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. smile.gif

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 (http://www.thedieselpage.com/duramaxconversions.htm) guide is now available....:D

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??

[More Power]

Not necessarily... I can make a recommendation and show how I did it, but making choices and doing the work are left up to the individual.

For example, if I had a cherry 1994 Suburban, I'd install a 1995 or newer dash (so I could more easily install the matching Duramax IP cluster). If you have a 1995 or newer vehicle, you're good to go with what you've got - in that the new IP cluster will fit with relatively minor mods.

On the other hand, there may be individuals out there that can do a great job producing a hybrid system. I know Lynch Hummer in St. Louis produced a couple of H1 Hummer Duramax conversions that used hybrid electrical systems (I last spoke to them in the spring of 2002).

A member in Canada converted a 1999 Chevy K3500 crew cab dually about a year ago. He is using a hybrid electrical system as well, but did install a new steering column matching his engine along with the matching Duramax IP gauge cluster. He never sent me any photos, so I suspect some details of his work might not be photogenic (just a guess). He's also not using an intercooler, which I consider essential. I would like to see his truck regardless...:)

Jim

[Petrella]

Allright Jim i appreciate your help and sorry for being a pain in butt, but one more question, if i was going to change the dash i would try to fit one out of a duramax like you did, but if you go that route im assuming you have to change all the heater and ac vents, boxes, and blower motor behind the dash? cause im pretty sure you dont have to do that on a 1995+ dash it looks the same setup as the 88-94 models. also what is a hybrid electrical sytem??
.

[More Power]

I'm pleased with the 2001 dash I installed, but wouldn't do it again unless that was the look I was trying to achieve. I did it to get the new Duramax IP cluster installed, not knowing there was another way.

One plus is that the new dash draws as much attention at the shows the truck has been in as the engine does. It's a mind bender for people looking at the inside/outside of the truck. That's cool! But, since the dash installation I've learned that the Duramax IP cluster will fit the 1995 or newer dash with a lot less work.

I recommend either producing a hybrid electrical system (using your old IP panel, etc.) or preferrably install a 1995-98 style dash (along with the Duramax IP panel).

You can leave your original HVAC system in place. Though the air ducting might need to be upgraded along with the dash. The few mods that might be necessary to get the new dash in place would be easier than installing a 2001+ dash (it's a big job).

Spend some time with the book once it arrives, then call me.... We can talk about your project.... :)

Jim

[Petrella]

Thank you very much Jim, i appreciate your time and help!!

[Petrella]

I just finished reading the whole duramax conversions book, and lemme say this is going to be one heck of a project. I was thinking of creating my own hybrid electrical system using my original dash and ip cluster 94 style. As for the gauges i was thinking of retrofiting the original 6.5 alternator onto the duramax therefore my tach will work again. The glow plugs light im sure i can trace the wire from the duramax harness and hook it up to my existing light in the dash. The speedo can be tapped into the ECM. I can purchase the duramax engine harness and the harness inside the cab, where i will have the plug for the tech 2 scanner, and look for engine codes and or performance chips. I can also hook up all the things like the BCM and the TCCM using the harness i stick under the dash. As for the steering wheel column im pretty sure i can wire it up like you did on Little red. I kinda have an idea where im going to take this project, i want to use the original 94 ip cluster, there is always a way to get the gauges working properly, even if i have to do what you say and that was installing the sensors from the 6.5 onto the duramax so they function properly. when i install the new harness in the cab i want to know if the duramax ip cluster connector can be left unplugged behind the dash, as i will be using the original cluster. See Jim im a perfectionist when it comes to apperance and the way the dash fits in the truck, its been in the family since new (12 years now) and i want to keep her all original (except for the drivetrain of coarse) that is why i want to put all the effort i can to make the 94 dash work perfectly with the duramax, i dont want to get into changing the dash, because i will probably have to spend an extra $1000 for door panels, trim, and the wiring harness for the new trim for the 4 power windows , cause i know the door panels on a 94 will interfere with the dash of a 95+ truck, (i checked today). Also in my suburban i have extra switches like rear windshield wipers, rear hatch, rear defog, auxiliary heater, and those are all switches i would have to refrofit into the new dash. I just pray this can all be done with the Duramax not storing any fault codes or always going into limp mode with the 94 dash. I just want your blessing Jim before i go out and buy an engine and transmission. If you think my plan sounds like it will work i will definately continue on with the project.
Thanx again for your time and patience Jim

Anthony.

[More Power]

Anthony,

Sure, it'll work.... Lynch Hummer did pretty much what you are contemplating using a 1997 H1. It should work without the IP cluster plugged in, but I would expect a series of related non-limp codes to be always present. I still get ABS and airbag codes, but there's no effect on performance.

I went the way I did in part because there's a limited amount of room to run harnesses and install fuse blocks/junction blocks/modules/etc., which I believe was simplified by using as much of the 2001+ stuff as possible.

Good luck!

Jim

[Petrella]

Ok cool, so if i decide to purchase an aftermarket performance enhancer like the Banks 6 Gun, or edge attiude, i will have no performance problems?

[More Power]

Programmers seem to be puzzled by not seeing everything a typical truck should have when it establishes communications with the ECM... When using an aftermarket programmer, it'll "look" at all of the electronics the truck should have. It'll interrogate each system and look for a response. The IP panel gauge cluster is one system that a programmer spends some time with, checking the fuel gauge, checking the oil pressure gauge, tach and so on... I'm not sure how yours might respond if you decide to use a programmer.

I can use a programmer on Lil Red, but it ponders things a bit longer than normal cuz it's looking for the airbags, ABS and the factory HVAC controller. My truck doesn't have these three things. I need to cycle the ignition a couple more times than normal to get it through the upload process, but it works fine otherwise. Again, I'm not sure how yours might respond when using a programmer and without an IP gauge cluster.

Otherwise, the Edge Attitude and VanAaken modules work great, without any issues. I'll be trying a Kennedy ECM here shortly.... one that's been tweaked for perhaps 600 on nitrous....:D

Jim

[Petrella]

If i purchased an EFI Live program from Kennedy, can i program the ecm to ignore my present fault codes, (for example disable codes relating to ABS, Airbags, and codes triggered by a non present IP cluster?

[More Power]

From what I know at this point in time, I think the EFI Live programmer just might be the ultimate programmer developed so far. It has the ability to do much more than a typical programmer, but.... it'll take someone with more experience with it to answer your questions. JK is using EFI Live to develop a programmed ECM for my unique application. I suppose we'll soon be finding out how this all works together.... :) I asked for a realistic goal of 600 horsepower, when using a factory turbocharger (but with 32 psi boost), factory injectors and when using nitrous. Other items of interest for special programming were the 3.42 gearing, 275/55R20 tires, eliminate the vehicle speed limiter, and raise the engine's governor.

Jim

[Petrella]

Jim i meant to ask you, as for the transfer case, will the transfer case from my 4L80 bolt on to the Allison, or do i have to buy one? Cause they sure are expensive!! and if do have to buy one can i still use my floor shifter rather than using the push button electric shift?

[More Power]

The 4L80-E/NP-241 transfer case to trans bolt pattern is identical to that used by the Allison/NVG-263 (at least the gasket is the same - I've used them interchangeably). I don't know if the trans output shaft is the same (diameter, # of splines, depth, etc)....

You should be able to use a manual shift transfer case. In fact they are/were optional in the 2001+ trucks. The wiring harness is different - due the lack of stuff on the manual version. I don't know for sure, but an electric shift wiring harness might work for a manual shift Txfer case - you'd just have some unused connectors.

Jim