combustion temperatures
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combustion temperatures

  1. #1
    Senior Member ICDEDPPL's Avatar
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    Default combustion temperatures

    What can be done to keep them down?
    Heads have signs of heat, oil is cooking under piston.
    1550 * EGTs from 5500-6000.
    Iron Eagle 345, no intercooler, 8psi, 900hp. 150* intake temp. low 12AFR cruising. Low 11`s @WOT
    13,000# heavy boat .

    I thought about giving it more fuel. ( Northstar engine after 20 seconds of WOT goes to 10.0 AFR to cool piston)
    Water injection.
    Intercooler?




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  3. #2
    Some guy obnoxious001's Avatar
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    What's your ignition timing set at?
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  4. #3
    steelcomp was here
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    Are you running piston oilers?
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.
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  6. #4
    Senior Member ICDEDPPL's Avatar
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    Ignition timing is based on MAP input. Basically 30* at 4000.. progressive to 35* 6000.
    Scott I thought about piston oilers, both motor are at machine shop now waiting their turn so this would be the time however with the spring oilers eating up volume and pressure I`m not sure dry sump could supply enough oil to feed both. Schumann pumps are already bought.
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  7. #5
    Some guy obnoxious001's Avatar
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    Quote Originally Posted by ICDEDPPL View Post
    Ignition timing is based on MAP input. Basically 30* at 4000.. progressive to 35* 6000.
    Scott I thought about piston oilers, both motor are at machine shop now waiting their turn so this would be the time however with the spring oilers eating up volume and pressure I`m not sure dry sump could supply enough oil to feed both. Schumann pumps are already bought.
    So you don't think that 35 degrees of timing is making your heat with 8psi and no intercooler and a 13,000 lb boat?
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  8. #6
    Senior Member ICDEDPPL's Avatar
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    Not sure what you mean. I have large chambers (134cc) It likes 35*
    The more timing I give it the lower the EGTs ( I understand etgs and combustion temps isn`t the same)
    You saying too much timing , boost and no intercooler is the issue?

    I`d agree with that. I`m trying to figure out how to lower it in it`s current state.
    water injection, lower the boost , intercooler..????
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    Senior Member wagspe208's Avatar
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    Coat the top of the pistons.
    Problem solved.
    Wags
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  10. #8
    Highaboosta Unchained's Avatar
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    I would be more concerned about the intake air temps than the EGT's on gas.

    I never found any useful tuning information from using EGT's because EGT's are highest at stoich.
    To pull a number out of the air and say that's high is a guess.
    My setup runs 1550 EGT at a part throttle cruising speed under vacuum. Doesn't hurt a thing.
    It burns clean and the plugs last for years.

    Twin Turbo 1800 HP V-Drive lake boat

    http://s621.photobucket.com/albums/t...t=MAH05771.mp4

    Quote Originally Posted by Trigger View Post
    No one cares about your buddies old antiquated garden hose technology.
    Quote Originally Posted by MAXIMUS View Post
    I think I could run more boost but it's a real hand full right now
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  11. #9
    Senior Member ICDEDPPL's Avatar
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    hard to find much info about piston oilers, anyone have experience about how much pressure they eat?
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  12. #10
    Senior Member wagspe208's Avatar
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    I have experience. We built a turbo piece for Washington University Engineering students back in the early 90's. (maybe 89 or 90) Drilled oilers.
    Let me ask you a question. What is your concern? Discoloration? Oil temps?
    Way back in the day.... the discoloration was a sign of cylinder temps. IF you weren't cooking oil, you weren't making much power.
    Fast forward 30 years..
    Again, what is the concern..... or goal?
    That is normal blown gas stuff.
    Wags
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  13. #11
    steelcomp was here
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    Quote Originally Posted by ICDEDPPL View Post
    hard to find much info about piston oilers, anyone have experience about how much pressure they eat?
    I've run piston oilers and T&D rockers with spring oilers and not seen any oil pressure issues with a wet sump and Melling M77HV pump.
    What Wags said...
    If God is your co-pilot, change seats!
    Acts 2:38, the perfect answer to the perfect question.
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  14. #12
    Senior Member ICDEDPPL's Avatar
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    Wags, it boils down to reliability.
    Bought this boat 3 years ago and it has been nothing but issues, from both drives being shot to the leaking headers and fuel tanks and beyond.

    The motors were fresh at that time but had many leaks, used oil, lots of blow by, wrong plugs, terrible valvetrain set up etc...
    I`ve been making things right and now I`m down to the last piece that I haven`t touched. The short blocks.

    This is a pleasure boat and I`d like to get a few seasons out of it without having to spend most of my day in the bilge or missing weekends in a very short season. I`d like to do everything possible to keep detonation/heat down and be able to run if I want to.
    Running it at WOT for a few miles without issues would be fantastic!

    I`ve got 4 motors in my garage , mine and a friends. His pistons after 100 hours look brand new on the bottom.
    His is a lighter boat by 3000lbs and his 468s make a 800hp. No intercooler 6psi Dart 308`s.

    Maybe I need to get a set of intercoolers but this thing has me drained at the current time $$$ (gas tanks, interior, exhaust last year, 2 rebuilds, bottom work etc this year)
    So I`d like to spend my money wisely and get the best bang for my buck cause everything I do is times 2.

    Maybe the burned oil is not an issue...





    It`s for the children!


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  15. #13
    Senior Member wagspe208's Avatar
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    IMO... you are worrying about a total NON issue.
    IF the oil cooking bothers you, spraying oil on the bottom of the piston may help a little. You still have the heat in the piston.

    HOWEVER, coating the piston tops will stop the heat transfer into the piston, this will stop oil cooking on bottom.
    AND, you are not reinventing the wheel.

    Spraying oil is way less common... PLUS, at 5000 rpm do you really think that oil is going where it is aimed, or just making more windage??

    Wags
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  16. #14
    Senior Member ICDEDPPL's Avatar
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    Running extended times at max TQ and load is an issue to me. Heat soak and high temps are an issue in an endurance engine. At 3500 I`m already pushing 4psi. Load is high.
    Piston oilers have been proven to work, many manufacturers use them today as do almost all modern Diesels.
    Coatings reflect more heat in the chamber and don`t allow it to be transferred to the cooling system doing the exact opposite to what I`m trying to prevent.

    Seems like you guys have a little clique here.. Guess I should get a lake boat and maybe then I`ll get some replies.
    Thanx for the input, I`ll see my self out.


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