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Thread: Got my 18:1's

  1. #21
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    My one question is this ????????????????/


    Why did GM not do it right instead of doing a half ass job on the cheap ???

    The costs that GM incurred with all the warranties and bad press on the 6.5 surely was far more than the cost of doing it right in the first place.

    Even the OPTIMIZER 6500 is a pretty good engine compared to the 6.5 from GM

    Too many bean counters getting into the mix maybe
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  2. #22
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    The 6.2 L Diesel engine was specifically designed from the start to be a Diesel engine by Detroit Diesel Division of GM (at the time) using gasoline engine technology and design approaches in the early 1980s to keep cost low. Their objective was to increase their fleet fuel economy average to meet ridiculous federal CAFE standards. It was designed for an entirely different reason than modern Diesel pickup engines are. Nobody foresaw what was coming.

    The 6.5 was a follow-up to the 6.2 to try to keep pace once Dodge offered the 5.9 L Cummins in pick-up trucks in 1990. Remember, the first 5.9 L Cummins offering did not have a charge air cooler. The 1992 and 1993 6.5s actually did pretty well and were very competitive in performance with the early Cummins/Dodges and the Turbo 7.3 IDI from Ford.

    With the addition of the turbocharger and once the evolving market began demanding more power from the 6.5, the "gasoline" engine design decisions began to be exposed. Instead of addressing the problems, the bean counters just let it ride. The electronic injection teething problems were justification in their minds to cut their losses and ignore the market -- until it became obvious that they were missing out.

    Enter Duramax.

  3. #23
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    Quote Originally Posted by ronniejoe View Post
    ...With the addition of the turbocharger and once the evolving market began demanding more power from the 6.5, the "gasoline" engine design decisions began to be exposed....
    But, the 6.2L diesel was designed by Detroit Diesel - not GM, though cost, application and performance goals were GM's. Aside from a few bolts, there are no 6.2L/6.5L diesel engine components that interchange with any existing gasoline engine.

    The Ford/International 7.3L diesel though, was originally derived from a gasoline engine - very robust gasoline engine.

  4. #24
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    Gotta love the bean counters.

    Whats sad is that GM engineers should have known that the stresses placed on the engine structure would cause issues.

    Detroit had made good diesel engines for years and should have known better.

    The 6.2 did a good job in getting the MPG'S up.

    An 86 K2500 4X4 with stock tires and 4.10 gears could easily get 25 plus mpg on the Hwy...

    The electronic injection was nothing but salt in an otherwise open wound...

    Way too little proving before it was unleashed on the public, plus the technicians were totally in the dark as to what the real issue was and how to fix it.


    As far as the block cracks and other points of self destruction goes...they should have looked at the data and been able to see what was going to happen.

    A deep skirt block (made of good iron) like the cross bolted Ford 427 side oiler's (Add a forged crank) and they would have had something...

    Cheeeezy iron and no bottom end beef and of course it was doomed..
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  5. #25
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    Quote Originally Posted by More Power View Post
    But, the 6.2L diesel was designed by Detroit Diesel - not GM, though cost, application and performance goals were GM's. Aside from a few bolts, there are no 6.2L/6.5L diesel engine components that interchange with any existing gasoline engine.

    The Ford/International 7.3L diesel though, was originally derived from a gasoline engine - very robust gasoline engine.
    First, Detroit Diesel was a division of GM at the time. In fact, it was part of Detroit Diesel Allison Division (DDAD as it was referred to then). This division structure did not change until after I started working for General Motors in 1983. I worked at DDAD Plant 8 in Indianapolis then, where gas turbine aircraft engines were designed and produced. So, I worked for Detroit Diesel Allison Division of General Motors. My paychecks said "General Motors" on them, just like the guys who designed the 6.2 in the 1980 time frame.

    Nobody said anything (at least I didn't) about using any interchangeable components from gasoline engines. What I said was, and what is fact is, that the design approach, methodology, technology and practices were borrowed from GM Powertrain's gasoline engine design manual to keep cost low. Their early advertising even said as much. Hence, the shallow skirt crankcase design, the lack of piston oil spray cooling (before 1997), the cast nodular iron crankshaft design, the crossed axis helical oil pump drive off of the cam, etc.

    Detroit Diesel was GM. That is a fact.

    On edit: It is also a fact that in the early 1990s, when I worked at Plant 5 in Indianapolis, Detroit Diesel 6V92 engine blocks were machined in Plant 5 alongside of the gas turbine engines. The 6V92s were even assembled and tested there for a while. It is also a fact that in late 1992, I was almost run over and killed by a wayward fork truck driver moving a stack of two 6V92 blocks at once so that he couldn't see in front of him. If I hadn't glanced to my right to wave at a coworker in a break area, I would not have caught sight of him coming up behind me and would have been crushed. I actually jumped over a guard rail into the break area to avoid being run over. The fork truck driver then saw me and slammed on the brakes nearly toppling the engines off the front.

    Again, Detroit Diesel was GM when the 6.2 L was designed. Therefore, it was a GM engine through and through. It is a false distinction to say that Detroit Diesel designed the engine, not GM.

    Back at that time, all of the gears for Electromotive Division (you know, the folks who made locomotives for GM?) were made at Plant 5. Also, many gears for Allison Transmissions were made there. The roots blower drive gears for the 6V92s were made there as well.
    Last edited by ronniejoe; 01-05-2018 at 14:46.

  6. #26
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    I heard one clown once mention that you can tell the 6.2/6.5 were warmed over gas engine because you can see where the distributor went in.

    Some folks just gotta make you laugh EH ???
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  7. #27
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    Quote Originally Posted by sctrailrider View Post
    ...and even the cam isn't the same grind....
    Say what?

    Any improvement over the standard 6.5 cam? Or should I say would there be enough performance difference to dig one up?
    1987 Jeep Grand Wagoneer...new 6.5 in process...diamond block, 18:1's, other goodies...


  8. #28
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    I am curious as to what they changed on the cam specs.

    A naturally aspirated engine has a sweet spot that is far different than one with a huffer..

    The cams used on the 6.5 I am told are the same as the 6.2

    Not sure about this.

    The low boost that the 6.5 runs likely can't really benefit much though.

    After getting into the Mercedes thing I am seeing that they use variable cam timing on both the intake and exhaust cams.

    Their 4.7 liter V8 twin turbo thats used in their GLS (About the size of Tahoe)
    delivers NEARLY 500 hp at about 5500 and 516 ft lb of torque thats full on at 1800 Rpm and the torque stays there up into the 5k area.

    Variable valve timing and a pair of huffers giitener done.
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  9. #29
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    Quote Originally Posted by Robyn View Post
    The cams used on the 6.5 I am told are the same as the 6.2

    Not sure about this.
    Exact same part number...

  10. #30
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    I've worked on the Mercedes 3.0 L turbo Diesel and 3.5 L M272 gas engine as used in the Sprinter vans.

    You can have them...

  11. #31
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    Quote Originally Posted by JeepSJ View Post
    Say what?

    Any improvement over the standard 6.5 cam? Or should I say would there be enough performance difference to dig one up?
    Unique Diesel ran the cam on a "cam doctor" so we would know what was what compared to stock.

    They are different, how much of a difference it will make I don't know yet, that one would be a lot of work to find out on a engine dyno..

    I'm not going to post the specs as it was our R&R and cost me to get the info for my build on this P400..
    1993 Chevy K3500

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