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Diesel swap?

Discussion in 'The Garage' started by ramses, Sep 5, 2004.

  1. ramses

    ramses 1/2 ton status

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    Im seriously thinking about swapping in a diesel engine in my 73 K20 after the 350 goes or maybe even before. Ive never heard of anyone doing it though. I dont know how much exactly there is to the process. And I dont know how much it will cost to revive a used diesel to put in. I guess a 6.2 is what im looking for since it came in the 80's trucks which were about the same as mine. Can anyone help me out with anything on this?
     
  2. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    Many people have done the gas to diesel swap. Here is on for example. http://coloradok5.com/forums/showflat.php?Cat=&Board=partsforsale&Number=1177524&page=1&view=collapsed&sb=5&o=31&fpart=1

    To actually convert it to diesel on your pink slip you have to go all out and change guages, diesel stickers, etc...this is what trustyK5 had to do IIRC. I wouldn't waist my time with the 6.2 or even 6.5 if it was me, to slow. A 12 valve 5.9 cummins would be the engine of choice with an NV4500 5 spd at the same time. The cummins will outlast the early detroit GM diesels by a long shot and they are much stouter. Not to mention there are plenty of after market parts available to get mind boggling power out of the mighty little cummins. Plus nothing sounds like a strait piped bombed cummins. I am very biased though because I have been bitten hard by the diesel bug and am looking for the right 98-02 dodge 24 valve cummins 3/4 4x4. /forums/images/graemlins/thumb.gif
     
  3. Diesel Dan

    Diesel Dan 1/2 ton status

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    It can be done, me and one helper did the entire swap in one weekend. Best thing to do is get an entire truck for a donor vehicle, that is what we did. I had a motor on the stand that I freshened with gaskets/bearings/seals. The donor had a bad motor but all we needed were the misc diesel parts.

    Your old gauge cluster will work, just need the diesel face-plate with glow plug/water in fuel lights. There is also a seperate wiring harness for these lights. If you have a choice I'd recommend '85+ for a donor, better glow plug setup. But then again, I always install a manual button anyway.
     
  4. ramses

    ramses 1/2 ton status

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    Well I would love a cummins diesel in my truck but I just thought a GM 6.2 would be an easier swap. I dont need anything faster than my stock 350 and it only pulls my truck at about 75 max with the new 35's on it. I mostly want better gas mileage so I can keep my truck as a daily driver because the 8 mpg is hurting my wallet lol. Id like to get at least 15 mpg and 75 mph top speed with 4.11 gears out of it or I dont want to waste my time with the swap.
     
  5. joez

    joez 1/2 ton status

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    Then you have to go with a 60 up front to deal with the 1100+ pounds of motor up front. To swap a 6bt into a rig that doesnt tow is just pointless. If you NEED a cummins in a non-tow rig, 4bt's are a much wiser and more practical swap. Besides, untill you start pumping large amounts of money and time into your 6bt, its still gonna be slow. yeah, you can get 600+ ft-lbs at the rear wheels no problem, but that doesnt make it a speed demon. My K5 on 33's will run to 60mph faster than a stock 12v cummins with a 5-speed.

    for what you are looking to gain, fuel economy, any mechanically injected GM diesel will work very well for you. I would try to find a 92-93 6.5TD though, as the extra power is nice for long hills and in higher elevations. Unless of course you want to turbo a 6.2 or N/A 6.5, then you could just go and pull whatever you find.
     
  6. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    In a K20 with I'm guessing a non OD tranny you will not get 15mpg at 75mph. Slow the hell down and maybe you could squeeze 15. At 65 you will be turning 2500RPM's with 4.10's and 35's and that is a lot for a diesel. For the best mileage I would bet around 2,000 RPM's would be ideal, I would be looking for an OD tranny too if you are looking for that kind of mileage at those speeds.


    P.S. IMHO 75mph is too fast for a 73K20 regardless of drivetrain. But thats just my opinion.
     
  7. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    I prefer the cummins which is why I said what I did regardless if the truck will be towing or not. Just a much better engine IMHO. Yes, the older 12v 5.9's are pretty slow but the 6.2 isn't any faster. My interest is mostly in the ISB 24V motors and stock they aren't bad, add a good programmer and get out of their way. /forums/images/graemlins/thumb.gif
     
  8. azblazor

    azblazor 1/2 ton status Premium Member

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    arveetek, trusty, and diesel dan have done this swap as well as others. The 6.2/6.5 diesels are good economical engines. I'm in the middle of one now as well.
     
  9. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    [ QUOTE ]
    Well I would love a cummins diesel in my truck but I just thought a GM 6.2 would be an easier swap. I dont need anything faster than my stock 350 and it only pulls my truck at about 75 max with the new 35's on it. I mostly want better gas mileage so I can keep my truck as a daily driver because the 8 mpg is hurting my wallet lol. Id like to get at least 15 mpg and 75 mph top speed with 4.11 gears out of it or I dont want to waste my time with the swap.

    [/ QUOTE ]

    I run my 6.2 with a SM465, 4.56's and 39.5" TSL's. not a great recipe for fuel mileage, yet cruising at 2500+ rpm on the freeway it manages a solid 16.2 mpg average.

    The swap itself isn't that bad, as mentioned a complete donor makes life a lot easier.

    Rene
     
  10. ramses

    ramses 1/2 ton status

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    Well it looks like im gonna try to find a donor truck with a 6.2 in it. It will probably be a while since I plan on finding a Dana 60 front end first though.
     
  11. Aquaman

    Aquaman 1/2 ton status

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    Keep in mind that the cummins has been toned down since they started putting it in their trucks. They have a whole hell of a lot of potential. Put in a Cummins and it won't take much to make it "bend-your-frame" powerful... /forums/images/graemlins/thumb.gif
     
  12. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    They have a whole hell of a lot of potential.

    [/ QUOTE ]

    800HP and 2,000ft lbs kind of potential under extreme mods.
     
  13. Aquaman

    Aquaman 1/2 ton status

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    [ QUOTE ]
    [ QUOTE ]
    They have a whole hell of a lot of potential.

    [/ QUOTE ]

    800HP and 2,000ft lbs kind of potential under extreme mods.

    [/ QUOTE ]Or (for instance) the suburban in TTC w/ twin turbo's and 1200 HP...

    The difference in Diesel HP/torque and Gas HP/Torque is the POWERBAND. Just think POWERBAND. Diesels are ALWAYS in the POWERBAND... Gas engines aren't.
     
  14. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    [ QUOTE ]
    [ QUOTE ]
    [ QUOTE ]
    They have a whole hell of a lot of potential.

    [/ QUOTE ]

    800HP and 2,000ft lbs kind of potential under extreme mods.

    [/ QUOTE ]Or (for instance) the suburban in TTC w/ twin turbo's and 1200 HP...

    The difference in Diesel HP/torque and Gas HP/Torque is the POWERBAND. Just think POWERBAND. Diesels are ALWAYS in the POWERBAND... Gas engines aren't.

    [/ QUOTE ]
    I spend a lot of time over at www.turbodieselregister.com and the consensus over there is that...that guys numbers with that burb doesn't add up. They think he is full of hot air, and as a cummins enthusiast myself 3400 ft lbs sounds a little too crazy to actually hold together. /forums/images/graemlins/screwy.gif
     

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