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Wastegate valves on diesel engines

Discussion in 'Technical Discussion' started by CSkipR, Dec 9, 2015.

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  1. Capt J

    Capt J Senior Member

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    I think what you're expressing, just getting soot getting the boat on plane is somewhat normal if you're giving it throttle somewhat fast, what happens if you slowly bring the throttles up to cruise? If you're not exhibiting smoking at idle to slow speeds and no visible smoke at cruise, then your motors are probably fine and would leave them alone.
  2. Capt Ralph

    Capt Ralph Senior Member

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    I just had a thought; Are there screens or salt filters in the engine room vents?
    Next time you take a run, pull the air filters off the mains and run at speed with the ER hatch open.

    I remember a small boat repower where you could not open the hatch because of an engine created vacuum.
  3. CSkipR

    CSkipR Member

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    Capt J
    I always throttle up slowly. My 9 hr trip from PB to PI on Mon and Tues. the boat has soot all over the cockpit, transom, entrance to engine room, under flybridge, and cockpit bolsters.
    Just don't believe this should be normal. Talked to Man person today and he wants me to run wide open and get readings on turbo boost and egt to start there.
    Skip
  4. CSkipR

    CSkipR Member

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    RC,
    There are screens in the engine rooms. Removed and cleaned them 3 months ago. Are you saying take the K&N filters off the turbos and open engine room door and run boat. Never noticed a vacuum when I open door while we are running.
    Skip
  5. Capt J

    Capt J Senior Member

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    No need to do either, just look at your inlet air pressure readout and usually it should be under -5, if it's high like -7 or more, you have a restriction somewhere. But I don't think that's the case. But if you have a camera phone, take a picture of each screen when running WOT, easy to go back to. Was the bottom and propellors clean (I'd imagine so since the boat was out of the water getting painted.) Some soot is always going to be normal and might be more pronounced if you have a tail wind, or if you have the enclosure closed on the flybridge causing a station wagon effect (even though Cabo's don't usually exhibit this much). It might just be the way it is.
  6. CSkipR

    CSkipR Member

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    Capt J,
    As you suggested bottom and running gear were just cleaned and painted while boat was out. We were headed into the northwind all the way up from Palm Beach so no tail wind. The bridge enclosure goes across the front and down approx 5 ft on each side. No vents were open on the polycarbonate.
    There is definitely some station wagon effect as were getting salt spray up on flybridge so this would exacerbate the sooting issue too.
    Skip
  7. Capt J

    Capt J Senior Member

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    Everything leads me to believe that everything is normal. If you were getting a station wagon effect and had everything closed on the bridge, it probably made it soot up more. Do you normally have some airflow going through the bridge from the front? I honestly feel everythings normal, but aren't there. It's also possible that your shiny new paint job is showing the soot a lot more. But, it could be injectors or something like that.
  8. CSkipR

    CSkipR Member

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    Yes normally have at least one of the front windows open. It was pretty chilly on Monday so didn't have anything open.
  9. CSkipR

    CSkipR Member

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    Here's an update. Replaced all the K&N air filters and it definitely has improved the sooting issue. I cleaned them annually but I guess as Capt J said replace them after a few years. Even the overheating on the A side of port engine has been reduced.

    Now the Man mechanic has said that my engines (2005) were the first common rails built and that the boost pressure was set low until they could determine how the engines performed. These same engines the boost was increased to 32 and mine are 28 so he is going to increase them by adjusting the waste gates. No adjustment needed to ECM.

    My question is will this increase in boost help the boat get up on plane faster? Thats what I'm hoping for. Not really looking for additional speed although okay if it does at cruise. Will 4 psi boost make much difference in performance?
    Thanks,
    C Skip R
  10. Capt J

    Capt J Senior Member

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    Yes, increasing boost will increase acceleration from around 1400 rpms to WOT, should also make more HP. Now, you'll make more HP with more boost so you should turn more RPM's at WOT. If you cruise the boat via load factor than your cruise speed should be higher. If you cruise the boat at a certain RPM point, say 1900 rpm's than your speed at the same rpm's will be the same since you're turning the propellors the same speed as before at a given rpm (unless you add pitch). More boost will also create more heat in the cooling system, but if you're running normal operating temps it shouldn't create an issue.
  11. CSkipR

    CSkipR Member

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    Capt J that is a great explanation. Is this example correct? If load factor was 80 running at 1800rpm and 75 at 1950 then my new load factor at 1800rpm should be lower correct?
  12. Capt J

    Capt J Senior Member

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    technically yes, if you're making more power, everything else being equal, your load factor across the rpm range (while in boost) should drop. But given that you're showing 80% at 1800rpms, and 75% at 1950 rpms, 1950 rpms would be a better rpm to run your vessel at as the information tells me that the motor's working harder at 1800rpm.
  13. Capt Ralph

    Capt Ralph Senior Member

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    I didn't think any of these CRMs (since new product) ran over 30psi. I am eager to hear the results.
  14. Capt J

    Capt J Senior Member

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    I'll have to look at the set of MAN 1100's I run, next time I run it. I seem to remember they run between 26-28 psi boost at 80% load depending on what RPM 80% load is. In that boat rpms at 80% load vary 125 rpms between full fuel and 1/4 tank.....Full fuel is around 2080 rpms, light around 2200rpms, boat does achieve 2360rpms WOT at full weight. If they make 28lbs at cruise I'd bet they make 32 at WOT, seems to me they did at WOT but cannot be certain.
  15. CSkipR

    CSkipR Member

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    Update. Man mechanic checked the wastegates by blowing compressed air into them. He said that we should be able to hear the waste gates opening and closing. I could not hear anything but he said he could. He then adjusted (tightened) the waste gates screws to improve boost and we went for a run. Very minimal results. One motor got to 29. Decided to turn them back to where they were. Right now kind of back to ground zero and will leave alone for awhile and do some fishing.
  16. Capt Ralph

    Capt Ralph Senior Member

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    Next big question. Are you using the engine sensors or did he plug in a real pressure gauge on the motors?

    Next, can you determine if both engines are trashing your transom or just one?
  17. CSkipR

    CSkipR Member

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    RC,
    He did not plug in anything other than to inject compressed air into the wastegates to see if any of them were stuck.
  18. Capt J

    Capt J Senior Member

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    I'd run it at 1950 rpms or whatever where it's at 75% load versus 1850rpms and 80% load.