power]

The Duramax conversion articles we've presented over the past three years were more topical in nature. The Project articles were designed to develop and maintain an interest in what we were doing, without boring readers with the tedium of the "nuts & bolts" - an overview, more or less. After all, only a very small number of people would be interested in the fine details.

However, I do have plans to release a full-blown conversion guide sometime later this year that contains many wiring diagrams, photos and technical details that would make it possible for the technical savvy DIY types.

There are a couple of Hummer businesses here in the US that offer turnkey conversions. I spoke with the guys at Lynch Hummer in 2002, after learning they had completed two Duramax Hummer conversions (and before I had gotten too far in our own conversion). Understandably, they expressed a wish to keep what they learned proprietary, because it was both costly and time consuming to learn what they learned about conversions. Their effort was considered an investment. I understood that. Learning what is necessary to complete something like this is substantial.

If you can wait a few months for the conversion guide, your project will be a lot less effort. [img]smile.gif[/img]

Jim

[Clarke F]

Jim,

I can wait a few months - it will be a lot cooler here in Phoenix if I wait... Better for working on the truck in the garage.

Lynch Hummer has now done five conversions - they finished their fifth (and last they say) just over two months ago. The owner is very happy and if you can imagine a Hummer H1 doing 110 MPH (by GPS) across the salf flats of Utah, you can see why I'm interested in getting this done.

Predator Motorsports in CA is offering H1 and H2 conversions to the Duramax/Allison/NP263 as well.

Sure, I could have someone else do the work - but this is my truck and considering how hard I off-road with it, I want to have the know-how and wherewithal to do any repairs or fixes myself. I doubt any conversion is going to come with a detailed schematic to help solve electrical problems... I might save time and money by "outsourcing" it - but at the expensive of having the experience of doing it myself.

If you need someone to run through your guide and instructions before public release, I'd also be happy to do this in tandem with my install...

Consider this an offer to be a paying Beta Test customer/editor. I could also add Hummer specific knowledge to the guide...


Cheers,

Clarke

[More Power]

To get you started, try to buy a complete salvage vehicle. You'll save a lot of money in the long run, and seeing how everything is factory assembled would be a help in putting together a conversion.

Jim

[markrinker]

I'll look forward to the guide coming out.

My dream Duramax conversion?

Replace a gas hog 7.4L OR 8.1L big block Mercury marine engine with a Duramax, utilizing a seawater-to-air intercooler. Extra credit: Swap in the twin turbo system under development at Banks Engineering.

The end result would be a much more fuel efficient, bottom end oriented powerplant for a 26'-28' cruiser, with a lifespan of 2,000 cruising hours or more before a rebuild would be necessary.

[JeepSJ]

If I were starting my project now, I think I'd go for a DMax. Who knows...if my '97 block decides to do its imitation of San Andreas, a DMax just may be in my future. I wonder if I could get it to work with my 700R4?

[markrinker]

Unless you have beefed that 700R4 to the max, I think a DMax would twist it in half in short order.

[JeepSJ]

Art Carr claims that it will handle 750ft/lbs. It is one of their K-case based super duty diesel towing special transmissions. Theoretically it should be able to handle a stock or slightly warmed DMax. Plus, I have a relatively light vehicle (4500lbs).

[markrinker]

Amazing. I have always been in awe of anyone that can disassemble, improve, and reassemble a transmission. Its a major pile of parts!

[More Power]

The Duramax Conversion guide is now available....

The Duramax 6600 diesel engine can be easily tuned to produce more than 500 horsepower at the rear wheels, while delivering 25 miles per gallon at 75 miles per hour in a 5,000-lb vehicle. Only a modern diesel engine can achieve results like this. In addition to appearing in several magazine articles, the conversion produced for this project series has drawn praise and compliments from nearly everyone who has seen it, and certainly from all those who have ridden in or driven the truck. We're sure you will be pleased with your own Duramax conversion.

The 1989 Chevy K1500 appearing here was the very first privately owned 1988-98 C/K LB7 Duramax diesel conversion. The actual mechanical details, wiring considerations, and background information presented here will help you produce a high-quality conversion of your own, and for the least amount of money. This is not a project for the faint of heart, but we've proven that a decent backyard mechanic who can perform some light fabrication and understand wiring diagrams can be successful.

