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 1 of 2 1 2 LastLast
Results 1 to 10 of 11
  1. #1

    Boost Measurement

    I'm trying to get measurements on turbos and/or blowers. The engines are DD 12-71 TAB, which I'm told means "turbo, aftercooler, and bypass." The BoatDiesel guys said I can't get a reading from the individual turbos and that I should hook into the airbox after the blowers and coolers. The picture shows the suggested place - I get 0.00 psi there, and everywhere else I connect a gauge.

    Even if that were to work, it wouldn't tell me anything about the individual turbos.

    Any ideas - anyone?

    Boost Connection.jpg
    Summer Star II
    1986 Christensen 70'
    Ensenada, MX

  2. #2

    Re: Boost Measurement

    The engines need to be loaded for the turbos to produce pressure. RPM by itself won't do anything.
    --- The poster formerly known as Scrod ---

    I want to live in Theory, everything works there.

    1970 36C375

  3. #3

    Re: Boost Measurement

    I think you would need two boost gauges per engine. You might want to look at Turbocators, which also measure EGT- another useful piece of information on turbocharged marine diesels. And he's exactly right (he deals with this stuff all the time); you won't see any rise in boost pressure or EGT until the engines are operating under load.

  4. Re: Boost Measurement

    You would have to pick up the pressure somewhere between the turbos and the blowers. Once past the blowers, the airbox pressure is common to both sources. A said above, the engines will have to be fully loaded to generate any boost pressure..

  5. #5

    Re: Boost Measurement

    You def shouldn't get zero there, but that's the airbox drain right? Want to make sure that stays open.
    SOUTHPAWS
    1986 52C Hull #391 8v92TA
    PENSACOLA, FL

  6. #6

    Re: Boost Measurement

    Quote Originally Posted by rustybucket View Post
    You def shouldn't get zero there, but that's the airbox drain right? Want to make sure that stays open.
    I think he's going to put the gauge before the check valve. That shouldn't hurt anything but, as stated, I don't think its going to give him what he's looking for as its after the blower.
    Sky Cheney
    1985 53EDMY, Hull #CN759, "Rebecca"
    ELYC on White Lake--Montague, MI

  7. #7

    Re: Boost Measurement

    Quote Originally Posted by SKYCHENEY View Post
    I think he's going to put the gauge before the check valve. That shouldn't hurt anything but, as stated, I don't think its going to give him what he's looking for as its after the blower.
    Agreed. I have threaded (plugged) ports on my charge air pipes going into the blower. Measuring air pressure there is the only place I know of that can give meaningful information.
    Semper Siesta
    Robert Clarkson
    ASLAN, 1983 55C #343
    Charleston, SC

  8. Re: Boost Measurement

    I don't see how the information gathered could be of any practical use other than to let you know that a turbo is shot. The 71 series doesn't know nor care that there are two turbos supplying the charge air. It does matter on the 12 and 16 cylinder 92 series engines since these are comprised of two separate engines bolted together and sharing a common crankshaft. The only exception is the 24V-71, which one would want to stay far far away from.

  9. #9

    Re: Boost Measurement

    Quote Originally Posted by kelpy View Post
    I don't see how the information gathered could be of any practical use other than to let you know that a turbo is shot.
    I think that's kinda the goal. Just something to alert you that something may not be right with one side. I don't think you get any practical info there other than a delta being a sign that something is not right.
    SOUTHPAWS
    1986 52C Hull #391 8v92TA
    PENSACOLA, FL

  10. #10

    Re: Boost Measurement

    Lot's of good info here, thanks. Now I have to wrap my head around all of it.

    Pressure v. load/RPM. The way I see the design, the turbo is a passive device with no waste gate or anything else to keep from transmitting the exhaust to the turbine blades and then to the compressor. It seems that even without load, there would be a lot of exhaust at high RPMs. So I guess what Avenger is saying that with additional load at a given RPM, more fuel is burned, more exhaust pressure is created and that's enough to make for significantly more boost pressure.

    Jim - yes two senders per engine, if the measurement is taken between turbo and blower. I have converted everything to digital, so I just have to add some virtual dials to the screens. I have already added EGT to the menu after wrestling with Garmin on the NMEA 2000 protocols - it's like pulling teeth these days with their tech support.

    Kelpy, Rusty, Sky - yep, that is the air box drain just above the check valve, and I agree that it won't tell me much more than the engines are running, although I just need to take out my earplugs to confirm that info. And as to the purpose, more info is better than less. This will give me baseline data (although it would be nice to have it 30 years ago) to know if things are going south(er).

    AND... Robert, is this the spot you are thinking to put the sender, on top of the blower, like in the photo below? I promise, maybe, to get to the paint job as soon as I can.

    SuperCharger.jpg
    Summer Star II
    1986 Christensen 70'
    Ensenada, MX

Posting Permissions

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