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  1. #1
    Jr. Mechanic
    Join Date
    Mar 2009
    Florida Gulf Coast

    Default 1990 6.2L diesel mild performance mods???

    Im taking it in for new exhaust tomorrow and have a few questions.

    Will hi-flow Flowmaster type exhaust, and K&N air filter help the 6.2L like it will a gas engine? It already has duels, but what type of exhaust, muffler, and air intake do you recommend for best performance?

    Im not going to do anything extensive like a turbo, just the exhaust and intake for now...unless there are other inexpensive options you would like to share.

    Semper Fi :fighting0037:

    1990 1500 Suburban 6.2L Diesel 4x4

  2. #2


    Intake and exhaust are always a good place to start. Opening up the exhaust on any motor will help it breathe better.


    '94 Chevy Suburban K1500
    3" exhaust w/ aero turbine non-baffled muffler
    CFM Technologies TB spacer
    CB w/ 44" whip antenna

  3. #3
    Jr. Mechanic
    Join Date
    Mar 2009
    Florida Gulf Coast


    Also, I dont have a book on it...what engine oil does it need?


  4. #4


    Diesels are really different than gas engines, increasing one thing without increasing the others wont neccessarily enhance performance like a gas engine, it can actually hurt.

    Think of this in terms of a triangle: Air intake, Fuel intake, Exhaust, all three must be increased in equal amounts or the result is high EGT's (possibly damaging), lots of black smoke, or stumbling.

    Earlier model 6.2's had an adjustable fuel control, you could turn up the fuel if you opened the intake and exhaust more. I dont believe the fuel control on your 90 model is adjustable (and it's expensive to modify the earlier models to work on your engine), so you need to look at a whole package.

    Newer Diesels can be enhanced by a new computer or add on controller that increases the adjustable items of the triangle in equal amounts (they have limits when increasing fuel and air but not increasing exhaust, this causes stumbling).
    Yours has some computer input but its more limited than later models and wont see as big of a horsepower increase.

    If you notice most aftermarket parts suppliers offer Diesel upgrades as a package, fuel, air, exhaust, and depending on the application or stage turbo enhancements.

    If your serious about upgrading the first mod I'd make is an EGT gauge.
    The second would be to save up for an upgrade kit.
    And if you really want to pull some ponies out of that engine look at Propane and water injection systems, I'm a big fan of these methods and have seen some awsum HP increases on engines subjected to this.

    One thing a Diesel does have in common with a gas engine is additional HP cost $$, the more HP you try to gain the more it'll cost ya.

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