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ok just how good are the 6.2s and 6.5s

Discussion in '1982-Present GM Diesel' started by bad_bo_ti, Mar 6, 2001.

  1. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    I have had several people tell me that both diesels suck. my step brother is a diesel mechanic and said that if i find a diesel engine let him have it so he can trick it out for me. should i even bother? let me know pros and cons of the gm diesels.
     
  2. surg82k5

    surg82k5 1/2 ton status

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    personally i love my '82 6.2 I think once a person stops trying to compare it to the pick up of a gas engine, it does great. i am completely satisfied with mine. i have no overdrive and i still get 17-18 on the highway. i don't think you could do that with an older 350 non overdrive. for me it scoots along just fine and it will pull whatever i need it to. i don't pull much so that is not a big deal. i think most people have a bad perception of GM diesels because of the infamous 5.7L diesel. this one was made from the 350 gas block and it couldn't take it. the 6.2 and 6.5 are diesels from the ground up. in my opinion they are great. if i could find another one i would get it. hope this helps

    sergio
     
  3. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    I love my Diesel. Yes...people compare it to the gas and say that it sucks. It doesn't. Its a very good engine and gets great mileage. I won't say its the best...but it ain't as bad as people make it out to be. They can and WILL go way over the miles that a gas won't. Heck...DieselBlazer and I the other day went muddin....we got more than enough to do anything. Plus that crawl is great...no skinny pedal at all. The idle is enough!!!

    SK-15
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  4. DSLBLAZER

    DSLBLAZER Registered Member

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    I agree with surg82k5 100%. I have put about 55,000 miles on my 6.2L blazer, and the only things I have replaced on it are glowplugs and a water pump. It now has 170,000 miles on it and the engine still runs strong! I have heard the late 80s 6.2s are better than the 6.5Ls. They have a little less power but it's nothing a turbo won't fix. Soon as I find another diesel blazer for the right price I will have 2!!

    Keven
     
  5. bad_bo_ti

    bad_bo_ti 1/2 ton status

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    well basically, what i am wondering is if it would be worth all the money to BUILD(not just put to gether but modify!!!) one up? what all aftermarket parts are available for the diesels?
     
  6. NewK5Guy

    NewK5Guy 1/2 ton status

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    First you should determine what you want to do. Resources like The Diesel Page(www.62-65-dieselpage.com) are great. Helped me greatly. The early 6.2 wasn't very powerful. GM made it to be economical and it is. The later version, the 6.5TD, is a trubocharged version with the block punched out to 6.5 liters. In fact, most 6.2 and 6.5 parts are interchangeable so parts are no problem. The turbo was added for a little more oomph. I'm still learning about diesels(I'm mostly a car guy), but from waht I've seen, it's worth it. The 6.2 in my 84 Jimmy is new, but the previous engine went all the way to 230k miles and change before letting go and it wasn't babied on that trip either.
    As for aftermarket parts, there are some and they are not hard to find. There are several companies that make turbo kits for the 6.2. Since the bottom end is nearly indestructable, there's no need to mess with it. Headers are there if you want them, plus there are several diesel specialty companies that can tweak for you, too. I just learned of one through my boss that can tweak injection pumps.
    If I was you, I'd get a 6.5TD so you'd have the turbo already. Plus, the 6.5's had a serpantine belt system.
    Despite how some people bash them, I'm not ashamed to own a diesel. True, it ain't no gas engine, but it does have it's perks. I live waking up the neighbors.
     
  7. AgDieseler

    AgDieseler Certified Scrap Producer Premium Member GMOTM Winner

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    I first got my 6.2L NA in my 1985 burban. 16 years and 300,000 miles later, it's still just as good as the day it was new. I'm still running the stock powertrain, but that'll be gone soon in favor of my project diesel. I've taken an old military 6.2, B&B and gone the race prepared route. A quick overview is that it's turbo-ed, 19:1 compression, 6.5L heads, and a high flow cooling system. Personally, I think that it's a great engine to build. I'm a big fan of the reliability, strength of design, economy, and the grunt of it's low end torque. Yeehaw for clackers!

    David
    '85 diesel burban
     
  8. AJMBLAZER

    AJMBLAZER Better to be lucky than good. Premium Member

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    Anyone know what the hp and torque ratings are for a modern 6.5L TD? There's the possiblity that I may spend at least 20 years of my life in New Zealand, and since my truck is like a kid to me, if I were to stay that long, the Blazer would follow me over. However, in the land of $4 a gallon gas and diesel, I'll take the 18+ mpg and power you can get from a diesel. Just checking my options. I don't have to worry about smog rules because I won't register it anywhere over here that has smog testing, and there aren't any emissions requirements or testing in NZ.[​IMG]

