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Duramax vs Old J20

i love J trucks too, but there is something to be said about having something new and RELIABLE bc all the parts bolted to it were meant to be there from the factory.

until your new injectors clog or your computer goes down...mechanically injected diesels are definitely reliable and would be far easier to work on for the average joe.

that being said, a 6bt swap is not a bolt in affair for a j20...search ifsja for a 6bt swap info. if you are going to tow with it you will need stronger axles on a 6bt. and you will need to reinforce the frame. there will be some cutting/trimming on the firewall and front clip as well. it has been done quite a few times successfully, just depends on how involved you get. a 4bt or and isuzu 4bd1t is a much better fit for a jtruck and you can use your stock axles...again far from bolt in, and maybe not enough motor in some situations. a turned up version of a 4cyl diesel is capable of good hp and torque numbers though, you would be pushing egt's hard towing up and down a lot of hills with a turned up 4cyl...

that being said, mileage wise there are guys pulling 25-30mpg with a 4cyl diesel in a jtruck. it all depends on gears, tranny and tire size...

im in the process of restoring a j10 so i can put an isuzu 4 banger in it. its a slow build, but if i put it together...then i will know how to fix it :)
 
Make sure you write down the part numbers and/or part applications (make/model/year etc) for everything you use in the swap... you don't want to be broken down somewhere going "did I use a chevy master cylinder or a dodge? Was it a 2500 or a 3500? craaaaap" :laugh2:
 
absolutely...when are you going to come to iowa to help me ken??? i could drag it out there on a trailer and you could just build it for me :)
 
if you pay for fuel I'm totally down for that, it probably wouldn't be worth it though.
 
the drivetrain that im going to get will probably be coming from pennsylvania....so ill be out that way any how. i'll just drop it at your house when i pick it up :)
 
The amount of money it would take to build a Jtruck to tow somewhat comparable as a newer diesel truck would not justify doing it. Not to mention, everybody says "if its done right, and I take my time, it should be reliable" BS. Custom stuff is never ever ever as reliable as something that a multi million dollar auto company, that has crew's of engineers, testings facilities, and spend years developing a single car can be. You WILL have issues with a custom ANYTHING that is going to be put to tow and be a DD. Yes you will have a cool truck, but when your buddy flys buy you in his GM/Ford/Dodge diesel as your sitting on the side of the road because something is acting weird and you cant figure it out.....your truck wont be so cool anymore.

Buy a J20, restore it and drive it on the weekends, or build a beater and go 'wheel it on the weekends. But buy yourself something thats going to take you to work and back and haul the toys around on the weekends and never give you an issue....if it does, take it to the dealer and have the warrenty take care of it....or at least you can go to the local parts store and get whatever you may need for it and have it be in stock.
 
Duramax vs Cummins, well I have had them both. So comparing apple to apples I will compare my 06 LBZ Duramax to my 07 Cummins 5.9.

Injectors failed, 6 on the Cummins 0 on the Duramax.
Transmission issues, too many on the Cummins 0 on the Duramax
Times stranded, 4 on the Cummins (multiple nights in a hotel) 0 on the Duramax

Overall reliability, Duramax/Allison hands down
Fuel economy, close but slightly better on the Duramax

My Dmax had 285,000 on it when I traded it. I was lured over by the MEGA cab. I ran the Cummins for 394,000 it just left a month ago.

Now some things you need to know about the Duramax. The original to 04 was an LB7 engine and was an injector eating monster. Next came the LLY 04.5 to early 06, good engine but did have a small number of people that had overheating isssues. 06-mid 07 was the LBZ, best engine in my opinion, after this you venture into more emission controls. 06 and up also get the 6 speed Allison.

Now back to the Cummins, if you stay pre common rail (02 and older) now were talking. I've had 6. 2 24 valves and 4 12 valves. Downfall of ALL of these (except the NV5600 6 speeds) are the transmissions. Big weak link. One other weak link is the lift pump, if it fails it can kill the injection pump, an aftermarket lift pump like the Airdog solves that.

It all comes down to money 15k and up a Duramax LBZ, you'll spend well over 20k for lower miles. Under 15k and you can get a nice 2nd gen Dodge, and if your not afraid of miles 10k can buy a decent 2000 or so.

My next toy towing rig will likely be a NV5600 equipped 2000-2002 Dodge in the 10k range. Just can't justify the 20k for a toy towing rig.
 
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Get the J20 and put a 6BT in it!

Got a J20 in mind? If you decide not to buy it I want to see it.

I tow with a 318 right now, it full on SUCKS on hills but does decently otherwise. Definitely wouldn't choose to do so voluntarily, but the price was right.

Seconded!

I'd love to get a pre-smog J20 chassis, throw a pre-smog 6BT (mechanical injection,) pair it up with a 47RE (standalone controller,) and set it up to run on Diesel, greasel, or WVO (two fuel tanks - one for Diesel/greasel only, one for WVO.

Or maybe pair it up with an NV5600 - I prefer manuals anyhow.

(Kinda like how I'd like to get an old M113 surplus chassis, fit it out to make it road legal, put it on a heavy diet, and give it a pair of 6BTs. Set up the greasel processing in the back, and pump out fry tanks on my way around the country... I think a Gavin chassis would make a damned decent travel rig, with a good refit.)
 
you live by me and have the same dream for a tow rig? I cant believe we've never met!
we definitely need to hang out some time when you get back.
 
Ive got to go with the 12 valve cummins... You can deliberately abuse those engines and they'll still keep going without a problem. And if you pour a little money into them you can make a hell raiser out of anything you put them in.. Buddy of mine bought a single cab short bed (custom made of course) with a 12 valve running built and running 44lbs of boost with an 8" stack coming out the bed, with dual auxilary overdrives.. thing was an absolute BEAST. Guy who owned it before him even ran regular weight oil through the thing for like 2 years, still never broke down once.
 
Diesel ricer spotted!

Stacks are dumb
 
lol this thing was no ricer by any means.. It was all blacked out tho on some 20's, wish i still had a picture of it. But as fast as that thing was it didnt matter what it looked like lol. Only thing faster than it i've rode in is my buddies 97 camaro with 6 speed, 383, launch kit, and alot of other goodies :D
 
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