Dismiss Notice

Welcome To CK5!

Registering is free and easy! Hope to see you on the forums soon.

Score a FREE t-shirt and membership sticker when you sign up for a Premium Membership and choose the recurring plan.

Diesel K5... not enough power

Discussion in 'The Garage' started by KGsK5, Aug 26, 2006.

  1. KGsK5

    KGsK5 1/2 ton status

    Joined:
    Aug 26, 2006
    Posts:
    343
    Likes Received:
    0
    Location:
    Havre de Grace, Maryland
    i have an 83 K5 blazer with the 6.2 L diesel in it... any suggestions to get some more power out of it? already thinking about exhaust and headers...
     
  2. uao85

    uao85 1/2 ton status

    Joined:
    Jan 2, 2004
    Posts:
    1,867
    Likes Received:
    0
    Location:
    Edge of insanity
    what gears do you have? That might be the easy fix, plus exhaust and headers wont do a whole lot.

    Remington
     
  3. diesel4me

    diesel4me 1 ton status Premium Member

    Joined:
    Jul 24, 2003
    Posts:
    17,534
    Likes Received:
    920
    Location:
    Massachussetts
    yowsa...

    The 6.2's are not known for blazing acceleration,especially when coupled to an automatic tranny,and 3.08 or higher ratio axle gears..GM used 2.73 and 2.56 ratios for economy in the 80's 1/2 tons often,they would bog down a big block,never mind a diesel!..

    I'd check the injector pump timing,and ensure a fresh,clean fuel filter (and AIR filter!) is used before condemming the motor..a good running stock 6.2 should have about the same power as a 305 gas motor..unless you put a turbo on it,its not going to be a ball of fire...diesels sometimes FEEL weak,but a lot of it has to do with gearing,and the fact its peak torque is delivered at a low rpm compared to gas engines..

    If I shift my TH400 manually,and let it wind up a bit higher than it would in the lower gears than it would if I let it shift automatically,my truck accelerates a lot better..the stock govenor in the tranny makes it shift "early"--which saves fuel and wear,and is best suited to the 6.2 's torque peak,but sometimes makes for sluggish take-offs..

    My 6.2 in the 82 K20 feels sluggish sometimes,and sounds "doggy",but when I look at the speedometer,I'm almost always exceeding the speed limit!..I think its a lot more powerful than the 305 in my other 2wd truck,especially when I'm plowing snow--my 400 small block I had in the 74 K20 couldn't push snow like the diesel can,thanks to the great low end torque and the extra weight of the diesel..and I can live with slower 0-60 times if I can get over 20 mpg!.:D
     
  4. 1985_K5_Silverado

    1985_K5_Silverado 1/2 ton status

    Joined:
    Dec 21, 2005
    Posts:
    984
    Likes Received:
    0
    Location:
    Corn Country
    There's always a Banks Sidewinder turbo kit, but they aren't cheap. I'm sure some folks can give you personal feedback on them.
     
  5. KGsK5

    KGsK5 1/2 ton status

    Joined:
    Aug 26, 2006
    Posts:
    343
    Likes Received:
    0
    Location:
    Havre de Grace, Maryland
    thanks for the input, i just put clean filters on it but ill check the injectors. would a chip or power programmer work for this old of a diesel? i no that you can get pretty huge gains from newer diesels but i havent seen anything for the old 6.2.
     
  6. beater_k20

    beater_k20 Banned

    Joined:
    Dec 9, 2003
    Posts:
    10,276
    Likes Received:
    0
    Location:
    Elkhart, IN
    its all mechanical, so no, a programmer wouldnt do you any good.
     
  7. Thunder

    Thunder 3/4 ton status

    Joined:
    Jul 20, 2000
    Posts:
    8,946
    Likes Received:
    1
    Location:
    Northeast Nevada
    :laugh: Unless you want to turbo it or convert to Gas TBI ............Get used to being in the slow lane.
     
  8. bear76

    bear76 1/2 ton status

    Joined:
    Oct 16, 2005
    Posts:
    1,065
    Likes Received:
    0
    Location:
    here
    Want more power, maybe I'll trade ya my 91 TBI.:D
     
  9. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

    Joined:
    Jun 13, 2003
    Posts:
    29,621
    Likes Received:
    1,365
    Location:
    Jersey Shore

    gear will, by far, give you best improvement in performance... what does it have now?
     
  10. u2slow

    u2slow 1/2 ton status

    Joined:
    May 9, 2001
    Posts:
    2,217
    Likes Received:
    0
    Location:
    BC Canada
    Diesel is more finicky with gearing than gas... overgear and you will regret what you lose on highway cruisability. You may want to work backwards; find out what the max cruise speed the engine seems comfortable with, then see how much of that you can afford to lose (gearwise) and still maintain the speed limit.

