4bd1t vs 4bd2t
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Thread: 4bd1t vs 4bd2t

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    Default 4bd1t vs 4bd2t

    Hi everyone,
    I have done a 6bt in a 96 Chevy 4x4 in the past, but this time would like to swap in a 4cly diesel into a 94 Suburban.
    I have spent hours researching and my mind in numb now. I am leaning towards the Isuzu this time, but only because I think it may be a quiter engine.

    Can someone help me understand the basic differences in the 4BD2T and 1T.
    What are the more disireable engines? why?
    What years should I be looking for.
    What are some problems (if any) they have?
    Where are most pepole getting theirs?
    Whats is the avg price for an engine complete with accessories alt. a/c p/s pump.......ect?
    Is 30mpg realistic? I plan on keeping stock settings for HP/tq.
    Why would the Isuzu be better than a 4bt? Other than exhaust and starter being on the correct side.
    Anything else a newb might need to know?


    On the 6bt swap I did I used a 4L80E and plan on it again.

    Leroy.
    1994 Suburban 6.5 diesel converting to Isuzu 4BD2T.
    1996 3500 4x2 GMC. With DB2 injection pump conversion
    1996 3500 4x4 dually crew cab w/Cummins 6bt and
    4L80E

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    Default

    Welcome, Leroy. You will find answers to all of your questions with a quick search of previous posts. While I like the earlier 4BD1T, several people here have had success with the 4BD2. I think 30 mpg will be a reach in a vehicle as large as a Suburban. I would like to hear more about your 6BD swap.

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    Default

    Thanks for the reply. Is it OK to post a link to another site ? I have some info there on my 6bt.
    I did find this info in the sticky, but still have the other questions.


    "4BD1T 1986 - 1991 116 HP w/manual transmission, 121 HP w/automatic These were 3.9 Liter 2-valves per cylinder, in-block cam, DI turbocharged. Essentially, all mechanical IP.

    4BD2T 1992 -1998 135 HP w/automatic transmission. These were 3.9 liter 2-valves per cylinder, in-block cam, IDI, turbocharged AND intercooled. Essentially all mechanical IP with ECU to speed up engine warmup, limit fueling when hot. provide staged glow plug operation and other misc enhancements. These will run fine without the ecu.

    The 4BD1T and the 4BD2T both share the same transmission bolt patern and the most common transmission in the US was the JR403E, a 4-speed automatic with 4th being overdrive. These transmissions are electronically-controlled. The manual transmission, which was less common, especially with the latter 4BD2T's was the 5-speed MSA-5D. 5th gear was 1:1, no overdrive."
    1994 Suburban 6.5 diesel converting to Isuzu 4BD2T.
    1996 3500 4x2 GMC. With DB2 injection pump conversion
    1996 3500 4x4 dually crew cab w/Cummins 6bt and
    4L80E

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    Default

    The 4BD2T is indirect injection and intercooled vs direct injection, non intercooled for 4BD1T. I believe the greater stock HP for 4BD2T is entirely due to tuning to take advantage of intercooling.

    The 4BD2T has a reputation for cracking heads, because of the pre-combustion pucks.

    4BD1T is very reliable and direct injection is more efficient than indirect. They are designed for long life and rebuilding - e.g. hard chrome plated cylinder liners.

    In comparison to a 4BT, many agree that the 4BDxT runs quieter and smoother. The stock 4BDxT torque doesn't peak as early (or quite as high) as a 4BT, but it is sustained over a larger rpm band.

    The stock, non wastegated turbos can be upgraded and the inline pump is easily tweaked for considerably better performance.

