Welcome to the Hatteras Owners Forum & Gallery. Sign Up or Login

Enter partial or full part description to search the Hatteras/Cabo parts catalog (for example: breaker or gauge)
+ Reply to Thread
Page 3 of 4 FirstFirst 1 2 3 4 LastLast
Results 21 to 30 of 35
  1. #21

    Re: Curious about using NA pistons in a turbo.

    Quote Originally Posted by rsmith View Post
    O god not this discussion again. Everyone need a lesson on stoichiometric combustion again?
    I missed it the first time. But I am NOT asking for it now.
    I looked it up and remembered the headache it gave me 45 years ago.
    [C + H (fuel)] + [O2 + N2 (Air)] -> (Combustion Process) -> [CO2 + H2O + N2 (Heat)]
    Ah, where did that Tylenol go? I feel that headache coming back.
    Last edited by Captain Ralph; 08-06-2020 at 09:29 AM.

  2. #22

    Re: Curious about using NA pistons in a turbo.

    Interesting discussion....

  3. #23

    Re: Curious about using NA pistons in a turbo.

    Lucky Dave.

    Excellent info. Thanks for taking time to get into the details.
    Brian L

    IMPETUOUS - 1984 Hatteras 53 ED MY Hull #CN720
    GOD'S GIFT - 1972 Chris Craft 42 Ft. Commander
    QUEEN B - 1974 Century 24 Ft Buccaneer
    GOD'S LITTLE GIFT - 1962 Johnson 19 Ft. Runabout
    MON AMI - 1984 Catalina 30Ft. Sloop

  4. #24

    Re: Curious about using NA pistons in a turbo.

    Great discussion, shame that it’s not easier to change pistons, I would like to throw a couple of dozen of NA pistons at my engines to see if I notice a difference.
    JMooney
    61 MY 1983 #341
    “Jerrie”
    Miami , FL

  5. #25

    Re: Curious about using NA pistons in a turbo.

    Quote Originally Posted by jmooney View Post
    Great discussion, shame that it’s not easier to change pistons, I would like to throw a couple of dozen of NA pistons at my engines to see if I notice a difference.
    Do one.... that way you have a valid comparison.
    1978 53' Motor Yacht "LADY KAY V"
    Hull number 524
    Chesapeake Bay

  6. #26

    Re: Curious about using NA pistons in a turbo.

    Quote Originally Posted by oscarvan View Post
    Do one.... that way you have a valid comparison.
    Sounds practical...LOL
    "The older I get, the faster I was......."

    1979 60C "Ohana" hull# 331

  7. #27

    Re: Curious about using NA pistons in a turbo.

    A previous poster mentioned “that knocking sound” Detroit’s make, misinterpreting it as detonation.
    The reason Detroit’s make that sound on injector firing is that they inject all the fuel at once, causing all the fuel to burn at one time (or all of it that can burn), hammering on the combustion chamber. Modern common rail engines are much quieter and run much smoother at low rpm due to the fact that the injectors are pulsed, spreading out the combustion process over time to lengthen, and lower, the peak pressure of the combustion stroke. This is done mostly to give better fuel economy, decreased emissions, and increase power output, but also makes the engine quieter. They are four stroke designs as well, but a common rail two stroke would be much quieter than a mechanically injected design.

    A big benefit of pulsed injection is reduced emissions. Injecting all the fuel at one time takes a larger injector, so the fuel droplets are larger. The problem is that compared to the oxygen molecules in the combustion air the even the smallest fuel droplets are thousands of times bigger. Much of the fuel remains unburned because the oxygen simply can’t get to it during the combustion stroke. This produces the sooty carbon emissions we all know so well, emissions difficult to address in emissions complaint vehicles and boats. Pulsing a smaller, higher pressure injector spreads out smaller droplets of fuel in the turbulent air flows in the combustion chamber over a greater period of time, promoting more complete combustion.
    Gasoline engines have this droplet size problem too, mitigated in large extent by mixing the fuel and air for some period before the spark event, so the fuel has (more) time to vaporize.

    Detonation and pre-ignition in spark ignition engines are unrelated phenomenon. Detonation in spark engines is due to insufficient octane to ward off detonation of the residual unburned charge near the end of the combustion event due to heating and compression of the fuel/air mixture.

    Pre-ignition is ignition of the fuel air mixture before the spark event, generally caused by something glowing red hot sticking out past the boundary gas layer in the combustion chamber such as a chunk of carbon, a protruding head gasket, or a spark plug several heat ranges too hot. Exhaust valves are this hot too, but don’t stick out of the boundary layer.
    "The older I get, the faster I was......."

    1979 60C "Ohana" hull# 331

  8. #28

    Re: Curious about using NA pistons in a turbo.

    Quote Originally Posted by rsmith View Post
    O god not this discussion again. Everyone need a lesson on stoichiometric combustion again?
    Stoichiometric air/fuel ratio is a gas engine (otto cycle) deal. Gasoline engines have a throttle on the intake controlling the amount of combustion air entering. The fuel system (past: carburetor, today Fuel Injection) meters the proper amount of fuel for the air entering.

    Diesel engine has an open intake with no control on the volume of air entering. Power output is regulated by fuel injected into the cylinder.

    Under nearly all conditions, a diesel engine is "lean burn", with amount of excess air in exhaust changing greatly over power output loads.. Under nearly all conditions, a gasoline engine maintains the same air fuel ratio.


    Combustion in diesel engine is not an explosion, it is a controlled burn. Also, one of the major controllers of efficiency in any heat engine is compression ratio. Doesn't matter if it's diesel, gas, turbofan/turbojet, steam (rankine cycle), etc.

    Post #6 has the good juice: https://www.physicsforums.com/thread...r-fuel%20ratio.


    Quote Originally Posted by Captain Ralph View Post
    Would you care to expand on this error or delete it.
    What would you call that knocking sound coming from that diesel engine?
    Last edited by jim rosenthal; 08-08-2020 at 10:16 PM.
    FTFD... i drive a slow 1968 41c381

  9. #29

    Re: Curious about using NA pistons in a turbo.

    We know near exactly how much air is entering a diesel engine. We know (the engineers) the static air flow, the boost from blowers and air boost from turbo chargers pending RPM and anticipated expanding exhaust gases.
    This is why we control base compression ratios, blower drive ratios, blower by-pass and boost from turbo pending expanding gases.
    Then we hope to maintain a proper fuel injection thru these increasing air flows and increasing pressures under a flying and further compressing piston with different injectors doing all kinds of amazing things to droplets of fuel.

    Now, if you believe we can do that all so well,,,,,
    I have a toll bridge to sell you over some prime swamp land. Cheap,,,, trust me....

    Guys, like tuning a swim fin or propeller. Johnny vs Jimmy racing engines. There is NO exact science on a given day. On our boats, our luvs, where we want our money to last a lil longer, There are some given rules. Don't cross the factory spec is a good #1 for reliability.

    You want to stretch your DD block HP, Some of us can spend a lot of your money. You want a stock block that will last a long time, keep in factory spec, no mater the science or what Johnny says.














    BTW; Jimmy's engines are faster..

  10. #30

    Re: Curious about using NA pistons in a turbo.

    Quote Originally Posted by krush View Post
    Hey Captain, have you ever been in an engine room that you don't have to crawl on your knees to get around or been on a vessel that left sight of land?
    Why yes I have, AND worked on the equipment and machinery also.

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts