6.2L vs 6.5L--what say you?

Discussion in '6.5 Performance' started by restoguy, Jul 15, 2010.

  1. restoguy

    restoguy Member

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    I'm sure that this has been hashed out before, but I tried searching and didn't find anything. If you have a link to a valid thread, please post it. Otherwise, I'm here to ask what you guys think about the 6.2 vs 6.5. Let me give you a little background into why I'm asking. I need to pull the engine in my '99 CCLB to investigate the sudden low oil pressure (and metal in the oil). It's not the original engine in the truck so it might be a newer Navistar cast, oil cooled 506 or an older block rebuilt by some less-than-respectable company. I'm hoping for the 'good' squiter, but my luck says not. If it proves to be something less desirable I will probably start over from scratch on the build. I have been looking for a 2001+ block, but have had trouble finding a used one. I was reading about Heath's LSR truck and noticed that he used a 6.2 as the foundation because he likes some of the design features better. Should I go the same route? If so, what are the better casting numbers to look for? What ones should I avoid? Never owned any 6.2's so I don't really know where to begin. Also, if I go with a 6.2, how do you guys feel about having my machinist put the piston oil cooling holes in the block? I want POC, but I realize that lots of people get by just fine without it, and just as many hate it all together. Last question. Is there any credence to the idea that the 6.2 might get slightly better fuel economy? I'm trying to tell myself that it might, just as a way to justify using a 6.2. OK, let's hear it.
     
  2. 3500GMC

    3500GMC Stand Your Ground

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    6.2's are awesome. Been around for a long time. Will be around for a long time to come.

    It's my opinion that a 6.2 block is stronger (GM for GM, stock for stock) than a 6.5. The difference is in the bore, and in that, the block isn't 'hogged out' as much around the main web areas. More meat in between the cylinders too.

    Heads are slightly different, be can be used with all 6.5 peripherals no problem. 6.2 heads have bigger valves and have the potential of flowing lots of air with some work. Pre cups will interchange.

    I wouldn't get too excited about the squirters, not a 'priority'..

    6.2's came in GM trucks at a time where the wheezer gassers were barely in the teens on MPG. The 6.2 is a MISER in stock form- effectively doubling the MPG of a gasser. As with anything, you start hotrodding it (boost&fuel) and leaning on it, the fuel mileage suffers.

    I am doing an '81 6.2 long block swap into the '93 6.5 one ton right now, as a matter fact.
     
  3. buddy

    buddy New Member

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    You dont want the oil squirters, just one more way to make the block weaker. The 599 casting of the 6.2 should be desirable. The difference is small, like 1/16" inch more metal could be left between cylinders compared to a 6.5. If using turbo youd want to use the 6.5 heads as they are designed to run with boost, whereas 6.2 was not.
     
  4. restoguy

    restoguy Member

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    I would use the 6.2 the same way I'm planning to build my 6.5. That being with thicker head gaskets to lower the compression a little(19.5:1), gear drive, girdle, Heath ECM(GLE), HX35, 4" exhaust, ATA charge air cooler, and maybe a few other goodies as I can afford them. What I want is to make 280-300hp at the crank and do so reliably. That's what I think a '99 diesel should have been, and deserves to be. I've got quite a collection of 6.5 stuff from my previous years of loving these things so heads, manifolds, injectors, etc. isn't a problem.(plus all the parts on the truck now) I just wonder if I should skip building one of the blocks I have and go find a good 6.2, if I can't locate a good navistar cast 6.5L.(this is assuming that the block in the truck isn't one) I want a girdle like the one that Inlinesix has been talking about, but I don't know if he'll have any avaliable when I get to that point so I'm going to see what my machinist thinks he can do to come up with something like that. LB7 power and mileage in my GMT400 with 5.7 vortec relaibility. That's the goal.
     
  5. bk95td

    bk95td 6.5 nut job/addict

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    Good used 6.5 blocks are extreamly rare and very expensive.6.2s are cheap and plentiful.There has been a few military take outs on the gov. liquidation auction in kansas. They go for a minimum of $150 http://www.govliquidation.com/list/c7601/lna/1.html
     
  6. Veg_Out

    Veg_Out Walking J Designs

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    I'm building a 6.2 to 6.5 hybrid now. I'll let you know.
     
  7. restoguy

    restoguy Member

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    Does anyone have experience buying stuff on govliquidation? I've looked at stuff on there before, but never bought on any of it. I just wonder what the process is like. If the goverment is involved I'm sure there's more hoops than a dog show!
     
  8. randomid25

    randomid25 Rattle-Trap Cap'n

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    The 599 is desireable but hard to find. Most are 660 2 piece RMS blocks. The difference in bore on the 6.2 is 2mm less than the 6.5 (101mm vs 103mm respectively). If the 6.2 heads are within warpage limits (.003" laterally, .006" longitudinally), I would just swap the precups with some diamond cups from a 6.5 and keep the larger valves of the 6.2 as the precups and valves are the only real difference. Pocket porting for a performance build couldn't hurt anything either.
     