    1992 Blazer Sport, 350 TBI, 4L60, 3" Flowmaster, K&N, 2.5" Rancho, 285/75R16 on 16x8 Baja's[​IMG]
     
  9. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    AJMBLAZER: Check yer email...I sent you the torque curves

    SK-15
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  10. RLBstein

    RLBstein 1/2 ton status

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    If you add a turbo such as Banks, you'll notice a big increase in power and fuel economy. And while your at it, add propane. It's 400 bucks and works on almost all diesels and you'll get a 25%-60% increase on top of that and even better fuel economy, I think they say 2-3 more MPG. Try the web site and check it out.
    http://www.dieselperformanceproducts.com/home.html

    85 Blazer on an 82 chassis, 6.2L Diesel, ORD flip, 35's with no cutting on a 4" lift.
     
  11. pcorssmit

    pcorssmit 1/2 ton status

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    OK, I promise to keep this post civil. [​IMG]

    ATS, Bully Dog, and others make propane systems. I have never tried one. A guy at work put one on a '97 K3500 crew cab dually 4x and really likes it, except for the slipping clutch. While they can increase your fuel milage, don't forget to take the added cost of propane into account.

    I haven't spent much time there, but I would think the 6.2/6.5 dieselpage would be a good resource (I spend a fair amount of time on the equivelant Dodge Cummins site). Theres lots of aftermarket upgrades for diesels, and I would highly reccomend a turbo for a NA diesel. Once you start modifying, a boost gauge and exhaust gas temperature (EGT) gauge are highly reccomended, and a tranny temp gauge for autos. I don't know what the max reccomended EGT is for a 6.2/6.5, for a Cummins its around 1300 deg. F.

    AgDieseler, what kind of power are you expecting from your new motor? If memory serves me correct, 19:1 is fairly low for a Chev., I take it you're planning on running a fair amount of boost? Not really sure what kind of boost those 6.2s run (w/aftermarket turbo), other than they are generally lower than factory turbo motors due to higher comperession. For comparison, the max boost I've got was 34 psi (empty, haven't towed anything heavy yet), and 24 psi stock. I think my compressions around 17:1. Is there a difference between the military and civie 6.2, or is that just what you could find?

    Pete



    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  12. AgDieseler

    AgDieseler Certified Scrap Producer Premium Member GMOTM Winner

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    The 6.2 will handle the same amount of boost a 6.5 will, properly outfitted of course. A Gale Banks turbo can give modest levels of 10 psi, and that is with the stock compression of 21.3:1. Because decreasing the compression raised the boost, I expect to run a healthy 10-15psi. It's a good thing the Banks turbo is non-wastgated, so that there's the constant release of manifold pressure. Otherwise, I'd expest to blow a gasket or two. Your compression in the Dodge is 17.5:1 as is the PSD and Dmax. I hope to get a solid 220-250hp and about 450-475 lbs ft. The 19:1s lower sombustion temperature, and therefore add life to the overall engine. It also helps that I have a gentle foot.

    David
    '85 diesel burban
    300,000 miles
     
  13. NewK5Guy

    NewK5Guy 1/2 ton status

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    Agdiesler, I don't know about that Banks system. From what I'd heard, the Banks was the only system that had a waste gate, while producing the least amount of power. The several other systems(I can't think of the names) were not wastegated, but produced more power(as opposed to the Banks).
    If you get a turbo, get a model with a wastegate of some sort. You'll be sorry if you don't. The turbo lag produced since the exhaust isn't blocked from the turbo will drive you crazy and make braking more difficult, especially if you are towing. Also get a blow off valve if you're running a manual tranny.
    If you want even more power(and you didn't mention this), opt for an intercooler.
     
  14. OFFRDK5

    OFFRDK5 1/2 ton status Premium Member

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    Roads? Where we're going, we don't need any roads!
     
  15. AgDieseler

    AgDieseler Certified Scrap Producer Premium Member GMOTM Winner

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    I'm already member #5159 on the page, and have been subscribed to the listserv since it started. I'm not running an intercooler, yet. It's an expensive external mod that needs to be worked in at a later date for fitment reasons. There's only so much space on the front grill, and the only kits are for later model trucks. Fabrication will be in order, and there isn't enough time for me to do that right now. But be assured, an intercooler is on the way. I'll probably go with the one from Kennedy.

    According to Jim Allen, both ATS and Banks use non-wastgated turbos. For safety reasons (like trying not to blow up the engine) I'm going to start with my non-wastegated system, and then if the turbo lag really gets to me, I'll fab something up. I don't do a lot of heavy towing, but rather a lot of wheeling. Like any other build up, one just has to "play" with the setup to find the right combination. I think I've found a pretty good starting place, and I'm sure that I'll be tooling with it every few...minutes.

