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Discussion Starter #1
I want to see how many people are running a relief valve set up off the pump instead of using just a gate valve

There are many Gasket fails using the old Gate valve set up I am wondering how many fails comparing the two set ups



Opinions???
 

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never ran a relief valve, no issues, its a good idea, IMO not a must, but keeps water pressure to YOUR liking, which also helps with temp control.
 

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No valve, no relief.


One valve where the water comes off the pump to shut it off in emergency. Make sure the exit hoses are double the intake and one size larger. (one hose feeding, two hoses dumping, 1/2 feeding, 5/8 exiting.


I dont like the idea of restricting flow to make heat. I also dont like the idea of adding more shit to complex the system.


Got moisture in the oil, RUN it HARDER.
 

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Used to over think things like some, now KISS is the new trick.

If the lines and overboard fittings are sized properly, none of the extras in my mind are necessary. Been doing this a loooooong time.

One over sized gate valve at the pump and a dump line sized for the engine HP.
 

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Im scared to "Build heat" in a jet engine that cooled with COLD lake water.


In a car at 180 coolant is circulated and STAYS at that temp. The engine is temp is pretty comparable to water temp.

In a boat where a guy has the valve cranked shut to provide a nice 160-180 WATER temp, I believe the ACTUAL engine temp us MUCH HIGHER. When I start my boat and its empty (of water), it takes about 20 seconds to fill the block and start pumping exit water out the back.


To take 60 degree lake water and put it in a heater that can heat it to 160 in 20 seconds, the heater element HAS to be WAY hotter than 160-180.

How HOT is your block when it can heat cold water to almost boiling in 20 seconds?
 

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Im scared to "Build heat" in a jet engine that cooled with COLD lake water.


In a car at 180 coolant is circulated and STAYS at that temp. The engine is temp is pretty comparable to water temp.

In a boat where a guy has the valve cranked shut to provide a nice 160-180 WATER temp, I believe the ACTUAL engine temp us MUCH HIGHER. When I start my boat and its empty (of water), it takes about 20 seconds to fill the block and start pumping exit water out the back.


To take 60 degree lake water and put it in a heater that can heat it to 160 in 20 seconds, the heater element HAS to be WAY hotter than 160-180.

How HOT is your block when it can heat cold water to almost boiling in 20 seconds?
While I would love to agree with you 100%, I can't...

I set mine and my customers boats up to run the idle temp around 150*F, the temperature will run much lower if everything is sized apropriately to keep the engine at, normally close to 120*-130*F at wide open throttle. I like the warm idle to help heat the oil up when cold. You get the best of both worlds and a better idle quality.

The water is somewhat restricted, but not much really...
 

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A stock application a relief valve or pressure regulator is not needed in my opinion, but on the higher HP levels say 700 and on up I think its a must. Also rpm plays a role in it as well. When your spinning the thing up past 6 k its pushing a pretty good amount of volume at a pretty good pressure.

I run both and set my bypass at 21psi to start dumping. It has plenty of temp in the engine and it wont pop out the freeze plugs or try to push out the head gaskets on a WFO burst.

To each there own, no extra plumbing really, just a dump from the relief valve.
 

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Im scared to "Build heat" in a jet engine that cooled with COLD lake water.


In a car at 180 coolant is circulated and STAYS at that temp. The engine is temp is pretty comparable to water temp.

In a boat where a guy has the valve cranked shut to provide a nice 160-180 WATER temp, I believe the ACTUAL engine temp us MUCH HIGHER. When I start my boat and its empty (of water), it takes about 20 seconds to fill the block and start pumping exit water out the back.


To take 60 degree lake water and put it in a heater that can heat it to 160 in 20 seconds, the heater element HAS to be WAY hotter than 160-180.