This was the very first privately owned LB7 Duramax retrofit conversion - installed in a 1988-98 C/K. In the beginning, we didn't know whether the engine and transmission would even fit within the confines of the engine compartment. The bigger question was whether it was even possible to get all of the electronics configured to produce a running and driveable truck. Every aspect of this conversion was breaking new ground, with no guarantee that the effort would be successful. After two years of solving puzzles, we arrived at a completed and running truck. The conversion guide offered here is a condensed outline resulting from hundreds of hours or work - covering a nearly two year period of time. All this background work will allow you to produce a conversion in a few weeks, knowing upfront that you'll be successful.

This color laser printed 60-page bound volume contains 104 images and diagrams covering what you'll need to know when installing an LB7 Duramax 6600 diesel engine and Allison 1000 automatic transmission into a 1988-98 classic C/K GM pickup truck or Suburban. Only those electrical connectors, connector pinouts, and wiring considerations that are necessary to produce a running vehicle are included. The plethora of remaining electrical considerations not directly related to getting the vehicle running and driveable are not included. We recommend that you acquire the wiring diagram books matching the model year of your vehicle and the engine package you're using. You'll need the additional resource material to address ABS, airbags, security (other than Passlock II), audio, and other misc systems not essential to produce a running engine and driveable vehicle.

The 1995 or newer C/K make better candidates for a Duramax conversion. This is because the new (2001+) instrument panel cluster can be installed in the 1995-98 dash with fairly minor modifications. Our 1989 Chevy dash design made installing the new instrument panel cluster more difficult, and is why we chose to install a 2001 dash in this truck. This was a significant undertaking, and is why we recommend beginning with a 1995 or newer vehicle. If you have a 1988-94 model year vehicle, installing a 1995-98 dash as a first step could be a better choice than attempting to use a 2001+ dash.

One of the guiding aspects of GM auto design is the fact they have standardized wire colors and electrical methodology - going back decades. While we haven't performed a conversion using an LLY or LBZ, the featured conversion volume will be a valuable guide when working with even GM's newest diesel powertrain.

Contents:

Introduction -
Mechanical - Fitting the Duramax/Allison into the chassis:
Electrical/Electronic Systems - Engine, Transmission, In-cab and Vehicle Lighting:
Intercooler - Fabrication & Installation:
Air Conditioning - Modifications and Special Considerations:
Intake & Exhaust Systems:
Checklist for that first start:
Electrical Connector C-201 - Steering Wheel Electrical Diagrams & Pin-outs:
Vehicle Lighting - Junction Block C3 & C4 Diagrams & Pin-outs:
End Notes, Marine & Motor Home Applications:
Full Size Motor Mount Drawings:

Jim

[Petrella]

Hi Jim, i havent received the book yet but i wanted to ask you, do you really have to change the dash on a 94 or can this conversion be done with using the original dash and gauges?

[More Power]

It is possible to install a D/A when maintaining the original dash and instruments. The motorhome conversion article we published a couple of years ago was done that way, and the owner is happy with how it turned out. However, you'll lose the tach, you'll lose the message (or DIC) center, SES light, as well as other instruments. And, it would make engine monitoring & diagnostics more difficult.

When doing a hybrid (i.e. maintaining the original IP cluster), you'll need to install all of the engine sensors that operated the old IP cluster onto the new engine. The new engine and its ECM will need all of its own original engine sensors as well. You'll have two sets of sensors on the engine.... Then there's the question of where to place two sets of fuse blocks (underhood & in-cab) , junction blocks and wiring harnesses. Room is tight...

Making the decision to replace the original electrical system was the single biggest hurdle I encountered, and not making a decision delayed progress by over a year. Once that tough decision was made, the truck was driveable 4 months later. I made the right choice. Any future troubleshooting will involve using the 2001 service manuals and wiring diagrams almost exclusively - any competent mechanic could do it. A hybrid system could be harder to work on at some future point due to the more complex nature of the interconnectivity and shared systems.

My goal was to produce a conversion that looks like it came that way from the factory... Most who see it say that very thing.

Jim

[Petrella]

So your book is based on a conversion providing that you change the dash??