    David
    '85 diesel burban
     
  16. pcorssmit

    pcorssmit 1/2 ton status

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    Just a thought, I had a buddy that put a Dodge intercooler in an '84 Chevy, I believe it was from a '94 +, they are bigger than the ones from the older trucks. The Chevy was a military 1 ton, so I don't think it had AC. He also had a Cummins and 5spd from a '92 Dodge, so the plumbing was different than on a 6.2. I myself would have liked to have the Cummins in a Chevy, rather than a Dodge, but don't have the time to do the swap. Not that I don't like the Dodge, but its just no Chevy.

    Not quite sure what you mean by "It's a good thing the Banks turbo is non-wastgated, so that there's the constant release of manifold pressure. Otherwise, I'd expest to blow a gasket or two." The whole purpose of the wastegate is to gaurd against excessive pressure, while allowing for faster spool up.

    As for a blow off valve, I've never heard of one on a diesel, I thought they were mostly used on the Hondas and such w/aftermarket turbos and 6" exhaust tips.
    Pete

    '83 K5, 350 TBI (ex 6.2), 700R4, NP208, Dana 60/14 bolt, 4.56s, Detroits, 3" lift, 15-39.5x15 TSLs
    '97 Dodge 2500 4x4 CC LB Sport, Cummins 5 spd
     
  17. NewK5Guy

    NewK5Guy 1/2 ton status

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    Doesn't matter what motor it's on, a blow off valve is used to vent excess boost pressure when the turbo is coupled with a manual tranny. When you accelerate with a manual, the engine revs, the turbo spools and boost is created. As it is created, it is used by the engine. The engine doesn't use all of it, hence the "pressure" in the intake which is the measured "added boost". Well, with the manual tranny, you take your foot off the gas to change gears. The engine revs down BUT the turbo freewheels, still producing boost(and lag in non wastegated applications). The throttle body is closed since your foot is off the accelerator and the boost pressure builds rapidly. That is where the blow off valve comes in. It vents the excess boost produced during the manual gear change. An auto tranny car doesn't need one since the engine does not "rev down" to change gears.
    I see my faux pas now. Diesels don't have throttle bodies so why need a blow off valve? I think one could still be used or needed to help moderate boost pressure in the intake. Wouldn't want to blow off a hose clamp or anything. Which also brings me to the speculation why diesel turbos aren't wastegated: the lag would help bleed down the boost pressure created and left over during the manual gear change by not letting the engine "rev down".
     
  18. AgDieseler

    AgDieseler Certified Scrap Producer Premium Member GMOTM Winner

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    When I say that I am glad to have a non-wastegated turbo, I mean that since there is a constant release of boost pressure, the chances of blowing a gasket are reduced. Even though wastegates allow a release of boost, there is still the pressure build up before the release. In my talking to diesel folks, I have learned that heavy duty diesels like those seen in semis are non-wastegated. This is due to the large loads that they carry. While a wastegate increases off the line performance, I am choosing to initially go the safer route and use a free flowing non-wastgated system. In addition, the Banks unit is such a high flow turbo that I probably won't have any kinds of trouble getting enough air.

    David
    '85 diesel burban
     
  19. I have seen more talk about turbos on 6.2's than I have heard in a long time. I am glad to know that so many peolpe on this page have diesels. As I looked at more power from a turbo from my 6.2 I found some problems. I decided to leave it stock. It save me money too be it is fun to talk about all the power you could have.
    I lived near a man who has set the speed record on the bonneville salt flats in Utah. He also built some of the first turbos of the 6.2. The dealers had him install his turbo on their new trucks. He explained that one of the reasons he stopped installing the turbos on the 6.2 is because the right rear cylinder would burn. The cylinder burned because the 6.2 does not have oil cooled pistons like the 6.5 has. Instreastingly enough, I have talked to two men personally that said the same cylinder (right rear) is the one they had problems with on their 6.5. If it will burn on a 6.5 it will probably burn faster on the 6.2.
    I don't pull alot either so I enjoy mine the way it is. It runs well, and worlds better, now that I am at sea-level compared to 4500 feet. During the move east, I pulled a car behind me climbing up to 11,100 feet over the Eisenhower Pass on I-70 just west of Denver. Then I wish I had a turbo. I understand that the propane (which can only be run with a turbo) has a soothing effect on the engine. It should increase your ecomony 35% to 45%, and your over-all mileage (figuring in the cost of propane) 15% to 20%.
    One other option would be to replace the timing chain with a gear set. The timing can fluxcuate 7 to 8 degrees on a tight chain (one that is not worn out). With the fuel injection pump being a very very presice piece of equipment 7 to 8 degrees is a lot. The timing gear set will reduce that number to 2 or 3 degrees. You can also try turning up the fuel and advancing the injection pump alittle.
    My diesel has been good to me also. It is not the fastest unit on the road and not the most powerful one either but it can run unside down, requires little maintainance, and once it is started it probably won't die on you.
     

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