Preasure relief or not
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Preasure relief or not

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    Senior Member holorinhal's Avatar
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    Default Preasure relief or not

    So I have read every thread on plumbing and I guess I am still a little confused.
    Is a preasure relief valve necessary or not? I just want to keep things as simple as possible. I will be running two -10 overboard dumps from the tstat housing. so just wanted to know if it is necessary or not.

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    Senior Member skippers WFOT's Avatar
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    i added one for my own peice f mind, but a properly plumbed engine doesnt need one i was told. jet boat diagrams dont use one and almost all the original boats never hd it. its your chioce, $50 and an extra hour of plumbing gives a safety net
    Last edited by skippers WFOT; 08-20-2010 at 09:34 PM.
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  4. #3
    I'm No Expert Shaun's Avatar
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    It's always the same argument, and this is what I think!

    As far as i know boats never came with pressure regulators or reliefs and i think the reason for that is that boats usually came with low HP/stock engines. You can run one line in and two lines out and not have a pressure problem and thats probably fine for the guy whos going to go out and cruise all day. But when you start going out there and standing on the throttle it's more important for you to properly keep your engine cool. You want to have positive pressure in your system to help remove heat from the block as well as ensure that you have no air/steam pockets. at WOT i have my pressure regulator set so that i see 25 PSI of pressure. When cruising around at 3-4 K rpm i see around 10-15 PSI.

    In my opinion if you are going to go out there and run it hard get a regulator or releif so you can set your water pressure at what you think it needs to be at. I run one -8 line in, and one -8 line out. I do NOT restrict the exit, i have a regulator right after the pump.

    Again this is just my opinion, no hard facts, just something i came up with in my head.
    Last edited by Shaun; 08-20-2010 at 10:08 PM.

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    Senior Member GT Jets's Avatar
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    I don't run one, I simply use a high quality gate valve with an adjustable packing land nut to snug it down so it wont move (I also run a Zip-Tie through it) I think the only time I would use a pressure relief valve is if there are huge pressure/temperature swings between idle and WFO....

    On the race boat we used a closed system and never had any issues because the cooling water went straight through the heat exchanger....

    My current boat just has the gate valve to the oil cooler to the front of the block, out of the t-stat housing twice, one to a dump line and one to a header control valve....Never had an issue with pressure, water temperature or oil temp.....
    GT


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    Senior Member lbhsbz's Avatar
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    Look at the surface area of the smallest fitting on your "in" line and make sure that the surface area of the smallest fitting of your "out" line is bigger...you'll be fine. Most of the fittings use 1/2" pipe threads, so 2 dumps and one feed will be fine, or one 5/8" dump and a 3/8" feed with no valve will probably be OK. Remember, pressure is made by a restriction on a given volume...reduce the restriction, reduce the pressure.

  8. #6
    Senior Member GT Jets's Avatar
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    Quote Originally Posted by lbhsbz View Post
    Look at the surface area of the smallest fitting on your "in" line and make sure that the surface area of the smallest fitting of your "out" line is bigger...you'll be fine. Most of the fittings use 1/2" pipe threads, so 2 dumps and one feed will be fine, or one 5/8" dump and a 3/8" feed with no valve will probably be OK. Remember, pressure is made by a restriction on a given volume...reduce the restriction, reduce the pressure.

    If you have enough pressure being generated by the pump, the 3/8" line can overwhelm a 1/2" dump line just for some worthless information....

    An example would be if there was 60# of pressure at max water flow, the 1/2" dump would have to not only flow the entire rate of water, but be able to drop the pressure by 66% to end up with 20#. Maybe, but doubt it...

    An ultimate wear ring make life kinda fun too.

    A flow control device (regulator or Ace Hardware gate valve) would be needed IMHO Also the valve should be present in case chit happen, like a blown hose...Boats sink fast with a blown hose.


    Hi Pat!
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

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    Senior Member lbhsbz's Avatar
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    Quote Originally Posted by GT Jets View Post
    If you have enough pressure being generated by the pump, the 3/8" line can overwhelm a 1/2" dump line just for some worthless information....

    An example would be if there was 60# of pressure at max water flow, the 1/2" dump would have to not only flow the entire rate of water, but be able to drop the pressure by 66% to end up with 20#. Maybe, but doubt it...

    An ultimate wear ring make life kinda fun too.

    A flow control device (regulator or Ace Hardware gate valve) would be needed IMHO Also the valve should be present in case chit happen, like a blown hose...Boats sink fast with a blown hose.


    Hi Pat!
    How does an ultimate ring make it any more fun than normal?

  10. #8
    Senior Member GT Jets's Avatar
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    Quote Originally Posted by lbhsbz View Post
    How does an ultimate ring make it any more fun than normal?
    The tighter tolerances can and sometimes do generate a bit more backside impeller pressure at WOT putting more pressure to the cooling line. A loose pump makes way less backside pressure. I have had to restrict the port on an ultimate wear ring deal in our small block pump (ran over 6500 RPM) because the pressure was ludicrous, never did totally figure that one out.
    GT


    Quote Originally Posted by Quickjet View Post
    Put a 300 on the back of it, Flywheel it and a nosecone. $15,000 later you'll have a 65 mph pile of shit......

  11. #9
    Senior Member lbhsbz's Avatar
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    Quote Originally Posted by GT Jets View Post
    The tighter tolerances can and sometimes do generate a bit more backside impeller pressure at WOT putting more pressure to the cooling line. A loose pump makes way less backside pressure. I have had to restrict the port on an ultimate wear ring deal in our small block pump (ran over 6500 RPM) because the pressure was ludicrous, never did totally figure that one out.
    What tigher tolerances? I run (ran...lol) my UWR at .025 radial and .015" against the shoulder just like Duane recomends. If I'm not mistaken, these are the same specs that Berk and A/T publish.