    Propane? :D
    http://www.members.shaw.ca/k2pilot/Propane article.html
     
  11. u2slow

    u2slow 1/2 ton status

    Joined:
    May 9, 2001
    Posts:
    2,217
    Likes Received:
    0
    Location:
    BC Canada
    A 6.2L with tall gears has no trouble using the fast lane ;). On-ramps, and hills around town might be a little embarassing though :o
     
  12. DieselDan

    DieselDan 1/2 ton status

    Joined:
    Jan 27, 2001
    Posts:
    1,056
    Likes Received:
    0
    Location:
    Vermont
    As troublesome as the (stock) 700R4 can be, it's a boon for the 6.2. Comparing my '89 Jimmy w/700 (before turbo) to CUCV M1009 (Blazer) w/TH400 and 3.08 is a big difference. That lower 1st of the really 700 launches and is a good marriage with the narrow power band of the 6.2
     
  13. uao85

    uao85 1/2 ton status

    Joined:
    Jan 2, 2004
    Posts:
    1,867
    Likes Received:
    0
    Location:
    Edge of insanity
    Dude tbi whatever will still be in the slow lane unless you dump a load of money into it.......I had a tbi engine, it sucked.......badly. Poor gas mileage, mediocre power, but on the other hand its somewhat reliable.............. If your wanting power, get ready to spend a fair amount of money no matter how you slice it. Whether its swapping in another engine, like the almighty tbi............or a different diesel like a duramax:wink1: :eek1: or a 4bt, modding the current 6.2, changing out your tranny to a manual or a 700r4, or just doing little things like gears, exhaust, or a combination of these choices.

    Regards,
    Remington
     
  14. beater_k20

    beater_k20 Banned

    Joined:
    Dec 9, 2003
    Posts:
    10,276
    Likes Received:
    0
    Location:
    Elkhart, IN
    poor gas milage? i'm guessing that the truck was either not stock, or just in a terrible state of tune. my C2500 gets around 17-18mpg no problem, and i drive like a psycho. i'll agree that power is a little lacking, but a good tune and some simple mods will fix that.
     
  15. KGsK5

    KGsK5 1/2 ton status

    Joined:
    Aug 26, 2006
    Posts:
    343
    Likes Received:
    0
    Location:
    Havre de Grace, Maryland
    any gear recomendations?
     
  16. beater_k20

    beater_k20 Banned

    Joined:
    Dec 9, 2003
    Posts:
    10,276
    Likes Received:
    0
    Location:
    Elkhart, IN
    nope, none at all... :haha:
     
  17. u2slow

    u2slow 1/2 ton status

    Joined:
    May 9, 2001
    Posts:
    2,217
    Likes Received:
    0
    Location:
    BC Canada
    I've vouch for the mediocre TBI economy & performance. I had one in my '91 crew, it was very similar power-wise to my the 6.2L Burb. Both had 4.10s, no OD, and 33's. Crew is (was) 7700#, Burb is 6000#. Economy is 50% better with the diesel.

    Turbo & propane are a couple of power adders. Swapping over to a different diesel may end up cheaper as you can find something used that's already got a turbo. I wouldn't snub my nose at a 7.3L IDI or a PSD for that matter.

    If I wanted power on a heavy rig like these with spark ignition, I would build a 400+ci engine and run propane.
     
  18. KGsK5

    KGsK5 1/2 ton status

    Joined:
    Aug 26, 2006
    Posts:
    343
    Likes Received:
    0
    Location:
    Havre de Grace, Maryland
    hahaha beater your all over the place tonight arent ya... much appreciated
     
  19. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

    Joined:
    Jun 13, 2003
    Posts:
    29,621
    Likes Received:
    1,365
    Location:
    Jersey Shore
    first things first... We need to know the tranny, t-case and tires you'd like to put on it... I'll assume 700r4 and 35's...

    second, you really need to figure out whats in the truck now with the stock 10 bolts and what the 14b and 44 you have are... is it a fullfloater 14b or semi? 8 lug 44?

    either way, here's a calculator to help you figure it out.. like mentioned, it looks like 4:10's would be decent...

    http://www.grimmjeeper.com/gears.html
     
  20. beastofablaze

    beastofablaze 1/2 ton status

    Joined:
    Apr 4, 2005
    Posts:
    441
    Likes Received:
    0
    Location:
    CA
    spending more money for more power is like having to pay for gas... it'll never change but the key is to get the most bang for your buck. I am saving for my afrs for my tbi sbc... gonna have about 6 or 7 g's into it but it'll be a brand new CA smog legal 430 hp 450 ft lb bb killer. Thats REALLY pushing the 454 tbi's limits... might even need to go to tpi. Since your a diesel tho you could throw in a blown 572 and not worry about smog so I say get a hot carbed 383... can't beat the power to money ratio... but you will sacrifice throttle response, some low end tq, and gas mileage if you go with the carb.
     

Share This Page