duramax or cummins

[red]

been searing around online at doing a possible diesel swap in my tow rig 87 dually chevy k30 (has a 454), mostly researching for a project in a year or so. have found a few motors that caught my interest and dont know which would be the best deal of them. this is curiosity that has me searching so unknown if i will follow through with it.

2 of the motors are 12 valve cummins, an 89 and a 93 both in running condition, asking price of 1000 and 1800 respectively. turbo and all other engine mounted accesories included and in the 200k mile range.

1 is a 2002 cummins 24 valve (rolled truck) with 160k miles, asking 2200 and can be fired up as it sits. includes same accessories but not the computer. wondering if the 24 valve can be setup to run on a mechanical pump to remove the computer or does the 24 valve require it?

last option is an 02 gmc sierra with dmax and allison 5 speed. 174k miles, rolled truck (only front clip is salvageable body wise) and like the 02 dodge runs as it sits. guy is asking 5500 for the entire truck and has a 7.5" lift kit. think i could make about 2k back from selling parts not motor related. how much wiring does the duramax require?

 

[DieselCash]

The duramax would be the most sweet in an old truck like that! :thumbsup:

 

[red]

the lb7 dmax would be badass i'll agree, and so far the guy hasnt had any luck selling it but has only been up for 10 days. i get back stateside a little before august 20th and if its still available i'm definetly interested. unlike the other motors i'd have to purchase the entire truck. its an 02 with 174k miles and 5 speed allison. i'm somewhat hesitant because of the known injector issues with the lb7 though, and dealing with the computer is another big concern because i'm used to older diesels and carb to tbi gas, common rail is not something i'm used to working on but willing to learn. not a big fan of auto tranny's in a tow rig but unless i found someone with a zf-6 and manual computer that would be willing to swap i'd stay with the 5 speed alli and do some reliability upgrades to it.

what are the issues i would have to pay close attention to with the dmax/alli combo when its out of the truck?

 

[great white]

Check out Fermanator's Duramax/suburban swap thread:

http://www.thetruckstop.us/forum/showthread.php?t=10142

 

[THEFERMANATOR]

If you want more HP out of it, I would go DMAX. Between the 89 or 93 I would definately go with the 93 as it was factory intercooled. The 02 24 valve can be P-pumped, but this is a costly conversion and has some quirks with it. For simplicity and sheer power it is hard to beat the 94-98(the 96-98 is best) CUMMINS 12 valve. I personally couldn't take the noise of the CUMMINS, hence my choice to go DMAX. The DMAX is a powerhouse, and it is unbelieveable just how much power you can add in with just the flip of a switch. First figure out what you want from her, then go from there. Obviously though the 6.2/6.5 woukld be the easiest as it would be an almost drop in swap.

 

[red]

Check out Fermanator's Duramax/suburban swap thread:

http://www.thetruckstop.us/forum/showthread.php?t=10142

was reading this while you posted, :iagree: lots of info in there and an excellent job.


on a side note Fermanator pm sent with a few questions


the 87 k30 is my tow rig and daily driver, i understand that this project will take time to install (and lots of it), expecially if i go with the dmax which is looking better and better. the truck will be used for long highway trips and towing up to 15k pounds (2 offroad trucks or jeeps on a flatbed trailer) a couple times a year. reliability is #1, followed by power, fuel economy, and comfort. not going to be getting rid of this truck either so longevity is another factor. as the truck sits right now it meets some but not all of those goals, but who expects good fuel economy from a 454 anyways ):h. the 02 gmc probably has buckets too so theres another upgrade :smile5:.

looking to be in the area of 550ft/lbs of torque when i do the swap, and knowing me i'll probably get thirsty for more.

what would be a decent price for the 02 gmc, is $5500 too high or is that good for the shape its in?

 

[Acesneights1]

P Pumping a 24v is way easier than the electronics of a Duramax. I would go with the Cummins. The engine is a brute and simple to work on and does not need ANY electronics. As for the statement that a Duramax can get more HP than a Cummins, I disagree. Check out Rich's stealth bomber in the Dodge section. The Cummins can run well over 60 psi of boost if properly built. Cummins and parts can be had way cheaper too.
The noise is what makes it. Who want's a quiet diesel ??:rofl:
Just check the block on the Cummins. If it's a 53 block it's a boat anchor. If it's an 02 it is probably a 56 block which is the coveted one. I'd go with that.

