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  1. #1

    Curious about using NA pistons in a turbo.

    I am looking for more info about what happens when you use NA pistons in a turbo. I am not thinking of doing this to mine but curious about what happens when you do this.

  2. #2

    Re: Curious about using NA pistons in a turbo.

    You raise static compression and the added boost from turbos will likely cause detonation. I raced Blown nitro funny cars and just changing head gasket thickness (let alone higher compression pistons) up or down made a big difference.

    At least with the blown motor we could change timing, add or remove fuel easily, add or take away clutch, boost, change injectors in minutes etc.

    In a boat a DD doesn't have many options. You'd need more fuel; so bigger injectors to start. If not you'd be lean and lean builds heat and heat kills parts $$$$$.

  3. #3

    Re: Curious about using NA pistons in a turbo.

    He's not adding a turbo, he's putting regular pistons in a turbo engine. Not sure why.
    1978 53' Motor Yacht "LADY KAY V"
    Hull number 524
    Chesapeake Bay

  4. #4

    Re: Curious about using NA pistons in a turbo.

    Quote Originally Posted by oscarvan View Post
    He's not adding a turbo, he's putting regular pistons in a turbo engine. Not sure why.
    Naturals have a higher compression ratio than turbo configs.
    Semper Siesta
    Robert Clarkson
    ASLAN, 1983 55C #343
    Charleston, SC

  5. Re: Curious about using NA pistons in a turbo.

    If it had been a good idea, Detroit Diesel would have done it themselves. Lots of people have done through the years though. Changing twelve, sixteen, twenty four or thirty two pistons and injectors, no to menton any other parts required, to gain a modest amount of reliable horsepower is an expensive undertaking.
    Last edited by kelpy; 08-05-2020 at 12:56 PM.

  6. #6

    Re: Curious about using NA pistons in a turbo.

    Luckydave mentioned in another thread that he has NA pistons in a turbo motor. I did not want to derail the op thread so I posted the question here to try and learn more. His set up sounds interesting.

  7. #7

    Re: Curious about using NA pistons in a turbo.

    I didn't modify my engines, they came from Hatteras that way.
    According to Roger Wetherington, they made two 60C's like that, and they were the fastest examples of that hull.
    Was it a good idea? Good question. Mine have been perfectly reliable, but with a less careful operator......
    "The older I get, the faster I was......."

    1979 60C "Ohana" hull# 331

  8. #8

    Re: Curious about using NA pistons in a turbo.

    Quote Originally Posted by racclarkson@gmail.com View Post
    Naturals have a higher compression ratio than turbo configs.
    OK.... so the pistons are taller and/or the connecting rods are longer to reduce the space at TDC. Got it. Thanks.
    1978 53' Motor Yacht "LADY KAY V"
    Hull number 524
    Chesapeake Bay

  9. #9

    Re: Curious about using NA pistons in a turbo.

    IIRC on a 71 Series it raises the compression from 17:1 to 18.7:1.

    Regarding some of the previous posts:

    I believe the O.P. is talking about putting N kits in a Turbo engine. Not converting to a natural.

    Detonation is a gas engine thing. Not really an issue with a diesel.

    I know one DD guy who used to do it routinely on moderately turbocharged engines. I don't think he did it on the ones that were wound up to 1HP/cu in though. But he said he never had an issue with it and they ran super clean. Normally I wouldn't repeat things like that because you hear a lot of stuff, but in this case, considering the source, I'll make an exception.
    --- The poster formerly known as Scrod ---

    I want to live in Theory, everything works there.

    1970 36C375

  10. #10

    Re: Curious about using NA pistons in a turbo.

    No doubt it can be done especially on the weaker hp rated turbo engines but if you're building more hp it requires more fuel. Seems like a lot of ha$$le for such a minor gain. There is a reason DD settled on that base cr ratio (reliability/performance).

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