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305 vs 6.2L diesel

Discussion in 'The Garage' started by 1985K20, Mar 29, 2005.

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  1. 1985K20

    1985K20 1/2 ton status

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    RPO-LF3 305/V8(CA) 155HP 240/TORQUE K10 ENG. 81 TO 86

    RPO-LH4 379/V8(DIESEL) 135HP 240/TORQUE K10,20,30 ENG. 1982

    IT's coming from a pretty reliable source too, but my question is: dont a 6.2 diesel outrun a 305 for torque? :eek:

    I know the 6.2 will get that torque around 1500-2000 rpm but still same max. torque output!!! lol
     
  2. sled_dog

    sled_dog 1 ton status

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    thus why if I go to a 6.2 its gonna have the pump turned up, turbo, ported heads, and a good exhaust.
     
  3. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    Eh... the 6.2L has the horsepower characteristics of a 305 and the torque characteristics of a 350. That's why I don't like them. That and if anything injection related fails you're going to cry if you don't have a bunch of spare motors lying around.
     
  4. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    Say what? It cost me less than $350 to have all my injectors and injector pump rebuilt. That's less than the cost of a new carb...and I didn't need a collection of spare engines :confused: IP's and injectors commonly last over 150,000 miles before they need rebuilding. When they do need rebuilding the truck doesn't just suddenly stop running.

    My 6.2 accelerates about the same as my old 350, but low end grunt is way more. The biggest problem with 6.2's is that they most often got the stupidest gearing. A 6.2 with good gearing is more than fine as far as power goes.

    Rene
     
  5. Pookster

    Pookster 1/2 ton status

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    Stupid Gearing=20+Mpg on the highway. :xmas:

    Funny how people are now talking about spending several hundred dollars to gain 1 mpg.
     
  6. Jonny-K5

    Jonny-K5 1/2 ton status

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    what would a stupid gearing be for a diesel? you mean like 3.08 or 2.73?
     
  7. Jonny-K5

    Jonny-K5 1/2 ton status

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    i also noticed in the specs section here that there are two versions of the 6.2. one rated at 130, one at 148. what the difference between the two? why didnt they just make them all the better 148 version?
     
  8. MEPR

    MEPR 1/2 ton status

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    does that CA after the 305s numbers mean CA emmisions? If so what would the federal emmisions 305 be making?
     
  9. sled_dog

    sled_dog 1 ton status

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    huh? Rene and others get better than 15mpg with their 6.2s and low gearing. I don't know about you, but I've never done better than 10 mpg with any of my gas motor K series trucks.
     
  10. Emmettology 101

    Emmettology 101 3/4 ton status

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    I'll vote for the 6.2 diesel. Dont waste your money on a 305. If an SBC is want you want, save your cabbage and find a 350.
     
  11. tRustyK5

    tRustyK5 Big meanie Staff Member Super Moderator GMOTM Winner Author

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    There are two versions of the 6.2, and the difference between them is only the intake manifold. The 'C' code is found in all 1/2 tons and has a big EGR assembly on the intake which restricts airflow. The 'J' code is found in 3/4 and one tons and has a big open intake with no EGR. The 'J' code breathes better so it makes more power.

    Stupid gearing is 3.08's and a 700R-4. The 3/4 tons commonly got 4.10's and a TH400 (or SM465) and aside from getting less fuel mileage the 6.2 has no trouble spinning higher rpm's all day long. The ideal set-up IMO would be smoe deep gears and an OD tranny. 4.56's and 35's with a 700R-4 would get you into a good place for the 6.2...should be plenty snappy and in OD on the highway still get you 20 or more mpg.

    Mine spins 2550 rpm at 65 and it still gets 16.5 mpg...

    Rene
     
  12. CyberSniper

    CyberSniper 1/2 ton status Premium Member

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    It costs me $17 to rebuild my Quadrajet.
    I have $700 into my rebuilt 305 and the dynosheet started at 2250rpm and was already beating the diesel in horsepower and torque. I know below 2,000 the diesel kicks its ass but so does a 350. You can definitely tell it's a 305 at low rpm.

    I got ~11mpg towing my project rig with my 305-powered pickup at 65-70mph. She was spinning around 3,000rpm the whole time. Unloaded I get around 16mpg (usually 31-32 gallons to go 505 miles half of which is expressway and half of which is regular roads) on the highway with an average speed of 63mph. Around town I get like 1mpg but I drive kind of hard.

    The last time I priced 6.2L injectors and pump it was just under $700. Apparently they're cheaper now?
     
  13. Drey

    Drey 3/4 ton status

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    Thats what I have :mad: My OD jumps in and out so much I barely use it anymore, thanks to the 3.08 gears my tranny is about junk front driving in slight headwinds...
     
  14. sled_dog

    sled_dog 1 ton status

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    well 700R4s do that, thats why I leave them in 3rd gear till about 65mph then I shift into overdrive. its the recommended way to drive with a 700R4.

    My planned setup if I get the truck I am looking at is this:
    Turbo 6.2
    700R4
    4.10 gears
    33s

    With Overdrive and the nice gearing it should tow great and get upper teens in fuel mileage.(wet dream for me seeing as I've never had a vehicle do better than 10) Even at the higher cost of Diesel fuel I'd save hundreds each year on fuel costs at just 15mpg vs my present 8-10.

    I must admit I've trash talked 6.2s from here till next year but I'm becoming a convert. I just hope my dreams aren't dashed when I drive it :mad: But my 350 powered Suburban is a boat and it won't take much to impress me compared to that thing.
     