 

[paintballrepins]

what would be a decent price for the 02 gmc, is $5500 too high or is that good for the shape its in?

I got an 03 chevy for $4350 delivered, it was a rollover truck with 118k on it. When I was looking the prices ranged from 4k to 8k depending on the condition and the milage. I believe that I got a really good deal on my donor though, found it locally on craigslist. If you want I can send you some pics of the thing, don't have them handy... All I can say is the only usable stuff on it were the motor/trans and unbelievably the hood. The one downside was that the truck was 2wd. For my swap I'm using the nv4500 out of my truck and the existing drivetrain, except for the motor.

Once I get some time away from the wiring debaucle I will try to start posting up my endeavors. Right now I'm at two motors out, waiting for transmission parts, new input shaft and synchros, dashes pulled and wires sitting on like 3 benches...

As Fermanator said, for power I would go dmax, its just a matter of how good you are with wires, and all you are willing to change about the truck to aviod cutting wires. If you swap dashes and everything, a/c system, brakes, power steering, etc. you will have very little wiring issues, just plug and play, just dont miss any plugs...

Sorry for the novel. Just my 2cents

 

[red]

by all means any info you have feel free to post it up. been reading up on a 82 that was converted to a dmax (he also included some other work that i would not be doing) its definetly a big project and have been told of some obstacles that i was unaware of with the drivetrain.

for the wiring my 87 truck has electric windows/locks along with a good ac system. if the 02 uses the same amount of power for the window motors and locks, just different plugs i could splice into the wires there at the connectors. would run a vacuum pump to keep the stock hvac system working, going off of the other thread it would make for alot less work. trying to figure out what all exactly the dmax/allison computer NEEDS to be driveable without throwing codes. with the brakes my truck has hydroboost already, for the ABS system on the 02 i'm curious if the sensors can be rigged onto my solid front axle, if not then i would need help finding out how to reprogram the computer to forget about the ABS system.



on the other hand, the cummins would be alot less work.

 

[THEFERMANATOR]

Heres some links I've sent to red about his swap.

http://www.youtube.com/user/shoeboxchevy1
http://www.duramaxdiesels.com/forum/showthread.php?t=2447
http://www.thedieselpageforums.com/tdpforum/showthread.php?t=27851
http://www.thedieselpageforums.com/tdpforum/showthread.php?t=27620
http://www.thedieselpage.com/duramaxconversions.htm
http://www.thedieselpage.com/features/project2-16.htm
http://www.thedieselpage.com/features/ClarkDMConversion.htm

This ougta keep you busy for a few days of reading.

As for the ABS, if you run the stock cluster for the DMAX you WILL get warnings for the ABS AND the airbags. The only way around it is to install them. For an 01-02 the only thing you really lose by not using the stock cluster is the integrated trans temp guage, and the oil change light, other than that they are pretty basic clusters. As for what it NEEDS, EFILIVE will make it work with just the ECM and TCM. If you want tow/haul mode you will need thge BCM, and an instrument cluster to cut the board out of if you want a tow/haul indicator light.

The CUMMINS backed up by a NV4500 would be far and away easier, and cheaper to do though by all accounts. It all boils down to what do you want out of it. A P-pumped CUMMINS can make big HP, but won't be as driveable as a DMAX doing it. It all comes down to what do you want and expect from it, and what can your wallet afford. And remember the CHEAPEST AND EASIEST option is a 6.2/6.5 as it will just bolt in.

 

[red]

that reading should keep me occupied for awhile hahaha.

kind of leaning towards one of the cummins motors because of the initial cost and ease of wiring, but not decided.

to get one of the cummins motors in, going mechanical injection, would require a transmission to go with it (wont consider a dodge auto, nv4500 or the 6 speed). some fabrication for the engine cross member, motor mounts, intercooler added, and would most likely need to modify the power steering pump bracket to accept the gm power steering pump.

a 6.2/6.5 setup agreed would be the easiest and cheapest, my curiosity is would it be able to pull the heavier weight. 15k pounds (maybe a little high estimate) up here in the mountains reliably for years, and eventually make cross country trips. granted these trips will only be a few times a year but a big concern, and would like to be able to maintain 65-70mph on the flats towing that load. an intercooler and the ATT turbo along with a 4" exhaust would be definete upgrades.

if the abs, airbag, and built in tranny temp guage are the only things the dash is needed for i could just use the 87's dash and add in some aftermarket guages for the tranny temp, egt's, and boost. loosing tow/haul mode would be a downside. i thought the dash cluster was more plugged in to the computer on the duramax/allison on all the generations.


lots to consider and keep reading about

 

[Acesneights1]

62/6.5 are "ok" but the Cummins will make real power. So will the duramax but I personally think the less electronics the better. Both are excellent engines. It really only boils down to cost and ease of install.

