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What are the best pistons for off roading?

Discussion in 'The Garage' started by m1ndless, Mar 11, 2007.

  1. m1ndless

    m1ndless Banned

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    My friend has the same engine and is wondering which ones are best for a 350.

    Hypernumatic
    or
    Flat Top
    or
    Dual Core

    ???
     
  2. K5dreamer

    K5dreamer 1/2 ton status

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    the pistons you select arent really decided on by what youre going to be doing with the car or truck, but by how the engine is designed.

    Generally speaking i reccomend a flat top piston or a dish. avoid domes if at all possible. not because of the risk of valve contact but because a domed piston inturrupts flame front propogation and wont be as efficient as a flat top or dished piston. if you run a dished piston, look into a D shaped dish, that keeps a flat piston crown that will match up with the quench area on the cylender head. by maintaining this quench youll keep up chamber turbulance and combustion efficiency.

    im not sure what you mean by a dual core piston, that might be a technology that has come out that im not familiar with.

    as for the hypereutetic pistons (more than 12.5% silicon) the main benifit is that those pistons expand less, allowing tighter piston to wall clearances, but they are more brittle, so if they run into high rpms, lots of boost, or detonation they are more likley to fail.

    forged pistons are much stronger, but tend to expand more requiring looser piston to wall clearance, which can cause blow by and piston rocking when the engine is running cold.

    to really recomend a set of pistons, we'd need to know what engine you were building, compression, expected rpm performance range, power adders, and all that jazz.
     
  3. m1ndless

    m1ndless Banned

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    My friend must have been just messing with me for the dual core . hahaha thanks!!

    He wants to know if he should get chrome one since they resist heat better?

    how much power will it add with new pistons?
     
  4. 4xcrazy

    4xcrazy 3/4 ton status

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    enough to spin the tires,,, :haha: :doah: :D :haha:
     
  5. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    appropriate piston pullback springs are recommended...
     
  6. m1ndless

    m1ndless Banned

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    Do I look Retarded or something? I paid 25 bucks for this crap? Lol
     
  7. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Just bustin nuts... :D
     
  8. m1ndless

    m1ndless Banned

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    I know, I am asking this for my buddy though, so I was looking for real answers haha.
     
  9. K5dreamer

    K5dreamer 1/2 ton status

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    the ammount of power added by a set of pistons again is hard to predict because there are so many variables.

    as for the chromed pistons, im thinking he meant chromolly, which is a type of alloy, and not a coating.

    if you want a set of pistons that will reflect the heat, you want a set of pistons with a special thermal reflective coating on the piston crown. to be ideal you would also have your combustion chamber, exhaust port, and valve faces coated in the same thermal reflective coating. Mahle offers a set of pistons already set up with flat tops, thermal coatings on the crown, and anti friction coatings on the piston skirts. although the cylender bores need to be rehoned to take the added thickness of the pistons.

    again, if you would like some more specific details on what pistons to get, i would need to know how much overbored the 350 was, if you were keeping the same 3.48 in stroke, what heads you are running, how thick your head gaskets are gonna be, what length rods he is running, and all that jazz.

    i cannot stress enough the fact that you cant just order a set of pistons and throw them into an engine build, there are several things you HAVE to take into account to make sure you do the job right.
     
  10. ryoken

    ryoken Puppy Fabricator Premium Member GMOTM Winner

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    Well, K5dreamer pretty much covered everything... There's your $25 investment paying for itself...
     
  11. m1ndless

    m1ndless Banned

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    Hahah thanks. I will get back to you guys.
     
  12. rjfguitar

    rjfguitar 3/4 ton status GMOTM Winner

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    pistons don't really add power vs. another set of pistons of different material. The difference is in compression ratio, a different set of pistons can make more power, but doing so by raising the compression.

    Think of it as rods, there are a bunch of styles and materials used for rods that are for a big block Chevy, but one doesn't make any more HP over the other. They are hard parts designed a certain way to handle the load of higher HP made by compression, heads, camshaft, and/or forced induction.
     
  13. 76zimmer

    76zimmer Flyin Rat Premium Member GMOTM Winner

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    :haha: :haha: :haha:


    Do I understand this correct: that Hyper's are more susceptible to breakage than cast?
     
  14. dyeager535

    dyeager535 1 ton status Premium Member

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    Not more susceptible. Hypereutectics ARE somewhat brittle by nature, if they fail they will likely shatter. Cast probably wouldn't hold up any better *under the same circumstances*. May not shatter, but if you are asking the piston to do something beyond it's capabilities, it's going to fail.

    Plenty of hyper pistons being used pretty hard. Unsure what the OEM's are using now.

    There is no reason to use cast pistons anymore. Either use hyper's or forged depending on what the motor is being asked to do. Hypers are as cheap or cheaper than cast anymore.
     
  15. K5dreamer

    K5dreamer 1/2 ton status

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    generally the deal is hypers are for stock to mild performance, and forged are for fire breathers. as for the grey area in between, thats a situation by situation thing that would need to be addressed.
     
  16. NoReGrEtS

    NoReGrEtS 1/2 ton status

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    here is my hyper flat top w/coated skirts:D

    [​IMG]
     
  17. DEMON44

    DEMON44 Low-Tech Redneck

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    :D Heres my Forged JE blower slugs............for BBC though ;)

    [​IMG]










    BUT WAIT! what's this............. 8 friends?!?!










    Brooks Aluminum rods...........for the BBC. still haven't bought a crank yet......been to involved with the Cummins bombing :doah:

    [​IMG]
     
  18. blazin_blazer

    blazin_blazer 1/2 ton status

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    mmmmmmmm mmmmmmmm!
     
  19. NoReGrEtS

    NoReGrEtS 1/2 ton status

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    puts mine to shame:doah:
    OOOOOO BEEF!!!!!!:eek1:
    I want some specs:D
     

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