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1996 Suburban Cummins 12V Conversion Build up with pics

321K views 279 replies 56 participants last post by  dixiepc 
#1 · (Edited)
We are almost done with a 12V Cummins into a K2500 Suburban 4x4.

The Suburban is a 1996 GMC and was a 454 Vortec truck when we started. We used the original transmission 4L80E with a controller. We ended up putting a 1" body lift on to make life easier although it wasn't required.

This entire swap was done without discharging the Air Conditioning.

Most all of the swap parts were from Autoworldmt.com - they were great during this entire swap. They supplied the motor mounts, trans controller, A/C mount, alternator mount, transmission adapter and tachometer drive.

Transmission was move back 3" to accommodate the longer Cummins engine. We moved the transmission coolers to underneath the truck, we used the factory cooler and a cooler from Derale with a fan on it.


Here is the engine, it is from a 1993 Dodge:



Another engine shot:



This shows what we had to cut from the core support to use a 1994-1998 Dodge Truck Intercooler, we did end up cutting more than what is shown but not much:




Here the engine is sitting on the mounts in the truck:



Another in truck shot:



Here is a clearance picture with the stock IFS and the Cummins Oil Pan. It doesn't touch but it's close. We have to countersink a few of the bolts:



Originally we tried to use the stock dodge manifold but ran into clearance issues since this Suburban has dual heat and A/C:






We ended up using a 2003 Dodge Manifold which is a lower mount and cleared everything:



 
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#192 ·
Yep, still poking around.

Not sure if you are going to run a 6BT or a 4Bt but I am not sure a 4L60E would hold up behind a 6BT. My 2500 Suburban had a 4L80E in it stock which I used.

There are lots of different controllers for GM transmission. I used this one:

http://www.powertraincontrolsolutions.com/product/SimpleShift/

It is a cool unit, you don't need a laptop to set it up and you can change stuff on the fly.

You will also need an adapter:

http://www.destroked.com/prod_adapters.php

The place I got my mounts, Autoworld, sells Destroked parts so I just bought everything from them, including the controller.

Hope this helps.
 
#194 ·
I am running a 94 suburan and have bought every thing from auto world as well I just want to know what gears are you running in the diff my truck has 4 10 and my dodge pick up has 4 10 in it as well be I think the gear ratios in the overdrive of the dodge tranny are steeper than the 4l80e and I think I may have to change the ring and pinion out to compensate I was also thinking if I change the gEars I will go with 3 42 which will give me lower rpms in over drive and better fuel mileage. I think
 
#195 ·
Jd1950m Your gear ratio depends a lot on what your using it for and your tire size. If your doing a lot of towing or have larger tires the 4.10 my be better. If you want mileage go with a 3.42 range gear.

I had a 1st gen dodge with automatic (32" tires) that I put 4.10 gears in to help it in towing, I now have a 1st gen 5spd getrag with the same tires and 3.54 gears and it works great, if fact if I could put something like a 3.00 gear and use 4th gear for heavy towing I would probably do that. Fuel mileage starts dropping off on it above 70mph and the cummins really seems to like to cruise at a lower rpm anyway. There starting to raise the speed limits to 70 to 80mph here in Texas and I'm having a hard time keeping up. I using 3.73 in my Suburban project mainly because that's what in the ford axles I'm using. I plan to use 35" or 37" tires. Should give me a good cruising speed.
 
#196 ·
As of right now, I have 4.10 gears and ~32" tall tires, shooting down the freeway in overdrive and lockup it is turning about 2200 rpm at 65 mph.... too much, in my opinion. I do mostly towing with this vehicle so I am probably going to swap out some 3.73 gears which should put me at about 1900-2000 down the freeway at 65 mph.

I might go 3.42 gears but I haven't 100% decided yet. I am probably going to get a rear axle at the local pick-n-pull (~$250) with one or the other gear ratio and swap it in to see which I will re-gear to.

With the bone stock engine it would de-fuel and run out of power at about 75 mph. I had a buddy that had a 1994 Dodge dually with a NV4500 and 4.10 gears and he had the same issue until he raised the RPM like I did. With my pump turned up I can go 90 plus.
 
#197 ·
I've got 3.73 in my truck. IMO that is about perfect until you get to pretty big tire sizes. I've got little 245/75/16 (about 30" tall) tires and with the nv4500 and 3.73 gears I run about 1900 rpm at 65mph. Next set of tires will be probably 285/75/16 (almost 33") which should drop the rpms somewhere around 150-200rpm and be about ideal. As is, I can knock down 23mpg on the highway at 65-70mph. Can't ask for much more than that if you ask me. With the added weight of larger tires though its very rare to ever gain mileage by switching to a larger tire. I know this, as I'm just going for looks next time around.

I think that 3.42 would be lugging the motor if you run any halfway decent tire size. Might have a hard time keeping the turbo spooled at 60mph. But I haven't personally done it so I wont say it can't be done or anything.

Sent from my DROID RAZR using Tapatalk 2
 
#199 ·
I re-vamped my A/C bracket since I didn't care for the cowl hood very much.

It uses the stock dodge mount but it is mounted up above the alternator. I got a bracket from someone in Vegas and it utilizes the factory Dodge alternator and places the factory Dodge A/C compressor above it. Worked pretty slick except I modified it so I could run my stock alternator. I don't like that the Dodge alternator requires an external voltage regulator plus my factory alternator is a CS144 which is a great alternator. The bracket kit was $150-ish and then I had to buy the stock Dodge A/C mount and a couple pulleys and bolts. All total was about $300 for the brackets.

Here are some pics:










Stock Hood!!!!