  15. steve_kibbe

    steve_kibbe 1/2 ton status

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    My truck(3/4 ton gmc 6.2 465 410's) got 17-19 with 33's. No over drive :D
    Great going through granny, 1st, 2nd, but a slug in 3rd.......I wish it had a
    gear between 2nd and third. Anyways, getting a new to me 6.2 monday,
    Talk about gitty........ :woot:


    my .02, take it for whats its worth


    Steve
     
  16. dirtwarrior17

    dirtwarrior17 Banned

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    word...

    I don't know why you would compare a 305 and a 6.2... yeah the dies is down on hp but they all are. Unless you find a cheap 350 go with the 6.2. 350's are WAY easier to modify and if done right, can be nose to nose with the deisel at low rpms and go flying by it at around 2200. Of course that is coming straight from the anti deisel pro gas guy's mouth. 305 cid vz 379 cid and one is a diesel... hmmmm. 6.2!!!!



    1. turboed 350
    2. turboed 6.2
    3. hot rodded 350
    4. stock 350
    5. stock 6.2
    6. hot rodded 305
    7. stock 305

    I don't know why people buy 6.2s and then turbo em when if you did the same to the 350 it would make the same kind of numbers not to mention the hundreds of other mods you have with the 350. I know, I know its a diesel...
     
    Last edited: Mar 30, 2005
  17. PhoenixZorn

    PhoenixZorn 1/2 ton status

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    Funny thing about turbo diesels is that they require so much more boost for the same power increase as a turboed gas v8... at 15 lbs of boost on a single turbo, a v8 will double it's total horsies... if you have a 300hp 350 and drop in a turbo, you'll have a 600hp 350 when the stall kicks in on the turbo... if you put in a twin turbo setup, each with 15 lbs of boost, you have 30 lbs of boost total... run one for low/midrange rpm, and the other for midrange/high end rpm, or both for full range, and you will have a 350 pushing nearly 900 hp for about the cost of a _NEW_ 6.2L diesel... stock...

    You'd need something like 90psi of boost on a 6.2 diesel to get to 900 hp, and mind you, the boost affects torque too, but I don't know how much...

    Plus... turboing a SBC is just as effective on gas mileage as turboing a diesel... you'll pick up some good mpg with either one...
     
  18. dirtwarrior17

    dirtwarrior17 Banned

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    well said....

    that is why i think all 6.5 or 6.2 diesels vs 454(unless they care more about gas mileage than power) argument should be over with unless we're talking about the stock TD 6.5 ( which made 5 less ft lbs at 100 rpm higher than the bbc and something like 50 hp less than the bbc)

    Everytime you say the bbc made more tq at a lower rpm with another 50 to 100 hp you get 3 people saying "turbo the diesel". Sh$t makes me want to pull my damn hair out. turbo em both and see which one pulls harder.

    Rant over...

    peace.
     
  19. sled_dog

    sled_dog 1 ton status

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    wow you want to go into Turbo 350 territory? Too effectively run a turbo on a Gas v8 requires EFI. To do it on a daily driver will require a nice advanced EFI that can adjust quite a bit and is quite tuneable(not your stock TPI or TBI). That EFI alone would probably cost you a couple thousand and add the custom built turbo setup(Banks sells a kit nowadays I think). Now you have a barely streetable gas motor that still doesn't make the low end torque of a Turbo Diesel. Oh and after all that, you snap a rod and destroy your motor cause a stock 350 isn't built to run a good bit of boost.

    To Turbo a 6.2, put the kit on(can be found used cheap, or get a stock 6.5 setup), turn up the Injection pump a little.... oh crap thats it... And for very little $$$ too. The stock internals of a Diesel are far more forgiving to adding boost than those of a gasoline engine.

    You are absolutely right that Gasoline requires less boost to make more power but the driveability characteristics of a Turbo Diesel vs a Turbo Gas motor(no way you are streeting that 900HP turbo motor) are hands down better, especially in a tow rig application. Even the high horsepower Diesel guys don't really drive them on the street a whole lot.

    And Dirtwarrior, as for the BBC vs Diesel, why do you say "except the 6.5TD"? Because it was comparable in power? I mean do you really think a Turbo 6.2 is going to make no power compared to a 6.5TD? A lot of people use the 6.5s Turbo setup. I plan to add an intercooler, port the heads, and add a healthy exhaust. If I really go through with this I should make more power than a stock 6.5TD. And fuel mileage is the big issue for me. I want something that I can drive daily and tow with that gets better than 10mpg. And I can't see myself behind the wheel of a VW. My Dad's 04 Chevy 2500HD gets about 12MPG, I'd love to pull out a mid 80s pickup and get better mileage than him.
     
  20. dirtwarrior17

    dirtwarrior17 Banned

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    I said that because thats the only gm diesel from 88-98 that came with a turbo which means that any other turbo diesel should be out of the question when it comes to the bbc vz diesel debate. whether it be a 6.2 or 6.5 is going to need a kit for a turbo(Unless it was the rare 6.5TD that was offered for 2 years) which means $$$$. You can do the same to a 350 or 454 for close to the same cost.

    All I'm saying is that if you start with a stock 6.2 or 6.5 and pair em up with a 350 and a 454 then do the same mods to em the gas will make more power(6.2 turbo vs 350 supercharged and 6.5 turbo vs 454 supercharged). Once again im not knocking deisels but whenever the gas and diesels are compared everybody wants to bring up that if you turbo the diesel it will make more power...no sh$t. turbo or supercharge the gas and then compare em...

    If your going to say that the supercharge is an advantage over a turbo its not... turbo is free hp, supercharger takes hp to make hp, but then you have turbo lag. damn this is getting to be a can of worms
     
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