Piston Skirt Clearance Wiseco 454

Discussion in 'Gas Engines' started by rcull, Jul 24, 2016.

  1. rcull
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    rcull New Member

    I have been asked to fit a set of Wiseco forged pistons to a chevrolet 454 which is going to be used for a normally aspirated performance marine application. What piston skirt clearance would you recommend?

    For automotive purposes it would appear that they should be about .0045"-.005".

  2. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    It depends on the alloy. I think it really boils down to how much silicon in the alloy. It seems these expand more than say the 4032 alloy more commonly seen.
  3. Petros
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    Petros Senior Member

    if the operating conditions are the same in both applications (rpm, tempertare, throttle setting, etc), than the piston clearance would likely be the same.

    If you expect the operating conditions to be more severe, as in a racing or performance operation, you should find an outfit that bujlds racing engines, or similar application, and just call and ask them the same question.

    I once worked for a fully sponsored factory back auto racing team, we had developed clearances for all of the internal parts based on many engines ran on race tracks, some were the same as factory specks, but many were not. the owner was always willing to share what we learned to help others out.
  4. Jim Caldwell
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    Jim Caldwell Senior Member

    Talk to WISCO?
  5. BMcF
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    BMcF Senior Member

    I rebuild a lot of gasoline engines for both general service marine and performance marine applications. Forged pistons in a 454 would typically be fitted with 4-5 thousands of skirt clearance and hypereutectic pistons with as little as 2 thousandths.

    We seldom use forged pistons any more except in the higher performance builds and anything that is not naturally aspirated. But Wiseco makes a good piston regardless.
  6. rcull
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    rcull New Member

    I went on the Wiseco site and used their contact form, but have not heard back from them, disappointing. These Wiseco pistons are uncoated.

    Icon forged pistons which recommend similar clearances for automotive applications suggest that for "normally aspirated marine" you can run from the recommended street application clearance of .0045" to .006".

    For your comments:
    I had one marine builder suggest adding .001" for the boat as the owner is building close to 600 hp. I guess contributing factors are the boat is a lake boat and not running an intercooler so much of the engine is running quite cool while the combustion chamber can be very warm. He mentioned this condition can rip the skirts off the pistons. He also mentioned opening up the cooling system. I didn't quite understand, but I notice marine gaskets appear to have significantly larger cooling holes, so I expect that is what he is referring to.

    The owner had supplied automotive gaskets and says he has no issues running them unmodified. He has been running 120 degrees with the temp sensor mounted at the front of the intake. I have suggested he should consider mounting his temp sensor in a head and I will open up the gasket cooling holes.

  7. gonzo
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    gonzo Senior Member

    The crossover coolant in the marine intakes have one end blocked. That is to account for the open cooling system.

  8. keith_2500hd
    Joined: Jun 2016
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    keith_2500hd Junior Member

    they also take into account engine not being warmed up on acceleration, scuffing happens when cold/hot. most engine builders run some variation of 50w oil, it also takes longer to fill nooks and crannies.
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