  9. Acesneights1

    Acesneights1 New Member

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    Steel Soldiers has a whole sticky on buying from GL.
     
  10. 3500GMC

    3500GMC Stand Your Ground

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    Watch the injector angle on the early 6.2 heads with the long coarse threaded body injectors as there are no short injectors to be had to thread right in these heads. As we know, the 4&6 injectors are wedged behind the manifold on a 6.5 turbo. Makes things interesting for retro 6.2 N/A swaps. Been there, done that.
     
  11. restoguy

    restoguy Member

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    Ah-Ha! Thanks for that. I'll check it out.

    I'll probably use all 6.5L stuff from my truck except for the short block. I understand that the big valve heads are more prone to cracking between the valves and I don't know that they are as big of an advantage in a boosted application.

    Is the 599 the only 6.2 with a one piece rear main seal? I've grown quite attached to that design and it's oil control abilities.(in the gassers anyway)
     
  12. randomid25

    randomid25 Rattle-Trap Cap'n

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    Yep, its the only 1 piece RMS 6.2l.
     
  13. WarWagon

    WarWagon Well it hits on 7 of 8...

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    A 6.5 is no more than a bored out 6.2. To keep the rotating mass the same GM thinned out the 6.5 pistons vs. the smaller bore 6.2 pistons. Thinner pistons at the top mean they are easier to melt when you turn up the pump and abuse it. You did get a 3500 for abuse right?

    Save some cash and go with a 6.2. Buy new heads as your 6.5 heads likely have cracks. Or do military surplus 6.2 and specify they check the injector length. $950 plus shipping from Boyce with a 30 day warranty. You will not get a 6.5 from a junkyard for that.

    Replace head gaskets and use 6.5 injectors. Precups are a good idea.

    A re-built 6.2 from Heath diesel with ceramic coated pistons and balancing is cheaper than a 6.5 with the same treatment.

    Precups, a bad pre turbo exhaust leak, made my 6.2 repower smoke a lot. Make sure you replace exhaust manifolds, $100.00 each on ebay, when you pull the engine.

    But for $1200 shipped Boyce surplus 6.2, new heads gaskets, new starter I was back on the road in 3 weeks and total cash outlay ~$2000.00 recovering from a from a blown 6.5.
     
  14. bk95td

    bk95td 6.5 nut job/addict

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    14 more 6.2s added on gov liq. auction in fort riley this week. From what I'm told,it takes 4-6 weeks to get approved the first time. Much faster after that. Many times the container can be sold for what was paid for the engine and container. It's a $150 minimum bid for any item on the auction.
     
  15. 3500GMC

    3500GMC Stand Your Ground

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    I doubt you could GIVE me a used 6.5 from a junkyard... The 6.2 repower isn't really a slam dunk either. Just ask me. ):h
     
  16. bk95td

    bk95td 6.5 nut job/addict

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    Around here junkyard 6.5's go for $2000+[seen as high as $2800] with no mention of how many miles. You can buy a whole truck for that much or less.
     
  17. restoguy

    restoguy Member

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    I'm gonna keep my eyes peeled for a good 599 6.2L, in case my 6.5 has other problems when I get it a part. I would like to have a builder waiting in the corner so the project doesn't stall if I do need a block/crank. What years did they build the 599 as a 6.2? That info would make it easier to sort out potential candidates. I'm gonna check on those mills at Ft. Riley and Ft. Carson too.
     
  18. buddy

    buddy New Member

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    599 started in 92 I think, with the first 6.5 block choice, but 6.2s stopped being made in 93 I think and the 599 6.5 went to 94.
     
  19. restoguy

    restoguy Member

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    That's what I figgered. I think I have a 94 "599" 6.5L in my collection. I assumed that they didn't start making them until the 6.5L came out in 92 and quit after 93. Dang the price of the P400, making me go through all this!
     
  20. DaleA

    DaleA New Member

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    Greetings all. I have a 92 K2500 4x4 with a 6.5/4L80E with 162000 mi that's sitting in my garage at the moment. The po ran used motor oil mixed 10:1 with gasoline and after a year it quit running. (no surprise) upon teardown due to massive blowby, I found the cylinders are glazed over with a ridge so small I pushed the pistons out with no problem. The rings were worn down so much there was a 1/8" ring end gap wow. Other than that everything looks real good. I'm told that with the very small ridge I should ball hone the cylinders and put a rering kit in it (std rings) and bearings and throw it back together. However, I have just found an 85 1/2 ton 2wd with a perfectly running 6.2 and NV4500 trans that I got for $500. I'm thinking he 6.2 might not have enough power to pull a 7000lb trailer stock. So I'm thinking hmmm, since the 6.5 (599) is going to be a future project now maybe I can turbo the 6.2, it has 50K on a 030 rebuild that was done at 200k. My concern is maybe the motor is too worn to be turboed even at 5psi boost?
     

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