 

[Extremesounds13]

I would jump on the 24 valve in a heartbeat!! Is the guy keeping the truck computer or does he want the cummins computer on the side of the block? You won't need the truck computer just the cummins one, and as far as wiring the 24 valve in I could talk you through it on the phone and you would have it done it two hours flat!! Also the best thing about the 24 valve is with a quadzilla adrenaline, injectors, and a turbo, you will be 500+ horse power and 900+ ft/torque all for less than just the injectors would cost on the dmax. The truck would be a towing monster and still be an awesome daily driver, thanks to keeping the electronics. Just my two cents

 

[red]

decided i'm going with the cummins, will decide which one when i get back stateside in about 2 1/2 weeks! looking over the cost to do the dmax swap and if i were to follow through with it would end up taking me quite awhile to take care of all the little odds and ends that pop up. the add for the 02 24 valve has dissapeared, but adds for a few other cummins motors have popped up and hopefully at least one of them will still be available by the time i get back.

thank you very much for the help and input everybody, lots of good information. will probably be seeing a build/conversion thread in a few months

 

[THEFERMANATOR]

I would jump on the 24 valve in a heartbeat!! Is the guy keeping the truck computer or does he want the cummins computer on the side of the block? You won't need the truck computer just the cummins one, and as far as wiring the 24 valve in I could talk you through it on the phone and you would have it done it two hours flat!! Also the best thing about the 24 valve is with a quadzilla adrenaline, injectors, and a turbo, you will be 500+ horse power and 900+ ft/torque all for less than just the injectors would cost on the dmax. The truck would be a towing monster and still be an awesome daily driver, thanks to keeping the electronics. Just my two cents

DURAMAX injectors are not as expensive to buy as everybody makes it out to be. I bought all 8 of mine for just over $2K. With the 24 valve you get to deal with the wonderful VP44 that will die if your lift pump gets weak. The P-pumped CUMMINS is the best for all around power and reliabilty, but they ALL have there quirks.

 

[great white]

..I bought all 8 of mine for just over $2K...

Geez, my low powered 6.5 with it 250 dollar replacement cost for all 8 injectors doesn't sound so bad right now....

 

[Acesneights1]

I would not use a VP44 in a conversion. I would P Pump it. Aside from the cost, how long does it take to change injs on a dmax ? ON a cummins maybe 2hrs max.

 

[THEFERMANATOR]

I did mine in 6 1/2 hours, newer DURAMAX's take a 1-2 hours though. When I was deciding which way to go with my swap, I SERIOUSLY considered a P-pumped 24 valve backed by a 68RFE trans. When I started pricing out the pump, timing cover, gear, custom lines, and many reccomend injectors, I was looking at around $3K for the basic portion of the P-pump swap. If it hadn't been for the noise factor, a 94-98 12 valve would be sitting under my hood right now backed by an ALLISON. If the BURB was a manual, it would have been the same engine with a NV5600 trans.

 

[Acesneights1]

A p Pumped 24v with an Allison....now that is nice...Drop that in an Excursion or Burb and I'm home. 12v is no slouch either. The thought of the electronics in making a dmax work would be way more than I could handle for sure but it is always nice to keep it all GM.

 

[red]

picked up a 95 dodge 2500 donor truck about a week ago and started pulling the motor 2 days ago. 12 valve p-pump cummins, got everything except for the motor mounts removed, stuck there until the engine crane arrives which should be tomorrow. by the looks of it the computer doesnt need much info, crank position sensor, a 3 prong plug to the injection pump and thats basicly it. might be able to remove the computer all together but that will take more research, would make the swap easier if it can be. if not its about as much wiring as the 87 454 tbi thats currently in the truck.