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Hypothetical question...

Discussion in 'The Garage' started by MaxPF, Feb 20, 2007.

?

Which motor to replace a 350

  1. 383 stroker

    32 vote(s)
    71.1%
  2. 6.2 diesel with a turbo

    6 vote(s)
    13.3%
  3. Wheel stark nekkid on a mountain bike

    7 vote(s)
    15.6%
  1. MaxPF

    MaxPF 1/2 ton status

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    OK, let's say a guy has a Blazer that is a DD/weekend wheeler, and it will eventually need a new motor. Current motor is a TBI 350 with a freshly built 4L60 behind it. Said individual (:whistle:) has narrowed his choices down to either a SPFI 383 that would end up making around 400hp/450lb/ft tq, or a 6.2 diesel with a hairdryer that will make a similar torque number, but about half the HP. Said truck sports 4.56 gears and 33's, but 35's or 37's are in the plans when the 33's are worn out. So, there are some pros and cons to each setup. Here are some off the top of my head:

    383 pros:
    It'll make plenty of power and torque
    It'll cost less to maintain
    It'll be a simple swap, since it is replacing another SB

    383 cons:
    Worse milage than the diesel (with 35's or 37's - I don't expect the diesel to get very good mileage with 4.56's and 33's)
    More expensive to build (plans are for an internally balanced, US made 4340 crank, ETEC heads and an aftermarket sequential port FI setup... mucho $$$)

    6.2 pros:
    Better fuel economy (but not necessarily cheaper to run with diesel being more $ than gas and the need for ULSD additives, frequent fuel filter changes, etc.)
    It'll cost less to build (assuming the hard parts are all servicable - I know how much an IP and pistons will be, and it is still cheaper than the 383)
    It sounds kinda cool (not the loud obnoxious clatter of the older Cummins, more of a subdued knock/rumble)

    6.2 cons:
    Less power, and since it would be a TD it won't have any more torque without boost (where it will run when wheeling) than a NA 6.2 :(
    Potentially less reliable (we have all heard stories about broken main webs and broken cranks, especially when boosted)
    Tranny needs to be modified to shift properly, and a new TC would be needed
    Possible future emissions legislation could render it unregisterable without retrofitting to current emissions standards (i.e. particulate filters, NOx cats)


    I like the idea of being able to wheel all day on a few gallons of diesel, but the uncertain future of diesel fuel quality and emissions regulations gives me pause. Plus the fact that the gas motor will flat outperform it, although it will suck the tank dry much faster. The cost of the diesel conversion will be less than the build of the 383 (albeit not by much, and only if I score the hydroboost, filters, etc. from a donor vehicle), but it will be more work.

    The question is, which is likely to be more satisfying and less hassle over the long run. I've pretty much come to the conclusion that the 383 is the best choice (short of a 15MPG 454 :D), but I'd like to hear other people's opinions. Hypothetically, of course :wink1:
     
  2. 1977k5

    1977k5 3/4 ton status Vendor

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    If you are looking for an american made crank, I think you are stuck with either a machined factory 400 crank or Lunati ($$$$$$$$$$$$$, yeah I meant that many $ signs). With the power numbers you are talking about, a regular steel crank will serve you just fine.

    I get 13-14 mpg on the highway with my setup (vortec heads, 4.56 gears on 37's, ~3000 RPM @ 70MPH). If I had an overdrive I bet I could be in the 15 mpg range. I attribute my relatively high MPG to the vortec heads, 9.7:1 compression and premium fuel, a good ignition system and the roller cam.

    My vote goes to 383.
     
  3. 76zimmer

    76zimmer Flyin Rat Premium Member GMOTM Winner

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    I vote 383 also, but wonder how the auto will hold up. Is it beefed for more torque?
     
  4. MaxPF

    MaxPF 1/2 ton status

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    The Lunati is the crank I was going to use. It is already internally balanced with Mallory metal. $800 to my door :eek1:
     
  5. MaxPF

    MaxPF 1/2 ton status

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    Ayup. :D I knew I would be swapping the motor one day, so I planned ahead :wink1:
     
  6. BKinzey

    BKinzey 1/2 ton status

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    Go with a 6.5L not the 6.2L More power, better engine, problems have been worked out by GM or aftermarket.
     
  7. southernspeed

    southernspeed 1/2 ton status GMOTM Winner

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    383 with EBL ecu set up.


    But i'm biased 'cause I'm a petrol head and have no problem with global warming!:D
     
  8. TheAustrian

    TheAustrian 1/2 ton status

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    stroker! You have a k5 to have fun - right? fun is to drive a k5 with a V8 power plant with alot of mustangs and torque - right? so why spending time thinking about a diesel....? What does you cost a liter gas? Here we pay more than 1 euro = $ 1.31 for one liter (= 0.264 gallone)
     
  9. desertrat67

    desertrat67 Hawk Driver

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    3.8 litre(1 gallon) = $2.11 in my part of the country
     
  10. u2slow

    u2slow 1/2 ton status

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    I voted for the 6.2L. I like the economy, low/easy maintenance, and off-idle torque. Turbo would be nice, but at the same time I realize its an engine that will never behave like a hopped-up gas engine.

    There are also some hidden costs in converting from gas unless you have a donor with all the knick-knacks.

    In a truck, I'd do a 400 before I built/bought a 383. Cheaper for a basic build and more cubes.
     
  11. TheAustrian

    TheAustrian 1/2 ton status

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    still a bargain compared to our price.

    I'd always prever a gas engine before a turbo diesel when the gas engine has enough displacement. Power comes offhanded when you touch the throttle, is more aggressive and has much better acceleration. Also sounds better (but this is probably up to everybodies preference).
     
  12. gmc4cw

    gmc4cw 1/2 ton status GMOTM Winner

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    forget about future diesel emissions. The government can not have retroactive emissions standards. The only diesel motors that will have to ever pass an emission test are ones that were produced and put in new trucks after January 1, 2007.

    I still voted for the 383. diesels are have their place but it's so simple to swap the 383. Now if you stumbled across a duramax that would be another story. 350hp/660 lb-ft and variable geometry turbo vanes so it makes power at all rpm's.:bow: I drive the ones at work whenever I have the chance. they are fast.
     
  13. 79k20350

    79k20350 3/4 ton status

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    Unless the 383 is injected i vote deisel. It will run at any angle:bow: and run all day on a quarter tank
     
  14. 79k20350

    79k20350 3/4 ton status

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    And you can do low 20's-mpg with 37's:p:
     
  15. MuddinManny

    MuddinManny Banned

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    383 STROKER!

    NEED I SAY IT ANY OTHER WAY?
     
  16. k20

    k20 3/4 ton status

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    .......I missed where you listed big block in your poll, Im sure it was just an oversite ;)

    Of the options listed, I guess Id say 383.....but go big block anyway :D
     
  17. 1977k5

    1977k5 3/4 ton status Vendor

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    Ummm, mileage was mentioned as one of the important things for the motor of choice :rolleyes:
     
  18. MaxPF

    MaxPF 1/2 ton status

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    SPFI= Sequential Port Fuel Injection. That's the only way to get good mileage with the cam needed to make those HP and tq numbers. TBI and batch-fire port FI won't cut it.
     
  19. MaxPF

    MaxPF 1/2 ton status

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    Oh yes they can. There is nowhere in the Constitution that states that you can't have retroactive emissions standards. Some legislators in some states have already proposed such legislation.. Fortunately, the proposal never goes anywhere, but that could easily change.
     
  20. desertrat67

    desertrat67 Hawk Driver

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    I had to have my 82 diesel isuzu smoged in Phoenix back in 95.
     

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