    .....and WTF kind a small block was turning WTF kind of impeller to 6500? My bucket is no slouch, and I can't turn my A/B past about 6100 with my little big block.

  12. #10
    "Mad" Member Jet Mad's Avatar
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    IMHO it depends on a couple of factors.

    If you run an oil cooler for example it already bleeds off some of the pressure that goes to the block.

    If you run logs and the water is preheated in the logs before entering the block you shouldn't have a problem as well.

    I found that some setups in the old days ran a water pump and a thermostat housing that bled most of the pressure back to the water pump as explained below.

    I have had a 753 Hamilton Jet unit (3 stage) make so much pressure it actually lifted the heads(Holden 308). It has 3/4 inch feeds from the pump.

    I run a pressure relief valve with a good quality gate valve, 1/2 inch stainless hard line between the pump and gate valve and a by-pass thermostat kit and a 2" oil cooler on my Olds, and see 15Psi in the block. All fittings and pipes after the gate valve and pressure relief valve are stainless steel braided hose, with hydraulic crimped fittings, no pipe clamps. The Banderlog electronic header valve also feeds of the main line going to the oil cooler.

    Below is a explanation from a Packajet 455 manual on setups used in the 70's.

    Wikus

    COOLING SYSTEM

    This system is a thermostatically
    controlled make-up type circulating system
    (Figure 3). Water is continuously circulated throughout
    the engine by a low pressure, high capacity
    automotive pump. An excess flow of cool water
    under minimal pressure is always available to the
    system from the Jet-Drive. The pressure-balanced
    thermostat opens as the engine reaches operating
    temperature and hot water leaves the system, allowing
    cool water to replace it. The volume of hot
    water which is replaced by cool water is controlled
    by the amount of thermostat opening. Thus a constant
    operating temperature is maintained under
    any condition, whether idling for long periods of
    time or running wide open.

    In addition to the volume control provided by the
    thermostat, di rectional control of inlet and outlet
    water is afforded by the water manifold which sits
    atop the thermostat housing. The water ma"ifold
    initially directs most of the supply water to the
    circulating pump for filling the engine's water passages
    and it diverts excess water directly to the
    exhaust manifolds and high rise elbows (risers),
    which are cooled in a single pass. (Water enters
    at the front of the exhaust manifolds and passes
    once through the manifolds and risers.) From this
    point the water enters the exhaust stream and
    exits the boat. Since some cool water is always
    supplied to the exhaust manifolds and risers, they
    will always run cool.

    Also, no pressure build-up
    from the supply pump (Jet-Drive) occurs in the
    water manifold, because the hoses, exhaust manifolds
    and risers have adequate size water passages.
    Water which does not exit the engine
    through the thermostat is recirculated to the engine's
    water pump with no restriction to flow offered
    by the thermostat, which is in parallel with
    the path of recirculating flow. This water then
    mixes in the water pump with the cool incoming
    water added to the system and its temperature is
    reduced before re-entering the engine. Since the
    primary direction of flow within the water manifold
    is to the circulating pump, a continuous resupply
    (or make-up) of cooling water is always
    assured.


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  13. #11
    Senior Member moneysucker's Avatar
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    I use a simple gate valve on the inlet line. I did have to adjust it to semi closed position when running to build enough heat in the motor when running. I run 2 dump lines on my Blower motor and have never had any issues. My family cruiser had TT exaust and NO inlet valve at all and just free flowed through the motor. It worked and never milked the oil but that has since changed. I believe having the water preheated by the exaust helped make it work semi OK.

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    Super Moderator HammerDown's Avatar
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    Not in my set-up...one line into the block > two lines/dumps out = perfect pressure

    Thanks to LV JetBoy for the discovery
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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    Senior Member holorinhal's Avatar
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    My pump is set back to where I cannot run a hard pipe straight to the gate valve. Is is neccessary to have hard line.
    My plan was to run -10 braided line from pump to thru transom plate bulkhead fitting, then -10 from bukhead fitting to gate valve, then a "T". from one side of "T", a -8 up to header control valve. From the other end of"T", -10 to oil cooler, from cooler -10 to "T". From "T" two -8 lines to block water inlets. From T-stat housing, two -10 dump lines to overboard dumps.
    I would like to harline from the bulkhead fiting to the gate valve, but I am worried about the weight of the pipe and valve leveraged out from the bulkhead fitting and all the bouncing around that a boat does. is this not something that I should worry about?
    Does any one have any pics of how they plumed from pump to gate valve when the pump is setback with hand hole out side of transom....Hal
    Last edited by holorinhal; 08-21-2010 at 01:30 PM.

    I'm not here for a long time, I'm just here for a good time!
    If your not on the edge.......your taking up too much room......Drive it like you stole it!

    73 KONA Restoration http://www.performanceboats.com//showthread.php?t=10678
    '81 Spectra 20 Facelift http://www.performanceboats.com/user...-facelift.html

    18' Advantage http://www.performanceboats.com/jet-...k-project.html

  16. #14
    Super Moderator HammerDown's Avatar
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    Quote Originally Posted by holorinhal View Post
    My pump is set back to where I cannot run a hard pipe straight to the gate valve. Is is neccessary to have hard line.
    ...
    I did my own set-back and did run a hard stainless nipple right through the transom plate I also custom made.
    I would think a through-hull fitting is a good option > nothing wrong with it and easy to take apart if needed.
    I just opted for the hard line look.
    <img src=http://www.performanceboats.com/gallery/data/500/medium/06-30-11_1234.jpg border=0 alt= />

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