1994 Diesel Suburban Build

[aardvarcus]

Progress on the Suburban basically stopped when the 4Runner came. The Suburban doesn’t get used as much as it is loud and ratty inside. I have not worked on sound deadening and fixing the interior as I am deciding how to proceed with boat-tailing the rear of the vehicle, which I want to finish prior to re-doing the interior. I am determined to get this project off top dead center.

If I don’t do some drastic aero mods, this “project” will not achieve what I wanted (30 MPG consistently) and without doing some major bodywork will not provide me the “learning experience” I want to get out of it.

I bumped my thread in the Aerodynamics subsection with revised boat tailing plans, basically taper in the factory sides and taper down the roof, new rear door, and lots of associated work. (https://ecomodder.com/forum/showthre...tml#post615317)

When that is finished, I would want to redo the interior of the vehicle, new or refreshed seats, floor, headliner, dash, etcetera. I also need to refresh or replace the weather-stripping. At that point the vehicle would be more comfortable and should get more use.

Once I get there, I would be more willing to spend the money to re-gear or buy 3.42 differentials, build bumpers, belly pan, etcetera.

[Tahoe_Hybrid]

Originally Posted by aardvarcus

Hello all. I acquired a 1994 K2500 Diesel GMC Suburban to build up to eventually replace my 2005 Toyota Tacoma.

There were a lot of drivers into this decision. My basic requirement was low long term cost of ownership balancing cost, MPG, maintenance, insurance, etcetera. In addition the vehicle had to have room for my family and friends, able to tow and haul, and had to be 4x4. After significantly overanalyzing vehicle options (understatement) I decided a factory diesel 90s model GMT-400 Suburban was the right vehicle for what I need/want, realizing it will take some work to get it to the MPG I wish to hit.

I am very familiar with this GMT-400 platform having owned and worked on a 1991 K2500 LD truck, and several good parts from this truck will be swapped over (NV4500, NP241, etcetera). The suburban I got has 210k on the clock, but I plan on replacing the powertrain anyway and will eventually rebuild most of the major systems to end up with a like new vehicle. It functions now but I won’t be driving it until I get the powertrain rebuilt and have confidence it is reliable as I have no need for another vehicle until it can replace my Tacoma.

My short term goal is to hit 30 MPG consistently. My long term goal is to hit 40 MPG on most tanks. I think my current plan I will outline in a few posts below will get me at least to the first goal, the second goal will probably take lots of optimization of details beyond what is listed.

Please feel free to comment and offer suggestions, I post to get input and feedback.

Front end swap to a GMT900 hybrid that will take the front end to 0.34 from your "square brick" is.. probably 0.6-0.7 or so... also get the running boards and the two pieces that connect to them




(wont help the windscreen tho)


Get electrical fans from the hybrid they cool a 6.0l engine this will save about 1mpg or 15-20HP on the spot
Get a NNBS alternator or something with a bit more low end power (for the E-fans)


get the mirrors off of it as well
Rear Aero wing this will be hard to install as you have barn doors possibly consider a two piece setup...



on this 6.0l i was barely able to get 31MPG city (hybrid) so good luck with ICE only 100% stock

25-28 is what I see on the highway

but tonight I barely got 21 due to wind etc..

[101Volts]

https://www.dieselplace.com/forum/63...roject-12.html

Gonna leave this here. PrivatePilot added Water Injection to his 97, and it saw a 1 to 2 MPG benefit. He was only using tap water, there might be more benefit if you use a Water and Methanol Mix. I don't know all of the details, supposedly the 6.5 has detonation issues if you use much methanol and that'll destroy the engine?

[MeteorGray]

Using tap water can introduce deposit problems related to minerals in the water. So, it's best to use distilled water, at least if water injection is to be used long-term. Of course, distilled water would add around a dollar per gallon for the water used.

The use of water to quell excessive combustion heat might enable some timing advancement without early detonation, thus potentially increasing fuel economy. It can also keep combustion chambers free of carbon deposits, but if not careful it could results in a bit of rust as well.

The use of methanol would provide a few a more calories for the combustion chamber, thus potentially increasing MPGs and power. However, the methanol does not come free, and as noted, the operator must be careful not to overdo things to avoid potential engine damage. So there are costs and risks involved.

When the hydrated engine is used under a lot of load, such as in a vehicle used for towing over long distances and up high grades, it can take prodigious amounts of water and methanol. So, provisions must be made to contain adequate amounts of the mix on board.

The economy and efficacy of water injection depends on circumstances.

[aardvarcus]

Thank you all for all the suggestions.

The Suburban has already been swapped to dual 18” Thunderbird E-Fans and a NBS Duramax alternator. Alternator has way more amps at idle now. I had designed a two piece tail, but it wasn't going to get me where I wanted so I have decided to hold out and do major bodywork tapering instead.

I pulled some rearview mirrors off an Audi A4 at the junkyard, but I think I may hold out for some even better aero ones.

The vehicle now has the "work truck" front end off of my Chevy parts truck, with a conveyor air dam under the bumper. Got a GMC grille waiting to correct the brand labeling. Attached is a more recent photo for context.

My last four tanks before I slowed down on driving it were all 24 to 25 MPG. With a 1000 mile range I haven't had to fuel it up it since spring.

I don’t think the water or methanol will help me much as I am naturally aspirated, so I am not seeing excessive combustion temperatures to combat. As I have a new-ish 2010 GEP Optimizer under the hood, I don't want to risk any engine damage.

[cRiPpLe_rOoStEr]

Originally Posted by aardvarcus

I don’t think the water or methanol will help me much as I am naturally aspirated, so I am not seeing excessive combustion temperatures to combat. As I have a new-ish 2010 GEP Optimizer under the hood, I don't want to risk any engine damage.

I didn't remember the Optimizer was available naturally-aspirated too.

[aardvarcus]

cRiPpLe_rOoStEr,
Yes, the surplus military ones were all either Turbo with the rear center mounted turbo (aka van configuration) or naturally aspirated. The naturally aspirated ones were the more desirable version for truck replacement engines, because the turbo ones wouldn't fit (center/rear turbo hits firewall) and the intake bolts were drilled at a 60 degree angle vs 90 degree, making swapping difficult. So most of the turbocharged guys bought the naturally aspirated engines and swapped the stock turbo components over.

I am very happy with the naturally aspirated engine.

[cRiPpLe_rOoStEr]

Originally Posted by aardvarcus

I am very happy with the naturally aspirated engine.

Most of the people who prefered a naturally-aspirated over a turbocharged engine I have talked to were native Spanish speakers. They often complained the simple presence of the turbocharger decreased the overall reliability to some extent.

[aardvarcus]

Everyone,

It has been a while since I updated this thread. I went round and round on drag reducing designs and ultimately landed on tapering the rear sides of the cargo area in.

I have been working on this intermittently in my spare time, attached are some photos of the work in progress.

Upcoming plans are to finish the welding and build a new rear door, a single door to replace the factory barn doors.

Most importantly, my five year old renamed the vehicle "Burbie."