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  1. #1
    Join Date
    Feb 2006
    Posts
    185

    Default 6.5 military surplus engine

    I was at an antique engine show yesterday and a fellow there was selling new 6.5 mil. surplus engines. I'm needing a new engine for my '93 Chevy 2500 2wd, and at $2500, these are considerably cheaper than other sources I've looked up. I asked him if his 6.5 engines had the NA comp. ratio or the turbo comp. ratio and he insisted they were set up for turbo operation. Has anybody had any experience with one of these mil. surplus engines or knows what other identifying characteristics I can check to see if it's an NA engine? I seem to remember the comp. ratio on my old '85 6.2 was 21 to 1, and on my '93 6.5 TD it's 19 to 1. What block casting numbers should I look for and where are they located? Any help would be appreciated.

  2. #2
    Join Date
    Apr 2001
    Location
    Newberg Oregon
    Posts
    12,282

    Default

    Most all the NA engines are Turbo compatible.

    The 19:1 did not come out until tha late stuff. 98-2000 somewhere in there.

    The casting number is on the LH side rear right on top of the bellhousing flange, just below the head deck

    Last 3 didgts. 929, 599, 506 are all possible

    the 929 and the 599 will have 12mm outer main bolts and no oil squirt holes.

    The 506 blocks generally are to be shunned at all costs.

    The ones early 506's had the 12mm outer bolts and the large oil squirts. These were made for the 97 model year and were very prone to cracking the main saddles through the oil squirt holes.

    Been there done that.

    A 599 or a 929 would be an early block.

    Any of these can be used with the turbo. Just keep your max boost to no more than around 12 PSI.

    All early 6.5 TD's had 21.3:1 comp and were fine with it.

    The late stuff had the 19:1. This was GM's last ditch effort to keep things alive a little longer

    My 94 has 268K on the original pistons so ?????????/ go figure.

    The only real savings with the lower compression is that it will allow higher boost.
    Now this said, unless you use an aftercooler more boost (above 12 psi) is a waste anyway due to high intake temps and resultant high EGT's that come with it.

    Keep it close to stock and it will be a happy little camper.


    Good luck

    Robyn
    (1) 1995 Suburban 2500 4x4
    (1) 1997 Astro
    (1) 2005 Suburban (Papa Smurf)
    THIS IS BOW TIE COUNTRY

  3. #3
    Join Date
    Feb 2006
    Posts
    185

    Default 6.5 military surplus engine

    Thanks for your time, Robyn. Just exactly the information I was looking for. Particularly the block casting numbers and location.

  4. #4

    Default

    Unless its a 506 AMG block, thats the one to have. Look for two diamonds under the intake cast in the center of the valley of the block, also 506 will be cast in dots on each side of the valley. The 506 is the best or worst block, just depends who built it.

    The turbo HMMWV's use van heads, so you really dont want one of them unless swapping heads. Plus most turbo engines were in armored HMMWV's, they were worked alot harder(about twice the weight).

  5. #5
    Join Date
    Jan 2001
    Location
    New Hampshire - Live Free or Die
    Posts
    6,057

    Default

    Why would the military be unloading NEW engines? Past the best-if-used-by date? Caveat emptor!
    The Constitution needs to be re-read, not re-written!

    If you can't handle Dr. Seuss, how will you handle real life?

    Current oil burners: MB GLK250 BlueTEC, John Deere X758
    New ride: MB GLS450 - most stately
    Gone but not forgotten: '87 F350 7.3, '93 C2500 6.5, '95 K2500 6.5, '06 K2500HD 6.6, '90 MB 350SDL, Kubota 7510

  6. #6

    Default

    Well some AMG's are not so new now, they been building them for around eight years now. I was just pointing out that all 506 were not bad, to inspect closely you might get lucky.

    Most HMMWV pull out engines will be 6.2's, some will be GM 6.5's and a few AMG's will find there way through.

    I wouldn't be surprised if there were 50,000 AMG blocks in HMMWV's now.

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