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    Default

    Thank you that was very good info. I think I'll be looking for the 4bd1t. The 4bd1t's don't have the head cracking issue and "should" be cheaper as they are older right?
    If I remember right the block is cast with the identifying 4BD1T under the Turbo???
    Another newb question: When its time to rebuild one as long as there was no damage to crank........ect it would just need new cly sleeves, pistons, bearings, seals............ect
    1994 Suburban 6.5 diesel converting to Isuzu 4BD2T.
    1996 3500 4x2 GMC. With DB2 injection pump conversion
    1996 3500 4x4 dually crew cab w/Cummins 6bt and
    4L80E

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    The 4bd1t's don't have the head cracking issue and "should" be cheaper as they are older right?
    You'd think so, but it seems the 4BD2's are more abundant because they aren't so old. 4BD2T's had a longer run in the US than the 4BD1T's. I would guess more 4BD2T's were sold here.

    A head cracks and the engine starts popping out the intake, and the owner junks the 4BD2T. Many are OK other than needing a head.
    A friend that has a junkyard has seen half a dozen 4BD2T's come in the last couple of years, but never a 4BD1T.

    4BD2's can be a great source for parts for a 4BD1T. Don't pass up a free or cheap 4BD2. Block, crank, rods, cam etc can be used for your 4BD1.



    When its time to rebuild one as long as there was no damage to crank........ect it would just need new cly sleeves, pistons, bearings, seals............ect
    correct.
    And if the crank is damaged, get a new crank. The aftermarket has recently started selling new cranks in the US for cheaper than what most the junkyards are selling used cranks for.

    There's a good case for picking a 4BD1t over a 4BD2T, but don't rule out a 4BD2T
    Piston design and head chamber design are the major differences between the two. Most parts interchange.

    Brand new head castings are cheap, $350 for a 4BD2

    The IDI 4BD2's are quieter than the 4BD1's.

    The likelyhood of cracking a head on a 4BD2T in a Suburban is slim unless you're towing heavy loads and are running it hard and hot and ignore EGT's.

    I was looking for a 4BD1T for my next conversion, but ended up with another 4BD2T due to availability and am fine with it.
    83 FJ60 Land Cruiser 4BD2T, NV4500, WVO.
    82 FJ60 Land Cruiser. Trail rig. 4BD2t, H55, WVO

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    Default

    All very good points. I do want a quiter running vehicle too. What did you pay for your 2T?
    I guess it will come down to price and condition of a paticular engine. Does there seem to be anyplace that pepole seem to find there engines over another, like dovebid.com or ebay or........ect
    How do both engines like WVO for fuel? I know my 6.5 idi runs just fine with a mechanical IP.

    Thanks again
    1994 Suburban 6.5 diesel converting to Isuzu 4BD2T.
    1996 3500 4x2 GMC. With DB2 injection pump conversion
    1996 3500 4x4 dually crew cab w/Cummins 6bt and
    4L80E

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    As for where to get them, a wrecked or rusted out NPR Isuzu is the most abundant, however they were available as industrial and marine aplications as well, but I haven't seen either.
    Erik
    Isuzu Nut
    Deviant that's keeping the NPR (with the engine).
    http://www.4btswaps.com/forum/showthread.php?t=9646
    '94 4BD2-TC, HY35W (early) with 3" exhaust & exhaust brake, 'more power screw' maxed, defuel turned up, pump turned up internally by accident.

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    All very good points. I do want a quiter running vehicle too. What did you pay for your 2T?
    I got mine for free Gift from my friend at the junkyard. It had a bad crank and thrown rod though ,
    If i was looking I'd be checking Craigslist and looking behind shops in industrial areas. See if they have any trucks that look like they've been sitting. I found one that way.

    My 4BD2 runs fine on WVO. Just as good as my 6.2 does.
    83 FJ60 Land Cruiser 4BD2T, NV4500, WVO.
    82 FJ60 Land Cruiser. Trail rig. 4BD2t, H55, WVO

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    OK, well that was a good price. Thanks for the info. I'll keep doing the CL search.
    1994 Suburban 6.5 diesel converting to Isuzu 4BD2T.
    1996 3500 4x2 GMC. With DB2 injection pump conversion
    1996 3500 4x4 dually crew cab w/Cummins 6bt and
    4L80E

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