The bracket was supposed to use the stock Dodge mounting flange for the A/C, you cut it off of the piece that has the water outlet in it. When doing the conversion, I was frantically looking for the Sanden head (the back piece of a Sanden A/C Compressor) to convert to to the GM A/C lines, the one I found made the compressor flip over so the mounting on the stock Dodge mounting flange wouldn't work anymore so I had to build my own off of the bracket I received.
 

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#202 ·
Thanks! Those are all the pics I could find. I thought I took more but I didn't see any.

Here is his information: His name is Chad Reynolds. He lives in Vegas. His # is 702-824-5765

If you go this route, I do have an extra stock Dodge A/C mount that has already been cut off from the rest of the piece. I can get pics of that.

Thanks!
 
#201 ·
I'll send ya a pm when I'm not on my phone, I believe he used the same guy that I did for the a/c mount. Its a slick setup for sure.

Sent from my DROID RAZR using Tapatalk 2
 
#203 ·
Here's a few more pics.









I got my brackets from chadd too. He's a great guy. Have another set of mounts coming from him for my buddies truck. Should be here before this weekend.

Sent from my DROID RAZR using Tapatalk 2
 
#210 ·
Fantastic! I have a trade in the works for a 95 2500 Suburban MPV (fire chief truck) with the 454 and very few options. Very excited to convert to the Cummins. Thanks so much for posting all this info.

PS: I am kinda local to you here in Olympia. Maybe we can get together so I can see this bad dog in person? :)
 
#217 ·
I used the 1994-98 Dodge Radiator. Originally, I couldn't use the factory Cummins rad hoses because the a/c compressor was in the way.

I had it set up with a flexible 4-foot long radiator hose to clear everything:



The lower hose was a stock 94-98 Dodge hose that was shortened just a bit.

I have since swapped the compressor over to a stock Dodge unit but relocated and use the factory upper hose from a 94-98 Dodge:



Hope this helps.
 
#221 ·
I have a few updates on the old girl, thought I would share my experiences:

1. Put some new injectors from http://www.dynomitediesel.com/ (DDP). These injectors smoked a little more than stock and made a bunch more power.

2. I had the BD fuel pin in it and it when I pulled it out when doing some pump adjustments, it was scarring a little bit where the pin rides. Plus it wasn't very progressive (gets really deep really quick). I was concerned a little about the smoke at low throttle situations so I called Denny T and put his Stage 1 (less fueling at lower RPM's) pin in it and it absolutely love it, low throttle smoke is down and power is up! http://www.dennytperformance.com/FuelPins/index.html

3. Turbo whine in the stock turbo was getting louder so I replaced it with a BD Super Bee turbo for a 94-98 Cummins. Wow, what a difference! The turbo hits close to 35 psi and improved EGT's by about 100-150 degrees so far. The old turbo had a 3" ring on the stock turbo that immediately went to 3.5" and then after the bend down below the truck it went to 4". With the Super Bee turbo it is now a 4" exhaust all the way through and it actually fit -- it was tight but we cleared everything!


Some updates:

4L80E transmission: The transmission is holding up nicely. It has ~120,000 miles on it and it is bone stock from 1996. Still has the stock 454 torque converter on it too. It runs really cool, hits 125-150 when towing (when stopped, it will creep up to 180 or so but quickly lowers back down when the truck starts moving again) which is probably why it still lives.

4.10 gears: I need to change these out to 3.73 or 3.54 gears. I am probably going to find a FF 14 bolt in a wrecking yard with 3.73 gears to replace my FF 14 bolt with 4.10 gears to see how I like it before I commit to 3.73 or 3.54 gears.

Mileage: I get a consistent 15-18 MPG in the truck. The best I have ever got was 19.9 on a couple hundred mile trip keeping the cruise set at 60 mph (because of the 4.10 gears). The worst I have ever got was 12 mpg and that was a whole tank of towing our 8-9k travel trailer.


I still get a lot of PM's about this conversion and I don't mind answering questions at all. It was a fun conversion and I learned a lot so if anyone needs help, don't hesitate to ask.
 
#222 ·
Great build! Thanks for all the updates. This build is one of the reason I did this swap in my 98 K3500. I have a 93 motor also. I run the M&H #2 pin and a HE351 turbo. Which injectors did you buy? The reason I'm asking is I can max out my EGT's if I want to with my current setup. But only when towing. I'd like to add more power but I don't want to end up with crazy high EGT's. I did switch from 4.10's to 3.42's and like the gear gear alot. I also run 33's.
 

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#230 ·
I know you used the destroked tach kit. What voltage (5 volts or 12 volts) goes to the tach sensor and is the output just going to the 4x signal in the ECM? I made my own tone ring and sensor. I used a 5 volt reference and sent the signal to the tach and the computer and the tach would work, but the speedometer would act funny and the ABS light would come on. I pulled the signal from the computer and the tach worked fine with no ABS light. Just trying to see if I'm using the right voltage signal to the computer.
 
#233 ·
Hey Crummins, Love your thread, really informative and I appreciate your willingness to answer questions. I have a line on a similar swapped cummins suburban that is done well and wondered what you would value your vehicle at. I know value on these is difficult to gauge because you will never get paid for what you put into them. What do you think a similar vehicle like yours would go for?
 
#235 ·
Yeah, it is really hard to say. A nice diesel 6.5L Suburban blue books out at around 4k. I have seen them sell for 6-8k and those are usually in really nice shape - paint nice, seats not torn, etc.

Assuming everything (cruise, A/C, etc, etc) works on the converted Suburban I would probably say 12-15k and that is assuming it is nice.

Just a guess, hope this helps.
 
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