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Thread: one engine running hot

  1. #1
    Looking for advice and possible solutions to plumbing raw water
    in twin engine setup.
    One engine under heavy throttle will creep past 180 degrees with oil temp
    at 230 degrees. Water pressure pins gaffrig gauge 35 lbs plus.
    Other engine runs 110 water. Oil is at 210. Water presure is 25 lbs max.
    It seems to operate like this now with the addition of the superchargers.
    The engine will run approx 130 to 150 normal cruising (3000 rpm)
    When your on the sticks at over 4500-5000 rpm then she well creep up.
    Have not had opertunity to hold at 5000 for exstended time Due to water conditions and speed over 100. But I feel it will get hot. This is only happenning on one engine.
    The water flow is: thru hull pickup to strainer to merc raw water pump
    to power steering cooler to trans cooler to oil cooler then to front of
    crossover then thru front of Mooneyham intake then to each header
    then dumped thru 1 inch transom
    The water temp is being measured at one of the manifold dumps before entering header. Water pressure is measured back of head.
    All new water pumps. Back flush entier system. When idling looks like there
    is same amount of water coming out of dumps compared to other motor.
    I am thinking of adding some dumps to the back of the heads possibly
    3/8 id then out the transome. My thought is it will aid in releaving water
    pressure and at the same time allow more flow. What do you guys think???
    I am considering this rather then the merc dumps at the crossover this would limit the flow to the engine.
    I have played with the amount of the thru hull lenth by moving it in further
    thus not sticking out as far. This helps pressure but not temp.
    540 bowties
    Merlin cast iron heads
    Cometic Head gaskets
    Crane 741
    Intercooler (plumb seperatly)
    8lbs boost
    Timing locked at 32
    Arneson surface drives
    Please respond with any Ideas or thoughts
    Thanks in advance

  2. #2
    I cannot edit my posts on OSO so:
    Plumb the intercooler then oil cooler from a pickup in the hull. Run it through a strainer and have a press relief valve. That system will not flow until you get on plane.
    Feed the trans cooler and engine from the water pump.
    That should help.

  3. #3
    the feeds on the Lee intercoolers are only 1/2 inch do you think thats enough
    to feed the oil coolers also. I get approx 6 lbs water pressure at intercooler at 100+. That is with the # 16 dumps.

  4. #4
    the feeds on the Lee intercoolers are only 1/2 inch do you think thats enough
    to feed the oil coolers also. I get approx 6 lbs water pressure at intercooler at 100+. That is with the # 16 dumps.
    1/2 NPT? That is good enough for a -10 line at least. Most run -10 or -12 at minimum for the inlet all the way out.
    I run -10 in the whole system inlet, strainer -8 relief valve and -10 to oil cooler and out the transom

  5. #5
    Its a Female 1/2 npt hole in the back (Near Distributer) there is a S/S 1/2
    to -10 double male 45 adapter threaded into it. This comes from the
    Strainer. The dump of the intercooler is 3/4 female with adapter going to -16 hose rite out the transom. This is where I could splice in and add the oil cooler. Your thinking the oil cooler is preheating the incomming water.
    Then I will also need to install a releif dump in the engine plumbing.
    The strange thing is why dosnt it happen on the port motor? I am thinking
    restriction because of the higher water pressure. I have failed to mention one thing I have made a repair to a leaking header by jumping the water over the collector. Meaning Dry collector. I did this with 4- 3/8 id stainless
    pipes. one for each pipe. I used the same size as the feeds located at the bottom of each header pipe. But flow is still incredible when running. It has been like this for three years before the addition of the superchargers.
    I know Im cheap I will break down and get a new set for next season.
    Ill try a test this Weekend Ill plumb the two discharge of the intake. With
    like 1/2 inch then in the middle of that Ill Tee to a 1/2 inch dump rite out the back This may reduce water pressure as well as Aid in more flow thru the engine. Ill post results.

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