How HOT is your block when it can heat cold water to almost boiling in 20 seconds?
you are correct that in a total loss system of your boat engine that if the water is being heated to 160* in a matter of a few seconds the actual temp of the surface has to be much higher. I've never taken a temp gun to the river and tried it, but I guess I could.

lots of variables from one boat/one engine to another but I think the true temp of your engine is the oil temp.

running water temp at 160-180 in a boat at running cruise speed is high. they'll typically boil over at idle if you run them that high. water temp somewhere around 140 has seemed to work for me over the years.

think about an oil temp gauge so you can run it hard enough to keep water out of your oil. 210-225 at your extended cruise rpm ( where you typically run your boat)

S CP :wink2:
 

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I run a bypass and a full flow ball valve plus a ball valve at the pump to shut it all down if need be.
been doing this for a loooooong time on my bbf and bbc from 454 to 548 all under 6000rpm

motor runs 140-150 at idle and 130-140 at cruise speed

I also run a one way valve so the motor stays full of water when cut off.

as far as I know and by my pressure gauge I never get more than 10psi block pressure (WFO)
1/2 in and 2 5/8 out bypass set at 15psi
 

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Boss of the McIntyre Mob
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A stock application a relief valve or pressure regulator is not needed in my opinion, but on the higher HP levels say 700 and on up I think its a must. Also rpm plays a role in it as well. When your spinning the thing up past 6 k its pushing a pretty good amount of volume at a pretty good pressure.
I agree with this. Not so much the HP number but the RPM number (kinda goes hand in hand tho).

I spin 5600-5800. No bypass. Just ball valve. Large dump lines with jacketed headers. Never had an issue. Ran just a gate valve on my 18" SW, never had a problem.
 

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I have a pressure relief valve...but my boat also has a closed cooling system.
 

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I agree with this. Not so much the HP number but the RPM number (kinda goes hand in hand tho).

I spin 5600-5800. No bypass. Just ball valve. Large dump lines with jacketed headers. Never had an issue. Ran just a gate valve on my 18" SW, never had a problem.
I would take to Bobby Fry about that one. :shock:
 

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Boss of the McIntyre Mob
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I would take to Bobby Fry about that one. :shock:
Bob spins a little higher than 5800 RPM (and a LOT more than 700 hp). I would say 6k RPM or higher def have a pressure dump.
 

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No valve, no relief.


One valve where the water comes off the pump to shut it off in emergency. Make sure the exit hoses are double the intake and one size larger. (one hose feeding, two hoses dumping, 1/2 feeding, 5/8 exiting.


I dont like the idea of restricting flow to make heat. I also dont like the idea of adding more shit to complex the system.


Got moisture in the oil, RUN it HARDER.
X2 :))THumbsUp :thumb:
 

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I have a pressure relief valve...but my boat also has a closed cooling system.
you're running a water/water heat exchanger ?

got pictures ?
 

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Question: If I put a pressure regulator on the jetpump's water take-off (from pump to engine) is there any risk of damage to the jetpump from pressure building up between the regulator and the pump? Is there anything in the pump that will be damaged by regulating the water take-off to ~15 psi or so (the relief pressure of my pickup truck's radiator cap I noticed today)?

I have a Rex Maine thermostat kit on my engine with a 180 degree thermostat in it. It's my observation that the water does not siphon out of my engine when shut-off, the block remains full of hot water right to the thermostat housing.

Anyways, at anything above ~4.5K rpm's the water pressure gauge on my 454 BBC pegs at 30psi, and I don't particularly like that! I have Basset OTT headers and it's a challenge to get water to flow to those things without a gate valve on the hot water dump to create at least a little back pressure at low rpm's, but at high rpm's the pressure gets to be too much so... wondering if a pressure regulator should be in my future? Why or why not?

ps. I've had this boat with this setup since 1989, I run it gently rarely exceeding ~45mph (pulling water skiers and tubes and I love to kneeboard behind it with a 100 ft long ski rope!). Never any engine or pump problems to speak of, it's been very reliable but I've never been satisfied with the water pressure in the block I'm always fiddling with the gate valves it seems trying to balance block pressure vs these Basset pipes need for cooling water flow... there's gotta be a better solution!

- Michael
 

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"Relief valve, I don't need no stinking relief valve > one line in two dumps out the back > Rex Bypass T-stat set-up = 5-10 lbs of water pressure in the block. Plenty to keep a solid stream of water exiting (no hot steam spots in the heads) yet gentile enough pressure to never even think about blowing a head gasket.
 
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